At high speeds they wheels turn the same direction. That said, the front wheels will turn more, so they'll have more influence.

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!

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.

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!

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.

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)

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

+Klaus Scherer I assume it would, theres gotta be some threshold at which the back wheels change orientation

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.

+Jabba12000 0 In that system not very much. Minimum change and only at high speeds.

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 :-)

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.

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.

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

Not really. At high speed that would compromise lot of grip.

Yeah same thing, different manufacturers called it different things but yeah Nissan's hicas does the same thing. I have it in my 300ZX

+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

+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.

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 :)

Watch their video. It works the same

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.

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.

+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

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.

lol, that is idiotic

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?

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

+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.

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.

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.

Carlos Bernier Hiding in the closet. Doesn't want to come out for some reason (but I'll keep trying).

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?

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.

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

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.

I find it more attractive than looking at you folks.

Engineering Explained Lmao

+Daniel Mazurka Great for towing or carrying heavy loads. Worth it on a work truck.

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".