Rear end pushing side to side....

[turbocliff]

I have had my car at the track a few times on slicks, and always noticed that through the midlle to top of third gear, the rear of the car would push it self from side to side quite a bit. I chalked it up to haveing 29.5" tires with only 11-12 psi of air pressure, and figured that was to be expected.

However, Last night I was at the track again, but this time on 275-60-15 drag radials, and well....I really think the top end "swaying" was worse! It was more violent, and it almost felt like another few mile an hour, and I might actually start fishtailing...

What might be causing this? Alignment? Control arm bushings? My car is full weight, totally stock suspension.

 

[pacecarta]

rear controll arm bushings.
does your axle have a lot of side to side play , as in if you push sideways on the car does the body move while axle stays in place or are your . sounds like your axle not maintaining its thrust angle under the load
i run adjsutable uppers with spherical connector at frame and stock bushing in axle ,for lowers i have box steel fixed sleeved metal bushing lowers and you cant move my car side to side, only my tires deflect , the rims move with the body
you dont need to go as stiff as i did but the stockbushings on mine were worthless for holding the axle in place , most would reccomend poly bushings in the stock arms and box in the stock lowers
as for the front the bushing under the downpipe (passenger rear upper) gets worn out fast from the heat ,unless there is a sheild put over it when its replaced . hard to maintain steering if its worn out and the wheel moves around

 

[Sleeper-6]

I had a nasy sway on regular 225/60's whenever I would get into the throttle hard. I haven't gotten around to changing the rear arm bushings yet, but after I switched over to new Bilstein shocks it went away.

 

[turbocliff]

When the car is parked, and I shake the body, the rear end appears to be rock solid, the only movement is in the tires. The shocks I have are real mushy (prolly the factory 105K miles originals) I'm gonna make some balls out runs with more pressure in the tires to see if the problem goes away, the air pressure was less than what I thought last time at the track...

We'll see what happens.

 

[1991syclone]

When I first got my GN it had a side to side movement at higher speed. (Under WOT 3 and 4 gear, very noticable during the 3rd to 4th shift) I had checked the rear susp and saw no problems, doing some other work I loosened the lower control arm-pass side-when all the pressure was off of the arm I found the back brace broken. I put an extra plate on both side and rewelded, also gave a full weld to all the braces in the rear attachment points.

 

[Brian Collins]

we like to dance

My car does a little shimmy when i get on and off the gas at speed as well. I have some new stock arms (the trunk was completly full of parts when i got it last week) that I'm going to put on. Does anybody have any info on bushings? Where to buy? What kind? Part #'s? Thanks

 

[turbocliff]

Well, i never did end up changing anything in my rear suspension, and the "shimmy" is gone, the cause: I believe it actually had something to do with my slipping 200R4 tranny. I know this may not make sense, but since I replaced the rans with the TCI TH350, this problem has completely dissapeared, even with 28 X 10.5 slicks with only 10psi, there is no movement whatsoever, and on the radials, same thing....


Brian, any auto parts store should have stock replcement bushings, however you could find several aftermarket performance bushings from companies like energy suspension, ect.-

Ciff