A lesson on compression and rebound adjustments required pls

[Gibbo205]

Hi there

I've got a BMW E46 M3 which is a track car but also used as a daily from time to time. I've got the weight down to 1350kg, about 200kg stripped out and it is fitted with KW Clubsport coilover suspension and on the track the handling is pretty superb.

But on the road it is too harsh even using the road settings KW offer and in the wet traction is a struggle. So I was hoping someone who understands suspension compression and rebound better than myself could help explain how rebound and compression adjustments effect ride quality, handling, grip and feedback please?

The factory settings are:-

Road Basic Setting
Front
Rebound 6 clicks
Compression 1 full turn (6 clicks)

Rear
Rebound 12 clicks
Compression 1 full turn



Ring Dry Setting
Front
Rebound 6 clicks
Compression 0,75 turn (4 clicks)

Rear
Rebound 9 clicks
Compression 0,5 turn




Ring Wet Setting
Front
Rebound 9 clicks
Compression 1 full turn (6 clicks)

Rear
Rebound 12 clicks
Compression 0,75 turn


Note:

Compression is always 0,25 turn stiffer at the rear than at the front.

All adjustments should be made from the fully closed starting point (i.e. hardest settings) and wound off (softened) accordingly. Compression adjustments are made by click increments at the front, 0,25 turn increments at rear, Rebound adjustments are made by click increments.

Adjusters are easy to get to with the exception of the rear strut Rebound adjusters which are hidden by the boot carpet lining. You can cut a small hole in your carpet each side to facilitate regular adjustment.












I have tried the road setting above but it is too firm and traction/grip seems lacking. I have tried just further softening rebound and compression by just softening further, but my method has no thought to it, so be good to hear from others who know about suspension or have experience setting up coilovers please.

[SturdyHSV]

Gibbo205 said:

Compression 1 full turn (6 clicks)

Compression 0,75 turn (4 clicks)

So is half a turn 2 clicks, and a quarter of a turn 0 clicks?

Just thought it odd. I'll shut up and let somebody help you now

[Gibbo205]

SturdyHSV said:

So is half a turn 2 clicks, and a quarter of a turn 0 clicks?

Just thought it odd. I'll shut up and let somebody help you now

That is from the instructions which KW provide.

I would hazard if a full turn is 6 then:-
2 is just over quarter
3 is half
4 is nearly 3/4
6 is full turn

[klan8456]

Did you end up resolving this? I'm in the same situation with my E46 M3 on Clubsports.

[GreenV8S]

When you're talking about damper adjustments, make sure you're clear whether you're counting the clicks from the full-hard or fully-soft end of the adjustment range. I understand from conversations with damper designers that they usually measure the adjustment in terms of clicks from the fully-hard position since that corresponds to a fixed valve position (fully closed) - the 'soft' end of the scale is determined by the end stops in the screw mechanism and can be variable.

Obviously from the point of view of an end user, if you are counting the clicks in the wrong direction you're going to get completely wrong settings.

[klan8456]

GreenV8S said:

When you're talking about damper adjustments, make sure you're clear whether you're counting the clicks from the full-hard or fully-soft end of the adjustment range. I understand from conversations with damper designers that they usually measure the adjustment in terms of clicks from the fully-hard position since that corresponds to a fixed valve position (fully closed) - the 'soft' end of the scale is determined by the end stops in the screw mechanism and can be variable.

Obviously from the point of view of an end user, if you are counting the clicks in the wrong direction you're going to get completely wrong settings.

Yep, that's the procedure for the KWs - count from fully closed / hard position.

[Mignon]

No amount of changing damper settings is going to compensate for stiff springs. In fact low damper settings will actually make stiff springs feel even worse because they won't damp out suspension movement.

[gordmac]

Koni procedure given here: http://www.bimmerhaus.com/tech/shocktuningTN.html
Should work for any make though.