What happens when you are turning a corner at very high speeds? For example on a large off/on ramp. Does the car think you are turning or changing lanes?
I would like to know how the algorithm for 4-wheel steering is developed. Why is the angle for rear wheels limited to about 5 degrees (for most AWS cars I've seen) and not more? Thanks for the great explanations!
Have to think even at highway speeds, you won't put as much steering deflection into the rear wheels as the front(even though they're now turning the same direction) -- If you're going around a large curve, as you said WRT to slow-speed, you won't be "turning". The stability is more for quick movements or lane changes, so you have to find a way to differentiate between which actively while driving.
If this only shifts the car side to side at high speed, how would this work on a track or an autocross (solo) where there are high speed corners where the car needs to change direction?
It depends how hard you are turing and your speed, I had a mazda Mx6 with rear wheel steering and when you gerk the wheel or brake slightly it knew what you wanted to do.
Logan Chambers Keep in mind what you want is a very small change in angle on the rear to either generate stability or oversteer. My FWD Acura for example can oversteer but that's because I have the toe out set to 0.05 degrees on the rear. When you corner the outside rear wheel tries to get the rear to step out. With toe in the rear feels much more stable under braking and on high speed corners. A small change like that can change the characteristics of the car completely.
I think but might be wrong that it has something to do with side slip build up on front / vs rear axle. Might help make side slips more even between axles and that could increase performance.
would be cool if you could use the "high speed" set up of turning all 4 wheels to point the same way at low speeds too when parking. imagine you've just parked in a normal parking bay but a bit too close on one side... you could just shimmy forwards a few feet and at the same time increase the gap you want to make. straighten up and then move back those few feet with the increased gap without having to use too much steering input and having to steer one way and then the other to "swing" it into the desired position... which can just go too far or put you right back where you started :P also very jealous of the S4 video!!!!! in the market for getting one myself here in the UK :D
I think there has been concept cars made with that kind of steering in the past. Pretty sure they refered to it as crab steering. It wouldn't be hard for companies like lexus to add that to their current system. Just needs an input from the driver so it knows what you intend to do.
DrSasso that is a very good idea, I completely agree with you. This would give a very good help to most drivers in Ireland, I've seen many dissasterous drivers trying to desperately park their cars. They would usually end up causing an obstruction or just leaving the space entirely, also ruining other drivers moods.
Parallel parking is what I thought of, but shifting around in a parking spot would be very nice if it is too narrow for both doors to open. Also in high speed corners you could angle the car to compete body roll. (Would be like drifting with complete grip :D) But it would really need a way to controll it... Two steering wheels would be very confusing. Maybe (esbecially without manual transmission) there could be some kind of pedal to decide the ratio: Toes for parallel driving, heel for extreme cornering (relax for fixed back wheels) Sounds fun! I want that alot!
That was the best version because it was steering wheel dependent and speed dependent-by nature of the way you drive. It was just heavy but it was very strong and reliable, it rarely broke!
Cruz Ortiz You know the track record of corporations making quick decisions. The mechanism added more weight to the car and the car had a very weak engine, people complained about that. So, instead of just giving it a more powerful engine, they cut the mechanical version out and opted for the electric version. The electric version was good but it broke a lot because of the lazy way they wired the thing-lots of cheap wiring. When people complained about that, they took it out the U.S. market. The old mechanical version 1987 to 1990, was only in the overseas market, the U.S. never officially received that version, although you may be able to pick one up here and there in the U.S.
Why not have a 1:1 ratio between the back and front, wouldn't this give an even tighter turning radius? Also, independent rear steering would work better in some cases, like under braking to provide pigeon toeing. And with computers, you can have accurate ackerman with any angle.
I've got an idea in my head for an all terrestrial vehicle, where the wheels will need to be able to extend free of the body, and have been evolving my thoughtpath in the direction of using some sort of robot arms that have suspension in each limb section, hub motors and hubcaps which transform into variable pitch propellers. The interior of the wheel rim should be shaped like a manoeuvring cowl on a ship. In theory, the arms should give a completely smooth ride when on land, it would be possible to alter center of balance to become a true four wheel drive, four wheel steer/prop. With all of the current and pipeline vehicles and technologies in the works, the tech will soon be readily available to design and create the vehicles of our crazy childhood dreams! The future is finally here!
+Engineering Explained I had to do a school project on drifting and slip angle and when I looked into it it was amazing the complexity of it all. I can PM you the slide of it if you want. It's something crazy with the radius and tangents of the turn, angles and CG of the car in relation to the radius and a whole bunch of other stuff.
What happens in a high speed and very large diameter turn? Is the wheel angle of the rear wheel steering exactly proportional to the fronts at high speeds or does the amount change depending on something like steering angle?
Excellent video, as always. Somehow, though, I feel your videos have become a bit hasty. I recently watched an old one of yours and it was more laid back, and actually more detailed. Having said that, keep up the good work!
Dan I get excited and talk fast. I aim for the same detail, but I try not to repeat topics I've already covered (if applicable). Glad you enjoy the videos!
+engineering explained can you do a comparison between two similar cars where one car has four wheel steering and one is the normal two wheel steering?
Nice, but can u answer, how big bus rear wheels steer, the bus have 3 axles the front and thle last rear steer, how the last axle gets information from front? Its a big distance. With sensor, or with big rods from front to rear, or metal rope like in some small planes? THANK YOU!
the nissan 300ZX's have it with a hydraulic system. most people don't like it for maintenance and weight reasons. i personally think its a cool feature that should be implemented into more cars
rustybacon54 Yeah it'd be interesting to see if the benefits outweigh the negatives. I'd be curious to see some performance testing of cars with and without.
I think that is should be better for them to offer independent way to steer rear wheels in some situations : parallel parking , tight maneuvering , etc. For instance , it would be possible to zig-zag into parallel parking space .
Hi Jason, have a question about this. What happens when taking a curve on the highway (60mph)? I mean, this pseudo-parallel movement won't help on the turn... looks like. Thanks!!!
Jorge Concheyro The front wheels will be rotating more (looking from above) than the rear, so you'll still be turning, rather than simply facing forward and shifting left/right.
i own a St-203 6th gen toyota celica. it has 4 wheel steering, however it is only operating on the 'fast setting' where all four wheels turn in the same direction. do you have any idea what the problem is likely to be. This car is rare where i am from so most people are clueless. will have diagnostics done soon but any info you have would be great. (from Barbados)
Wouldn't the 'opposite steering' mechanism be better than the 'crab steering' at both low and high speeds? if stability is a problem the angle can just be reduced, no? I can imagine race cars would go around corners much faster with the 'opposite' rear wheel steering system.
please also provide the links where you study these topics so that we can read them for more detail you cant provide all information in one video i understand that
The rear wheel steering in the Rx-7 was called DTSS, Dynamic Tracking Suspension System, and if you had enough g-force (essentially load) on the back wheels going through corners, it would allow the rear wheels to slightly adjust their camber, not steering. It was essentially loose bushings put on the back wheels. I think 1983 was the first year to have this.
I'm looking to set the low speed variant of this on a monocoque chassis with 13 inch rims and a drexler style differential is there any particular area of physics I must look at such as ackerman. Could you point me in sort of a general direction of what data I need so the car doesn't oversteer or understeer
Think mid engine transaxle, but mounted up front. Scobaru fwd boxes are a good option if your home building a rwd, mid engine car, and want to do it on the cheap, plus boxer low CofG. You can also use regular transverse fwd engines and boxes, but that makes for a shorter wheel base, or funky layouts.
But see in like a Cadillac 500 Eldorado the engine is like right in the middle of the strut pillars and it looks from the eye I can see is no way you can cram a transmission so it lines up with the axles.
kevin soos I just had a look at the tranny on one of those and its a weird bird, but its not too difficult to describe (changed my mind about that statement mid way through writing this, but I'm a sucker for punishment lol). Basically, think of a mid engined transaxle again, but shifted to the right (looking from in front of the hood), offset so it sits beside the cylinder V, and rotated 180*. Basically power is shifted from being inline with the engine by either gear, or chain (not sure what they used) to be inline with the gear box that runs beside the right side of the engine. The gear box is then run bassackwards (rear of car---> Front of car), and power is taken off like a FWD transmission, and passed under the engine through CV shafts. To simplify, Think of the transmission as an Inverted J A trip to google images will make this a whole heck of a lot clearer
What if I'm driving at a low speed then accelerate, are they going to turn on the opposite direction then go straight then turn in the same direction as the front wheels?
+Cameron Sours so general motors are bringing back rear wheel steering systems it think they should offer it as a option on every vehicle across all GM brands and as a kit that can be fitted onto any GM brand vehicle in any GM brand service center any where in the world
Could I buy and fit an AWS all wheel steering system onto any car? What mods should I do and how much it would cost to get a hands on even if its a used one? Planing a little racing project 😀 thanks
What's the relationship between bore/stroke ratio and the "torqueyness" of an engine? Imagination tells me a longer stroke increases torque, but the Integra Type R is one of the highest revving factory engines ever made, and it uses and undersquare engine, and for example the old Ford Windsor 302 V8 used an extremely oversquare engine, but it's very low revving and full of torque. So what gives?
Mostly because you're trying to equate revs with torque - and they are two separate entities. Torque is independent of how high the engine revs - horsepower is linked to engine revolutions - not torque.
I thought I was trying to equate bore/stroke ratio and torque, and bore/stroke to rpm, independently of torque. I know torque and rpm are independent of each other, but I don't understand the relationship between bore/stroke ratio and those two separate things.
ExactlyPrecisely Torque is related to compression ratio. Bigger compression ratio= bigger bang = more torque. This is also why diesel engines typically have more torque.
Compression ratio doesn't equal a bigger bang - compression ratio allows more energy transfer to the piston for a longer duration. That equates to more torque when *everything else remains equal*. If you want a bigger bang, add more air and fuel. That's what turbocharges/superchargers, and overall engine displacement increase is for. In a simplistic standpoint, the bore/stroke ratio in itself means nothing. If you match everything else up (fuel delivery, intake porting, overall engineering) like a Buick 455 (huge bore/short stroke) and an Olds 455 (small bore/huge stroke), they make nearly identical power at the same RPM. The reason why large-stroke engines sometimes produce more torque at lower RPMs is because they are engineered to operate lower in the RPM range due to the larger mass/inertia and velocity differences in the rotating assemblies. The absolute fact is - it's comparing apples to pears here. He's comparing a fuel-injected high-compression 4 cylinder to a mostly carbureted 8 cylinder. Nowadays, everything from the fuel type to the compression ratio all the way up to fuel delivery, air induction, cooling, and intake design all have an impact on overall torque, peak torque, and where that torque is delivered in the RPM range.
Okay it makes sense now. So an increased stroke produces no increase in mechanical advantage, and so it does not influence the torque production of the engine. it's other factors like you said, fuel delivery, compression ratio, all that stuff that is deliberately designed to make the engine the way the engineers want it to be. And it just so happens that I saw two very different engines both leaning on opposite extremes of the ways engineers design engines, and noticed a single aspect of them that was different, and thought that had something to with it when in fact it really doesn't. Thanks for taking the time to answer my question GammaCruxis.
My infiniti has 4 wheel steering. When I cut the wheel I cannot see a difference in the rear wheels. Maybe it doesn't happen in park? Typically about how many degrees would the rear wheel turn?
Hey Engineering Explained , i was looking into some flywheel kinetic energy recovery system, pretty intresting theme that you definitely should make some videos about. But they use a wet clutch to connect/disconnect the flywheel from the wheel, so i was wondering if there would be any friction loss in the wet clutches? Or would the rotational inertia in the clutches cause them to separate completely, also the the oil should slow down the flywheel pretty much?
Acura's P-AWS employs a different system that independently actuates each rear wheel separately. This allows both wheels to toe in during hard braking to improve stability, something this Lexus system cannot do.
Every home built system ive seen was built with a solid axle (used 2 front axles). Usually use a hydraulic system and a joystick or switch of some sort to control it manually as well. One of the greatest things ever when backing up a trailer. You will probably want some way to be sure that the rear wheels return to center (truck i drive at work just has a light on the dash) and a system that holds pressure (so that the wheels stay at what ever position they are moved to)
A good idea in theory... in practice the implementation and 20 years of aging can make a bit of a difference. Nothing like your car's system randomly deciding to work on a particular corner, ripped mine out.
It adapts the torque distribution to the two wheels, so that it transfers power to the wheel that needs it, rather than the wheel that spins and skids. The need for the differential gear in the first place, comes from the fact that the two wheels have to spin independently while turning, since they both take a different path length around the corner. Normally, there is a cluster of bevel gears that allows them to rotate independently, and can transfer power to both wheels, as long as both wheels equally grip the road. However, when you are stuck, and one wheel has traction while the other skids in place, all the power is transferred to the skidding wheel by default, and you need it to transfer to the wheel that grips. An automatic torque-based differential provides a direct connection to the ring gear of the differential set, for the outside wheel when you are turning, so that power has a bias to transfer to the outside wheel while turning, where it is needed the most. This also allows it to transfer power only to the wheel that grips, when one wheel is skidding, by engaging one clutchpack or the other.
It operates via some function including variables mainly such as speed and steer as well as yaw and pitch and other things so the car won't just jerk the rear wheels the opposite direction when you hit the limit
Very incomplete in my view. You didn't explaine that the system also works with the esp to stabilize the car without using the breaks. It is specialy efective in breaking in unheven susfaces by using the rear wheels to auto counter-steer it can reduce the breaking distances by a huge margin.
Cars with power steering have a planetary gear that is driven by a motor, in addition to the steering wheel, and the common output drives the rack and pinion steering. The motor assists the action of the driver, by moving the ring gear, while the driver's steering wheel moves the sun gear. The carrier arm drives the steering, adding up the power from the driver, with the power from the motor assist.
No other car has and all mechanical 4 wheel steering system like the 3rd gen prelude. Every other car 4WS is based of a electrical module/motor. My thought is what if the sensor or motor fails during a turn and stays stuck. You won’t be able to drive the car at all lol
+Sean Klimczak All highways curve eventually. The front steering angle can certainly be larger than the rear, and even if it wasn't you could maneuver through highway bends.
I doubt the engineer didn't think that through. The rear steering system will decouple from the motor and center to its default position due to caster angle effect. Similar to what happened when you turn the front wheel and it centered itself automatically.
rear wheel steering adds so little to driving dynamics that I say is just not needed in fact all it does is adds expences to the manufacturing price. Durring driving front angle is not visible, rear angle is almost nothing. What you rally want for stability and performance is constant all wheel drive like quattro or similar.
in cases where the vehicle is long it is nice I am sure. I have a long, and have vehicle. unfortuantely I doubt they make one that is in my price range but right now my vehicle is long enough I almost have to get clearance by the state to turn. ha ha. So I can see it being useful for long vehicles, but I am sure it is a very shiny penny and not something the factory would offer but a customization shop might
I wish japanese car manufacturers had been a bit less rushed in introducing their 4ws systems, it got a reputation of being a high-maintenance, expensive gimmick with little actual benefits. With modern stability augmentation computers it would be something entirely different it was back in the late eighties...
Here in Australia, it's very common on nissan skylines (as we've been importing these since the mid 90's). Nowadays, though, the whole HICAS system is either removed entirely or locked with a solid bar.
I searched this thinking it's a relatively new concept and it seems ur isn't. So why now are car manufacturers adding this feature as a special feature.
Because most drivers aren't willing to pay for it. It's a feature that improves your steering performance, but you pay for it both in the cost of the extra parts, and in more parts to maintain. The fixed rear wheels are sufficient for most drivers, and that's what most drivers settle with.
Engineering Explained I am planning to make a video about 4 wheel steering 😊 I am going to make it in my native language which is malayalam . You could have include Some industry examples with this like hicas and quadrasteer .
This rear steering is just another waste of the consumers money. It Is not necessary or needed for domestic use. There are better features or options to spend the money on.
It's not a direct system. It's computative - it calculates how much your "wrenching" the steering wheel and adjusts accordingly. That's why it's called "active" not "passive".
Reminds me of a Honda Prelude. That car was ahead of its time.
Always wondered how it handled shifting sideways vs actually turning. That's badass.
What happens when you are turning a corner at very high speeds? For example on a large off/on ramp. Does the car think you are turning or changing lanes?
At high speeds they wheels turn the same direction. That said, the front wheels will turn more, so they'll have more influence.
after reading this title what immediately came into my mind is wow, now i can drift at 5km/h and without burning my tyres
lol
I would like to know how the algorithm for 4-wheel steering is developed. Why is the angle for rear wheels limited to about 5 degrees (for most AWS cars I've seen) and not more? Thanks for the great explanations!
Have to think even at highway speeds, you won't put as much steering deflection into the rear wheels as the front(even though they're now turning the same direction) -- If you're going around a large curve, as you said WRT to slow-speed, you won't be "turning". The stability is more for quick movements or lane changes, so you have to find a way to differentiate between which actively while driving.
If this only shifts the car side to side at high speed, how would this work on a track or an autocross (solo) where there are high speed corners where the car needs to change direction?
It depends how hard you are turing and your speed, I had a mazda Mx6 with rear wheel steering and when you gerk the wheel or brake slightly it knew what you wanted to do.
Also, the front tires have a much higher degree turning angle if you're turning in hard.
Thank you
Logan Chambers Keep in mind what you want is a very small change in angle on the rear to either generate stability or oversteer. My FWD Acura for example can oversteer but that's because I have the toe out set to 0.05 degrees on the rear. When you corner the outside rear wheel tries to get the rear to step out. With toe in the rear feels much more stable under braking and on high speed corners. A small change like that can change the characteristics of the car completely.
I think but might be wrong that it has something to do with side slip build up on front / vs rear axle. Might help make side slips more even between axles and that could increase performance.
would be cool if you could use the "high speed" set up of turning all 4 wheels to point the same way at low speeds too when parking. imagine you've just parked in a normal parking bay but a bit too close on one side... you could just shimmy forwards a few feet and at the same time increase the gap you want to make. straighten up and then move back those few feet with the increased gap without having to use too much steering input and having to steer one way and then the other to "swing" it into the desired position... which can just go too far or put you right back where you started :P
also very jealous of the S4 video!!!!! in the market for getting one myself here in the UK :D
DrSasso Ahh, that would be interesting - could help with correcting parallel parking yes.
I think there has been concept cars made with that kind of steering in the past. Pretty sure they refered to it as crab steering. It wouldn't be hard for companies like lexus to add that to their current system. Just needs an input from the driver so it knows what you intend to do.
DrSasso that is a very good idea, I completely agree with you. This would give a very good help to most drivers in Ireland, I've seen many dissasterous drivers trying to desperately park their cars. They would usually end up causing an obstruction or just leaving the space entirely, also ruining other drivers moods.
Parallel parking is what I thought of, but shifting around in a parking spot would be very nice if it is too narrow for both doors to open. Also in high speed corners you could angle the car to compete body roll. (Would be like drifting with complete grip :D)
But it would really need a way to controll it... Two steering wheels would be very confusing. Maybe (esbecially without manual transmission) there could be some kind of pedal to decide the ratio: Toes for parallel driving, heel for extreme cornering (relax for fixed back wheels)
Sounds fun! I want that alot!
1000 likes and 19 dislikes. That's incredible. What a channel
My Honda Prelude SI was 4WS 1988 it was awesome! All mechanical no electric motor or wires! It was nice!
That was the best version because it was steering wheel dependent and speed dependent-by nature of the way you drive. It was just heavy but it was very strong and reliable, it rarely broke!
Yes it was badass I wonder why the discontinued it
Cruz Ortiz You know the track record of corporations making quick decisions. The mechanism added more weight to the car and the car had a very weak engine, people complained about that. So, instead of just giving it a more powerful engine, they cut the mechanical version out and opted for the electric version. The electric version was good but it broke a lot because of the lazy way they wired the thing-lots of cheap wiring. When people complained about that, they took it out the U.S. market. The old mechanical version 1987 to 1990, was only in the overseas market, the U.S. never officially received that version, although you may be able to pick one up here and there in the U.S.
Why not have a 1:1 ratio between the back and front, wouldn't this give an even tighter turning radius?
Also, independent rear steering would work better in some cases, like under braking to provide pigeon toeing. And with computers, you can have accurate ackerman with any angle.
thnxx for this topic i am currently working on this project :) i like all of your videos
I've got an idea in my head for an all terrestrial vehicle, where the wheels will need to be able to extend free of the body, and have been evolving my thoughtpath in the direction of using some sort of robot arms that have suspension in each limb section, hub motors and hubcaps which transform into variable pitch propellers.
The interior of the wheel rim should be shaped like a manoeuvring cowl on a ship.
In theory, the arms should give a completely smooth ride when on land, it would be possible to alter center of balance to become a true four wheel drive, four wheel steer/prop.
With all of the current and pipeline vehicles and technologies in the works, the tech will soon be readily available to design and create the vehicles of our crazy childhood dreams!
The future is finally here!
In 2018 still useful!
Things to do EE on next:
Wrinkle wall tires
lenco transmissions
Slip angle
Anti-lag
Super0dp I have two videos on anti-lag. :) Might tackle slip angles sometime though.
+Engineering Explained I had to do a school project on drifting and slip angle and when I looked into it it was amazing the complexity of it all. I can PM you the slide of it if you want. It's something crazy with the radius and tangents of the turn, angles and CG of the car in relation to the radius and a whole bunch of other stuff.
What happens in a high speed and very large diameter turn? Is the wheel angle of the rear wheel steering exactly proportional to the fronts at high speeds or does the amount change depending on something like steering angle?
the rear wheels get about 4 - 10 degrees to turn (on older models) so the front wheels still do most of the work.
xkblxcripple Gotcha, this makes more sense :-)
Thanks for the video!
Excellent video, as always. Somehow, though, I feel your videos have become a bit hasty. I recently watched an old one of yours and it was more laid back, and actually more detailed. Having said that, keep up the good work!
Dan I get excited and talk fast. I aim for the same detail, but I try not to repeat topics I've already covered (if applicable). Glad you enjoy the videos!
Is the manual 4 wheel steering the best Honda it's amazing with that
+engineering explained can you do a comparison between two similar cars where one car has four wheel steering and one is the normal two wheel steering?
Weird. That looks awesome.
Can you explain how the 88-91 Prelude 4WS works and how it compares to this days tech. Plz tag me so I can see the video
Can you do a video on passive rear steering?
Nice, but can u answer, how big bus rear wheels steer, the bus have 3 axles the front and thle last rear steer, how the last axle gets information from front? Its a big distance. With sensor, or with big rods from front to rear, or metal rope like in some small planes? THANK YOU!
YES! Searched for this, was hopeful your channel was going to have a video on it, and so, here I am! :D o/
the nissan 300ZX's have it with a hydraulic system. most people don't like it for maintenance and weight reasons. i personally think its a cool feature that should be implemented into more cars
rustybacon54 Yeah it'd be interesting to see if the benefits outweigh the negatives. I'd be curious to see some performance testing of cars with and without.
Engineering Explained What was the fastest car through Road and Track's slalom in 1988?
this guy really knows his sruff
do you always need a control system or there is a mechanical linkage ??
Do rear steering wheels have king pin axis and scrub radius?
I think that is should be better for them to offer independent way to steer rear wheels in some situations : parallel parking , tight maneuvering , etc. For instance , it would be possible to zig-zag into parallel parking space .
Is Nissan's HICAS an example of this kind of system, or does it function differently?
Hi Jason, have a question about this. What happens when taking a curve on the highway (60mph)? I mean, this pseudo-parallel movement won't help on the turn... looks like. Thanks!!!
Jorge Concheyro The front wheels will be rotating more (looking from above) than the rear, so you'll still be turning, rather than simply facing forward and shifting left/right.
i own a St-203 6th gen toyota celica. it has 4 wheel steering, however it is only operating on the 'fast setting' where all four wheels turn in the same direction. do you have any idea what the problem is likely to be. This car is rare where i am from so most people are clueless. will have diagnostics done soon but any info you have would be great. (from Barbados)
does this work with independent suspension? PLEASE SAY YES
+M80 Gaming and this also can be controlled from inside the cab of a car
Yeah
+Engineering Explained yesss I am going to spent a shit ton of money on 1 truck buy the time I get out of collage
+M80 Gaming What truck would that be?
costom
Can we see a follow up on the pros and cons on this system?
Wouldn't the 'opposite steering' mechanism be better than the 'crab steering' at both low and high speeds?
if stability is a problem the angle can just be reduced, no?
I can imagine race cars would go around corners much faster with the 'opposite' rear wheel steering system.
Not really. At high speed that would compromise lot of grip.
How much would that install be on an suv? like a pathfinder
Check Renault's lineup from 2008. GT/4Control = four wheel steering.
please also provide the links where you study these topics so that we can read them for more detail you cant provide all information in one video i understand that
Is it true that older generations of the RX-7 have a rear wheel steering? If so, how does it work in this case?
+KingLuigi96 Don't know, but Honda Prelude used to have it.
+KingLuigi96 Yep. Many Japanese cars around that era had it. Some examples include Toyota Celica, Nissan GT-R, Prelude, 3000gt. It works the same.
But only the JDM cars? so the old japanese cars that weren't sold in japan didn't have this right?
KingLuigi96 I think so, but I am not 100 % sure that all of them did
The rear wheel steering in the Rx-7 was called DTSS, Dynamic Tracking Suspension System, and if you had enough g-force (essentially load) on the back wheels going through corners, it would allow the rear wheels to slightly adjust their camber, not steering. It was essentially loose bushings put on the back wheels. I think 1983 was the first year to have this.
I'm looking to set the low speed variant of this on a monocoque chassis with 13 inch rims and a drexler style differential is there any particular area of physics I must look at such as ackerman. Could you point me in sort of a general direction of what data I need so the car doesn't oversteer or understeer
hey I was wondering if you could do a front wheel drive explanation but without a transverse engine. Like in an audi or older Cadillacs
Think mid engine transaxle, but mounted up front. Scobaru fwd boxes are a good option if your home building a rwd, mid engine car, and want to do it on the cheap, plus boxer low CofG. You can also use regular transverse fwd engines and boxes, but that makes for a shorter wheel base, or funky layouts.
yup identical to longitudinally-mounted mid-engined transaxles.
But see in like a Cadillac 500 Eldorado the engine is like right in the middle of the strut pillars and it looks from the eye I can see is no way you can cram a transmission so it lines up with the axles.
kevin soos I just had a look at the tranny on one of those and its a weird bird, but its not too difficult to describe (changed my mind about that statement mid way through writing this, but I'm a sucker for punishment lol). Basically, think of a mid engined transaxle again, but shifted to the right (looking from in front of the hood), offset so it sits beside the cylinder V, and rotated 180*.
Basically power is shifted from being inline with the engine by either gear, or chain (not sure what they used) to be inline with the gear box that runs beside the right side of the engine. The gear box is then run bassackwards (rear of car---> Front of car), and power is taken off like a FWD transmission, and passed under the engine through CV shafts.
To simplify, Think of the transmission as an Inverted J
A trip to google images will make this a whole heck of a lot clearer
Oh ok. I think I got the picture. What should I search on google to get the best picture.
why do they install this low reflex motor instead of 2nd servo system but with oil pressure motor and worm gear?
Gotin Fuklio Electric will be quicker to respond and more efficient than hydraulic.
i mean electric makes some delay while hydraulic can remove this problem if the system is at high pressure
What if I'm driving at a low speed then accelerate, are they going to turn on the opposite direction then go straight then turn in the same direction as the front wheels?
+Klaus Scherer I assume it would, theres gotta be some threshold at which the back wheels change orientation
New Cadillac CT6 will have this as well. Interesting to see how it is received in a luxury car.
+Cameron Sours so general motors are bringing back rear wheel steering systems it think they should offer it as a option on every vehicle across all GM brands and as a kit that can be fitted onto any GM brand vehicle in any GM brand service center any where in the world
Could I buy and fit an AWS all wheel steering system onto any car? What mods should I do and how much it would cost to get a hands on even if its a used one? Planing a little racing project 😀 thanks
What's the relationship between bore/stroke ratio and the "torqueyness" of an engine? Imagination tells me a longer stroke increases torque, but the Integra Type R is one of the highest revving factory engines ever made, and it uses and undersquare engine, and for example the old Ford Windsor 302 V8 used an extremely oversquare engine, but it's very low revving and full of torque. So what gives?
Mostly because you're trying to equate revs with torque - and they are two separate entities. Torque is independent of how high the engine revs - horsepower is linked to engine revolutions - not torque.
I thought I was trying to equate bore/stroke ratio and torque, and bore/stroke to rpm, independently of torque. I know torque and rpm are independent of each other, but I don't understand the relationship between bore/stroke ratio and those two separate things.
ExactlyPrecisely Torque is related to compression ratio. Bigger compression ratio= bigger bang = more torque. This is also why diesel engines typically have more torque.
Compression ratio doesn't equal a bigger bang - compression ratio allows more energy transfer to the piston for a longer duration. That equates to more torque when *everything else remains equal*. If you want a bigger bang, add more air and fuel. That's what turbocharges/superchargers, and overall engine displacement increase is for.
In a simplistic standpoint, the bore/stroke ratio in itself means nothing. If you match everything else up (fuel delivery, intake porting, overall engineering) like a Buick 455 (huge bore/short stroke) and an Olds 455 (small bore/huge stroke), they make nearly identical power at the same RPM. The reason why large-stroke engines sometimes produce more torque at lower RPMs is because they are engineered to operate lower in the RPM range due to the larger mass/inertia and velocity differences in the rotating assemblies.
The absolute fact is - it's comparing apples to pears here. He's comparing a fuel-injected high-compression 4 cylinder to a mostly carbureted 8 cylinder. Nowadays, everything from the fuel type to the compression ratio all the way up to fuel delivery, air induction, cooling, and intake design all have an impact on overall torque, peak torque, and where that torque is delivered in the RPM range.
Okay it makes sense now. So an increased stroke produces no increase in mechanical advantage, and so it does not influence the torque production of the engine. it's other factors like you said, fuel delivery, compression ratio, all that stuff that is deliberately designed to make the engine the way the engineers want it to be. And it just so happens that I saw two very different engines both leaning on opposite extremes of the ways engineers design engines, and noticed a single aspect of them that was different, and thought that had something to with it when in fact it really doesn't. Thanks for taking the time to answer my question GammaCruxis.
how would I get about to checking 4ws can I use turntables or wheel alignment equipment
My infiniti has 4 wheel steering. When I cut the wheel I cannot see a difference in the rear wheels. Maybe it doesn't happen in park? Typically about how many degrees would the rear wheel turn?
+Jabba12000 0 In that system not very much. Minimum change and only at high speeds.
Hey Engineering Explained , i was looking into some flywheel kinetic energy recovery system, pretty intresting theme that you definitely should make some videos about. But they use a wet clutch to connect/disconnect the flywheel from the wheel, so i was wondering if there would be any friction loss in the wet clutches? Or would the rotational inertia in the clutches cause them to separate completely, also the the oil should slow down the flywheel pretty much?
Can a jdm Honda prelude drift since it has 4ws
No corner roll induced rear steer, a la Mazda fc rx7/ Porsche 917? :)
my active rear steering makes a rattling noise upon putting key switch in ON position why? Is it messed up?
The 3rd generation honda prelude is one of the few cars which a mechanical 4 wheel steering system which is pretty much bullet proof
How about passive rear wheel steering?
4WS Honda Preludes had that.
ExactlyPrecisely Those were all active. The one's in the earlier Porsche's that reared steered via the bushings were passive.
N9olan You learn something new everyday :)
Sheldon Coopers Fun With Wheels
Good video,
Do you know how they did the rear wheel steering with the early honda/ acura prelude.
Hello. Great vids! :) Could you explain how a powercommander Works on a bike?
Acura's P-AWS employs a different system that independently actuates each rear wheel separately. This allows both wheels to toe in during hard braking to improve stability, something this Lexus system cannot do.
Watch their video. It works the same
it would be nice to have something like that to cut the truning radius on my truck, but then you loose the solid axle right?
Every home built system ive seen was built with a solid axle (used 2 front axles). Usually use a hydraulic system and a joystick or switch of some sort to control it manually as well. One of the greatest things ever when backing up a trailer. You will probably want some way to be sure that the rear wheels return to center (truck i drive at work just has a light on the dash) and a system that holds pressure (so that the wheels stay at what ever position they are moved to)
How exactly will the rear wheels get steered when reversing the car out of a parking space?
A good idea in theory... in practice the implementation and 20 years of aging can make a bit of a difference. Nothing like your car's system randomly deciding to work on a particular corner, ripped mine out.
check out porsche 918 spyder. 3rd best lap time on Nürburgring
+M.a.D. try in 20 years time though
+M.a.D. try in 20 years time though
GMC Quradsteer pickup and SUV and Toyota MegaCruiser are the only 4 wheel steering trucks offered to the general public.
tengu190 1988-91 Preludes offered a mechanical 4WS system on their cars.
Many companies offer limited 4ws on limited luxury models. Nothing like what the GMC Quadrasteer or Toyota MegaCruiser had.
In the lexus example at the end, it looks like planetary gears.
Prior to seeing that, I was thinking, why not use a worm gear?
Is it the same with HICAS?
Yeah same thing, different manufacturers called it different things but yeah Nissan's hicas does the same thing. I have it in my 300ZX
How come my s13 feels like its the opposite? At high speed the back wheels kick out.
Mine is making a weird clicking noise when switching key to ON ..what’s wrong with it ?
I have this on my Lexus GS 450h feels weird but nice helps cos this is a big car.
Do be aware that the Porsche 911 has an available rear wheel steering system based on an adjustable toe link.
How old are you? I can't tell if you're 17 or like 40
Andrew Harris-Goodall And clearly it's one of those choices.
Engineering Explained Clearly. Alright, it's obviously somewhere in between. Realistic guess of 27. Is that close?
3rd Gen Preludes had a 4WS option
What is meant by automatic torque based differential
It adapts the torque distribution to the two wheels, so that it transfers power to the wheel that needs it, rather than the wheel that spins and skids.
The need for the differential gear in the first place, comes from the fact that the two wheels have to spin independently while turning, since they both take a different path length around the corner. Normally, there is a cluster of bevel gears that allows them to rotate independently, and can transfer power to both wheels, as long as both wheels equally grip the road. However, when you are stuck, and one wheel has traction while the other skids in place, all the power is transferred to the skidding wheel by default, and you need it to transfer to the wheel that grips.
An automatic torque-based differential provides a direct connection to the ring gear of the differential set, for the outside wheel when you are turning, so that power has a bias to transfer to the outside wheel while turning, where it is needed the most. This also allows it to transfer power only to the wheel that grips, when one wheel is skidding, by engaging one clutchpack or the other.
What happens if l turn my steering wheel at low speed and then l hit the "high speed low limit" while keep cornering?
It operates via some function including variables mainly such as speed and steer as well as yaw and pitch and other things so the car won't just jerk the rear wheels the opposite direction when you hit the limit
are these used in formula 1 cars?
Very incomplete in my view. You didn't explaine that the system also works with the esp to stabilize the car without using the breaks. It is specialy efective in breaking in unheven susfaces by using the rear wheels to auto counter-steer it can reduce the breaking distances by a huge margin.
lol, that is idiotic
Any fellow 4ws lude owners here? :3
Does a car with electric power steering work the same way?
Cars with power steering have a planetary gear that is driven by a motor, in addition to the steering wheel, and the common output drives the rack and pinion steering. The motor assists the action of the driver, by moving the ring gear, while the driver's steering wheel moves the sun gear. The carrier arm drives the steering, adding up the power from the driver, with the power from the motor assist.
No other car has and all mechanical 4 wheel steering system like the 3rd gen prelude. Every other car 4WS is based of a electrical module/motor. My thought is what if the sensor or motor fails during a turn and stays stuck. You won’t be able to drive the car at all lol
What if there was a curve in the highway?
+Sean Klimczak All highways curve eventually. The front steering angle can certainly be larger than the rear, and even if it wasn't you could maneuver through highway bends.
imagine if that electric motor got stuck lol
I doubt the engineer didn't think that through. The rear steering system will decouple from the motor and center to its default position due to caster angle effect. Similar to what happened when you turn the front wheel and it centered itself automatically.
rear wheel steering adds so little to driving dynamics that I say is just not needed in fact all it does is adds expences to the manufacturing price. Durring driving front angle is not visible, rear angle is almost nothing.
What you rally want for stability and performance is constant all wheel drive like quattro or similar.
in cases where the vehicle is long it is nice I am sure. I have a long, and have vehicle. unfortuantely I doubt they make one that is in my price range but right now my vehicle is long enough I almost have to get clearance by the state to turn. ha ha. So I can see it being useful for long vehicles, but I am sure it is a very shiny penny and not something the factory would offer but a customization shop might
I wish japanese car manufacturers had been a bit less rushed in introducing their 4ws systems, it got a reputation of being a high-maintenance, expensive gimmick with little actual benefits. With modern stability augmentation computers it would be something entirely different it was back in the late eighties...
Well, I think it's better to simply say technology improves over time.
3000GT comes to mind. Amazing vehicle in some ways, but todays 3000GT's still alive mostly have their rear wheel steering welded.
Here in Australia, it's very common on nissan skylines (as we've been importing these since the mid 90's). Nowadays, though, the whole HICAS system is either removed entirely or locked with a solid bar.
What happens when you're turning slow and increasing speed rapidly? Say a large radius turn or donuts.
I searched this thinking it's a relatively new concept and it seems ur isn't. So why now are car manufacturers adding this feature as a special feature.
Anyone made one with steering in the back. Drive and engine in the front and steering at the back permanent .
🤘
So how come more cars don't have it?
Because most drivers aren't willing to pay for it. It's a feature that improves your steering performance, but you pay for it both in the cost of the extra parts, and in more parts to maintain. The fixed rear wheels are sufficient for most drivers, and that's what most drivers settle with.
The only application this is relevant to is off road vehicles.
By the wire systems suck hard
Where's project integra?😩
Carlos Bernier Hiding in the closet. Doesn't want to come out for some reason (but I'll keep trying).
I remember the GTR R-34 having the same system ...
Engineering Explained
I am planning to make a video about 4 wheel steering 😊 I am going to make it in my native language which is malayalam .
You could have include Some industry examples with this like hicas and quadrasteer .
Please dont Look that often and Long on the Whiteboard
I find it more attractive than looking at you folks.
Engineering Explained Lmao
"1,000th like." :{
This rear steering is just another waste of the consumers money. It Is not necessary or needed for domestic use. There are better features or options to spend the money on.
+Daniel Mazurka Great for towing or carrying heavy loads. Worth it on a work truck.
so..should you be on the highway...and something happens in which you need to quickly turn off to a side or something..youa re fucked.
It's not a direct system. It's computative - it calculates how much your "wrenching" the steering wheel and adjusts accordingly. That's why it's called "active" not "passive".