E36 Top Hat changed to M3

[wrs 120]

Recently I changed to M3 top hats (pre-96 type) - I'd previously changed the LCA bushes to the M3 type. The extra castor is excellent.

Over the weekend one of the swaybar nylocks came a bit loose and while tightening it up I noticed the spring ledge on the strut will likely not clear the strut tower wall if I was to hit a really big bump. There's about 45mm clearance from the ledge to the inside of the wheel arch/inner-guard so it would need to be a big bump. However, it it was ever to happen the back edge of the spring ledge would make contact with the body of the car. The M3 has a smaller diameter ledge and spring - I'm guessing this is the reason why.

So, how to fix it - looks like I'll need to change to M3 struts.

Has anyone else changed to M3 top-hats on non-M3 struts and noticed a clearance issue?

[M3AN 4016]

Pre-'96 top hats? I thought they were the same as or similar to non-M ones. It's the '96 (Evo) ones that have the extra caster built in. Maybe that's the same for the 3.0, I can't remember.

Either way, the Evo, with the offset tophats do have less clearance and that's why the Evo springs are conical, I assume the shocks match the springs so will be smaller than non-M ones.

If you go to M3 struts I'd also change to M3 droplinks (strut mounted). 

[wrs 120]

Yeah, thanks. Already have the M3 droplinks. I wish I'd known there could be clearance issues before fitting the M3 top hats as I sourced early E36 non-M3 struts to get the top swaybar mount. These were then modified by Stocks for Koni adjustables. Might have to go with adjustable top hats instead so I can set the castor to the maximum possible without clearance problems. Have to re-cert anyway so may as well get everything sorted prior.

Edited March 28, 2021 by wrs

[wrs 120]

Cool, thanks. That sounds like a totally workable solution. If I drill the right sized hole the studs can probably be pressed back in. 1.5 degrees loss of castor should be ok as a compromise to save a lot of additional expense.

[wrs 120]

Yep, gain over standard but a loss of 1.5 from what I have now (7.5 deg)...

[wrs 120]

Does anyone have a set of these they can measure for me please?

I'm after the distance from the top pf the mounting plate to the bottom of the bearing.

https://3a663eb0fef48c6d2d60-a88f8ebfcdb877ad223e888bfcb7f7ec.ssl.cf1.rackcdn.com/154569_x600.webp

[wrs 120]

Thanks, No camber offset. I have the type that has the small diameter rubber which looks like it could be a bit longer than the wide rubber type. I think the offset Evo type (probably the same as yours) has the same diameter rubber area (small) as the type I have which means it should be the same overall height.

When I changed from the standard E36 centered top hat to the M3 type it was taller in height by what appears to be about 20mm.

 

[wrs 120]

Cheers, thanks