Understand Your All-Wheel-Drive System | Know it All with Jason Cammisa | Ep. 04
Вставка
- Опубліковано 15 жов 2024
- All AWD systems will help with additional traction, but the layouts have dramatic effects on handling. Most AWD systems induce understeer, but some can actually help a car handle even better.
Marketing departments often fib about the capabilities of their company's AWD system. In most cases, no, your car can't send all of its power to just one axle - unless the other axle is in the air. Manufacturers often leave that little detail out.
To understand what your car's AWD system can and can't do, you need to understand its base layout - if it's a FWD-based car, like a VW Golf R, that happens to have AWD, it can never decouple its front wheels - only add power to the back. It can send 100% of its power to the front wheels, but never more than half to the rears.
If it's a RWD car like a BMW 3-Series, it can never decouple the rear wheels, only send some power to the fronts. It can send 100% to the rear, just not to the front.
Then, there are fixed-AWD systems like Subaru's "Symmetrical" AWD. That system sends power to all four wheels - but can only send it all to one axle if the other is, you guessed it, in the air.
---
Subscribe to our UA-cam channel for new videos every day! bit.ly/HagertyY...
Visit our website for daily automotive news, cars stories, reviews, and opinion: www.hagerty.co...
Stay up to date by signing up for our email newsletters here: www.hagerty.co...
Follow us on social media:
Facebook | / hagerty
Instagram | / hagerty
Twitter | / hagerty
If you love cars, you belong with us. Hagerty Drivers Club is the world’s largest community for automotive enthusiasts. Members enjoy valuable automotive discounts, exclusive events and experiences, roadside service created specifically for collector vehicles, and a subscription to the bimonthly Hagerty Drivers Club magazine. Join Hagerty Drivers Club here: www.hagerty.co...
Like what you see? Watch our other series including:
Redline Rebuild | Engine Time-lapse videos from start to finish bit.ly/RedlineR...
Barn Find Hunter | Tom Cotter searches the country for abandoned cars bit.ly/BarnFInd...
Chip Foose Draws a Car | Reimagining popular cars with new designs bit.ly/HagertyC...
Contact us:
Suggest and feedback - tips@hagerty.com
Press inquiries - press@hagerty.com
Partnership requests - partnerships@hagerty.com
![The Porsche Carrera GT is fine. Until it’s not. - Spotlight feat. Jason Cammisa - Ep. 7 [UHD 4K]](http://i.ytimg.com/vi/uf3SDCFRDe4/mqdefault.jpg)
I joined this channel just for Jason
Same.
Same
Same
Same
Yes me too that's my name too😝
Jason, you need a part 2. There’s so many other variants of AWD systems that I’d like you to complain about. 😀
^this
Can you also talk about putting a slightly larger tire on a regular AWD car to get the 1.05 turns in the rear? LOL Killer video...but we need the difference between 4WD and AWD explained as well. Thumbs up...
YEAH.. WHAT ABOUT 4MATIC ?
@@adnanjusic4890 I'd think that 4MATIC is pretty the same principle as BMW's xDrive, or is it not?
@@HimTortons Dont know, maybe. Why Jason did'nt mention it..
This channel better keep Cammisa or we will all just drift over onto whatever channel will pay him enough to stay. One of the best car guys on YT and other channels have messed up not keeping him.
is he still?
As an owner of a 2018 Subaru Forester XT I'm surprised to see that you didn't mention Subaru's symmetrical AWD.
He did mention Audi's system, which is basically identical (they're both Torsen systems). I say this as someone who went from a WRX to an A4, aside from the A4 having an open rear diff vs the WRX's LSD, both behaved mearly identical.
@@S50Sinner my understanding was that the TORSEN Audi's of the 80's are all but gone now, replaced by versions more like the Haldex system. "Quattro" used to mean "symmetrical AWD", but no longer.
@@jbrovage Torsen is still present on all S ans RS models (excluding the TT and type 3) and was on the base models as well until 2015 when a Haldex-like system was introduced for certain A models. Needless to say, the A3 and TT have been Haldex all along.
@@jbrovage I have a rare AWD system in my rig and would like to have Jason give it the rundown. Apparently in 1999 Chevy had some sort of agreement with Subaru... LSS - My 1999 Suburban has 3 modes for the drivetrain - "2WD" (Rear only), "Auto 4WD" (employs some Subaru derivative for when wheel spin in detected, it will engage the front) and then "4WD" where it locks it all in, lets me drive in 3ft of snow but only in a straight line.
I am also intrigued, seems Subaru has like 4 different AWD systems right now, based on clutch packs and viscous diffs, wonder if that makes a difference in handling. For example I own a 6MT Crosstrek, dont know if it is Torsen or what kind, but it works amazing on dry surfaces but doesnt give me optimal traction on wet, slippery ones when I try to drive fast.
So where does the Subaru system fall? Asking for all the Subaru vapey bois. Thanks
I like how there’s an entire video on AWD Systems, and they don’t mention Subaru even once.
Subaru doesn’t exist in Jason’s world. Subawho?
The head gaskets fail so often you forget about the awd nonsense. Zing!
I agree, I wanted an explanation for my STI
Subaru vehicles equipped with manual transmissions use a viscous limited slip center differential (VCD) AWD system
How is there an entire video about AWD and not a single mention of Subaru??
Maybe because subaru awd is garbage or maybe because he felt it was irrelevant or maybe he is not a subaru fan ????
Let him reply ... oh wait he won't, he has more important things to do than to respond to questions and complaints by the viewers
@@ACommenterOnUA-cam Subaru arguably has more all-wheel-drive cars on the road than any other single manufacturer. So it’s only logical that A video solely about all wheel drive would include Subaru. To your second point, he responds to lots of comments.
@@ColtCapperrune does not matter if your logic is truth or false. Its their video, their choice to use what content they want.
And i have yet to see any replies from him.
Salty much? Did an STI cambered out vapey boi steal your gf??!
@@ACommenterOnUA-cam Calm down kid, Jesus.
This guy is, arguably, the best automotive journalist I have seen in a very long time! Bravo Jason
I just wanted to say I love you, Jason. There's just no two like you. Period.
too short, need more Cammisa this week...
Search "Camisa" in Portuguese and I hope you'll find your sentence funny like I found
I've owned several AWD. All power to the front and AWD when required (No driver input) Great system but knowing it's limit is the key. I also owned 4WD (Standard and automatics - locking front hubs and full time hubs) Again, great results but knowing their limits is the key ! The different types of transfer cases is another key point (chain vs geared etc. etc. etc.) The combinations are endless. Over the years I've found that Jeep has one of the better systems (with locking differentials) BUT, knowing it's limits is always the key.
Great video !
I got murdered on the golf R subreddit a few weeks ago for dropping this knowledge. lmao
As I was about to comment... my MK7.5 R (2019) would rotate under power in snow forsure, wet most of the time, and dry sometimes. It had to do with tire choice and setting in the computer. On snow tires, it would rotate easily in snow by stabbing the gas, flicking in, letting off and stabbing again to hold the drift. Wet wasn't too hard and It took more work but also would in dry.
On summer tires it understeered heavily following this practice, likely because the rear didn't have enough power to overcome the traction in the front. Oddly enough, it would only power on drift in Normal drivetrain and Suspension mode in the dash. Race mode again made it understeer, sometimes even in snow.... and I think this is because the car was then programmed in Race mode for throttle lift oversteer like a FWD car.
Likewise, my quickest times 1/4 & 0-60 were in Custom mode. Suspension hard for less weight transfer, drivetrain in Normal, Steering in comfort. In Race mode setting it would smoke the front tires until the rear diff kicked in and it was abrupt making a whirr as it did it. In Normal it would squat and rocket like you'd expect. Possibly because Normal is locking the coupler sooner, expecting snow? That was my thought. It also wasn't stock power with the 7speed DSG.
If you're not familiar these settings I talk of, they are pre programmed and selectable. Comfort, Normal, Race and Custom. I liked the car, just had to know how to modify the Suspension and Drivetrain settings for your driving.
@@tanktheram You're describing the Scandinavian flick (basically what was being described in the audi section), which is by definition not rotation under power. You are using the change in weight distribution in the car caused by letting off the gas to rotate the car, but that's not rotation under power. That's what you have to do to get a golf to rotate. There's nothing wrong with that, it just has different handling characteristics (which IMO are much safer for most kinds of street driving), but it does not rotate under power.
@@pandapv while I completely understand that, having been taught and raced under SCCA sanctioning.... plus the memes on the net alone could have taught me that 5 years ago.
However once into the slide, the car allowed me to continue the slide with heavy throttle application... meaning he wasn't 100% right. The Golf R would "power on drift" sometimes even without the flick but took LOTS of prodding.
What you missed in my extended comment was the fact that depending on drivetrain mode - it would lock the rear sooner or more aggressively for longer.
@@tanktheramAs Jason said, just own it
depends, I've seen golf R's with programmed Haldex and they do AWD all the time, it can be done safely too, know a guy in town that had a 800hp Golf R with an 07k and had no issues for over 60k miles. That thing wasn't just a straight line monster. It genuinely whooped on track, it turned fast and kept up with a Lamborghini Huracán Performante like it was a video game, I'm not even a good driver and I was able to keep up in the turns and the straight. Full interior no weight reduction.
Good video, so many people that don't understand the difference!
One thing though, the SQ5 still has a torsen differential with permanent 4WD and a base 40/60 split, not FWD as stated. The regular Q5 though, and most other quattro models, are unfortunately stuck with the lame FWD so called "quattro ultra" nowadays.
Also the 3.0 TDI has torsen in the Q5 the quattro ultra has 500 nm of torque limit
Generally speaking for Audi: Transverse=Haldex, Longitudinal=Torsen.
@@jonathanpeterson1 true ! So as long as you're dealing with a "big engine" Audi you're not doing so bad ! ;-)
I was going to say this as I own an SQ5, but you said it well and politely. And I will tell anyone who will read it, this SQ5 is so amazing in bad weather, I have never driven anything as good in ice, snow, rain, mud, up hills, down hills... it's good.
@@jonathanpeterson1 no, Quattro Ultra is longitudinal setup with permanent fwd and rear wheels controlled via 2 clutch packs (not Haldex)
The SH-AWD in my Acura TL is surprisingly good. Flooring it around a corner is a blast, it sends power to the outside rear wheel making the car rotate better.
Not only that it can overrotated the outside wheel. Spinning it faster than it would normally. I have it on my 11’ RDX and it's a blast in the canyons.
Yea. I'm a Audi Quattro guy but that TL is one Asian car I'd own. Nice car.
@@teedot1186 Same! That's why i picked it. It's been a blast to drive. ESP around San Francisco lol
I love those!!!
That’s torque vectoring- very nice. My highlander does that too.
Your videos are like main-lining an automotive engineering degree. Thank you for them, I am learning so much!
Great video; I learned a lot. Thank you. I love all wheel drive high performance cars. I once had an accident in Austria in my 1997 German-spec BMW 325 ix that ripped off both rear wheels and sent me down an adjacent ski slope. After calling a tow truck that could not get onto the ski slope, I literally drove the BMW down the hill with ONLY the front wheels pulling. So in this case, there was NO power going to the rear wheels because they were literally gone. Yeah, what was left of the rear axles was spinning a bit. But it worked, and drew quite a crowd of skiers who had never seen an all-wheel drive BMW and were stunned to see the front wheels spinning in the snow.
One note about clutch packs: Now I drive a BMW X3M Competition and while I love the AWD, I do notice that at crawling speed up a super-steep hill while turning sharply on pavement, there is a bit of "binding" between the front and rear wheels. The computer is probably going crazy trying to manage the clutch packs.
That is typically what happens when the wheels are locked together too tightly for the turn. I would assume it is made like that for low speed crawling for maximum traction. I'm actually impressed it does that
Outstanding! In 25 years of being a car enthusiast, a past owner of a golf r, Audi quattros, and now Bmw 3 / m3’s, this explains so much. The golf r was brilliant but I hated how hard it was to engage the rear wheels. Another brilliant discussion by Jason!
I solved the same problem with my RS3. Get a Haldex controller (you can set 50:50) and have a 2.5 d negative camber for the front wheels.
I have become addicted to Hagerty and Jason! I wish I had close friends like this with so much knowledge and passion to cars.
As a 2013 Volvo r-Design driver (Haldex 5), there is a trick to a solid power slides... over inflate the rear tires, drive way too fast into a corner, give it a confident flick on entry, and shove your accelerator through the firewall. It wont hold it as long as a M3 or Mustang, but it's enough to enjoy. In the wet or on loose surface roads, you can outdrive surprisingly quick cars.
Hagerty keeps forgetting to add their videos to playlists. The Know It All Playlist only has the first 2 episodes in it.
Yeah, I think he'd still rather be primarily writing for a magazine then UA-cam.
I've lived in MN my entire life and this is about my thirtieth winter season as a driver. I live in a pretty decent sized city (100k) and while I've had AWD vehicles at different times in my life I've kept my wife and I in AWD for the last 5-6 years. We had two wagons: an 06 Audi A6 and 05 Subaru Outback XT, 10 Mitsubishi Endeavor and now 99 CRV and 19 Highlander. The main thing is simply getting around and most any AWD will accomplish this but there is a fun quotient as well and while the wagons did understeer you could get them to rotate. You just have to stay committed (especially in the Audi) or your going to slam a curb. Both were predictable as well and you could drift them back and forth as much as you like correcting them easily with a quick counter on the wheel. I didn't spend much time in the Endeavor but the CRV is very neutral as is the Highlander which is not as much fun but more confidence inspiring. I drive the CRV and love it! I miss the Audi and to some degree the Subaru but they had limited space and required high octane (among other special fluids).
A mk 8 golf R can send 100% of its REAR axle torque to either side which equates to up to a maximum of 50% of its total torque. This is because it has a clutch pack for each side and can fully engage one side only if needed.
Edit: it also does not have a rear differential, only a ring and pinion between the two clutch packs. Very cool design when you look at it.
It's an electronic clutch pack differential like the ones Ferrari has been using for 20 years
@@BigUriel except electronics have improved how much ?
Love that 78/79 ford at the beginning!
Honda's SH-AWD system is amazingly simple. I'm surprised it wasn't invented decades before, since it was a completely mechanical system when Honda first introduced it in the 1986 Civic Wagovan.
(basically it is a 4wd system with a torque converter added in the rear driveshaft to allow f:r axle speed differences)
They should use it more imo for their performance cars. Fwd civics are good and all but AWD ones will be rad
My 2002 Volvo V70 xc Cross Country is Front Wheel Drive-All Wheel Drive (Haldex). Its wonderful in straight ahead driving, a formidable drag racer on snow & ice-covered roads running studded winter tyres & ok in corners as long as I am careful with the throttle. Take the bend slow & easy & once you get straightened out, hit the throttle. On a snow-covered bend, I gave it too much throttle & it tried seriously to drive off the road. And, once you over-throttle it, nothing gets better, more throttle & your trip to the ditch comes faster. Letting off the throttle & it slowly loses speed, on the wrong side of the road.
Great video. This is the first one I've seen. You nailed everything. I especially like the Corvette thinking he's doing a burnout, when you're talking about clutches. Haha. Bravo.
This video just became my anthem, this topic has been my personal crusade for years.
I love these kinds of videos! Now lets hear about Jason’s advice on dodging salesman tricks in charging extra when buying a car
Oh man, this topic deserves more episodes. When you start throwing your attesas and symetricals into the equasion things get really interesting
This was one of the best, concise explanations I've seen so far! Kudos!
No one does auto journalism like Jason - GOAT
Pastor Jason preaching the truth!! 🤟
Dude, Jason may be the smartest person ever!
At age 16, I once neglected to take Dad's old 1974 Toyota Landcruiser out of 4WD (H4, not L4) when I got to the bottom of the ski hill. I was a relatively new driver back then. The drive back home was on almost straight roads, but by the time I got home through the city I had almost shredded out a new set of very expensive Firestone Town & Country tyres. My father was not impressed, but he still managed a laugh, and I learned a valuable lesson.
Subaru and Mitsubishi, as well as the Classic Audi quattro longitudinal engine layout, are symmetric AWD, in that the power goes through a center differential, and then the front and rear differentials.
According to my understanding the group-B Audi locked the center differential until the final evolution of it, in combination with the engine longitudinally hanging over the front axle the car had to essentially be driven like a rocket - applying a thrust vector to counter the current vector to go in the desired direction (driven sideways).
Haldex systems can lock the back axle to the front and are programmed to release lock to allow turning (inherently putting most of the power to the front). Although they can be reprogrammed to just remain locked and then have to be driven like a group-B Audi. Also, you can incur a speed differential with slightly smaller diameter rear tires, whether you let some air out of them, or stretch them on some wider wheels. Then you would transmit more torque to the rear like the over-geared systems.
Ford Focus RS and Honda SH-AWD (as applied to their FF platforms) are interesting in that they can independently lock each over-geared rear wheel to the front, thus they can temporarily send more power to the rear and even each rear wheel, thus able to do some serious torque vectoring.
My favorite is symmetric AWD systems with modifiers that only need to operate sometimes, so it has a fundamental AWD attribute that can then be tuned and dialed right in.
Subaru electro-hydraulic center locking differentials, as well as Mitsubishi EVO electro-hydraulic center and rear (AYC) differentials are this category. AYC is special in that it is a differential that can force a speed difference similar to Ford’s and Honda’s, but isn’t the fundamental part that transmits power to begin with. When not working an EVO X is still AWD, just with a rear open differential.
However, when AYC is working, the car drives like a fundamentally front-engine'd symmetric-AWD car, but AYC is torque vectoring the rear (modified) from direct steering input. So it is mostly proactively driving under your control, and not reacting unlike every other system. By their very nature they can't have the clutches in a partial lock all_the_time while you're driving, so they will always be FWD with reactionary AWD/RWD characteristics.
The Ford F150 Raptor is interesting in that it has an electro-hydraulic clutch as well as a hard lock in its transfer case - So it can be programmed partial torque amounts to the front axle, like the GT-R and other cars.
OMG I’ve been waiting years for someone, anyone in the car media industry to rant about fake-ass AWDs (Yes I’m talking about you HALDEX) properly. You are the Best Jason!
There’s nothing “fake” about a haldex AWD system. It’s still AWD it’s just that adding a PTU to a front drive car does not suddenly make it handle like a rear wheel drive car. And that’s OK. I have a RWD car for giggles. I have an AWD car to commute in. I don’t care about at the limit handling on my commuter because that’s not what it’s for- it’s for getting my ass to work no matter what BS is happening outside.
Fake? I drive Passat B8 4motion, and on the winter it's very competent. Jason is talking about when you push the car to the limit, but on every day basis it's no different. I also had a Audi Q7, and I didn't really feel that big of a difference on my commute. Btw, I live in Sweden
@@yosefm170 Ughh… I don’t think you get what I’m talking about… haldex itself is a genuine awd system and I admit that. If a fwd-based system can send any power to the rear, it is in fact awd. But the fake part is in its marketing approach. All the haldex-using car companies boasts its ability to send 100% of the power to the rear and yet it never can (under normal driving circumstances ofc). This is now misleading consumers and That’s what’s fake about it.
@@SebastianXe90 now I understand what you ment :)
@@SebastianXe90 is a torsen type amy different?
Such an awesome video! Thank you so much, I think so many people are missinformed on this subject.
The video clips for this were awesome, as is Jason. I really like the simplicity and feel of the AWD 62R/38F split in my 01 325xi (originally bought for my wife's snowy commutes, but now my modified toy... it performed well in a moderate amount of snow, even on all seasons, but as a daily it's still fun).
I had an 01 330i. Just rear wheel. With snow tires, it was just fine. RWD works well in the snow. Then I had the opportunity to have a 2010 328i XDrive... All season tires made driving in the snow a piece of cake. The same exact day, it took me half an hour to back into my driveway from the side of the road in my FWD Malibu. Definitely showed me the difference between an AWD system and a 2WD system. Snow tires are a must, no matter what, but all seasons on an AWD will definitely treat you well.
@@JoiceVaderd Agreed! I wish I had kept my 92 Prelude with a OE JDM LSD too... it would pull through the snow!
And this is why i fell in love with the E63s when it came out with its AWD system... You activate drift mode and you get all those 750Nm going only to the rear wheels... You can turn it off, it's a rear wheel drive based AWD system.... Glad the M5 came with it too afterwards! Such an amazing car the E63s is....!
And now you have to add the Yaris GR to the "overdrive" fwd list. Don't think it's coming to the USA, but it is an awesome car with an amazing story behind it. Might be last of the kind. Really enjoy your shows, there are many car guys out there, you strike some sort of great balance. Thx.
Yea the GR four awd system is very interesting. It has overdrive and the clutch pack is constantly slipping
Somebody please give Jason Cammissa a platform in which to spread his knowledge, wisdom and gripes.
Just curious, why did you seem to specifically not address Subaru’s all wheel drive systems?
He did, when he talked about the quattros
It’s the same setup as the Audi one mentioned.
@@rodrigoalmendro3118 my understanding of Audi’s Quattro and Subaru’s AWD systems are different at the transmission. Kinda similar, but the viscous couplers or I should say coupling systems are quite different. Subaru uses a transmission that is quite similar to a traditional rear wheel drive unit. I’m not as versed on Audis systems, but I believe that they are quite a bit different. You and the other gentleman that commented that they are the same could be correct, but I find it odd the Subaru, who are specifically know for AWD, as is Audi, we’re not mentioned at all.
@@williamkerry2626 I agree with you, but what I ment is that he adressed all permanent awd cars. Not that subarus and audi's specially that model, have the same drivetrain.
Subaru is like audi, the sti is like the sh-awd, evo, and focus rs.
Haldex in the volvos isn't all bad, it's pretty great in the snow, especially if you're an aggressive driver. Understeer if you turn casually, snappy oversteer if you stab it. Fun stuff.
3:33 Not sure why RWD F80 M3 used to show "RWD based AWD", though the GTR R35 4 wheel drift is well cool
Yeah I was gonna say
Editor’s little mistake I guess... but we get the point I guess
Probably to show a downfall of a rwd platform car out of grip and oversteering, while the GTR is able to hold itself sideways because it has an AWD system.
@@CrazyWeeMonkey gtrs awd is rwd based
It was being used to show a RWD car.
Jason for the win. When he left that unmentioned magazine he worked for, I stopped reading it shortly afterwards. Wonderful to see him in front of a camera again. A true car guy.
Recently found the channel and love Jason's work so far! But... being an ex-Golf R owner and now an S3 owner, I really don't understand all the hate for the Haldex systems? I'm not disillusioned as to how much power can go to the rears, but the system definitely makes both cars handle far better than they would without them. The Golf R is a go-kart! I had mine at APR Stage 1 and it was incredible fun on any road! The S3 is most definitely not as nimble as you trade handling for comfort (*cough* weight *cough*), but it's also no slouch! And in the rain or snow, there's no question as to how much better it makes these cars behave over anything driven by 2 wheels (front or back). Also Haldex is less complex, lighter, cheaper, and provides better fuel economy than a more traditional AWD system. Yeah I can't swing the rear around, but I really don't care to do that the majority of the time I'm driving around, so it seems like a fine trade for being a daily driver with the ability to have a lot of fun when desired.
And yeah, like others mentioned, please make a part 2 as there's definitely more to cover on this topic (Subaru?!?!?.... Lamborghini??!?!)
I had cupra leon 290 frontwheel and now formentor vz with 4drive and with the formentor is I believe the biggest advantage massive traction. Leon was unable to put the power into the road even with the best tyres. Formentor is able to go all-in even in the f*cking rainstorm. The handling with 4drive feels more understeered but in the end is much more confident and enables better handling as you wrote. The cupra leon 290 had better times on track than leon 300 4drive because of weight and traction. As normal roads dont offer traction 4drive is always much better in my opinion
Blip the parking brake, the rear end will come around. Then juice the throttle.
I want to note the BMW Style 5 just in screen and slightly blurred is a work of art.
1:07 Open diffs always send 50:50 regardless of conditions. The max force a tyre can apply is equal to normal force*coefficient of friction. It's not some electric current to travel in the path of least resistance. The wheel which has less traction will spin faster because it has no resistance compared to the wheel which has. It looks like all the torque has gone to the wheel with least traction but that's wrong. It still gets 50:50
This is much better than many videos about this subject. However, occasionally you mixed up "power" and "torque" when talking about what is transferred. For example a locked differential ensures each each side/axle is spinning at the same speed. The torque sent to each side will vary and since power=Torque*speed the power sent to each side will vary. Thus an old school part time 4WD system doesn't send equal power front and rear. Rather it sends what ever torque is needed to keep the velocity the same front and rear. Regardless, this was a good video to watch.
Talks about AWD, leaves out Subaru 🤣
yeah , i wanted to hear that too .
@JasonCammisa
He isn't gonna talk about them because subaru has a lot of forms
Also he isn't talking about every car manufacturer
This video was (rightfully) complaining about the Haldex type AWD systems which are found in cars with sideways engines. They really are a bandaid afterthought to a vehicle with a transverse engine and transaxle.
Subaru's AWD setups are all very similar to the original Quattro in how they are laid out.
- Both are Symmetrical
- Both are longitudinal
- The front differential is in the lower front part of the transmission, right behind the bellhousing
- The engine resides entirely infront of the front axle center.
There are differences with the center differential. The basic manual transmissions have a set of spiders gears with a viscous coupler to divide power and are 50/50. Some of the STi can change how the coupler works to set the power distribution. Automatics use a different coupler system without spider gears - CVT ,4EAT and they are front biased but are ALWAYS powering both front and rear at different levels.
The old old Subarus just have a lock to lock the center differential; there either 4x4 or front wheel drive. Very similar to the early Audi quattros as well.
They were both a longitudinal front wheel drive (ever notice how far back the axle was on the older Audis with longitudinal engines?) with the transaxle / transdiff /whatever looking nearly identical. Then, at some point, the ability to power the rear was added.
The true quattros are still just like a Subaru. Whereas the stuff in the Golf and smaller ones are Haldex.
Compare items on ebay - 284203799448 is a Subaru 4-EAT transaxle and item 153581209924 is a similar vintage Audi quattro transaxle.
Yeah, subaru is the best.
@@kcfreeman3021 just save up for regularly scheduled headgasket failure, lol.
You don’t need to get three wheels in the air to flex 100% power to one wheel. Just move north and find patches of ice. I live in downtown Chicago and the ally behind my row house has been covered with ice patches for about a week. Urban use for crawl control on my LX 570.
Something that wasn't addressed is something like the Subaru AWD system. More so, how would the AWD systems mentioned compare to the STI's 3 differential AWD system?
The STI's system is closed to the BMW/Jag system mentioned in the video, except the center diff has a static split (from 35/65 F/R to 41/59 depending on year) and the computer controls clamping the packs to change how much the center "locks" when there is a differential in speed between front and rear axle. The "problem" with the Subaru layout is that it forces the engine to be entirely in front of the front axle line (hence the short flat-4), but it does save a little bit of weight/packaging space compared to other RWD-biased AWD systems.
The 1986 Quantum Synchro I owned back in the day had the three position switch on the console to lock some or all of the three diffs (as you said it went straight when all were locked) but would not get stuck. It was a station wagon with a 5 speed and 5 cylinder engine with 411 rear gearing P7 tires. It was a ball to drive...........but only got about 18 mpg.
Kinda wish I still had that car sometimes.......
Informative and entertaining as always. Would love to hear your thoughts on electric AWD systems, where different motors power different axles, and compare them with the traditional AWD systems you mentioned here.
It's both easier and not at the same time. Each motor has it's own specs, so obviously a combined load rating can't be sent to each axle. Good news is that you can choose the power limits at both axles to allow more or less whatever bias you want. Tesla's are heavily rear biased systems by default (they don't publish official numbers, but the general consensus is somewhere around 2/3 rear 1/3 front as far as motor power ratings).
@@aspecreviewsthat was literally my third sentence....
Jason is the reason why I am here!
A true know-it-all wouldn't use the terms "power" and "torque" interchangeably. This video is surprisingly correct, and covers a lot for how short it is. But I think it would be most helpful to explain that only open differentials split torque equally or 50/50, and locked differentials send equal motion to each wheel. Sending equal power to each wheel only happens when driving in a straight line with open differentials and no slipping wheels. Literally no AWD system "sends power". They only send torque or motion. If they send torque, the resulting wheel speed determines power. If they send motion, the available grip determines power.
And yes, the innovation of overdriving wheels and using clutch packs to vector torque is awesome, but brings worries of clutch wear. Rear-biased or rear drive only Torsen setups are most useful, reliable, and fun in real life.
Pedantic. Know your audience would be a great thing for you to learn.
Perfect description of all types of AWD system. Thank you.
Except the most common one lol
*breathes heavily in subaru*
I’ve got three different types of AWD/4WD systems. My wife’s Hyundai Tucson is front wheel drive most of the time, supposedly. I’ve never pushed it in low traction areas. But in front of the shift it has a little diagram showing how you can lock all three diffs, and it’s called “Diff Lock” right on the button. I pressed it while parked once and it seemed to show that the front, center, and rear axles each had a “lock” padlock symbol on it. Weird but rad if it’s true. I will say that it’s peppy for what it is and there’s no perceptible torque steer, and I once stomped it in anger on the side of the Hwy in the grass from dead stop and all four wheels definitely spun but it seemed like the front did the most steering, as opposed to my ML320, which exhibits mild, very mild oversteer with ESP off in the same conditions. No donuts, and never feels front wheel drive, but definitely feel all four wheels all the time, yet never understeer under power the way Jason said any AWD system would. The Merc system basically is 4WD all the time and I’m pretty sure the center diff is either locked or very little slip is allowed, as it’s never left me with the front wheels spinning and nothing from the back. Plus, it uses brake assisted limited slip for its version of a limited slip with clutches in the diffs, which chatter and can wear out. It uses the various wheel speed sensors as well as its gyroscope to put power where needed and apply brakes to force this action. Left rear spins in the mud, a little brake to just that wheel forces more to the right rear, same up front, and front to rear. If both front wheels are spinning it will apply enough brake to the front ones, with the highest speed one receiving the most brake pressure, until any and all other tires catch up and speeds are matched unless steering angle or yaw are telling the computer that a front wheel should be allowed to spin at a different rate than the other. The Jeep Quadra-Track is similar, thanks to the Daimler-Chrysler merger. Then there’s my 2006 Burban. There’s 4WD auto, 4WDHi, and 4WD Lo, with Lo being a stupid low granny gear in true all locked up diffs all around and could possibly pull a house off its blocks. I once had it badly stuck in my backyard and in 4Lo at full throttle, which would probably mean a top speed of like 15 or so, maybe 20, but it limits e fine speed in that mode, to I think around 3500rpms. 4WDHi is also locked diffs all around. But 4WD Auto is different, where you could just leave it in that mode all the time and drive around in dry weather in pavement, no problem. The deal is that if the wheel speed sensors determine that the rear wheels are going just a little faster than the fronts, it applies a clutch pack in the transfer case, bypassed in4WDHi, and seamlessly becomes 4WD, but the front actuator only deploys part way, and does not lock the front diff, and of course the center is t locked either. Of note is that if you have the G80 rear differential, you have what I think it the greatest diff setup for off reading. It’s purely mechanical, not connected with any wiring, no clutches, only a Park pall like mechanism and counter weights for each rear axle shaft gear, and if one wheel turns at more than 100 RPMs than the other, the difference in speed allows an otherwise in-synch pall to swing into place and literally lock the two sides of the rear axle together as if you had a spool or welding your rear diff. You can feel it hit when it dies, and it remains that way until both wheels go the same speed long enough for it to release the pall. If you have it engaged and are turning as you come out of the mud and onto pavement it will still hop around until you go straight for like 20 feet or so, but if you are turning at all it won’t release. That diff has saved my ass by. Eig a full and every time lock that performs unlike any other diff. Other types unless they are like the air lockers, only lock up with wheel speed differences, like this, but if the wheels come to a stop, those clutches disengage, and when you set off again you lose those precious feet of positive grip to get out of that mud hole or over that hard obstacle unweighting opposite corner wheels. With the G80 it stays locked, even from a stop. I have been caught in the mud with out 4WD on and also not engaging , but that spool like rear axle when engaged got me out of deep mud, 2WD only.
1 - love the Know it All series of videos!
2 - if bmw xDrive is always rwd except when it decides to send power front wards - whats up with the claim that the xDrive m340/440/40 models are "more rear biased" than the 30 series?
All i can think of is 40 models have rear e-lsd as standart
Most likely refers to how the center clutch calibration was done, saying that it is more rear axle biased means that in similar driving conditions the computer on the Ms sends less power to the front in comparison to the computer of the non-M sisters
You might get the impression from this video that Audi uses a Haldex system, but Quattro systems are Torsen systems which are nominally 50/50 and can send 75% of power to either axle. if your Audi engine is mounted longitudinally then its a Torsen system, if its mounted transversely it is Haldex. I never gave much thought to this, but living in Colorado we have quite the variety of AWD systems in the family garage and driveway - two Audi Quattro cars in the family (Q7 and B7 A4 manual), a 335i M-sport Xdrive manual, a Porsche 911 C4S manual which I gather is similar to Xdrive in that it powers rear wheels first (though curiously no marketing name other than "4") and a Tesla Model S P90D - which I guess can send power anywhere anytime it wants to and apparently shifts power from front to rear as hard acceleration is in progress. Oh yeah, one lonely (but fun) RWD BMW 535i M-sport manual.
Every Subaru owner felt offended after watching this video :)
lol I'm a Subaru driver and it's true
Agreed!! What about the only AWD worth talking about? SUBARU
Yes, you slighted us Subaru owners.
Yeah..but aren't they perpetually offended. :)
@@eston911 Well, it oversteers almost as much as Gold R so maybe it's good he didn't mention it...lol
This is the clearest and most concise explanation possible, amazing work!
About getting out of trouble, many of these haldex type AWD systems have very small rear diffs that overheat in a few seconds and the computer turns it into full FWD until it cools down, the most spectacular examples of this are Honda CRV And Toyota RAV4. These systems are nearly useless, helpful in light snow but is it worth the extra weight? I would not choose the AWD option.
Better off fitting winter tyres instead to a FWD car.
@@khalidacosta7133 you need winter tyres regardless of how many wheels are driven, AWD won't make your tires grippier in cold temperatures, change their tread pattern for one more suited for snow or make them grip on ice
I’ve watched every video in this series today. Can’t get enough.
“While this often happens… in rental cars” 😂 best quote of the whole video!
I just needed the HALDEX system for the occasional snow WA gets. It’s working great so far so no complaints here
Im totally fine with my FWD cars. Im not a drifty boy. I love how confidence inspiring my evo awd system is too. Its never gonna side out in any sort of unpredictable manner. If it slides its because I forced it to and even then the computer somehow just knows exactly what I want it to do and does it.
The 'FF' Ferguson AWD system using a viscous center clutch allows for that 'under-driven' rear wheel situation in a part-time awd vehicle. Under normal driving, the vehicle drives and performs like any other FWD, but when front wheel slip occurs (open diff of course), the rising temperature in the center clutch pack engages the rear at a 50/50 torque split. The purpose of the underdriven rear is to *keep* the temp up, thereby speeding up the engagement rate. Get it right and its completely seamless and undetectable, get it wrong and every single component from the rear tires forward grinds itself into dust. Most manufacturers avoid potential problems and simply use a viscous clutch and the same ratios front and rear.
You made a whole video on awd and managed to mention honda infinitely more than subaru. Think about that
baffled .
lol
Because Honda's system was a true clutch type Torque vectoring setup as opposed to Subaru's that use brake actuated torque vectoring. The SVX had an active diff. That's about where that ended. They aren't proper AWD systems, more like brake assisted 4wd.
@@d1sturb3d119 subaru uses an LSD center diff, nothing to do with brakes.
@@drakedbz We're not talking about the center diff. Any competent system out there has an LSD for the center diff. We're talking about the rear and front diff. The rear diff has no ability to control torque left to right. Subaru uses the brakes to control torque whereas Honda has a clutch type LSD with electronic control to split torque that gets to the rear diff 100% left to right.
Hence Subaru uses brake actuated torque vectoring as opposed to active diffs that are superior.
Quite a good one, even though I am not sure what was said about the SQ5 was quite correct. It does not have a Haldex unit like the Q3.
Exactly. I was confused right there. I thought it was a new type of Torsen. He probably tested the SQ5 without the optional sport rear diff.
No mention of the torsen system, eh ?
I TORSEN??????......I TORSEN!!!!!!!!
I would take too long, because at the beginning torsen was 50/50 then it was 40/60 etc. And now torsen is gone, Ultra Quattro has taken its place.
@@DuBstep115 Torsen diff at 40/60 is still used on 4runner limiteds.
@@jamesmac8424 It was good system had that in my audi A5
@@DuBstep115 Yep, loved it in my b8 S4.
Great video as usual.
The problem is the confusion between torque and wheel speed....a modern AWD operates like a clutch based LSD...the only thing these systems do is sending wheel speed.
The torque is always the result depending on the grip of each wheel.
SH-AWD rules and deserves more love
It's a nice system, sadly it isn't on anything that develops noteworthy power or anything that could be safely tracked.
@@shawndejong6699 safely autocrossed... Maybe. Enjoyed? Nope. It's a Honda it's built and designed for durability and predictability. You have to modify them to get crazy performance. S2k fanboys don't start, you've never driven one.
@The Hooniverse You are so right. It is a very underrated system that works fantastically!
@@shawndejong6699 sadly noone bothered with it except the Spoon guy that modded the Honda Legend to demonstrate this.
Especially eSH-AWD...
So much info in such little time, its great but please make it longer!! Its better for both of us i promise. I want more content and hey, more money for the channel
Jason - what are your thoughts on the Mk8 Golf R and the A45 with their "Drift" modes?
Those are the cars with the center clutch pack that slips like the Focus he showed drifting around. A temp band aid he called it. They produce heat.
@@tellyourmomisaidhi5804 Everything produces heat...
While stationed at Ft Campbell KY, in the 90's. My commander wanted to up grade and replace our older Hummers with the new models. While there were a few advantages to the new model there were huge disadvantages as well. The newer models had open differentials, so it really wasn't all wheel drive, it was one wheel spin! The older models had limited slip differentials. I could drop one wheel off into a deep hole, lifting the opposing wheel on the other axle all but off the ground and the two firmly planted wheels would pull us right out of that hole.
What about AWD v true 4x4? Would love to hear your explanation of the difference. I have a 2016 Grand Cherokee with 4x4 drive.
The common US interpretation is, that it is a selectable AWD without a center differential. Just like the first variant described in the video. There is permanent drive to one axle and you can choose to connect the second axle in a "on/off" way without a differential. The most primitive way to do it.
@jesuis baizuo A lot (perhaps even most) of 4x4s have an auto mode that will dynamically send power to the front when the rear is slipping.
@@scotth5503 dynamic lol, that 4x4 auto mode is a hysteresis switch.
AWD is a vehicle with an open differential in the transfer case allowing the vehicle to drive on dry roads with all wheels being (somewhat) powered. 4WD refers to a transfer case with a closed center differential (locked) where at all times power is being sent to both the front and rear axles, meaning this setting cannot be used on dry roads. Many vehicles (including my 1998 Jeep Cherokee XJ with the optional N242 transfer case) have both settings available.
Great video. One correction. In your hypothetical jump/wheelie you would still not get 100% of power to rear wheels. AWD clutches are not sized for 100% power they would slip reducing power to rear wheels.
I have actually witnessed a 2dr Jeep Wrangler rubicon (lockers) driving up a steep rock ledge end up on one wheel for a few moments. Highlighting the power (pun intended) of a true mechanical 4WD system with lockers.
Isnt the SQ5 a torsen quattro, not a haldex "quattro"?
Yes. And the Q5 isn't haldex either. It is quarrto ultra which is a different system entirely, though the basic operating principle is similar. And he left out a few more types of AWD systems. "Know it all"? I don't think so
I have an 09 Escape 4wd that I have gotten to spin in place on snow and ice, a video on how the automatic 4wd system on this and other vehicles with a like system and how it works would be AWESOME!!!!
Great video! Was hoping to hear at least one mention of the Lancia Delta Integrale, a front engined car with AWD, rear TorSen differential, and a 47 front/53 rear split (on 16vs). The GOAT when it comes to 4wd rally cars.
I dont know exactly how that system is designed, but it sounds like the overdriven rear axle he talked about at the end. Torsen differentials are very strong, but they have 1 downfall, if 1 wheel loses traction it will only transfer the maximum amount of torque the slipping wheel has to the other side. If 1 wheel was in the air it would transfer next to nothing to the other
Nice rant. It's good that Jason remembered to state that all of this only matters on the limit. A couple of problems, though. First of all, 4wd rally cars of recent memory have been able to steer quite well even without center differentials. WRC teams threw those away for a few years, when active center locks got banned. And secondly, Audi SQ5 actually has a real center differential, unlike Porsche Macan. Audi's diff is even slightly rear balanced. The car just has otherwise been designed not to be tail happy. And then there's the new Toyota GR Yaris, which seems to be quite playful, even though it has the exact fwd-based system, that Jason thought the Audi had.
Subaru? Audi Quattro? It's quite a bit different than the group B monsters of yore.The actual torsen system and not haldex..
That's what I thought.
Depends on the model
The Audi he was talking about with the Porsche uses "Quattro with Ultra Technology" which is another form of a Haldex type system. It's NOT Torsen.
@@blankname8553 yes I'm well aware which is why I posed the question.
@@blankname8553 that’s not true, unless I misheard and he said Audi Q5.
I heard him say Audi SQ5, which comes with the proper Quattro system with a mechanical center differential, it’s not haldex. The standard Q5 comes with haldex, the SQ5 does not.
I got the 2nd gen VW Touareg. It uses Torsen diff, which is very different than haldex. No computer, it's all mechanical. Up to 80% power to rear wheels, up to 60% to front wheels. Pretty darn good!
I "belive" the urquattro system also hade a Torsen diff, but it was very balanced so it was Hard to control in the bridge between over/understeer......
Heard so from drivers.
Interesting video. But how the heck did you do an awd video and not mention Subaru? LoL
The Buick Jump will forever remain a classic!
THANK YOU! Finally someone said it!
Cammisa makes this channel. Pay him more now!
When I add blinker fluid to my 2006 Camry, all four wheels turn in the same direction. You're talking nonsense.
Some would argue that if you lock both front axle you will send 100% of the power to the rear on a haldex ✌ great video love Jason aka discount Sandler Camisa 😁
I knew all of that before but I can still hear Jason tell me about it 57000 times over.
The Evo was smart about it the Center Diff was helical in the non-ACD models. No clutch packs.
You can have a Haldex rear biased system, you just have to stick the engine in the back like a Porsche.
Yes, i remember they did build them this way for some time! (the awd Lamborghinis since they are Audi owned and the Audi R8 are the same way)
Noob here
Isn’t the RWD system also a Haldex system but it instead of the Front wheels being the ones locked to the Engine it’s the rear ones? So basically aren’t they the same just the wheels that are locked are the Rear ones not the Front ones?
@@anonymoussoap8310 Yeah this is jus a difference between Jason using Haldex as a blanket term to describe permanently-powered front axles and the comments using it as a brand name for any of the AWD systems VAG uses based on the same principle of one permanently-powered axle.
There is a bit of a difference.1: Haldex is (or was?) a company that manufacturerd the diffclutchpacks. With that, the rear diff and the clutchpack are one unit And the axle closer to the engine is always powered.
2: Systems like X-drive, 4matic+ (and the one Jaguar uses ect): Those have their normal rear diffs (or with a LSD) and they also have a "transfer case" where the power is coming out of the gearbox a second time and via a second cardan shaft is going "back" to the front into the front diff This transfer case is basically a clutchpack that can close 0-100% and thus bring a max of 50% of the power to the front wheels.
In summary the difference between a Haldex and the other partial systems is where the connection happens and what is inside the differential housing.
With Haldex the connection is made "inside the differential" with the others "inside the gearbox"
There are several generations of the Haldex system. The first ones were mechanically controlled and only locked when the difference in speed between the propelled and non propelled wheels exceeded a certain value. (a bit like with a torsen diff, but with clutches) The new generations are electronically controlled and so can be closed before the driven axle looses traction. (not everybody programms it that way, but it is possible)
The other systems are electronically controlled from the beginning.
Little sidenote: Haldex (if i am not mistaken) is a swedish company, while x-drive and most of the other of these systems, are designed and built by Magna (in Austria) by contract for the manufacturers. (Magna designes and makes awd systems for almost anyone except Suzuki, Subaru, Lada and Toyota from what i remember but they aren't very vocal about it. Those few companies do it themselves. And yes, even for Jeep they have done systems in the past. Don't know about the present)
@@nirfz Almost all of the powertrain systems that car manufacturers use are designed and produced by someone else. They are companies like Magna, GKN, BorgWarner (who bought Haldex) and Jtekt (the Asian choice). If the car manufacturer happens to have their own transmissions, they might also have 4wd or awd systems. For example the 4Matic system from Mercedes might be their own, but I'm not sure. The original 4Matic is actually a planetary center differential that has a small lock up clutch to get you out of trouble. After you get some speed the differential works as an open differential, that might have some rwd bias. But these days 4Matic name is linked to probably half a dozen different systems.
Finally, somebody focusing on what's really important instead of trying to explain "the difference" between 4WD and all-wheel drive (...that does not exist, ..unless you have 6-wheeled vehicle...)
Just one wheel on ground? Rock crawlers “hold my beer”
Your presentation is so entertaining.
Subaru?
A very complicated subject, that very few understand, explained in a way I hadn't heard before and explained well. Good job. Now two questions.
1) What if one installed slightly larger tires on the rear of their Golf R, thus overdriving the rear tires? Success or just successfully confusing the computer?
2). What if one took a front wheel drive transversely mounted engine/transaxle and custom built a car to accept this drivetrain in a mid-mounted longitudinal position with one halfshaft driving the front axle and the other halfshaft driving the rear axle? Just think about it...
You'd never want to have mismatched tire sizes on an AWD vehicle. It would damage the center diff.
@@Robert-un3cf Damage will only if the center differential is a LSD, locker or fixed like in transfer cases. The whole point of a differential is to allow for a speed differential between it's outputs.
Considering the varying methods that manufacturers use to implement AWD systems I would tend to agree with you in most situations. And considering the repair costs if damage did occur it is better to not risk it.
But different tire sizes have been used in motorsports for decades, most notably in oval track racing where the outer drive tire is larger than the inner drive tire resulting in the car wanting to turn into the corner, this also results in the drivers actually having to turn the front wheels to the outside of the track to get the car to go straight on the straightaways.
Skipped Subaru.
50/50
@@DuBstep115 And add understeer...(and ringlands, rev hang and crappy enteriers)
@@bokiNYC what is enterier, a dog breed? Terrier?
The Quadra drive system in Jeep Grand Cherokee WJ models can actually send 100% of the power to one wheel. It uses gerotors in all three differentials to bias power between front and rear, and side to side. Even in the offroading community this power is often overlooked but I have been off road many times in a WJ and it simply cannot get stuck and out performs Rubicon Jeeps in every situation except where ground clearance and articulation matter more than traction.