88 Formula Twitch in the Rear

[TopNotch]

My "new" 88 Formula has a "twitch" in the rear. You can feel it on the highway when you let off the gas and then accelerate again. It occurs during the crossover from deceleration to acceleration.
I'm thinking that is the 88 rear knuckle bolt hole looseness problem I have heard about, but I would like to hear from others before I buy stuff from Rodney Dickman. He sells new 88 knuckle long bolts, and a knuckle "girdle kit" to cure the loose bolt hole problem.

[f85gtron]

I had twitches in my 85 that didn't go away until I did my own alignment using the string method. If you can, do your own. I found the alignment shops where just getting close, then leaning on the sensors to get the right numbers. I vowed to either stand and watch them, or do my own from then on.
That may not be your problem, but mine was associated with accel and decel as well.
Ron

[TopNotch]

The 88 rear knuckle is unique to that year, and so any 84-87 rear problems may not apply. The problem with the knuckle bolt hole is well documented on Pennock's, as in this thread:
http://www.fiero.nl/forum/Forum2/HTML/133458.html
The fix Rodney sells is described here:
http://rodneydickman.com/catalog/product_info.php?cPath=26_43&products_id=352
But some folks on Pennock's say it won't work. I'd like some discussion from other 88 owners.

[Fierofool]

By your description it sounds like torque steer?  It changes direction when you quickly accelerate or decelerate?  Anything lateral like bolts or bushings can do it.  Trailing arm bushings, cradle front bolts.  The one thing common to all years are the rear struts.  If you remember all the problems I went through with replacing so much of the suspension parts on my 86 and the very last thing that hadn't been replaced was the rear struts.  A bad rear strut allowed it to twitch due to roadway imperfections and also change directions when accelerating or decelerating. 

It requires a very trusted friend who's very familiar with automobiles to do this, but it could be put on ramps and while observing from underneath, have your friend lock down the brakes with the engine running and shift from Reverse to Drive while watching for unusual movement.  A bad strut wouldn't show up with this because there's no up and down body movement as while driving.

[TopNotch]

It requires a very trusted friend who's very familiar with automobiles to do this, but it could be put on ramps and while observing from underneath, have your friend lock down the brakes with the engine running and shift from Reverse to Drive while watching for unusual movement.  A bad strut wouldn't show up with this because there's no up and down body movement as while driving.

I wonder if that could be done with a video camera and a light, instead of a person under the car. It would certainly be safer.

[Raydar]

Before you do anything, just tighten the long bolts. My car (the gray one) did that.
Getting on the gas would cause the car to want to go left. Getting off the gas would cause it to try to go right.
Tightening the bolts fixed it.

I also had a similar situation with the red 88. Was caused by a slow leak in the right rear tire, and a "dead" shock on the left front.
Stepping on the gas would cause the car to "rock" on the left rear and right front wheels, causing a severe squat to the right rear. That also tended to make the car push to the left.

Two different situations, but try the easy stuff first. 

[TopNotch]

The bolt on the passenger side was noticeably looser than the one on the driver's side. Tightening it improved the twitch quite a bit, but there seems to be a tiny bit still. I'm thinking that the knuckle hole is enlarged a bit, and I'll have to do something about that some day, but it's good enough for now.

[Raydar]

Good deal!