Top Mounts and Camber Arms

M

Mikey_Boy

Member
Hi Folks,

Looking to get the chassis on my Z4M Coupe tightened up a bit more (I'm running B10 Bilsteins plus a few other chassis goodies) - the castor differential is driving me a bit nuts (pulls to the left slightly) and looking to get cambers correct front and rear so looking to fit adjustable top mounts and rear camber arms to get the geometry absolutely spot on.

Any recommendations? Happy to spend some cash getting this right...! :thumbsup:

Thanks in advance!! :driving:
 
Mikey_Boy said:
Hi Folks,

Looking to get the chassis on my Z4M Coupe tightened up a bit more (I'm running B10 Bilsteins plus a few other chassis goodies) - the castor differential is driving me a bit nuts (pulls to the left slightly) and looking to get cambers correct front and rear so looking to fit adjustable top mounts and rear camber arms to get the geometry absolutely spot on.

Any recommendations? Happy to spend some cash getting this right...! :thumbsup:

Thanks in advance!! :driving:
Click to expand...
The Turner top mounts seem to be the default choice if you're willing to spend money, they look pretty well made. Be aware that some of the cheaper mounts don't allow you to adjust the castor.
I have the Turner rear adjustable camber arms, which again are very nicely made and very light, but as I found out, they're a cinch to adjust on an m3 but on the Z4M the nearside exhaust routing means it's not so easy :(
Bear in mind the rear camber arms are designed originally to be sacrificial in the event of a clout back there so consider whether some of the cheaper arms out there have thought about this in their design. I think I'm right in saying Turner have.
 
Thanks Tom - a set of these then:

https://www.turnermotorsport.com/p-340466-front-adjustable-cambercaster-plates-e46-m3-turner-motorsport-street/?pdk=AQE

I'm guessing the Z4 is the same as the M3? Looks like these fit the Bilsteins..

Plus these:

https://www.turnermotorsport.com/p-340474-rear-adjustable-camber-arms-pair-e36-e46-e85-turner-motorsport-streettrack/?pdk=Aw

Looks like I'll have to raid the piggy bank... :o
 
Yeah those are the topmounts, same for e46/e85.
With the camber arms I would probably advise the bushing variant, I have the solid spherical mount version and they do make themselves known, depends on what you want to do with the car.
Also bear in mind for installation they require the exhaust to be dropped and the diff to some extent in order to reach the bolts near the diff, not a small task, you may want to wait or do some other things around that area at the same time.
 
With regard to adjusting caster/camber, most people tend to increase -ve camber to get their desired performance increase, but for a road car, increasing caster is far preferable.

When you increase -ve camber, the car is more ready to turn and on our bumpy roads, the steering becomes very twitchy through "bump steer", which makes driving a tiring process because you need to correct the unwanted steering inputs all the time. However, if you increase caster instead, the steering has a tendency to steer straight ahead and will only turn with driver input, and here's the interesting bit, when you do turn, -ve camber on the outer front wheel also increases with the extra camber! Consequently, you find that the car is much easier and relaxing to drive and responds better to driver input without being twitchy. :thumbsup:
 
Tom - thanks as always for the help - you know my car (having seen it at Spa) so you know it's a road car that sees a track once in a while (not like your track focussed beastie!!) so I'll be definitely be going for the bushing variant on the camber arms.. :thumbsup:

Exdos - always appreciate your advice! :D I'm looking at a (very) small castor increase at the front to help with the dynamic camber issue you highlight and a very small static camber adjustment if that's needed - tramlining is something I definitely want to avoid, but that lovely feedback you get with the right castor/camber balance is what I'm aiming for - I removed the camber pins a while ago and you might recall I followed your excellent set up posts to the letter - I'm now chasing the detail and dialling out the factory mismatches as best I can.
 
I have the Turner rear arms on my M3 bought from mirror john, an excellent bit of kit and great quality etc
 
Thread revival time....! :D

I'm just getting around to fitting Turner adjustable top mounts now (yep, they took MONTHS to arrive) so looking to set up the front end right finally.

Looking on t'internet, I see that E46 M3 castor is 6.9 - 7.9 degrees - does the same number apply to the Z4M?

If so, I'm looking at setting the front end to:

- 1.5 degrees camber
+8.0 degrees castor
0.00 Toe

I'm hoping that will sharpen up the front end a bit and help with dynamic camber on turn in... :thumbsup:

The standard castor value for the Z4M is what I'm struggling to find so any help there is appreciated.

Many thanks! :driving:
 
Mikey,

IIRC, the OEM castor angle is 6 degrees. Since your Turner mounts are adjustable, you can experiment to find the optimum values.

If I were you, my starting point would be, zero toe, minimum negative camber and maximum caster, so you can see how the change in caster angle affects both turn-in and straight line stability. You'll soon feel how it works and then you can fine tune to your taste. :thumbsup:
 
Thank you Exdos...! :thumbsup:

I'm having the car set up tomorrow and heading on track at the end of the month so I'll report back with the results...

:driving:
 
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