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  #1  
Old 11-10-2006, 10:25 AM
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Default Rear camber adjustment

Since I've fitted uprated H&R ARBs, there is now increased tyre wear on the insides of both front and rear tyres. I attribute this to the lack of bodyroll which accentuates the negative camber that I deliberately put on the front by swapping the top mounts over, and at the rear as a consequence of lowering the car.

I now want to correct this problem and have zero camber on all the wheels. I've now returned the camber to zero at the front by swapping the top mounts over again, but to adjust the camber at the rear, I need to fit some new trailing arm bushes with camber adjustment. I've found the parts on the Bavarian Autosport website. http://www.bavauto.com/shop.asp

Has anybody here fitted these camber adjustable bushes, if so, what camber adjustment is possible? Has anybody bought anything from Bavarian Autosport before?
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Old 11-10-2006, 10:44 AM
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You'll still have some negative camber on the front if the ride height is lower than standard, that's why I wouldn't think about swapping my top mounts as it will give too much IMO.

As for the trailing arm bushes, I'm not sure how much they alter the camber but it looks like you have to be careful to press them in at the right position as they are eccentric, and once fitted you'd struggle to adjust it again?

I've noticed with my Coupe compared to my 2.8 Z3 that when lowered the negative camber wasn't as excessive/noticeable as the 2.8 (the wheels on that really dipped in at the top noticeably).
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Old 11-10-2006, 10:53 AM
THE ANIMAL THE ANIMAL is offline
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Exdos you need adjustable front top mounts and rear ones the rear ones will sort your camber out for you and the fronts you can adjust camber and castor.

rears http://www.ground-control-store.com/...php/II=6/CA=11

front soft option http://www.ground-control-store.com/...p/II=143/CA=11

front race option http://www.ground-control-store.com/...p/II=700/CA=11
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Old 11-10-2006, 11:12 AM
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Quote:
Originally Posted by THE ANIMAL
Exdos you need adjustable front top mounts and rear ones the rear ones will sort your camber out for you and the fronts you can adjust camber and castor.

rears http://www.ground-control-store.com/...php/II=6/CA=11

front soft option http://www.ground-control-store.com/...p/II=143/CA=11

front race option http://www.ground-control-store.com/...p/II=700/CA=11
I don't think the rear setup is a true coilover on Exdos' car (it still uses the rear springs) so I can't see how the adjustable rears will alter the camber (but it does say for conventional springs on that website :? )
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Old 11-10-2006, 11:47 AM
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ANIMAL,

Thanks for the links.

c_w,

I had new wheels and tyres fitted at the same time that I fitted KW Variant 2 last year. I drove with a lowered set up from then. The KW V2 was a disaster on the MC and I replaced it with KW V3 in February this year. At the time of changing to KW V3, I measured the tyre depths on all 4 wheels and the tyre wear was very even across all of the tyres, so, even if there was a bit of negative camber by lowering the car, this didn't seem to affect tyre wear.

At the same time that I fitted KW V3 I swapped the front top mounts in order to experiment with negative camber. Very shortly afterwards, I uprated to H&R ARBs. Now, some six months or so later, I find that there is more tyre wear on the inners of all 4 wheels, including the rears, although I haven't changed the camber on the rear at all. If anything, the wearing of the inners in the past 6 months is actually worse on the rear tyres than it is on the fronts although there was less negative camber at the rear than I had on the front wheels. To me, this suggests that the ARBs are preventing almost all body roll, whereas before, the OEM ARBs permitted some body roll which made the outside of the tyres wear when cornering to cancel out the wearing of the inners when travelling in straight lines.

If my deduction is correct, and the ARBs resist almost all bodyroll, then as I see it, if I have zero camber all round, then the contact patch of the tyres will be the greatest at all times, even when cornering, which will improve the grip and will also result in even wear across the full width of the tyres, both front and rear. I think that if I'd kept the OEM ARBs, then the negative camber wouldn't have created this uneven tyre wear.

As you know, I'm always happy to experiment to learn more, and in the light of my experiment with negative camber and uprated ARBs, I think the car will perform better with the uprated ARBs and zero camber all round, rather than with OEM ARBs with some negative camber. As always, I'm willing to back my "hunches" and be proven wrong.
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  #6  
Old 11-10-2006, 05:38 PM
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ANIMAL,

I've looked at the Ground Control rear shock mounts, but I can't see how these will adjust for camber. As I see it, they can only adjust the alignment of the rear shocks. To adjust for rear camber, the trailing arms need to be tilted laterally in some way, either by fitting eccentric bushes, as per the ones on the Bavarian Autosport website, or by welding new trailing arm brackets onto the rear subframe. I don't fancy the latter option.
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  #7  
Old 11-10-2006, 08:49 PM
THE ANIMAL THE ANIMAL is offline
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Ok what this does is allow you to adjust the rear mount point of the shock which holds up the top of your rear housing now with this adjustment you can put some washers in between where the rear shock bolts onto it to space it out and do some adjusting from the top and push out your camber back to what you want. You should be aiming for .5 to 1 neg camber for best results with the way you drive.

Not much neg camber on the rear of the car always helps with traction.

Now if this doesn’t work im not sure if this will fit exact but it should as the rear ends are almost identical except for some beefing up but you’ll need to take of your rear subframe and fit this bit of kit. You’ll have full adjustment.


https://secure5.nexternal.com/shared...products%2Easp

bottom of page 2 in the E30 suspension section.

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  #8  
Old 15-12-2006, 01:15 PM
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I've now sorted out this problem. 8)

I originally intended to opt for the easy option which was to fit some adjustable eccentric polyurethane trailing arm bushings. However, when I took delivery of the AKG adjustables, I couldn't imagine that these things would retain their settings for very long driving on UK roads, so I returned them to the supplier who kindly agreed to give me a full refund.

Removing the OEM retaining bolts for the trailing arms was a pig of a job, and in the process I ended up removing the subframe from the car, but managed to do this whilst leaving the differential and trailing arms and wheel hubs supported under the car, which allowed me to leave the brakes untouched. Now that I had the subframe off the car I decided to go along the "plan B" route and fit polyurethane subframe bushes, Ireland Engineering's adjustable camber and toe brackets and polyurethane trailing arm bushes. I knew before I attempted to start the job, that this was probably the best solution, but I fought shy of doing the job out of laziness.

The job in itself is not actually very technically difficult, but as a task it is very physically challenging when you are working alone and with the car only lifted a little off the floor. I took great care to be sure that I properly aligned the camber and toe brackets to the horizontal and vertical planes when I welded them onto the subframe. I also took care to make sure that the OEM positions of the original bracket holes were used as my reference points when I cut the slots in the subframe brackets, so that all my adjustments can be referenced to the OEM positions if I wish.

When I refitted the subframe and put everything back together on the car, I've found that it is possible (although a bit tricky) to adjust the camber and toe settings from under the car, even with the wheels on the car.

My biggest worry with having polyurethane bushes on the back end was that they might considerably increase NVH and that I might get squeaking from the trailing arm bushes during movement, especially since I'd read that many members of the Bimmerworld forum had experienced this. Anyway, I've just been for a test drive on nice dry roads and give the MC some decent abuse and I haven't got the dreaded squeaking nor any other rattles or noises. The car now feels very tight and "together" and there is very little increase in NVH.

Immediately after my test drive I took the temperatures of the tyres and I've now got a pretty even temperature across the full width of both rear tyres which shows that the contact patch is greatest and the tyres are now working acrosss the full width and not mostly on the insides, as before. I think that I've achieved my objective.

There are a couple of good write-ups on the Bimmerworld forum of how to do the job, but I'll do a write up specifically with tips and tricks which I discovered whilst doing the job for those who may feel inclinded to tackle this job themselves.

Here's a photo of my DIY laser alignment system:
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  #9  
Old 15-12-2006, 01:20 PM
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as always john a good write up!
think ill be leaving mine to a garage!
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