I should explain my question. Had my Z4MR for nearly 8 years now. It came with standard shocks but H&R springs on 19" Avant Garde M359s, currently with Michelin PS4S tyres. The car has clocked up 84K miles. The front shocks are I think original. The rears were changed around 54K. The H&R springs added around 64K miles. The only issue I had with the car's handling was that on really bumpy roads it struggled for traction and in extreme cases bounced like it trying to throw me out of the car, hanging on like a rodeo. Most of the time to be fair it was ok and there were known roads where I knew I'd have to back off a little. There was one particular dual-carriageway where if accelerating off a round-about and over a crest in the road the traction light would always activate. It's always been like that though.
So I took the plunge and decided to fit a Bilstein B12 Pro kit - B8 shocks with the Eibach springs figuring my shocks were due for a refresh and it might improve the traction and ride issues a little. Alignment was done supposedly to E46 M3CSL settings but looking at the numbers I think it's a severe interpretation of the CSL tollerances perhaps but seems to drive well on good surfaces. The car handling seems very much improved, not so much bouncing and traction seems great. Many others reporting an on-rails feel with this kit and I would not disagree with that.
The issue I have though, and I have since seen this same issue reported by others with this kit, is the way it now deals with impacts from things like sucken drain covers or particularly sharp pot holes or those 2-3 inch wide trenches that often get dug across our roads and then badly filled in and the tarmac sinks. The car now hits those type of things with an awful bang at the front, as if there is no suspension. Not sure if that's something bottoming out or the spring just being too hard to absorb the impacts. It's unbearable.
So at last the question - I have seen some threads here and other forums where some had re-installed the OEM springs at the front and it resolves that hash banging. I'm not sure how that works with the B8 as it's a shortened shock designed to work with lowered springs as far as I understand. In any case I don't have the OEM springs. I was thinking if fitting the H&R spring back in the front might improve things. Drops the front 25mm vs 20mm for the Eibach so not too different. So is there anyone out there running B8 shocks with the H&R springs or have any insight as to why this B12 Pro kit is soo bad as dealing with our terrible roads.
I know 19" wheels isn't helping me and I should probably have gone with the KWv3 but if there's a quick win by changing the front springs it's maybe worth a punt?
So I took the plunge and decided to fit a Bilstein B12 Pro kit - B8 shocks with the Eibach springs figuring my shocks were due for a refresh and it might improve the traction and ride issues a little. Alignment was done supposedly to E46 M3CSL settings but looking at the numbers I think it's a severe interpretation of the CSL tollerances perhaps but seems to drive well on good surfaces. The car handling seems very much improved, not so much bouncing and traction seems great. Many others reporting an on-rails feel with this kit and I would not disagree with that.
The issue I have though, and I have since seen this same issue reported by others with this kit, is the way it now deals with impacts from things like sucken drain covers or particularly sharp pot holes or those 2-3 inch wide trenches that often get dug across our roads and then badly filled in and the tarmac sinks. The car now hits those type of things with an awful bang at the front, as if there is no suspension. Not sure if that's something bottoming out or the spring just being too hard to absorb the impacts. It's unbearable.
So at last the question - I have seen some threads here and other forums where some had re-installed the OEM springs at the front and it resolves that hash banging. I'm not sure how that works with the B8 as it's a shortened shock designed to work with lowered springs as far as I understand. In any case I don't have the OEM springs. I was thinking if fitting the H&R spring back in the front might improve things. Drops the front 25mm vs 20mm for the Eibach so not too different. So is there anyone out there running B8 shocks with the H&R springs or have any insight as to why this B12 Pro kit is soo bad as dealing with our terrible roads.
I know 19" wheels isn't helping me and I should probably have gone with the KWv3 but if there's a quick win by changing the front springs it's maybe worth a punt?