First post - first problem - lean - Page 2

Thorney · 02-03-2010, 09:42 AM

If its something that has developed over time then I'd agree its likely to be a spring (which actually isn't that common on CSL's but rampant on M3's). However it may well have always been like that and now you're just noticing it more, the bodywork on the car is notoriously innacccurate, when we set the cars up we do it on the chassis rail and the shock body to make sure its the car thats level, if the bodywork is out then c'est la vie, its the car you want set up right not the body.

Ben · 23-05-2010, 08:12 PM

well here's an update with a confusing outcome :

not long after this thread was started (after you kind replies - thanks chaps) I dropped the car off at BMW to investigate the lean, my original estimate of a 40mm difference side to side was, with hindsight, a gross exaggeration, but still the car was leaning, after a crude measurement, 15 - 20mm. Anyway, after a day down at service they called to say the car was perfectly fine and they had calculated that the difference was 5 - 7mm which is within their tolerance of ±10mm. I was skeptical following my previous observations so on my arrival we took it outside, so to speak, to a very flat car park and applied the tape measure. Sure enough I struggled to reproduce measurement exceeding 10mm. Felt a bit of a wally but it wasn't a complete wasted trip as they fixed my dicky handbrake. So I drove it home and put it to bed in the garage.

So this was all over a month ago, being a nice day today I decided to give it a run out, in the car park of our destination I noticed lean again and on measurement back home in the garage this afternoon, I observed a 15mm difference side side with the tape, from floor to top of arch 670mm passenger side, 655mm drivers side. So I dug out the jack and did some investigating. Got it up in the air, and saw no signs of a broken spring, spring pads matched and nothing else unusual. Dropped it back down again.........hey presto, 670mm bang on both sides.

So this must be down to a problem with some dynamic suspension component?? maybe damper wear over time?? inconsistent rebound?
I'll keep an eye on it and see if it settles at its previous level. As a quick fix I'm tempted just to bung in a thicker spring pad, am I right in thinking standard pads on the CSL are 5mm at top and bottom?

Its become a bit of a mini project now, and I'm curious more than anything to find the cause, so any ideas would be welcome.

Ta

b.

karbonkid · 23-05-2010, 09:30 PM

I would take to a specialist if concerned and forget BMW as I find them mickey mouse and only good for replacing parts under warranty (if you have warranty). Im guessing you have OEM suspension, as with coilovers the height may differ slightly due to the varying spring preloads required to acheive the optimal corner weight setting, unfortunately there often has to be a bit of a compromise on looks to acheive the perfect balance in handling. Not sure what the lean may be about. Where are you located?

daniel · 23-05-2010, 09:50 PM

which side? your fuel tank is on the drivers side as is steering etc so this will increase the droop on that side. store it low on fuel and see what happens.

DuncanR · 23-05-2010, 11:09 PM

Ben,
put your wallet on the passenger seat mate, instead of in your hip pocket !

NZ_M3 · 24-05-2010, 01:14 AM

Every single CSL I've measured have had the left rear quarter sitting high - it's normal.

The factory allows a 10mm tolerance between left and right side.

Remember these cars were engineered to be left hand driven, so it is normal for the left hand side to be sitting a couple of mm higher.

What you might be seeing is the swaybar binding and holding one side up more compared to the other. What I would do is check the U bushings on the sway bar mount to make sure one isn't worn out compared to the other and put some graphite grease in it to allow the bar to move.

Also measuring from the ground to the top of the arch isn't the correct way of measuring - tyre pressure difference could also cause it to be out completely. The correct way to measure (and it is how BMW measures) is from the bottom of the rim to the top of the wheel arch)

Stock spec is 610mm +/-10mm for the front and 600mm +/-10mm for the rear.

I've yet to measure a CSL that doesn't have a rear left sitting between 7 to 10mm taller compared to the right rear - NEVER (more if you have a light weight aftermarket muffler - the muffler alone can contribute to about 3mm difference)

02-03-2010, 09:42 AM	#11
Thorney S5 - Full Throttle Join Date: Sep 2007 Posts: 469 Casino cash: $3876	If its something that has developed over time then I'd agree its likely to be a spring (which actually isn't that common on CSL's but rampant on M3's). However it may well have always been like that and now you're just noticing it more, the bodywork on the car is notoriously innacccurate, when we set the cars up we do it on the chassis rail and the shock body to make sure its the car thats level, if the bodywork is out then c'est la vie, its the car you want set up right not the body. __________________ http://www.thorneymotorsport.co.uk

23-05-2010, 09:30 PM	#13
karbonkid S6, Sport On, Traction Off Join Date: Nov 2008 Location: Sussex Posts: 1,912 Casino cash: $10231	I would take to a specialist if concerned and forget BMW as I find them mickey mouse and only good for replacing parts under warranty (if you have warranty). Im guessing you have OEM suspension, as with coilovers the height may differ slightly due to the varying spring preloads required to acheive the optimal corner weight setting, unfortunately there often has to be a bit of a compromise on looks to acheive the perfect balance in handling. Not sure what the lean may be about. Where are you located? __________________

23-05-2010, 11:09 PM	#15
DuncanR CSL Register Uber-poster! Join Date: Sep 2009 Location: Olney, Bucks Posts: 3,735 Casino cash: $9984	Ben, put your wallet on the passenger seat mate, instead of in your hip pocket ! __________________ " I use Gleaming Kleen.... for that new car look " I wish I had used - Race Data Systems - Motorsport Data Loggers forgive me Nathan !

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23-05-2010, 08:12 PM	#12
Ben Mode S1 - Starting Out Join Date: Feb 2010 Posts: 29 Casino cash: $1182	well here's an update with a confusing outcome : not long after this thread was started (after you kind replies - thanks chaps) I dropped the car off at BMW to investigate the lean, my original estimate of a 40mm difference side to side was, with hindsight, a gross exaggeration, but still the car was leaning, after a crude measurement, 15 - 20mm. Anyway, after a day down at service they called to say the car was perfectly fine and they had calculated that the difference was 5 - 7mm which is within their tolerance of ±10mm. I was skeptical following my previous observations so on my arrival we took it outside, so to speak, to a very flat car park and applied the tape measure. Sure enough I struggled to reproduce measurement exceeding 10mm. Felt a bit of a wally but it wasn't a complete wasted trip as they fixed my dicky handbrake. So I drove it home and put it to bed in the garage. So this was all over a month ago, being a nice day today I decided to give it a run out, in the car park of our destination I noticed lean again and on measurement back home in the garage this afternoon, I observed a 15mm difference side side with the tape, from floor to top of arch 670mm passenger side, 655mm drivers side. So I dug out the jack and did some investigating. Got it up in the air, and saw no signs of a broken spring, spring pads matched and nothing else unusual. Dropped it back down again.........hey presto, 670mm bang on both sides. So this must be down to a problem with some dynamic suspension component?? maybe damper wear over time?? inconsistent rebound? I'll keep an eye on it and see if it settles at its previous level. As a quick fix I'm tempted just to bung in a thicker spring pad, am I right in thinking standard pads on the CSL are 5mm at top and bottom? Its become a bit of a mini project now, and I'm curious more than anything to find the cause, so any ideas would be welcome. Ta b.

23-05-2010, 09:50 PM	#14
daniel S4 - Getting the hang of it Join Date: Sep 2009 Posts: 247 Casino cash: $11332	which side? your fuel tank is on the drivers side as is steering etc so this will increase the droop on that side. store it low on fuel and see what happens.

24-05-2010, 01:14 AM	#16
NZ_M3 S5, Sport On, DSC M-track Join Date: Jun 2008 Location: Auckland, New Zealand Posts: 1,434 Casino cash: $13579	Every single CSL I've measured have had the left rear quarter sitting high - it's normal. The factory allows a 10mm tolerance between left and right side. Remember these cars were engineered to be left hand driven, so it is normal for the left hand side to be sitting a couple of mm higher. What you might be seeing is the swaybar binding and holding one side up more compared to the other. What I would do is check the U bushings on the sway bar mount to make sure one isn't worn out compared to the other and put some graphite grease in it to allow the bar to move. Also measuring from the ground to the top of the arch isn't the correct way of measuring - tyre pressure difference could also cause it to be out completely. The correct way to measure (and it is how BMW measures) is from the bottom of the rim to the top of the wheel arch) Stock spec is 610mm +/-10mm for the front and 600mm +/-10mm for the rear. I've yet to measure a CSL that doesn't have a rear left sitting between 7 to 10mm taller compared to the right rear - NEVER (more if you have a light weight aftermarket muffler - the muffler alone can contribute to about 3mm difference)