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Discussion Starter · #1 ·
I think my car is afflicted with it...
It just started when i lowered my car the last 1/2" or so...
It swerves crazily on rough pavement...

Will offset rack bushings fix this?
How hard is it to change rack bushings?
 

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subscribing :D
 

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Discussion Starter · #3 ·
Maybe I should try to put this on a different forum...but which?
 

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Try the road racing/auto x forum
 

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What is Bumpsteer? Is it a mysterious term that racers use to excuse their ill handling racecar? The technical explanation is a change in toe caused by suspension travel or an unwanted steering input caused by such a toe change. If you already understand that explanation you probably have fixed any bumpsteer you may have had. If not, imagine driving through a parking lot. The right side of the axle has a speed bump and you try to go around. You miss, the right front tire hits the speed bump and your car steers itself to the right even though the steering wheel did not move. Now imagine you are going to turn a corner and you choose to go through the corner at a very high speed. As you approach the corner you turn the steering wheel in and the car begins to roll. As you have the steering wheel set in position to carry you through the turn, the car continues as the suspension compresses on the loaded side of the car. The front wheel turns in more than you had originally intended, causing the car to turn more sharply. You correct the steering wheel in the opposite direction pulling the car out of its roll and you miss your intended path through the turn. Both of these examples illustrate bumpsteer and are undesirable when maximizing the handling performance of your Mustang. Two things happened when the vehicle crossed the speed bump or when the vehicle entered the turn. First, there was suspension travel, the wheel, spindle, a-arm and other components moved upward as it crossed over the speed bump or when the vehicle began to roll into the turn. Second, this suspension travel caused the wheel to change direction even though the driver did not turn the steering wheel. This change in wheel direction made the vehicle turn in a direction not intended by the driver.

When the suspension travels up and down, the wheel moves up and down in an arc or half circle around a pivot point. This pivot point is not a physical location or suspension part but is an imaginary point on the chassis, similar to a vehicle's center of gravity. The distance from the pivot point to the wheel and spindle is equal at all points in the wheel's range of vertical movement. The tie rod and steering rack must be positioned so that as the wheel moves up and down, the tie rod follows an arc which is parallel to the arc followed by the spindle. If the steering rack or tie rod is not positioned correctly, the distance between the steering rack and wheel may differ from the distance between the pivot point to the wheel at different suspension heights. When this occurs the steering rack will push or pull the spindle as the suspension moves up or down thereby turning the wheel and causing a change in toe angle.

The direction the front wheels are pointed is called toe angle. When both wheels are pointed parallel there is 0 degrees toe. When the front of the wheels are pointed inward, there would be positive degree toe or what is called toe in. When the front of the wheels are pointed ******d there is negative degree toe or what is called toe out.

Here at Steeda Autosports we offer solutions for your mustang to improve handling and minimize bumpsteer. We have our offset steering rack bushings to raise the steering rack, which helps prevent bumpsteer. Our offset steering rack bushings bring the rack closer to the pivot point to minimize bumpsteer. When a Mustang is lowered another unwanted result other than bumpsteer would also be a change in the geometry of the front suspension. To improve this, we have our exclusive X2 ball joints, which corrects the geometry of a lowered mustang. Our X2 ball joint raises the spindle in relation to the a-arm, restoring the roll center on a lowered Mustang. X2 ball joints improve steering response, reduces body roll and maximizes your mustang's handling. When using our X2 ball joints it is recommended that you relocate the tie rod pickup point. This can be accomplished with adjustable tie rod ends, which is also known as a bumpsteer kit. Give us a call today for technical advice about offset rack bushings, bump steer kits, and other ways of improving your mustang's performance.

This is a description directly from Steedas Web Site.
 

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Discussion Starter · #6 ·
without crawling under my car at this time....how hard is it to install steering rack bushings? I hope...that the rack does not have to be removed....

I wonder if the offset rack bushings fix my problem...
 

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Very well put NITROSTANGRACING!!!!!!

Kyle
 

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I can't take responsibility for that statement. I went direct to Steeda's website and pasted it here. I figured that would be the easiest thing to do.

To replace the bushings yes the rack does need to be removed. if you disconnect the Tie Rods from the Steering Knucle and undo the bushing mounitng bolts you might be able to pull the rack far enough away to get it done.
 

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so i have a flamin river quick ratio set-up. it came with the steering shaft, rack, energy suspension bushings(not off-set but the car isn't lowered), and new tie rod ends. are these tie-rod ends the ones i would want to control bumpsteer?
 

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Discussion Starter · #10 ·
if your car is not lowered, bump steer is not a problem you'd have.
 

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that's a good writeup on bumpsteer, but that's not what mike's problem is. Mike's problem is tramlining. Searchy searchy, lots of info on it.
 

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Discussion Starter · #12 · (Edited)
i'll be damned..something else!

after searching, it appears that i have done all i can do...bushings, strut tower brace, camber plates...

BUT, this problem did not arise till after i lowered my car that last 1 inch or so....

perhaps bumpsteer is part of the problem, at least...

i found the quote:

"Make sure you do not have too much caster. With maximum caster when you get in a rut the car will want to steer strait but the rut is not totally strait causing the car to "hop" out of the rut at spots."

i will try to reduce my castor...
i increased the castor when i lowered the car, too....
 

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I don't know about that caster thing, but when you lowered the car, you naturally increased the negative camber, and it can have a big effect on tramlining because the tires will try to "climb" the sides of the ruts. If you didn't dial it back out, that could be an issue.

And when you increased the negative camber you also toe'd it out...if you didn't correct for that, that'll be an issue too.

I would not reduce caster...the more positive caster you have, the better off you'll be on many levels, up to the point where you have so much you raise the end steering arm on the spindle too much and cause bump steer but I don't think that's your problem.

But when you say "rough" pavement, do you mean ruts in the same direction of the car, or bumps across the road and/or potholes?
 

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Discussion Starter · #14 ·
well, the place i noticed it worst was when turning over some bumps...rolling deformed pavement....not parallel ruts

my camber is better than it's ever been...i got the camber plates at the same time i lowered it further...

i did increase castor at the same time...

from what you have written on this and other threads...i seem to have symptoms of both tramilining and bumpsteer.. but it seems bumpsteer is more of an issue because:

the tires were the same as before the suspension adjustements were made (more castor, lowered suspension, less negative camber, and deleting the strut-top bushings as a result of the new camber-castor plates)
 

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Did you have the car professionally aligned? What are your alignment settings? How is your tire wear since installing the springs and c/c plates? What kind of tires are you running? What wheels?

These are all questions that could have some bearing on your problem.

When I had my '83 GT and I lowered it with Eibach springs I had really bad bumpsteer problems, not to mention very bad tire wear. I added a set of c/c plates and got a professional alignment and the car handled great. Fast forward to my '90 GT and I've got the same plates, same wheels (Pony wheels), and stock springs but the steering is all over the place more than my '83 ever was and I've noticed it even more from one brand of tires to another.

Carson
 

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Discussion Starter · #16 ·
yeah, Firestone aligned the wheels, after the camber plates were installed, and i had them align the wheels to the specifications that MFE gave me..which i trust happily

the tires are Nitto 555 245/45/17 up front.

the tire wear looks perfect..unlike before i had the plates, which was wearing the inside edge a little faster than the rest of the tire
 

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Well, it is possible that the lowering plus the extra caster raised the tie rod ends enough to invoke more bumpsteer so maybe I shouldn't have been so rash about it NOT being the caster. Dial a lot of it back out (don't worry about the minimal effect this will have on toe for a short test), take it back over the same portions of roads, and see if it makes a difference. If it does, I thnk it's safe to say some offset rack bushings would probably help.
 
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