Easiest way to understand the operation of an open-diff is: No matter what, an open diff always splits the drive torque 50/50 across the axle. Therefore you are limited to 2x the tractive force of the wheel with the least grip available. So if you have a 2wd car, one wheel on ice and one wheel on tarmac, the total available driving force is 2x the force achieved on ice. With a locked diff in the same scenario, you get the force from the wheel on tarmac + the force from the wheel on ice. this result in more grip, but you now have a torque difference across the axle which will cause the vehicle to yaw (rotate). The open diff has less traction but drive torque is always the same across the axle so vehicle will not yaw. Hope this was helpful :)
Overall, the video is pretty good, and reasonably informative. MOST people, even otherwise experienced car people, have a hard time understanding how a differential works. Your explanation and demonstration goes a long way towards helping them. I DID think it was funny that Dallas was trying to do the drawing and explaining, but you were the one giving him info and pointers off screen! Even so, you both tag team well and made it good to watch.
Dallas and I just recently started collaborating and this video is pretty recent. Diffs will sometimes make chattering noises or you'll have poor or inconsistent engagement. Honestly with stuff like this I'd take it to a transmission shop you trust to check it out.
That principle of wheels spinning in the same direction (when up on jacks) with a limited slip diff can be a little confusing. My 2000 Suburban with a locking diff works differently. It behaves like an open diff according to the test, however when I open the cover plate it is definitely a locking diff. Looking into this a little further, I found that the GM version of locking diff depends on centripetal force from little spinning drums inside the diff. The tires need to be spinning fast enough for those devices to rotate outward, locking the spider gears. So, our old standard test on jack stands with hand rotation of the tire fails to identify the GM locking diff. Better to trust RPO codes int the glove box, ha ha.
But if the truck was stuck and trying to lock the axle from a stand still I don't believe it could. If the power is transfered to the free wheel how could it spin fast enough to lock both wheels when it really counts? I don't know any knowledge of the GM design you have explained. It just sound like an open diff with no advantages except traction control at speed
good vid..but just a tip: if you have an eaton truetrac; and try this, one wheel will spin forward and the other backward, so this test doesnt always work to determine a LSD diff.
good video and all, covers all the points, but a camera angle that shows both tires as you turn them by hand would've really driven the point home. on your own, jacking the vehicle up and getting underneath where you can see both the tires at the same time as you turn one makes it real easy to tell if your axle doesn't have a tag.
The side that spin will be the side with least weight, not the most. You say engine spinning clockwise places weight on the right rear? Fine, but then it's the left rear that will have least tracktion and will start to spin.
Didn't GM often use differentials with a counter weight lock? So under normal operation it would react like an open differential until one wheel spins at a certain speed faster than the other causing it to lock up and act as a regular posi. How would you tell if you have one of those without burning out and taking a look?
Anthony, been looking at your library for Drive shaft U Joint replacement for G35/350Z...Have you done it on your 350Z? ...I prefer not going 1 piece and keeping the car OEM 2 piece...I noticed the OEM U Joints have pressure dimples holding them in place instead of clips...Any advice/Part Numbers for replacement is appreciated.
@@AnthonyJ350 Exactly! I don't want to increase NVH...On the contrary, I would like to restore the quietness of the car when I bought it new...I've tried extensive sounddeading to keep it out...So I did some diagnosing and found the noise coming from the front Driveshaft U Joint... I pushed the U joint at 90° from each other... There was play in one direction...Now I'm researching options.
@@AnthonyJ350 Looks like that's the way it is going to happen. Both Z/G OEM driveshafts are discontinued. U Joint part number is sketchy at best. Perhaps Z1 Motorsports can help. If I come with a good p/n ,I'll share it with you.
@@AnthonyJ350 So far I may have 3 options. 1st.Get an aftermarket U Joint (Ebay) possible fitment issues ($25) .2nd Get an aftermarket front drive shaft ($110) 3rd Get an aftermarket one piece drive shaft ($500+)
I have been told that my Jeep Commander Overland with the 5.7 Hemi has lockers. Others have told me no way... Can you tell me by the info I just gave you? It does have the QD2 in it. Thanks
so i have a question about what type of diff i should use on a project. i am building a dual tracked vehicle with a differential and brakes for steering, 2 master cylinders, one for each tracks with a diff in the middle. i am wondering what type of diff would be better to use, my thought was open so one track could be comletly locked up to allow a very tight turning radius but i wouldn't have the traction for both tracks going in deep mud unless i ride the brakes for that track to force it to slow down or stop to allow the other one to turn. i am just asking because i am having a hard time trying to figure out if that would be the best choice. thanks
Explosive Gaming Why not electronic or air lockers so you can lock them for maximum traction or disable one or both when you want a better turning radius.
so you say a locking diff so for better traction when i need it but when i dont need it i can unlock it for better turning. Im far from an expert on differentials i focus more on engines and transmissions but i do know a little about diffs, so if i do use a locking diff would it have the same properties as an open that i need for turning when its unlocked or would it be different
not sure if you got your car fixed but looks like the touareg has 3 locking differentials and i believe the rear is LSD when it is not lock'd as well. i would advise finding you another VW dealer or audi dealer unless there is a transmission shop locally that is familiar with foreign cars and that specific chasis of the VW autogroup (cayenne/q7/touareg) speaking of which although the labor rate might be high i would expect a porsche dealer to at least give you a thorough diagnostic call them
+Don Green It depends upon the application as to how the diff is set up. Some grab more than others. A racing/off-road unit will have more grab than a street unit.
Dan Dewalt What type of locker is it? I know the Eaton TrueTrac needs a little resistance to engage so if one wheel is in the air sometimes applying the brake lightly helps it engage.
Hey you guys should have more views ! What's up with that? I'm suspecting a differential problem with my volkswagen touareg and can't get any help from the VW dealer. How can I tell if the differential(s) are going bad? This is terrible service from VW.
It really doesn't hurt to take your diff cover off! I'm one to learn by doing, so if there is something physically wrong you'll see the signs as soon as you take your cover off.... ( if a bunch of metal fragments fall out of that fluid, you got a problem! ) otherwise, a rear end shop is your best bet ! you wouldnt take a brokent toaster to an airplane mechanic would you? 6FU
AnthonyJ350 I'm curious why the the wheel rotates the other way because your examples means that the wheels fight each other and the car wouldn't move.
+Gary wood I'm just learning about differentials myself so I won't pretend to be an expert. But I would imagine that it's because of the way it is geared. When the power is actually coming from the engine as opposed to your hand just spinning it, then both would spin in the same direction.
+Erik Stålman A LSD (limited slip differential) transfers SOME of the power from a spinning wheel to a non spinning wheel, but still allows you to turn with ease. An open diff allows you to power both wheels with equal POWER, but at different (a differential in) speeds to go around corners. The problem is that when you have more POWER than TRACTION, the wheel with the LEAST traction (left or right) will spin. Watch a VW Golf go up an icy or muddy hill. sometimes the left wheel spins, sometimes the right wheel spins. A locked diff forces both wheels to turn at exactly the same speed. This is great for traction, but bad for turning and bad for tires wear if you have some traction (like in the rain).
Clutch type lsd will spin both tires in same direction if you turn one by hand. The gm g80 locking diff you can spin on tire real fast and you will hear a lock clunk and the other tire wil jerk forward. A Torsten style lsd if you spin one tire by hand it will turn other tire in opposite directions like and open diff.. Only two ways for sure tell. Stomp gas or open the damn diff cover you prolly need change that damn oil anyway.
+TheBanomanew This is true. Torsen differentials behave as open differentials when one or both wheels are off the ground or under the unlikely condition where you have a 100% traction loss with one wheel. Your car's VIN can sometimes tell you what kind of differential you have.
My 89 IROC -Z 5speed car tpi motor had a factory 3:43 Borg &W rear end wit rear disc brakes! Great car! Tough engine! Trans n rear end was on weak side, should of held up to just bolt on mods. But No! My 02 mustang GT can take a beating daily n has for 13 years! My old iroc only had 40000.0 miles on it? Cause trans or rear end was always busted!!! My GT has got 250000.0 miles cause she tough n never busted n lots of fun to drive, n gets 26mpg on interstate!
why go to the effort of explaining a differential in leymans terms before getting to pretty much the end of the video before actually getting to the point of the video?
Jack up both rear wheels n turn wit ur hands on tire if other tire on other side turns same way its a LSD! If tire turns other way its a dawg leg! N will only spin one tire! Not good fer drag racing! U fwd dudes get u a rwd! Or say home!
+Scotty Jones ever hear of a Torsen, Quaiff, or viscous LSD? They're used in some FWD cars. It's a LOT harder to get a FWD to hook up, but it can be done.
POSI is GM's name for limited slip. Limited slip will transfer power to both wheels but will also have the ability to "slip" in a clutch based application.
What kind of diagram was that!? "Canadian"Also don't give people advice on how to use a jack/jack stands especially using a fucking thin book as a Chuck?! Smh stick to video games "A"
Easiest way to understand the operation of an open-diff is: No matter what, an open diff always splits the drive torque 50/50 across the axle. Therefore you are limited to 2x the tractive force of the wheel with the least grip available. So if you have a 2wd car, one wheel on ice and one wheel on tarmac, the total available driving force is 2x the force achieved on ice. With a locked diff in the same scenario, you get the force from the wheel on tarmac + the force from the wheel on ice. this result in more grip, but you now have a torque difference across the axle which will cause the vehicle to yaw (rotate). The open diff has less traction but drive torque is always the same across the axle so vehicle will not yaw.
Hope this was helpful :)
I really like this explanation man, thank you for sharing this!
Overall, the video is pretty good, and reasonably informative. MOST people, even otherwise experienced car people, have a hard time understanding how a differential works. Your explanation and demonstration goes a long way towards helping them.
I DID think it was funny that Dallas was trying to do the drawing and explaining, but you were the one giving him info and pointers off screen! Even so, you both tag team well and made it good to watch.
Dallas and I just recently started collaborating and this video is pretty recent. Diffs will sometimes make chattering noises or you'll have poor or inconsistent engagement. Honestly with stuff like this I'd take it to a transmission shop you trust to check it out.
That principle of wheels spinning in the same direction (when up on jacks) with a limited slip diff can be a little confusing. My 2000 Suburban with a locking diff works differently. It behaves like an open diff according to the test, however when I open the cover plate it is definitely a locking diff. Looking into this a little further, I found that the GM version of locking diff depends on centripetal force from little spinning drums inside the diff. The tires need to be spinning fast enough for those devices to rotate outward, locking the spider gears. So, our old standard test on jack stands with hand rotation of the tire fails to identify the GM locking diff. Better to trust RPO codes int the glove box, ha ha.
But if the truck was stuck and trying to lock the axle from a stand still I don't believe it could. If the power is transfered to the free wheel how could it spin fast enough to lock both wheels when it really counts? I don't know any knowledge of the GM design you have explained. It just sound like an open diff with no advantages except traction control at speed
good vid..but just a tip: if you have an eaton truetrac; and try this, one wheel will spin forward and the other backward, so this test doesnt always work to determine a LSD diff.
This doesn't apply to all differentials, the Torsen LSD in a Miata acts just like a open diff, it requires load on the wheel to engage.
good video and all, covers all the points, but a camera angle that shows both tires as you turn them by hand would've really driven the point home. on your own, jacking the vehicle up and getting underneath where you can see both the tires at the same time as you turn one makes it real easy to tell if your axle doesn't have a tag.
The side that spin will be the side with least weight, not the most. You say engine spinning clockwise places weight on the right rear? Fine, but then it's the left rear that will have least tracktion and will start to spin.
The GM automatic locking differential (G80) only engages when there's a difference of 120 rpms between the wheels.
Jeffrey Prokopowicz That's true. The one on my truck would spin in the same direction when taken off the ground though (both sides in the air).
Didn't GM often use differentials with a counter weight lock? So under normal operation it would react like an open differential until one wheel spins at a certain speed faster than the other causing it to lock up and act as a regular posi. How would you tell if you have one of those without burning out and taking a look?
jack up one side of rear end and hit the gas
milldabeast519 Uh unsafe lol
number3665 put er infront of a wall... Obviously . lol
Jack up axle, spin one wheel by hand as fast as you can, if its got the flyweights it'll lock up with the other. It doesn't take alot of speed
+number3665 when i do a burnout only one wheel goes most of time time very rarely can i get 2 too spin. I Wish 2 would spin all the time
Anthony, been looking at your library for Drive shaft U Joint replacement for G35/350Z...Have you done it on your 350Z? ...I prefer not going 1 piece and keeping the car OEM 2 piece...I noticed the OEM U Joints have pressure dimples holding them in place instead of clips...Any advice/Part Numbers for replacement is appreciated.
No I haven't ever tried doing it yet. Why don't you want the aftermarket 1 piece? Vibration?
@@AnthonyJ350 Exactly! I don't want to increase NVH...On the contrary, I would like to restore the quietness of the car when I bought it new...I've tried extensive sounddeading to keep it out...So I did some diagnosing and found the noise coming from the front Driveshaft U Joint... I pushed the U joint at 90° from each other... There was play in one direction...Now I'm researching options.
@@stealthg35infiniti94 I would just pull the driveshaft out, have a drive train shop install a new u joint with a grease fitting.
@@AnthonyJ350 Looks like that's the way it is going to happen. Both Z/G OEM driveshafts are discontinued. U Joint part number is sketchy at best. Perhaps Z1 Motorsports can help. If I come with a good p/n ,I'll share it with you.
@@AnthonyJ350 So far I may have 3 options. 1st.Get an aftermarket U Joint (Ebay) possible fitment issues ($25) .2nd Get an aftermarket front drive shaft ($110) 3rd Get an aftermarket one piece drive shaft ($500+)
I have been told that my Jeep Commander Overland with the 5.7 Hemi has lockers. Others have told me no way... Can you tell me by the info I just gave you? It does have the QD2 in it. Thanks
+Jeffrey K You can actually call the dealership with you VIN and they can tell you what options the vehicle left the factory with.
if lockers then it's a switch to disengage it.
so i have a question about what type of diff i should use on a project. i am building a dual tracked vehicle with a differential and brakes for steering, 2 master cylinders, one for each tracks with a diff in the middle. i am wondering what type of diff would be better to use, my thought was open so one track could be comletly locked up to allow a very tight turning radius but i wouldn't have the traction for both tracks going in deep mud unless i ride the brakes for that track to force it to slow down or stop to allow the other one to turn. i am just asking because i am having a hard time trying to figure out if that would be the best choice. thanks
Explosive Gaming Why not electronic or air lockers so you can lock them for maximum traction or disable one or both when you want a better turning radius.
so you say a locking diff so for better traction when i need it but when i dont need it i can unlock it for better turning. Im far from an expert on differentials i focus more on engines and transmissions but i do know a little about diffs, so if i do use a locking diff would it have the same properties as an open that i need for turning when its unlocked or would it be different
Explosive Gaming Yes, try searching elocker or electronic locker and you can research its properties.
not sure if you got your car fixed but looks like the touareg has 3 locking differentials and i believe the rear is LSD when it is not lock'd as well. i would advise finding you another VW dealer or audi dealer unless there is a transmission shop locally that is familiar with foreign cars and that specific chasis of the VW autogroup (cayenne/q7/touareg) speaking of which although the labor rate might be high i would expect a porsche dealer to at least give you a thorough diagnostic call them
How much slip will a lsd slip ?
When u turn the wheel on one side
Can u hold it still on the other wheel
Or will it still move to some degree?
+Don Green It depends upon the application as to how the diff is set up. Some grab more than others. A racing/off-road unit will have more grab than a street unit.
I have a 2002 camaro v6 how can I make both wheels spin the same way? And any idea of how much it would cost?
You can buy a limited slip from Eaton or Yukon Gear. With labour it'll probably be a $1200 upgrade but the car will drive a lot better after.
I have a go Sierra z71 and it has a locker in it but when I jack it up one tire spins the opposite way
Dan Dewalt What type of locker is it? I know the Eaton TrueTrac needs a little resistance to engage so if one wheel is in the air sometimes applying the brake lightly helps it engage.
What's it mean when you spin one tire and the other don't move at all both tires are off the ground 76 chevy van 30
That's right , that's what I
said in the video if you watched it!
When you take off is it normal to feel a tug or like bump as your taking off please help
Can an open diff have a posi unit installed? I have a 68 impala with open and want to change gearing and have posi. Thanks
John Unger Yup, Positive Traction is GM's term for Limited Slip. Look into something from Eaton at your transmission shop.
May I ask what type of wheels are on the red truck ?
The ugly kind 😂
Hey you guys should have more views ! What's up with that? I'm suspecting a differential problem with my volkswagen touareg and can't get any help from the VW dealer. How can I tell if the differential(s) are going bad? This is terrible service from VW.
How to u fix the open diff?? Meaning... to make both spin instead of one
You need a traction device, like a clutch or hellical limited slip, or a locker. There's also spools but aren't recommended for the street.
LoL @ the hubcap.
When i turn my wheel the other doesn’t turn at all. When I go around to the other side and turn the wheel the opposite wheel doesn’t turn ?
It's most likely an open differential
@@AnthonyJ350 dang it
my cadillac brougham won't spin unless I'm going up a hill and only one side spins
+Steadman Williams You likely have an open differential. The wheel with the least traction will spin.
It really doesn't hurt to take your diff cover off! I'm one to learn by doing, so if there is something physically wrong you'll see the signs as soon as you take your cover off.... ( if a bunch of metal fragments fall out of that fluid, you got a problem! ) otherwise, a rear end shop is your best bet ! you wouldnt take a brokent toaster to an airplane mechanic would you?
6FU
Nice try lads, but you don't have much idea.
Care to elaborate? I'm always interested in hearing other people's theories.
AnthonyJ350 I'm curious why the the wheel rotates the other way because your examples means that the wheels fight each other and the car wouldn't move.
Hey I don´t really understand what a LSD does compared to an open or locked diff... Happy for answer!
+Gary wood I'm just learning about differentials myself so I won't pretend to be an expert. But I would imagine that it's because of the way it is geared. When the power is actually coming from the engine as opposed to your hand just spinning it, then both would spin in the same direction.
+Erik Stålman A LSD (limited slip differential) transfers SOME of the power from a spinning wheel to a non spinning wheel, but still allows you to turn with ease.
An open diff allows you to power both wheels with equal POWER, but at different (a differential in) speeds to go around corners. The problem is that when you have more POWER than TRACTION, the wheel with the LEAST traction (left or right) will spin. Watch a VW Golf go up an icy or muddy hill. sometimes the left wheel spins, sometimes the right wheel spins.
A locked diff forces both wheels to turn at exactly the same speed. This is great for traction, but bad for turning and bad for tires wear if you have some traction (like in the rain).
That was as much use as indicators on a submarine😂 ( Only joking, great explanation well done)
Steve McIlroy Haha thanks
We call it a Pig in the axle plant.
Clutch type lsd will spin both tires in same direction if you turn one by hand. The gm g80 locking diff you can spin on tire real fast and you will hear a lock clunk and the other tire wil jerk forward. A Torsten style lsd if you spin one tire by hand it will turn other tire in opposite directions like and open diff.. Only two ways for sure tell. Stomp gas or open the damn diff cover you prolly need change that damn oil anyway.
+TheBanomanew This is true. Torsen differentials behave as open differentials when one or both wheels are off the ground or under the unlikely condition where you have a 100% traction loss with one wheel. Your car's VIN can sometimes tell you what kind of differential you have.
yeah, but what if the clutches are worn on the posi???
Guess you need a rebuild or a new limited slip anyways.
My 89 IROC -Z 5speed car tpi motor had a factory 3:43 Borg &W rear end wit rear disc brakes! Great car! Tough engine! Trans n rear end was on weak side, should of held up to just bolt on mods. But No! My 02 mustang GT can take a beating daily n has for 13 years! My old iroc only had 40000.0 miles on it? Cause trans or rear end was always busted!!! My GT has got 250000.0 miles cause she tough n never busted n lots of fun to drive, n gets 26mpg on interstate!
It has a borg warner trans. And a gm rear end. I had one with a blower motor and never had rear end problems
Torsion differentials spin different directions
why go to the effort of explaining a differential in leymans terms before getting to pretty much the end of the video before actually getting to the point of the video?
Zoom into what your trying to illustrating please. Difficult to see. Thanks.
I seen ol Ford helping out a Chevy again, chocking the wheel
Lol yup
WOW GUYS YOUR SO SMART LMFAO
if in my car ane foult is there so plz can u teel me
lol @ the ford book
Or you could check online using vehicle year, model, etc,,,,,
fricking hubcaps!
Non mechanic minded wannabes , aslo im a mechanic of 25 years so dnt keyboard bash me back . Because I'll put you to shame
doesnt apply to torsen diffs
Jack up both rear wheels n turn wit ur hands on tire if other tire on other side turns same way its a LSD! If tire turns other way its a dawg leg! N will only spin one tire! Not good fer drag racing! U fwd dudes get u a rwd! Or say home!
+Scotty Jones ever hear of a Torsen, Quaiff, or viscous LSD? They're used in some FWD cars. It's a LOT harder to get a FWD to hook up, but it can be done.
limited slip and posi are not the same. with limited slip u still have 1 wheel spin
POSI is GM's name for limited slip. Limited slip will transfer power to both wheels but will also have the ability to "slip" in a clutch based application.
Haha bunch of amateurs
Not very bright these two.
What kind of diagram was that!? "Canadian"Also don't give people advice on how to use a jack/jack stands especially using a fucking thin book as a Chuck?! Smh stick to video games "A"
Thanks for the feedback!
Stick to your day jobs.
Thanks for the feedback!
What is this😒
Stuff