MurcoRS

I've noticed the straight-line tracking in my '89 RS has steadily worsened over the last 2-4 years. Turning it's fantastic, but it just won't stay straight without constant correction. I've checked for the notorious cracked frame - not there. I've replaced lliterally EVERYTHING in the front end and had it aligned twice in the last year and it's actually getting worse! I'm at my wits end and nobody can find a problem they can point to explain the crappy tracking. I've even changed the rear-end and LCA's to eliminate any questions about the rear.

coolram62

iTrader: (2)

Is your tracking problem a constant one?What I mean is does it do it more/less depending on speed or type of road.Also what wheel setup(tire size/rim width) is on her now as opposed to what came on her?The condition of todays roads leave a lot to be desired.Face anything anywhere from frostheaves caused by weather and heavy truck traffic - same for grooves worn into lanes.this is most fun in heavy rain.You also have grooves cut on interstates for rain/snow flow and to aid traction in adverse weather.This will pay havoc with low profile wide tires.Also with the steering,have you replaced the rag joint?This will allow wander in situations like you meantion.And the car will still turn in good.

Lo-tec

Who did the alignment, do you trust them, and to whose specs? Did you get a printout with where it is set afterwards?

naf

iTrader: (7)

Original steering box? Haven't made any adjustments to it?

MurcoRS

I live in Florida and the roads are in relatively good shape that I drive on. The rag joint is tight, the steering box is a new AGR unit and the draglink, Idler arm, tie-rod ends, and ball joints are all heavy-duty Moog parts. The struts and strut mounts are new KYB parts and I'm running stock IROC front rims that have been checked for trueness and balance with Yokohama AVS100 tires. The alignment was done by 2 separate shops that both came highly recommended by other local 3rd gen owners using stock '87 IROC specs and the printout showed near perfect 4-wheel alignment. The car came with the 15" rally rims and has always had somewhat vague steering since new, but this is different as the car used to track straight. I've added a Spohn wonderbar and SFC's and an Edelbrock STB, checked the subframe bolts for looseness, had the frame checked for straightness and stress cracks, it all seems perfect! I'm at a complete loss as to this condition.

Guest

What about the bushings?

3.8TransAM

Tires.

No one mentioned it.

Could be out of round, belt whoely or partially seperating or worn out or just crappy tires.

later
Jeremy

naf

iTrader: (7)

Those don't look like crappy tires.

Is there play in the steering or is it more of a steering correction problem over center? How long have you had the AGR box and was there a noticeable change (improvement or degradation) to steering after you installed it?

Wheel bearings will also cause a problem like this and will worsen over time. You'd probably have noticed brake rotor problems by now if they were bad though.

Zepher

iTrader: (1)

I have tracking problems also on uneven roads or roads with grooves in them, but I know it's the width of my wheels since I had no issues when I had the 16x8's and 17x8.5 wheels up front.
and it wasn't the tire brands either as I had 6 different brands of tires on my 2 sets of 17x9.5 and my 18.9.5. and the 17x8.5 and my 2 sets of 16x8's..
Oh, I had slight tracking issues when I had 16x9.5's with 255/50/16's.

are you running 255/50/16 tires?

Lo-tec

Is it possible to post the printout of your last alignment. Factory specs are ok, but you can do better. I know an extra 1/2 degree of camber on the pass side is recommended to compensate for road crown, which will make it not track straight on a crappy road. My camber is set even on both sides, and my car does it on a crowned road.

Guest

Unless there's something wrong with the tires themselves (like they are defective), its not those tires. I was wondering myself, but saw they were ES100's and passed on that thought. I have some 225/60/16's on my truck and they are very good tires, #2 on my current list. Only downside is a stiff sidewall, but thats better than the useless nonexistant sidewall on a, oh, Bridgestone RE750. Those suck, if he had those I'd blame the tires for sure. I have some on the back of my 86 and I'd hate to think of how terrible the car would feel with 4 of those pieces of junk instead of only 2.

Just a .02, if you've driven thirdgens for a while you know that things like water puddles introduce some unwanted tracking/directional change with the stock suspension. I changed over to ES poly up front and that went away completely. I'd be looking at those bushings, if they are stock rubber and are a weak durometer (I dont know, but they might be given your car didnt exactly have the performance suspension to begin with), that could be the problem right there, not to mention they are likely pretty worn at this point in time. Putting big tires on cars that had skinny tires can create tracking and handling issues if the suspension isnt up to the task.

Norm Peterson

Only slightly off topic, but what specifically did you find lacking in the RE750's? Include tire and wheel size and if possible, inflation pressure information, and some description of the driving that made whatever deficiency noticeable.

Norm

Guest

245/50r16, Z rated I think. 16x8 GTA wheels. Tire pressure doesnt seem to matter, though if I inflate them to max pressure they're a little better. I've tried from 12psi to 44psi or whatever the max on the sidewall is, 2psi increments. The problem is reaction time, the tires sit around and wait for instructions, or something. My thought is its weak sidewalls. It gets really bad if you're near the limit and the back end wiggles for whatever reason, like steering input or a bump. At that point, its downright scary. The back of the car, with these tires, will wiggle around like a pendulum in those instances. I can even sometimes feel the rear end floating under hard acceleration. I hate it. Worst tires I have ever used in this size, bar none... and I've been using tires this size since the mid 80's. Ultimate grip is fine, if not pretty good... but you gotta have nuts the size of the continent to want to go there. I tried some other tires I have around (have too many rims+tires) and even MT ET Streets are more stable in a corner.

And Bridgestone... they had some sort of 30-day test drive guarantee thing... wasnt worth the paper it was printed on. They pushed me off and pushed me off until it was the 31st day, and then they said "Oh, its past 30 days, sorry, we cant help you." I'd have filed suit but it just wasnt worth my time.

MurcoRS

The lower control arms are new dorman OEM replacements with poly-graphite bushings, the tires are less than 500 miles old, and there was little difference with the AGR box. The rotors are new Bendix pieces with Timken bearings installed properly. I went through great pains to make sure the kingpin axis hit the center of the tires contact patch perfectly, and it does (drove my alignment guys nuts). I'm obviously missing something and I put most of these parts on at the same time yet the tracking problem is progressing. With what I have put into this car it should drive like a slot car and I'm getting to the point of tearing the entire front apart and stich-welding every seam in the whole front end!
Thanks for all of the input guys. I'm sure I'll find the problem and can almost guarantee it'll be some stupid oversight...

xplane

EDIT: nevermind i just read the info on your site and you already done what i was gonna say.

naf

iTrader: (7)

I looked at your site and you've done an excellent job on your car. I can't imagine your problem is in the linkage from the pains you've taken.

Have you looked at the input from the steering wheel to the box? Is your tilt column tight? Rag joint good? You've probably already replaced it with a u-joint, from the lengths you've gone to.

Is there any play in the wheel at all? Turn the steering shaft by hand and observe the pitman arm for movement, watch the rag joint for play when you do this. Follow through to the wheels.

Does the steering tighten up over center? Does the wheel return to center on its own? Twitchy steering at center without play points to a bad, or improperly adjusted, box, but I can't imagine that AGR box would be off.

Norm Peterson

I hate to drag this thread semi-off topic again, but could you also provide the same data for your front tires? Sometimes there is enough difference front to rear that it's hard to tell just where the root cause lies.

Norm

Ratchet

I noticed you have directional tires. Are they mounted with the correct direction of rotation?

Ric

Free Bird

iTrader: (1)

What simptoms of bad wheel bearings would effect the brakes? Sorry to highjack post, but I'm having similar steering problems along w/ sharp slow turn "skipping" and brakes locking up on me.

naf

iTrader: (7)

Bad bearings can contribute to uneven rotor wear and brake "shimmy".

Describe your sharp slow turn "skipping".

Free Bird

iTrader: (1)

It happens when I'm parking, or making very sharp turns. It's almost like the wheel is skipping across the pavement or both tires aren't pointed in the same direction. It's hard to explain, but it doesn't feel right at all.

Norm Peterson

Sounds like either your toe is way off or something's loose. Check all the tie rod ends and the idler arm

Norm

Guest

245/50zr16, Bridgestone RE730 on 16x8 GTA rims. Its not the difference in the fronts. I ran BFG DR's, MT ET Streets, Michelin Pilot Sports, Dunlop D40M2, and Dunlop SP8000 with those fronts and it never did that, not until the RE750's went on was there a problem. The RE750's also do that if I put them on the back of my other car that has Michelin Pilot Sports. Visually you can see the sidewall give way when you push on the car, and can feel it more than any of those other tires.

Speaking of, and back on topic, how about checking the REAR suspension on your car? Its not as likely to cause issues but might want to make sure there isnt anything funny going on there either.

gtomike66

Check your strut bearings. They're just rubber donuts inside the steel housing and could be cracked. Should be able to tell without disassembling-if you know what to look for. Otherwise have an experienced front end shop check em out.

xplane

have you figured this out yet? if not pop the hood and watch the steering box when ya turn the steering wheel does it move any? before i fixed mive it would move 1/4in at least but since i didnt see any cracks i left it alone but then about a month later they were real noticeable and the box was moveing 2+ inches when i moved the wheel. this would cause the car to wander a little at fist but as the cracks got worse the car would go crazy at the slightest waves in the road. you say you have had it checked but i would still do the simple check of poping the hood and watching or haveing someone else watch.

railroad

You are simply getting bumpsteer and the related tire wear over time as a result is adding to it getting worse. if you can rotate your tires, then do so and it should improve a bit for awhile again. need to add a bump steer kit to correct the tierod geometry.