I've just inherited this '85 2M4 and it's been a blast to wrench on and drive. (I havent got into the engine yet... the jury is still out.)

I had the left rear tire go flat on me while driving 65+ on the freeway. Any twitch to the steering and the car acted like it was rolling on one caster wheel in the middle of the chassis. I pulled over, put on the spare and prceeded to the tire shop. The left rear tire had good tread on it except where the Alien had burst through it. The right rear tire was fine. Minimal treadwear on both. There was no damage to the rim at all.

Now I've got two new rear tires on it and I'm still experiencing the same feeling when at freeway speeds. Below 50 mph it's hard to notice.

I'm running 185/70R13's on it presently. The tire shop said that my tire pressure was low on the fronts. (approx 20psi).

Any ideas on where I should look first?

Kendall
'85 2M4 - 5spd Isuzu
'67 LeMans/GTO clone 6.5 litre TH400
All the rest aren't Pontiacs, so what does it matter?

definitly make sure all tires have correct pressure.. next look at your rear struts... give the car a good shove downward.. if it comes up and then settles they are good.. if it boobles around a lil bit before settling they are bad.. that is more then likely your problem

check the status of the rubber in all the control arm bushings, front and rear.
check the front and rear balljoints for play.
if those all look good and tight, you may just need an alignment. (tho if they are stock, I suspect that the rubber has gone soft in some of the bushings. and your alignmnet is out of whack from it.

Did the bounce test earlier and I'm not seeing anything more than a normal return to level.

I was afraid that it was going to come to this as I've checked the camber (string and weight) and they don't seem to be too far out of adjustment.
I had someone shove on the car laterally so that I could see if there was movement and I didn't see hardly any. I'll make an appointment with my mechanic and have them check all the rubber to see if it's worn/soft. I'll let you know what I find out.

Kendall

When you eyeballed the camber was it neg. IE the top was in. If you don't have enought Neg. camber they get real loosy goosy.
If you stand back and look at the wheels the camber is enough that you should be able to see the camber is neg. just eyeing it...

[This message has been edited by Dodgerunner (edited 08-14-2006).]

Yes, it has negative camber. (Tire tops tilted inboard) Dunno if it was too much or not as I was just eyeballing it.

Kendall

[This message has been edited by Icelander (edited 08-14-2006).]

Also may want to jack the front of the car up and check for any movement in the wheels. Once you have the front of the car properly supported place hands at the 3 and 9 positions and push with one hand and pull with the other, then place hands at the 6 and 12 position and push with one hand and pull with the other. If you have any play, then you need to be looking at tie rods or wheel bearings.

Should I do this while the steering wheel is locked?

Kendall

Yes, make sure the wheels are straight also. You don't want the steering wheel to move while doing this. Also it doesn't take much pressure for this check.

Icelander im here..

your IN now ok?

Rob

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Rob's two Fieros will eventually be one 6" longer convertible

Did you have your front tire balanced while at the shop? when was the last time it was aligned?

Check/inspect and torque all your suspension parts to specs, cradle, strut to knuckle, ect, ect..

quote Originally posted by Butter: You are correct. It only takes one REAR tie rod end to be loose and you will be trying to "catch the wobble". A rear tie rod end will lead one way in a pull and lead the other way in deceleration. I found that at about 65mph would "Keep You Catching". Tire alinment will help improve gas milage too.

This could apply you too.

The alignment has helped but I still get the problem to a lesser effect. My toe-in was wrong on all four wheels. I've got ~0.003 extra negative camber in the left rear, but the alignment guy said that it wasn't really an issue and that I'd have to hog out the holes in the strut's knuckle bracket to be able to adjust. I'll worry about that when I replace the struts.

I was thinking that I might try to replace the rear tie rods to see if that doesn't fix the problem. (Tho currently I'm waiting out the rain to bleed my clutch again. Archism #4 to be used this time.)

My goal is to get the Fiero to a point where I can keep it on the road safely and then I need to dedicate some time/resources to my LeMans. Once I get the electrical issues resolved with the LeMans, I'm seriously considering replacing all the Fiero suspension parts and converting to a coil-over system with the bump-steer modification.

Thanks for the input.

I'll let you know what I find out.

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Kendall (Icelander) Whitlatch
'85 Fiero 2M4 - 5spd Isuzu
'67 LeMans/GTO clone 6.5 litre TH400
All the rest aren't Pontiacs, so what does it matter?

This will sound kind of far-fetched, but I had a similar experience with my '88 GT. No problems with the car until I put new tires on the rear. Suddenly I had a car I was nervous to drive at freeway speeds. It was the same "one caster wheel in the middle" feeling. I played with the tire pressures and the alignment with no effect. I chalked it up to a bad (inexpensive) set of tires I'd put on until I upgraded my wheels.

Well, I put up with it for a couple hundred miles and then it was gone. Turned out it was the little nibs of rubber on the new tires. I had never experienced this before and I've bought a lot of tires in my lifetime (but not for a Fiero).

So, maybe that's the problem. If they've still got the nibs, maybe it'll be better when they've worn off.

I think it's the cradle bushings. Try going with a solid one like Darrell Mores makes. They can be bad even though they look good.

Anything wore or sloppy that alows the rear tires to move relative to each other, will feel nasty. Ideally, rear tires should allways be paralel to each other, and perpendicular to the road at all times. Fiero IRS is a compramise at best, but can be made to work nicly by following the above rule.

I did put a brand new pair of tires on the back-end... I never really noticed the ride till after the tires were installed.

Maybe I'll swap the slightly worn fronts to the rear and see if I still get the problem.

Webbee: Can you replace the cradle bushings without dropping the engine out, or is it a pull-it-out-burn-out-the-old-ones type of deal?

Kendall

quote Originally posted by Icelander: I did put a brand new pair of tires on the back-end... I never really noticed the ride till after the tires were installed. Maybe I'll swap the slightly worn fronts to the rear and see if I still get the problem. Webbee: Can you replace the cradle bushings without dropping the engine out, or is it a pull-it-out-burn-out-the-old-ones type of deal? Kendall

You will have to drop the cradle at least a few inches. The rear bushings dont give rotation like the fronts.

When you hammer the front bushings out and the new bushings dont fit, that means you gotta burn the old ones out and use the metal collar for the new ones. This happened with my poly bushings from FieroStore.