Offset Control Arm Bushings and Caster on '96 M3

[wanderlust]

I've got a '96 M3. The car is my daily driver and will not be tracked. The suspension is mostly stock except for Racing Dynamics swaybars. A previous owner installed the '95 offset control arm bushings. The wheels sit noticeably far forward in the wheel wells with very little clearance, but rubbing seems fairly minimal and the liners aren't any worse off than they'd be on any car from that year. Caster measurements were recently taken at 8.4 degrees (L) and 8.1 degrees (R). My question is, should I replace the bushings with the stock centered ones and what handling changes should I expect?

[aeronaut]

If you're not getting rubbing, then there's really no big issue with that much caster. I've run that much on my track-ish car. I can't think of any other downside. Reducing caster will slightly reduce steering self-centering, but I doubt you'll notice the difference between 8deg and 7deg.

So, from what you've said, it comes down to looks. If you can live with the wheel being that far forward in the well, no need to change the bushings IMO.

[bluptgm3]

Move back to 1996+ centered CABushings. There is no benefit to offset bushings.


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[deboM3]

I'd go centered

[MauiM3Mania]

I ran TreeHouse control arm brackets (same offset as '95 bushings) for five thousand miles. As said earlier, the only thing was the visual. A degree more of caster doesn't cause a problem.

[bluptgm3]

Actually slows steering response slightly. Plus can cause rubbing issues in some cases.


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[wanderlust]

Does anyone know how much a return to centered bushings will change the toe angle? I'm wondering if there's a way around getting another alignment.

[bluptgm3]

Probably cannot avoid an alignment in this case of a geometry change.

Simply replacing struts and/or tie rods could be accomplished without a rack alignment - Pick a tire tread location that is symmetrically the same on both tires, measure the distance between the two (just under front bumper) and check that distance after part replacement. Adjust tie rod length as required.


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[tiMASTER]

I run this way on my ti.

It's fine.

You could go to centered bushings but you cannot avoid an alignment whenever you mess with front suspension. (Unless you get your tires really cheap!)

[bluptgm3]

The 'ti' king pin/steering knuckle, FLCA, and bearing plate/guide support geometry is different than the 1995 M3 and 1996+ M3, though more similar to the 1995 M3.
The 'ti', 325/323/328 and 1995 M3 can use more caster and one of the reasons that camber plates are a popular choice.
One could use the 1995 M3 offset FLCA bushing or the 1996+ strut bearing plates on the 'ti', 325/323/328 however watch for 'ti', 325/323/328 spring 'hat' clearance to strut tower - ask me how I know. 'Hat' clearance can be gained by using the 1995 M3 spring 'hat'.

The 1995 M3 and 1996+ M3 are also different from each other. 1995 uses the offset FLCA bushing to add caster, 1996+ uses a centered FLCA bushing and adds caster via geometry changes to FLCA, king pin, and bearing plate.

And yes an alignment would be recommended in the case of swapping to dissimilar geometry affecting parts.


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