Rear End Bump steer.

ricardoa1

Registered User
Ive now put some miles on the suspension to fully feel what the car is doing and not feel foreing to the the set up.
Now comes the part that bothers me about the set up that I am now trying to eliminate. Although wheel hop and handling have gone down and up respectively. I now have what feels like excessive bump steer in the rear of the car. Only happens on really uneven surfaces the rear end likes to shift left to right it hard to explain but everytime one of the rear tires hit a bump or hole the rear wants to come out and catches itself. It is starting to get annoiying. Ive been reading on the internet about these issues on car with wide tires which my car now has 285s, and inproper wheel alightment.
Now before you guys beat me down with, "should have left the rubber bushings, so the toe link compensator does it job. I dont see how it applies to my problem although it could.

So what is happening to my rear suspension that is doing this. I also feel like the rear tires are very hot all the time small drives gets them to pick up dirt and small pebbles and stones and can be heard on the inner wheel wells when they fly off the sticky tire.

Did my aligment shop do a very poor job or did I shoot myself if the foot.
 
Did my aligment shop do a very poor job

Here is my bet.

I had this problem on the black one and it went away with an alignment.

I currently have this on the white one as well, but half the front suspension has now been replace and it is now ready to get an alignment.
 
IMO the first step would be to have the alignment verified. Did the shop give you a sheet with the final numbers after they did the job?


cheers
Ed N.
 
When I pay to have an alignment done, I want a printout with the specs. Especially if you know that the mods to the car could cause potential issues, if the alignment isn't bang-on.


cheers
Ed N.
 
I agree about triple-checking the alignment.

I don't know what suspension changes you've made but I have to wonder if it is too stiff? If the suspension can't absorb bumps the car will just skip across them. I only mention this because I've gone too stiff on a couple cars over the years----cornering is great on a glass smooth surface but the car just jumps all over the place if cornering over bumps.

<shurg>

Just a thought

DD
 
I have added poly knuckle busings and lower control arm inner bushings are also poly. I have addco sways the 1 1/4 ones and Stiff progressive lowering springs with the Tokico ARC.
I forgot to change out the upper camber adjustment bushings the one that connects the upper arm to the subframe. I remember the guys at sears trying to move those after I told him that it was an adjustment point but I no changes in camber was seen on his computer. So he only adjusted the toe adjustment. In the rear. I am not sure if the bushing could have gone bad, but it should be made out of aluminum in the center and tuning the bolt should move it enought were the machine should pick up degrees.

I then went to another shop and payed there cause the wheel became off center. And I had a bad experience with Sears after they went for a beat ride on my car. I got that aligment for free so I did not want to go back an complain. The second shop did an alightment and found the tie rod busted so i brought it back a second time to the second shop. I dont think the kid touched the rear just the front. The car is straight but has the above problems.
 
how wide are the rear tires, the front? The wider the tire, the less on-center it will feel, especially on a road grooved from heavy trucks and such.

My gut tells me there is something wrong with the alignment. Either that or maybe a loose subframe?
 
Wondering is not a big issue tires are 245 fronts and 285 rears. It is the bumps that cause the rear to kick out left or right depending on the bump.
 
If the rear camber was never adjusted properly, I think that you need to start there. Generally once the MN-12 cars are lowered, you end up with excessive negative camber, especially on the rear. It's likely that you have over 1 deg. negative, when all you need is 0.4 to 0.5.


cheers
Ed N.
 
Several of the folks that have aligned my car did not know how to set the rear camber. They were looking for eccentric cams external like there are for front camber and rear toe adjustment and seeing none assumed the car could not be adjusted. I had to "instruct" them about the eccentric BUSHING and how camber was to be adjusted. I agree that changing ride height has big effect on alignment. My car was ALL out of whack when it was raised from a 1.25" drop to stock ride height.
 
I had teh same issue and still hav eyet to get it fixed.....They werelike you hav eno eccentics to adjust..I was like..OOHH YEESS III DDOOOOOOOOO ITS THE DAM BUSHING!..

Anyway I have bigger fish to fry at the moment
 
Even with the eccentric in the bushing the rear may be tough to get aligned properly when lowered. Somewhere around here someone actually cut some slots in the upper control arm to allow for more adjustment.
 
Question is does that eccentric go bad and strip or what not. I saw him turning it and spinning the bolt and not changes were made to camber. But TOE STARTED TO GO OUT OF WHACK.
 
Where the cam is positioned shouldn't affect toe unless the lower bushings are not allowing the knuckle to pivot in them... Though I would think that would indicate other issues. That cam basically pulls the top of the wheel in or away from the subframe.
 
Thats why it was so strange.
BMWs have no problems with the wheels kicking out at the bottom and that is supposed to increase handling to a point but, I like to hear from people with my symptoms on stock bushings.

The camber bushing is made out of alum on the inside. and the bolt should be a sliced bolt that tuns the guts of the bushing. I dont want to replace the bushing if I dont have to. Seems like that bushing should only go bad on the rubber side but even if the rubber was damaged it should provide adjustments since the rest is metal.
But why didnt I get any adjustment when we turned it.

getimage.php
 
Back
Top