17 replies to this topic

[MazdaSteve]

I have a '99 with TORSEN. Under acceleration the car torque steers to drivers left, enough that you need to compensate with steering input to keep the car tacking straight. Under engine braking, the effect is reversed and the car wants to torque steer to driver's right. When the car is in a neutral state (maintenance throttle), the car tracks straight and true. Any ideas where to look? I've checked:

Alignment
Cam bolts
TORSEN functionality & mounts
Upper & lower control arm bushings
PPF
Ball joints
Sub-frame mounting bolts

Any help or ideas will be appreciated.

[Adam Molaver]

how did you check the alignment? sounds to me like the rear wheels are not tracking in the same plane as the fronts - imagine both rear wheels offset towards the passenger side relative to the fronts. or possibly toe was measure with toe plates..toe plates can show zero toe, but that is combined for both sides. so if left rear is toe'd out, and right rear is toe'd in, plates show zero toe, yet it sure as hale won't drive like it

ahm

[Jim Drago]

Sounds like one of your cam bolts on the rear lower control arms is loose, probably the front on passengers side

[MazdaSteve]

Adam, alignment was checked with strings and toe plates. The rear wheels are tracking straight in relationship to the fronts based on my string measurements.

Jim, I will check the cam bolts again. They are tight, but my understanding is they can stretch so who knows.

I appreciate the input.

[Alberto]

Have you tried swapping tires around? I've had something similar when using a tire that had more tread than another on the rear.

[DES4]

I don't think thrust angle or any other alignment setting could be the culprit here; it would be consistant under acceleration, braking and steady throttle. Same goes for a tire problem; neither should cause a direction bias change dependant upon load.

Something has got to be loose/broken/cracked to cause a shift in direction like that.

[Bench Racer]

How about cracked/broken differential mount or wasted differential mount bushing?

[DES4]

How about cracked/broken differential mount or wasted differential mount bushing?

Would not discount this altogether, but I'd suspect a part that's allowing the alignment to change under load; anything that holds the uprights in position (control arms, take-up points, subframe mounts, etc.) need to be looked at very closely. Suspension needs to be checked hanging (unloaded), as well as with the car's weight resting on it. Brakes on and off; you really need to try and duplicate the shift, or you may have a tough go at isolating it. Usually, there'll be a thud or bang at the time the shift happens.

[High Chair]

I had the something happen many times and I can tell you with almost 100% certainty what it is. The lower rear ( rear of the car)outboard bolt (hook to the upright) on the lower control arm is loose (the long bolt near the tire with a 17mm nut and a 19mm bolt). Double wrench it to make sure it is tight. Even if the nut is tight make sure that is not a result of screwed up threads. The first time that happened to me it took 3 weekends before I found it. That acceleration left/deceleration right is nothing I had experienced with any other issues (broken parts, loose cams, etc). It is a problem all its own. If that does not make sense you will have to wait until I stop drinking in London!!

[MazdaSteve]

Thanks fellas. Will take another look when I get it back up on the lift.

[Glenn]

Steve look close at the upper bushing on the rear uprite as well. And plus 10000 on Jamies ideas

[MazdaSteve]

Found the problem - the lower differential spacer was broken that is between the diff and PPF. Also, the shoulder bolt that goes through the spacer was in place, but it was the wrong bolt and the metal locating bushing was not there.

[KentCarter]

Found the problem - the lower differential spacer was broken that is between the diff and PPF. Also, the shoulder bolt that goes through the spacer was in place, but it was the wrong bolt and the metal locating bushing was not there.

And that fixed it??

[Jim Boemler]

Surprising you didn't hear things flopping around under there.

[MazdaSteve]

Yeah Kent, imagine that.

[KentCarter]

Yeah Kent, imagine that.

I just wouldn't have thought that would have any affect on the rear suspension geometry.

[Bench Racer]

Thanks for sharing.

[MazdaSteve]

Kent, I don't get it either. I thought the problem as due to a changing toe condition. As soon as I tightened up the PPF to diff, the problem stopped.