Great info and research, it doesnt go unappreciated. I'm watching this thread before replacing my rack
Anyone know about steering rack updates?
- Thread starter destrux
- Start date
The new gen Corollas have zero dead-spot in the center.. my mom just was just issued a rental with 20k miles, and my friend's mom owns the Type-S or w/e and same thing. At first I thought something was up because even the slightest input moves the car.
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I checked tonight and the Supra innter tie rods are M14-1.50 thread, same as the 94-04' Mustang (older Mustangs use a different thread). So if the lengths are correct, the mustang rack will thread onto the supra outer tie rod ends and it will be THAT simple. The Supra inner tie rods won't fit the mustang rack, so hopefully the mustang rack with the inner tie rods on it is about the same width (length?) as the Supra rack. I'm going to see if I can find that info later.
Haven't found any swappable spool valves for the OEM rack yet, still looking though. I might see if I can modify some original spool valves on a lathe. I think I know what needs to be done. First I have to convince my boss to buy a lathe.
Haven't found any swappable spool valves for the OEM rack yet, still looking though. I might see if I can modify some original spool valves on a lathe. I think I know what needs to be done. First I have to convince my boss to buy a lathe.
Any luck on that info yet? Would be pretty awesome to have something easily modified to work. Normally I'm not crazy about power steering, but considering the rubber up front I'll be running, it will be appreciated.destrux;1893948 said:
As for the lathe, I find that with every new tool I buy, I end up finding a use for it that I wouldn't have ever thought of. For example, never thought I'd need a shop vac. Those things are pretty damned useful for cleaning up cobwebs in the garage, as well as the seams/cracks that dust likes to settle into in said garage.
te72;1894291 said:Any luck on that info yet? Would be pretty awesome to have something easily modified to work. Normally I'm not crazy about power steering, but considering the rubber up front I'll be running, it will be appreciated.
As for the lathe, I find that with every new tool I buy, I end up finding a use for it that I wouldn't have ever thought of. For example, never thought I'd need a shop vac. Those things are pretty damned useful for cleaning up cobwebs in the garage, as well as the seams/cracks that dust likes to settle into in said garage.
Shop vac + fine wordworking skills = home made vacuum forming table
But anyway, anything can be made to fit
Or you could use something like this: http://www.retrorack.com.au/I still need to check if the rack length (inner socket to inner socket) is the same or close to the same as stock as this is critical to the bumpsteer curve. If the rack length is too long for rack lowering and outer tie rod spacers to fix, or too short for inner tie rod spacers to correct it, the car will end up with an unacceptable amount of bumpsteer. The only solution I know of outside of the rack that can correct that is custom length upper and lower control arms.... which is out of the scope of my project ambitions. This is the only thing I can see that might kill this rack swap idea.
If you need help visualizing the problem (I did)... here's a diagram I borrowed from circletrack.com
I haven't had much luck finding this info online. With all the guys road racing mustangs, I'm surprised nobody has this stuff posted anywhere.
If you need help visualizing the problem (I did)... here's a diagram I borrowed from circletrack.com
I haven't had much luck finding this info online. With all the guys road racing mustangs, I'm surprised nobody has this stuff posted anywhere.
Yaaay at least you understand the bumkpsteer concept
(not to mention akerman angle)
My old Z Car had THE WORST bumpsteer of any production car I've driven...
Short stroke shocks to limit travel helped but it was something I never got around to correcting..
(not to mention akerman angle)
My old Z Car had THE WORST bumpsteer of any production car I've driven...
Short stroke shocks to limit travel helped but it was something I never got around to correcting..
At least if you change something it's for a reason better than "So and so did it" or "it looks trick"
Yes, I try not to blindly follow trends. I have seen too many friends ruin their cars and waste their money that way.
Found a nice article detailing the process of fitting a proper rack and pinion unit, and dialing in (er... out) bumpsteer.
http://woodwardsteering.com/images/cat05 pdf 64-79.pdf
I'll post it here for future reference... I tend to use this place like a notebook. When I forget about a project, then rediscover it a year (or five) later this thread will pop up in google and I'll remember why I did (or didn't do) something.
Found a nice article detailing the process of fitting a proper rack and pinion unit, and dialing in (er... out) bumpsteer.
http://woodwardsteering.com/images/cat05 pdf 64-79.pdf
I'll post it here for future reference... I tend to use this place like a notebook. When I forget about a project, then rediscover it a year (or five) later this thread will pop up in google and I'll remember why I did (or didn't do) something.
I have a 91 and when the stupid PPS is operating like it should, the steering is terrific and I believe it is the original rack in the car. When the PPS goes out however, it makes me wish I had a manual rack because power assisted steering with out the power assist is worse than manual steering. Just my two cents.
I took a vehicle suspension class in college and stumbled upon the pdf of the textbook we were using. It was old (over 10 or 15 years) but covered a wide range of topics and a wide range of suspensions. If you'd like it as reading material or even to browse through let me know, it's on my other laptop though.
edit: Fundamentals of Vehicle Dynamics, by Gillespie, 1992.
edit: Fundamentals of Vehicle Dynamics, by Gillespie, 1992.
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Sidewinder, just because an idea isn't new, doesn't mean it isn't still applicable. Would be wise to remember that (which it seems you do since you brought that book up)...
Destrux, I understand most of that diagram, except for the intersection point. Is that where the steering column mounts to the rack? It's kinda late and has been a long day for me, I might be misunderstanding it somehow. Never thought the ball joint traveled that far, unless there is an upper ball joint as well that I'm forgetting?
I suppose if I looked up what bump steer is, I might have a better understanding of this thread, but that will have to wait for the time being...
Destrux, I understand most of that diagram, except for the intersection point. Is that where the steering column mounts to the rack? It's kinda late and has been a long day for me, I might be misunderstanding it somehow. Never thought the ball joint traveled that far, unless there is an upper ball joint as well that I'm forgetting?
I suppose if I looked up what bump steer is, I might have a better understanding of this thread, but that will have to wait for the time being...
The intersection point is an imaginary point, it doesn't represent the location of any actual part of the car. It's almost impossible to measure on the car, because everything is in the way.
Look up the bumsteer article on circletrack.com and give it a read, they explain it better than I'd be able to.
Thanks Sidewinder, I just downloaded it from some college FTP I found. I'm always up for learning something.
Look up the bumsteer article on circletrack.com and give it a read, they explain it better than I'd be able to.
Thanks Sidewinder, I just downloaded it from some college FTP I found. I'm always up for learning something.
Hi te72,
Here is a quote from "Turn Fast Race Driving... "Bump steer-- is the introduction of steering input caused by a bump in the road surface. When a wheel travels up and down over a bump, it actually swings in an arc. If the steering tie-rod does not swing in the same arc as the suspension, the wheel will have an increase or decrease in toe and will result in a slight steering effect. Virtually all suspension geometries on street cars have some degree of bump steer, through it will be very slight. However, modifying a car's suspension by using lowering springs can increase the amount of bump steer. Bump steer causes tire scrub, and loss of traction if experienced during cornering. If you're altering you car's suspension, measures should be taken to minimize or eliminate bump steer."
Van
Here is a quote from "Turn Fast Race Driving... "Bump steer-- is the introduction of steering input caused by a bump in the road surface. When a wheel travels up and down over a bump, it actually swings in an arc. If the steering tie-rod does not swing in the same arc as the suspension, the wheel will have an increase or decrease in toe and will result in a slight steering effect. Virtually all suspension geometries on street cars have some degree of bump steer, through it will be very slight. However, modifying a car's suspension by using lowering springs can increase the amount of bump steer. Bump steer causes tire scrub, and loss of traction if experienced during cornering. If you're altering you car's suspension, measures should be taken to minimize or eliminate bump steer."
Van
te72;1896142 said:Sidewinder, just because an idea isn't new, doesn't mean it isn't still applicable. Would be wise to remember that (which it seems you do since you brought that book up)...
Destrux, I understand most of that diagram, except for the intersection point. Is that where the steering column mounts to the rack? It's kinda late and has been a long day for me, I might be misunderstanding it somehow. Never thought the ball joint traveled that far, unless there is an upper ball joint as well that I'm forgetting?
I suppose if I looked up what bump steer is, I might have a better understanding of this thread, but that will have to wait for the time being...
Thanks for the info Van. That makes sense actually, although I never really knew that was an "issue", I just always thought that was how cars were. Didn't know there was much to do to fix it...
How I'm understanding it then, is basically if you were to let go of the wheel when driving in a straight line, hit a bump, and the result of the bump would cause the wheel (because of the suspension's "bump steer" factor) to move on its own.
How I'm understanding it then, is basically if you were to let go of the wheel when driving in a straight line, hit a bump, and the result of the bump would cause the wheel (because of the suspension's "bump steer" factor) to move on its own.
No, what you're thinking of there is caused by a change in wheel offset causing a change in the scrub radius, or torque steer effect being caused by wide wheels.
Real bumpsteer won't move the steering wheel. You could weld the rack solid in a straight line and the bumpsteer would still cause the tires to steer. If you hit a dip in the road going in a straight line (with equal compression on both sides) it would do nothing but change the overall toe in/out and the bump steer would cancel itself out side to side... you would probably not feel the bump steer. If you dive into a turn and one side compresses and the other droops (or if you hit an offset dip in the road) one tire will bump steep differently than the other and the car will feel like you jerked the steering wheel off path. The problem is the driver will usually then try to correct, overcorrect, and make the problem feel even worse.
Real bumpsteer won't move the steering wheel. You could weld the rack solid in a straight line and the bumpsteer would still cause the tires to steer. If you hit a dip in the road going in a straight line (with equal compression on both sides) it would do nothing but change the overall toe in/out and the bump steer would cancel itself out side to side... you would probably not feel the bump steer. If you dive into a turn and one side compresses and the other droops (or if you hit an offset dip in the road) one tire will bump steep differently than the other and the car will feel like you jerked the steering wheel off path. The problem is the driver will usually then try to correct, overcorrect, and make the problem feel even worse.