4 Wheel Steering
06-25-2003, 09:51 PM
#13
Senior Member
Join Date: Oct 2002
Location: Rockville, Maryland
Posts: 144
Let me tell you... I have extensive personal experience in this matter....
I bought a 1988 Prelude Si model in college... it had basically every option EXCEPT the 4 wheel steering (4WS).
I drove it like that for a few years and got very used to how it handled during aggressive driving with just the regular two wheel steering.
Then I decided I wanted 4WS. Turns out all the older Preludes ALL come SET UP for it from the factory. You just need 3 extra parts. 1) rear steering box 2) steering shaft that runs down the tunnel 3) Front steering rack that has the 'take off' to steer the rear wheels. I bought all the parts at the junk yard for a few hundred bucks and swapped them in myself and got the car aligned to factory specs.
The way the system worked on the OLDER 1988-1991? Preludes was ALL mechanical with no computer controls at all. At smallish steering inputs, it steered all four wheels in the same direction, but with the fronts steering about 2-3 times "quicker" than the rears. This made the car swerve at high speed GREAT. When you very first turned the wheel just a few inches like in a high speed swerve, the fronts and backs turned almost the same amount! You could be slicing through other cars at 100+ mph with almost no drama at all. It felt like you were going 20 mph. The only car that I've ever driven that even comes close to the high speed swervability of that Prelude is my FD. Keep in mind my Prelude was riding on 195/60 R14 all seasons too! At maximum "same steer" the rears would be at something like 1.6 degrees and the fronts were at about 4-5 degrees I think. (I don't recall for sure)
Now if you kept turning the wheel farther, the fronts continued to turn even more just like normal, but now the back tires started going back to a straight ahead position.
If you REALLY turned the wheel even MORE like in a parking lot situation or parallel parking, the rears would steer even more and actually be pointing in the opposite direction fairly noticeably.
If I recall correctly, this car held the slaloming record in a major magazine for several years before being dethroned.
The handling was great at speed and I could EASILY beat cars on my favorite twisty roads with at least double the horsepower and tire size/quality of tires. It was just so easy to go fast.
Parallel parking was a JOKE... I could fit into spots that looked impossible because it was SO easy to flip the car around with the rears steering in the opposite direction. This mod also cut 3 feet off the turning diameter, so I could bust out U-turns where a much smaller car would require a 3 point turn to avoid hitting the curb. It was particularly fun at low speeds with passengers... you drive in a parking lot and then turn the wheel very hard and very fast and you could "feel" the back of the car moving around in a strange way... it would freak them out sometimes...
The down sides? Only two that I ever encountered.
1 - The rear steering actually made it HARDER for dumbasses to park that weren't used to it. Example... Imagine you are parallel parked very close up against the curb. Your natural reaction when you go to leave is to turn the wheels hard left, and pull off the curb. The only problem is that with 4WS, this actually made the rears get CLOSER to the curb and "trap" you in. Once you were aware of how much steering wheel angle resulted in what action on the rear wheels, this is not an issue... My step mom got very frustrated by this one day in DC though hahahahahahah.
2 - If you were coming around a 90 degree turn very hard, and made the mistake of lifting on the gas too much, this shifts weight to the front.... Coincidentally, the amount of steering wheel turn angle where you tend to be during this manuever is about where the rears start to swap directions. I managed to spin the car out once right after I put the 4WS on because I believe I was going too fast, transferred weight to the front while at the same time the rear wheels changed their angle of steer from kinda keeping the back end "tucked in" to letting it "swing wide" and this caused just enough instability to upset the car and spin it. After I got the alignment fixed (it was probably way, way off) this never happened again, but sometimes you could feel the weight moving back there sort of like the way the FD rear suspension "sets" in a hard turn.
All in all, it was an awesome system. I think the main reason we don't see it on more cars is that you just would never appreciate it unless you drive your car at 9/10ths and most people don't even drive their cars at 3/10ths.
I wish the FD had it!
Brian
I bought a 1988 Prelude Si model in college... it had basically every option EXCEPT the 4 wheel steering (4WS).
I drove it like that for a few years and got very used to how it handled during aggressive driving with just the regular two wheel steering.
Then I decided I wanted 4WS. Turns out all the older Preludes ALL come SET UP for it from the factory. You just need 3 extra parts. 1) rear steering box 2) steering shaft that runs down the tunnel 3) Front steering rack that has the 'take off' to steer the rear wheels. I bought all the parts at the junk yard for a few hundred bucks and swapped them in myself and got the car aligned to factory specs.
The way the system worked on the OLDER 1988-1991? Preludes was ALL mechanical with no computer controls at all. At smallish steering inputs, it steered all four wheels in the same direction, but with the fronts steering about 2-3 times "quicker" than the rears. This made the car swerve at high speed GREAT. When you very first turned the wheel just a few inches like in a high speed swerve, the fronts and backs turned almost the same amount! You could be slicing through other cars at 100+ mph with almost no drama at all. It felt like you were going 20 mph. The only car that I've ever driven that even comes close to the high speed swervability of that Prelude is my FD. Keep in mind my Prelude was riding on 195/60 R14 all seasons too! At maximum "same steer" the rears would be at something like 1.6 degrees and the fronts were at about 4-5 degrees I think. (I don't recall for sure)
Now if you kept turning the wheel farther, the fronts continued to turn even more just like normal, but now the back tires started going back to a straight ahead position.
If you REALLY turned the wheel even MORE like in a parking lot situation or parallel parking, the rears would steer even more and actually be pointing in the opposite direction fairly noticeably.
If I recall correctly, this car held the slaloming record in a major magazine for several years before being dethroned.
The handling was great at speed and I could EASILY beat cars on my favorite twisty roads with at least double the horsepower and tire size/quality of tires. It was just so easy to go fast.
Parallel parking was a JOKE... I could fit into spots that looked impossible because it was SO easy to flip the car around with the rears steering in the opposite direction. This mod also cut 3 feet off the turning diameter, so I could bust out U-turns where a much smaller car would require a 3 point turn to avoid hitting the curb. It was particularly fun at low speeds with passengers... you drive in a parking lot and then turn the wheel very hard and very fast and you could "feel" the back of the car moving around in a strange way... it would freak them out sometimes...
The down sides? Only two that I ever encountered.
1 - The rear steering actually made it HARDER for dumbasses to park that weren't used to it. Example... Imagine you are parallel parked very close up against the curb. Your natural reaction when you go to leave is to turn the wheels hard left, and pull off the curb. The only problem is that with 4WS, this actually made the rears get CLOSER to the curb and "trap" you in. Once you were aware of how much steering wheel angle resulted in what action on the rear wheels, this is not an issue... My step mom got very frustrated by this one day in DC though hahahahahahah.
2 - If you were coming around a 90 degree turn very hard, and made the mistake of lifting on the gas too much, this shifts weight to the front.... Coincidentally, the amount of steering wheel turn angle where you tend to be during this manuever is about where the rears start to swap directions. I managed to spin the car out once right after I put the 4WS on because I believe I was going too fast, transferred weight to the front while at the same time the rear wheels changed their angle of steer from kinda keeping the back end "tucked in" to letting it "swing wide" and this caused just enough instability to upset the car and spin it. After I got the alignment fixed (it was probably way, way off) this never happened again, but sometimes you could feel the weight moving back there sort of like the way the FD rear suspension "sets" in a hard turn.
All in all, it was an awesome system. I think the main reason we don't see it on more cars is that you just would never appreciate it unless you drive your car at 9/10ths and most people don't even drive their cars at 3/10ths.
I wish the FD had it!
Brian
06-26-2003, 03:56 AM
#15
Senior Member
Join Date: Nov 2001
Location: Ames, IA
Posts: 4,773
My sister had a '91 SI and that thing handled great without the 4WS...I can only imagine how much better it would have been with it. Of course, she had Tokico suspension on there, so that helped.
The 3000GT's 4WS system is variable with speed too...the car actually crab-walks over 55, from what I read when it came out. (I used to want a VR-4)
The 3000GT's 4WS system is variable with speed too...the car actually crab-walks over 55, from what I read when it came out. (I used to want a VR-4)
06-26-2003, 07:19 AM
#17
Senior Member
Join Date: May 2003
Location: Dover DE
Posts: 989
Nissan has had it on a lot of cars in the past
Nissan Skyline R32, R33, R34
Nissan 300ZX Z32
Nissan Silvia S13, S14, PS13, RPS13
The system is called HICAS basically a computer generated steering system. Using inputs from the steering rack the rear is adjusted accordingly. Although not as much as some of the Mazda, Toyota and Chevrolet you are talking about. The system has different setups for different speeds and in the Nissan it is not designed for paralell parking but more for high speed. I can feel it changing in the GT-R especially in a curve when you hit different engaging speeds. On the GT-R it tends to feel like the *** end is going to come around on you, but due to the camber on a GT-R it acctually helps plant the tire harder.
I can't remember the name of the Mazda in Japan that has it, but it is drastic the way the wheels move out, the car is the size of a Cosmo, it might be a Millenia
Nissan Skyline R32, R33, R34
Nissan 300ZX Z32
Nissan Silvia S13, S14, PS13, RPS13
The system is called HICAS basically a computer generated steering system. Using inputs from the steering rack the rear is adjusted accordingly. Although not as much as some of the Mazda, Toyota and Chevrolet you are talking about. The system has different setups for different speeds and in the Nissan it is not designed for paralell parking but more for high speed. I can feel it changing in the GT-R especially in a curve when you hit different engaging speeds. On the GT-R it tends to feel like the *** end is going to come around on you, but due to the camber on a GT-R it acctually helps plant the tire harder.
I can't remember the name of the Mazda in Japan that has it, but it is drastic the way the wheels move out, the car is the size of a Cosmo, it might be a Millenia
06-26-2003, 10:32 AM
#18
Senior Member
Join Date: Aug 2002
Location: Mike is a Liar!
Posts: 4,848
someone mentioned having the wheels turn parallel.. the new chevy trucks do that.. and they say it makes changing lanes easier since the truck just kind glides sideways..
I remember seeing a 4ws Prelude at my Buddies shop.. that thing is crzy how the tires turn out.. and then lock in straight position.. as you staighten out the wheel..
I remember seeing a 4ws Prelude at my Buddies shop.. that thing is crzy how the tires turn out.. and then lock in straight position.. as you staighten out the wheel..
06-26-2003, 10:43 AM
#19
Senior Member
Join Date: Aug 2002
Location: Denver, CO
Posts: 4,985
Yes, that's true.. most 4WS systems work like this:
Low Speed
/ /
\ \
High Speed
/ /
/ /
So at low speed the steering radius is decreased, and at high speed, both axles head in the direction of steering input. Ever seen the 300ZX or Nissan Hicas/Super Hicas systems at work? The turn is more like a toe change than anything.. Very minimal amount of steering from the rear. Also, to answer Phins' question, if I recall correctly the S13's with 4WS were considerably heavier and more difficult/expensive to replace parts. Specifically because of the increased number of components add weight and complexity to an otherwise simple mechanism (rear drive).
Low Speed
/ /
\ \
High Speed
/ /
/ /
So at low speed the steering radius is decreased, and at high speed, both axles head in the direction of steering input. Ever seen the 300ZX or Nissan Hicas/Super Hicas systems at work? The turn is more like a toe change than anything.. Very minimal amount of steering from the rear. Also, to answer Phins' question, if I recall correctly the S13's with 4WS were considerably heavier and more difficult/expensive to replace parts. Specifically because of the increased number of components add weight and complexity to an otherwise simple mechanism (rear drive).
06-26-2003, 11:58 AM
#20
Senior Member
Join Date: May 2002
Location: California
Posts: 22,465
Originally Posted by TheCamel' date='Jun 26 2003, 04:19 AM
I can't remember the name of the Mazda in Japan that has it, but it is drastic the way the wheels move out, the car is the size of a Cosmo, it might be a Millenia
mike