Rear Steering Rack Causing Steering Vib? 92Q

[rrack]

I finally got the girl running the best she's ever been. Well, with one exception. I've still got that pesky vibration in the steering wheel and body. It keeps changing. Sometimes it's there and sometimes not. Most of the time between 25 and 45 mph it's the worst. At about 70-80 it is almost gone. I've rounded it down to two possible things. The drive shaft or the rear rack. I've been reading a bunch of the old postings concerning the shaft and the balance problems. I'm in the process of dropping this one and checking the balance. However, the vib can be felt in both the body and the steering wheel and sometimes it's not that bad. This leads me to think that it's someting worn out. I keep thinking it must have something to do with the front rack or something up there.

I took it to the dealer for an aligmnment and they said that the rear rack has too much play and needs to be replaced. The front rack is fine. They said that this "may" cause the steering vib. Is this true? They couldn't make any guarantees. They were kind enough to have the ticket printed out when I went to check on the alignment. $1,400 for the rear rack! I said no way! They wouldn't check anything else without replacing the rack first.

Anyway, I can't remember if I actually read it somewhere or had a dream about it but, is there a bracket that replaces the rear rack and does away with it? I'd like to eliminate the rear rack as a possibility before I move on to the shaft.

btw...filing DTPA lawssuit next week for the other lil problem I had...and still no T3 receipt....I even spoke to the new lady there and she said she was going to mail it out 3 weeks ago...will call again tomorrow.

[maxnix]

Robert, is this a t model with HICAS? Or is the rear rack actually the rear subframe?

[Highway Q45]

For what it's worth, I was told by a dealer also that the rear rack had too much play in my 91Q w/ HICAS. I took it to another good alignment shop and they were able to align it with no problems. The steering wheel vibe in mine was all from tension rods but I see you've done those also. I don't think the HICAS comes into action all that frequently; seems hard to believe it would wear out before the front rack which takes some much load from a heavy nosed Q. I've had more steering vibes caused by marginal tire balance problems; once rebalanced on a Hunter 9700 my Q is smooth as a butter. These cars are so sensitive to balance, bushings, and general alignment issues. Hope this helps.

Steve

[rrack]

Thanks guys. I forgot to add...it does have HICAS. I'm just puzzled with this problem and can't seem to pinpoint it.

[DAEDALUS]

I have to wonder how much will a slight shimmy in the rear wheels actually translate to the steering wheel. I would think that you could tell based on whether the vibration is dependent on speed or RPMs...if equal then yeah, it's probably one or the other. If you feel the shimmy and kick the car in neutral, is it still there? If so, what happens when you rev the engine? Rotate the wheels and see if it changes at all.

[rrack]

Yep...already tried that. If I throw it in neutral it doesn't affect the vib. Even if you rev it...no change. It has a nice purr of an idle and has new motor & transmission mounts. After rotating the tires it also doesn't change except the steering wheel is now off center. Maybe the front rack, rack bushings, carrier bearing or front wheel bearings? I did notice that the right front makes a slight drag noise when i spun it when I rotated them. It makes no sound when driving though. I'll pull out the big gray bible and do some more reading. I am sooooo tired of trying to track it down.

I did however find that HICAS Eliminator Kit in the Stillen catalog. I knew I wasn't crazy. The one they show is for a 90-93 300zx though. I'm gonna call tomorrow to find out if they make one for the Q.

I guess I'll be forced to take it to a shop after we close on the house. That is when I find a good shop.

[DAEDALUS]

I believe, from what I've seen, that the only differences between the HICAS and non-HICAS models are 1) bushings in steering knuckle instead of ball joints, 2) different rear subframe, and 3) rear links instead of steering arms. I'm curious as to how the Stillen kit attaches to the subframe. The suspensions of the 300zx and the Q are extremely similar. I would guess that the link would have to be of a slightly different length, but otherwise I would not be surprised if the kit worked on the Q. I wouldn't bet money on it, but it's worth finding out more if you're serious. Do you know if the Stillen kit allows adjustable toe-in like the stock non-HICAS Qs?

[rrack]

From what it looks like it allows it to be fully adjustable. Simply plug the lines and hook up the tie rods to each end. Then you adjust the rods for tow. I didn't have a chance to call today but I will soon. The pic in the hardcopy catalog actually shows it on a car. Here's the online catalog link.

http://www.stillen.com/search_...earch

I know that several other parts for the Z fit our Qs. However, I don't know if this is one of them. It may be worth a shot if my rear rack is actually toast.

[DAEDALUS]

I assume that bolts to the frame, or it would be no good. Given the amount of adjustability in the tie rods, I think there's a fair chance it would work, as long as the threads are the same. I'll have to find out if my friend's '93Z has HICAS.