Need help with steering problem

[SPD TRP]

O.K.
Here is the deal.
I am having some problem with my front end shimmying at hiway speeds.

Before you say tires, I already put new tires on it Monday, this week, and have had them balanced 4 times and had it aligned once.
The last time they were balanced, I noticed a ever so slight hop in the front tires so I persuaded them to put on two new front tires.

I just knew this was the fix, but NO, same vibration.

All the Supras in the community, someone has to have had a related problem.

I can't help thinking that this is a problem that does not involve tires.

The PPS works just like it is supposed to, easy at low speeds and needing more steering effort at speeds.

This vibration comes in at about 64MPH all they up to about 100MPH, with speeds under 60MPH smooth as silk.

I have big plans for this car as it was and probably still is a good platform if I could only sort this problem out.

Any help would be appreciated.

Thanks

Wayne
3rdtimearound

 

[TurboSupra7]

I have the exact same problem, and I too got new tires and wheel balance. I am starting to think that my wheel bearings are bad. When I hit bumps I also hear a jingly sound from the bottom of my car. The previous owner put some aftermarket springs on my car and the alignment is way off, dunno if that has anything to do with it.

 

[suprabad]

Sounds to me like it's either your ball joints or your upper control arm bushings. Check them for play per TSRM. Replace as necessary.

I had the same problem and that's what turned out to be the culprit. I'll bet the front wheels hop around and the steering wheel feels like it wants to jerk right out of your hands when you are going around a bumpy corner. That's a sure sign of the ball joints or control arm bushings.

 

[SPD TRP]

I have already changed the lower ball joints with the OEM Toyota ones, as well as the rack bushings.

Went to a buddy's shop today and dicked around with the tires swappn left front with right rear and so on, We were able to eliminate alot of the vibration.

Our thoughts are that it did get better with the tire rotating, since the tires I got are Yokahama 420's, which I understand are crap. He aligned it again and thoroughly checked out the front end, "everything is tight" per my tech buddy. We also rebalanced the tires and checked the road force--these tires didn't do too well with 2 tires at 20 and 21 . We put the tires thaqt had the lowest road force up front and that seemed to help.

What kind of tires are you guys running?

My tech buddy told me that if I could afford them, Michelins are the best.
He is the second person to tell me that.

Wayne
3rdtimearound

 

[mrnickleye]

Well...certainly good tires help everything. You said those tires are new. I doubt the tires are the problem, after all you've done so far.
I've had a couple of cars that had similar shimmy. Check to make sure your rims aren't bent. Even a tiny bit (like 1/8") will multiply out at the road/tread. Put the truest rims up front.
I had to buy one new rim to get a shimmy out. It was 1/8" at rim, over 1/4" at tire tread.

 

[SPD TRP]

Yeah the tires are new, but not very good ones.

 

[mrnickleye]

Get the car up on a rack (jack it up at home will also work) and spin the tires by hand. Look for any out-of-round, up-down in the tire. look for any sideways movement in the tread. Re-read my prior post about even a small amount out. :icon_bigg