FWIW, I've got SE shocks and sport springs on the back and it's far better controlled than with worn sports shocks!
Rear suspension knock - UPDATE
- Thread starter Zummerset
- Start date
UsernameIanG
New member
Hi, I had this issue with my E86 after fitting B4’s. Came across a y-tube video of a guy who recorded the top mount flexing under load. Even though he had tightened the top nut as tight as possible the internal metal sleeve was still able to move slightly and cause a knock. I wasn’t convinced myself as I couldn’t see how it could do that. He apparently ground back the sleeve to increase the clearance. I put two additional washers one either side of the top mount and the knocking disappeared. By way of confirming my fix, Some years later my car failed an MOT due to a perished top mount rubber. At the time I couldn’t do the job myself so had the garage replace the top mounts. Being BMW specialist the job was done by the book which resulted in the non spec additional washers being omitted. Passed MOT but on driving away I immediately noticed the knocking had returned. I refitted the washers which again cured the knocking. Hope this helps.
Interesting.
I could see and feel slightly movement in both the febi bilstein and lemforder top mounts. (Both new and assembled correctly)
Thinking this was the problem was I switched to the polyurethane top mount.
Can no longer see or feel any flex/movement, but the knock is louder. Presumably because of the more rigid top mount.
Will see if swapping to another pair of dampers fixes the issue.
I could see and feel slightly movement in both the febi bilstein and lemforder top mounts. (Both new and assembled correctly)
Thinking this was the problem was I switched to the polyurethane top mount.
Can no longer see or feel any flex/movement, but the knock is louder. Presumably because of the more rigid top mount.
Will see if swapping to another pair of dampers fixes the issue.
Devon
Attleborough, Norfolk
As I found when I kept putting together one side wrong repeatedly. I forgot the bump stop, I forgot the dust sleeve etc etc. And that was the second side. I should have my spanners confiscated
Maybe one day then, in the far, far distant future.
I bought a pair of those and welded the mounting bolts to them. That way I could pass the bolts through the body so the nuts are up inside the wheelarch.
It allows me to take the dampers out quickly as I no longer need access to the top from inside the car.
Useful really with the amount of times I'm messing about with dampers etc.
It allows me to take the dampers out quickly as I no longer need access to the top from inside the car.
Useful really with the amount of times I'm messing about with dampers etc.
Right, I managed to get hold of some 2nd hand Monroe dampers. They worked fine as they had smooth compression and a nice slow extension after being compressed.
I assembled them, leaving off the dust covers, just in case, and the result is....
No difference!
As the saying goes...arse!
The only positive is the bump compression is slightly less than the Bilsteins which has resulted in a slightly smoother ride.
I can't get it to make the rattle by bouncing the back end and large bumps or speed bumps don't really cause an issue, it's more broken surfaces that result in the rattle.
I'm thinking is the reason it doesn't rattle with the dampers removed, is because it's so much softer and so doesn't cause the rattle until it's firmed up by connecting the dampers. It isn't the dampers (or mounts) themselves?
Hmmmmm......
I assembled them, leaving off the dust covers, just in case, and the result is....
No difference!
As the saying goes...arse!
The only positive is the bump compression is slightly less than the Bilsteins which has resulted in a slightly smoother ride.
I can't get it to make the rattle by bouncing the back end and large bumps or speed bumps don't really cause an issue, it's more broken surfaces that result in the rattle.
I'm thinking is the reason it doesn't rattle with the dampers removed, is because it's so much softer and so doesn't cause the rattle until it's firmed up by connecting the dampers. It isn't the dampers (or mounts) themselves?
Hmmmmm......
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That’s it
I’m struggling to recall but I think we assumed it was equal spacing
But it wasn’t
I believe so, the rubber spring seats are present top and bottom.
Really appreciate you giving it thought. It's driving me mad. The rest of the car is great after sorting front and rear subframes and suspension and also converting to hydraulic steering.
Such a small thing but it is proving so tricky to pinpoint.
Really appreciate you giving it thought. It's driving me mad. The rest of the car is great after sorting front and rear subframes and suspension and also converting to hydraulic steering.
Such a small thing but it is proving so tricky to pinpoint.