E85 Castor Adjustment

E

eddiemunster

Member
Hi

Has anyone fitted castor adjustment bushes/bottom arms, to allow increase castor? I've done the same conversion on my TT Mk1, it makes a massive difference, but it has been so many times that people can literally rattle off the parts/supplier so that you can buy everything you need without having to guess as to what fits etc.

Regards
 
Snoop D said:
Are you looking into something like this?
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Wow, that's a LOT of additional castor there, that's nigh-on 6-8 degrees I would imagine!! Most kits appear to be 2-3 degrees, which is about what I'm running on my Mk1 TT with a similar modification (although that's done from the bottom arm) and the difference on that is nothing short of incredible.

My Z4 has new shocks and springs, and I've done a 4w on it to factory specs, but the front end is still quite tramp happy.
 
Fairly sure the Z4M lollipop bushes are offset to increase the castor a bit? You can certainly get aftermarket ones that are, powerflex for instance
 
mjennings23 said:
Fairly sure the Z4M lollipop bushes are offset to increase the castor a bit?
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Yeah, it's about another degree or so.

Cheap mod, especially if you can get a second hand pair of someone that's switched to poly. They don't wear anything like as quickly as the non-M lollipop bushes.
 
mjennings23 said:
Fairly sure the Z4M lollipop bushes are offset to increase the castor a bit? You can certainly get aftermarket ones that are, powerflex for instance
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Are they a bolt-on solution? I haven't had the suspension off, I'm guessing there's no manual castor adjustment and therefore when the 4w alignment is done again they won't dial out what the bushes have just dialed in?

Regards
 
You have to press m bushes into non m housings, I've got them on my car and it makes an improvement.
 
eddiemunster said:
G600 said:
You have to press m bushes into non m housings, I've got them on my car and it makes an improvement.
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Bearing press?

Better turn in or less wandering..... or both? :-)
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Yes, took a couple of tons to press mine out. I've noticed better turn in and slightly heavier steering, not noticed and change in wandering but I'd already changed most bushes by the time I fitted the castor bushes so it was already pretty good.
 
part numbers and pics here https://forums.m3cutters.co.uk/threads/z4m-eccentric-bushes-worthwhile-and-for-extra-steering-feel-and-cheap-easy-mod.96456/
 
terryo said:
part numbers and pics here https://forums.m3cutters.co.uk/threads/z4m-eccentric-bushes-worthwhile-and-for-extra-steering-feel-and-cheap-easy-mod.96456/
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I've ordered those, but, I have a feeling that they're standard fit on the Z4 3.0 and not just the Z4M so I'll be fitting like for like more than likely.... :D

For anyone that's interested, I used a pry bar on the wheel itself and even with a few mm of travel on the bush itself, it translated to probably 15mm-20mm of wheel movement towards the back of the wheel arch! The movement on that bush was so small that even my very, very strict MOT tester didn't raise it as an advisory.

Regards
 
eddiemunster said:
For anyone that's interested, I used a pry bar on the wheel itself and even with a few mm of travel on the bush itself, it translated to probably 15mm-20mm of wheel movement towards the back of the wheel arch! The movement on that bush was so small that even my very, very strict MOT tester didn't raise it as an advisory.

Regards
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Can you explain how exactly you did this check? As my driver's side front wheel sits waayy too forward and it's burning all the arch-liner!
 
Snoop D said:
Can you explain how exactly you did this check? As my driver's side front wheel sits waayy too forward and it's burning all the arch-liner!
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I actually put a locking knuckle bar on a wheel bolt on the passenger side, with the front of the car on axle stands, and I stood next to the passenger side indicator on the wing and lent onto the knuckle bar to see how much movement there was. I suspect it was more than 20mm, but that's a conservative estimate.

Regarding your car, I'll guess that at some point your bush has failed, someone has ordered a new bush (the Z4M variety), and as that's eccentric it'll add more forward castor to the wheel/shock and that'll be why it's so far forward in the arch. However, it shouldn't be more than about 15mm-20mm (I can't be specific as I can't measure mine as I haven't put the new bushes on yet) and it certainly shouldn't be touching the front arch liner. I think it's about .5 degrees additional, but that's measured from the arc of movement so I'd guess at around 20mm maximum.

Are your top mounts A. In good order and not perished, and B. Standard and not a modified version that allows adjustment? For the wheel to sit that far forward you'd either need adjustable top mounts, which are easy to spot, or modified front wishbones with ludicrously eccentric bushes. Do you have 19s or 20s on it?

edit - if your driver's side bush is completely f*cked, that'd force the wheel forward quite a bit, but the car would tramp on white lines/raised tarmac like an absolute bitch so you'd know it was knackered.
 
eddiemunster said:
Snoop D said:
Can you explain how exactly you did this check? As my driver's side front wheel sits waayy too forward and it's burning all the arch-liner!
Click to expand...

I actually put a locking knuckle bar on a wheel bolt on the passenger side, with the front of the car on axle stands, and I stood next to the passenger side indicator on the wing and lent onto the knuckle bar to see how much movement there was. I suspect it was more than 20mm, but that's a conservative estimate.

Regarding your car, I'll guess that at some point your bush has failed, someone has ordered a new bush (the Z4M variety), and as that's eccentric it'll add more forward castor to the wheel/shock and that'll be why it's so far forward in the arch. However, it shouldn't be more than about 15mm-20mm (I can't be specific as I can't measure mine as I haven't put the new bushes on yet) and it certainly shouldn't be touching the front arch liner. I think it's about .5 degrees additional, but that's measured from the arc of movement so I'd guess at around 20mm maximum.

Are your top mounts A. In good order and not perished, and B. Standard and not a modified version that allows adjustment? For the wheel to sit that far forward you'd either need adjustable top mounts, which are easy to spot, or modified front wishbones with ludicrously eccentric bushes. Do you have 19s or 20s on it?

edit - if your driver's side bush is completely f*cked, that'd force the wheel forward quite a bit, but the car would tramp on white lines/raised tarmac like an absolute bitch so you'd know it was knackered.
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Thanks for getting back to me. That makes more sense now - I noticed this too when I was loosening the wheel bolts with a breaker bar.

I don't have Z4M bushes installed but they were replaced with Lemforders a while back - incorrectly installed without preload prior to torquing down bolts to spec.

I have just inspected the top mounts and the black round rubber in the centre sit at different orientations to one another (don't know if this is a sign that the drivers side has twisted to another position). I have 19's lowered on H&R springs and yeah, it does handle awful and is very crashy indeed!

Have a look at my thread if you like:

https://z4-forum.com/forum/viewtopic.php?f=2&t=117928&start=15

Thanks! :thumbsup:
 
Snoop D said:
Have a look at my thread if you like:
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My rule of thumb is that anything that moves on a car, or has a sensor, buy genuine BMW or from a company that makes for them. I wouldn't touch Lemforder with a barge pole, the pressing/stamping on pattern parts is mostly awful and when you compare them to what came off the car you can really feel the difference. Cast is always better than pressed, most pattern suspension components are the latter and that's why I'd rather refurbish what came off than put new on.

I suspect this mish-mash of pattern parts isn't helping your problem, and by the sound/looks of it someone has incorrectly installed the top mount or the main bearing in the mount has completely failed and that has pushed the shock forwards. If there's play in the wheel, testing it in the manner we've described, it can only come from the wishbone or the top mount so it's easy enough with your pry bar to see where the culprit is. However, don't be surprised if there's play in both ends, and be even less surprised if there's play in a bush that you've just replaced albeit with a cheaper pattern part.

Sadly, it's a game of cat and mouse with problems like this, the only real way is to strip it all down, inspect, replace and then rebuild. Expensive, if you're paying someone else, but it'll guarantee that you'll find your problem and be able to address it.
 
i have just changed my strut tops. Most parts shops want to sell E36 ones for Z4 use, but the aftermarket versions i looked at don't have the locking pin found on factory E85 strut tops. the 3 body mounting holes are slotted and the factory used a locking pin in the strut top to fix the location. they may have had a few versions to marginally change location if they found camber or caster was just a little off spec, but there is only 1 part number in BMW system. The shock shaft should site perfectly concentric within the mount, and it does not make any difference how its installed.
 
eddiemunster said:
My rule of thumb is that anything that moves on a car, or has a sensor, buy genuine BMW or from a company that makes for them. I wouldn't touch Lemforder with a barge pole, the pressing/stamping on pattern parts is mostly awful and when you compare them to what came off the car you can really feel the difference. Cast is always better than pressed, most pattern suspension components are the latter and that's why I'd rather refurbish what came off than put new on.

I suspect this mish-mash of pattern parts isn't helping your problem, and by the sound/looks of it someone has incorrectly installed the top mount or the main bearing in the mount has completely failed and that has pushed the shock forwards. If there's play in the wheel, testing it in the manner we've described, it can only come from the wishbone or the top mount so it's easy enough with your pry bar to see where the culprit is. However, don't be surprised if there's play in both ends, and be even less surprised if there's play in a bush that you've just replaced albeit with a cheaper pattern part.

Sadly, it's a game of cat and mouse with problems like this, the only real way is to strip it all down, inspect, replace and then rebuild. Expensive, if you're paying someone else, but it'll guarantee that you'll find your problem and be able to address it.
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Thanks for the advice! :thumbsup:

I'm lucky I kept my old wishbone lollipop bush housings then! I'm thinking of going down the Powerflex route. So should I just buy the Powerflex bushes with the black metal casings and press these into my old original lollipop housings? Or should I buy a complete set of control arms with the Powerflex lollipop bushes already installed? Only problem with this is that they don't specify what brand of control arms they use...
 
terryo said:
i have just changed my strut tops. Most parts shops want to sell E36 ones for Z4 use, but the aftermarket versions i looked at don't have the locking pin found on factory E85 strut tops. the 3 body mounting holes are slotted and the factory used a locking pin in the strut top to fix the location. they may have had a few versions to marginally change location if they found camber or caster was just a little off spec, but there is only 1 part number in BMW system. The shock shaft should site perfectly concentric within the mount, and it does not make any difference how its installed.
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I noticed this too on other BMW's. Aftermarket ones don't seem to have the locating pins at the top of the strut like the originals, but all other bolts/studs line up in the top mounting...
 
Snoop D said:
I'm lucky I kept my old wishbone lollipop bush housings then! I'm thinking of going down the Powerflex route. So should I just buy the Powerflex bushes with the black metal casings and press these into my old original lollipop housings? Or should I buy a complete set of control arms with the Powerflex lollipop bushes already installed? Only problem with this is that they don't specify what brand of control arms they use...
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I wouldn't use those "OEM spec" wishbones, even from the hi-res pictures you can see they're pressed rather than cast, and/or considerably less substantial than the item fitted to your Z4. Just press out the old bushes/joints, press the new ones into your old wishbones.
 
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