Re: 350 tires

Mar 31, 2004 Last reply: 22 years ago 9 Replies


The Nissan dealers in western Canada are covering worn out front tires on


> all 350's that are still under warranty. The problem is the geometry,
> under braking the wheels toe in a little, under acceleration they toe out > a bit.

Sounds like they are putting bump steer into their cars again? The early Z's had it bad (it's -not- a good thing!) and require the front lower arm pivots relocated to fix it. Might need something like offset rack bushings to fix it on these?

On the early Z's they didn't have major tire wear issues from this but had narrow tires so probably weren't as affected. I have a feeling the tread pattern would affect this wear as well. If the toe changes with the susp compression/extention (which is has to for accelleration to change the toe on a RWD car) then it has bump steer. You'll feel this as the wheel moving when you hit bumps.

On the early Z's you'd really feel it with a good handling car (i.e good springs and stuts/big sway bars and good tires) when cornering hard and then hit a bump with one wheel, lowered cars were worse. At 100MPH+

-SPOOKY- is the only way to describe it! Raising the lower control arm pivot point will get rid of it.

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Talks about bump steer spacers which don't do much...

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Shows modding the front crossmember on an early car, I don't move the mount points outboard as much as he did. Also shows a shot of what bump steer is caused by, like I said maybe you can move the rack to fix this if it's what is going on. You can look under the car and see if the tie rod is parallel with the lower control arm.. If not this is the problem.

I think they intentionally engineer bump steer into cars so racer "wannabees" get some feedback as to how fast they are going. Without it, many people would drive cars too close to the limit without knowing how close they are? Most cars have it and have to have it removed before the car really handles good. The 90-96Z's didn't have enough to worry with and I'm kinda surprised to hear the newest ones have this issue.

How long would a set of tires last under this condition?

Thanks.

Ray

Nope, the early Z's not early ZX's.

?? Bump steer has nothing to do with camber change, it's about toe change i.e. steering the car when a bump is hit.

The front had horrible bump steer on the early Z's, I'm talking about the

70-78's. The type shocks have nothing to do with susp geometry. I guess "non-race" street car people might not notice this flaw? I raced for many years and this was very obvious the first time I drove a Z, especially a lowered one as this makes it even worse. See my other post explaining the cause-fix for this well known problem with those cars.

I was comparing the new to the old. Someone posted that the toe changes with susp movement. That is bump steer and all the 1st gen Z's had it. Somehow this other guy started talking about rear susp and 280ZX's? Isn't the problem they are having with the front tires and the front alignment?

Anyway, it's all speculation until someone brings one to me to have it

-fixed-. There is a fix, just might not be real simple, then again it may be?

But the problem I believe is the front tires...

Early Zs -- you must be talking about the ZX models starting in 1979. Datsun changed to the 810 suspension that year. The old Z from 73 through 78 had an IRS that did not change camber as I recall when hitting a bump. Never had a problem with bump steer in my 75 with Konis.

Talking about the rear suspension -- my only racing experience (autocross) was many years earlier with a modified Sunbeam Tiger. Different kettle of fish there though.

Oh ok. I know my car used to knock when I first got it. almost like a pinball machine when you win a credit.

that knock shifted the wheel. I was under the impression that is what ya was talking about.

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