Rear bump stops for Bilstein shocks?

[FRFNUGN]

I'm replacing my EDC suspension with the B12 pro-kit (Eibach springs, Bilstein B8 sport shocks). Fronts were straightforward, didn't need any bump stops as the B8s have internal bump stops. On the rears however, I've run into a different problem.

First off - the shaft diameter is smaller on the Bilsteins (non-EDC) than OEM (EDC), which means I need to buy non-EDC upper shock mounts, which I didn't know before starting the install. Not a big deal, easy to reconcile.

What I don't know is what to do with the rear bump stops. The factory bump stops sit on the top of the shaft just below the threads where the diameter increases. With the Bilsteins being a smaller diameter, the bump stops slide down the shaft and will just sit on the top of the shock body now. Therefore, once installed, the bump stop won't be captured and will just slide around up and down. Technically, it'll do it's job, as it'll just get smashed, but it won't be smashed in-line most likely. I don't see a difference in part numbers between EDC and non-EDC bump stops, so what am I missing here? The rear Bilsteins do NOT have internal bump stops, so there's got to be something external installed. Should I shorten the stock ones, and find a washer to make a seating surface for them on the top of the shaft?

[tlrid3r]

You are totally ok. My ohlins was the same way the bump stop rested on top of the shock. No issue.

[FRFNUGN]

Originally Posted by tlrid3r

You are totally ok. My ohlins was the same way the bump stop rested on top of the shock. No issue.

It doesn't bounce around on there at all? It is just a plastic dust shield, so I suppose you probably can't hear it at all inside, but it just seems like it'd get slightly out of alignment, and then you hit a bump and it catches the edge of the dust shield and just smashes it. But no problems for you, eh? Guess I'll just throw it back together then! Thanks for the reply.

[Richbot]

Is it smaller diameter or something? If not bump rubber will probably get stuck in the metal cup on the upper mount the first time you hit a good bump and stop moving. That's all that holds the stock stop in place just friction

[tlrid3r]

Originally Posted by FRFNUGN

It doesn't bounce around on there at all? It is just a plastic dust shield, so I suppose you probably can't hear it at all inside, but it just seems like it'd get slightly out of alignment, and then you hit a bump and it catches the edge of the dust shield and just smashes it. But no problems for you, eh? Guess I'll just throw it back together then! Thanks for the reply.

I mean there is a bit of play but they stay. Maybe sounds like yours may have a lot of play on the shaft. Can you take a pic and share

[FRFNUGN]

Looking at it again, I see that the bump stop is just very tight to the OEM shaft with friction, but the part that sits on the diameter change is the black metal cap (which then gets pushed into the plastic cap on the underside of the body). I suppose the bump stop riding up and down the shaft isn't a problem, but the metal cap was more what had me questioning it. The ID of the cap is a perfect fit over the OD of the shaft, so it should stay centered and flat as there's no play there. Maybe I just need to make it a bit more snug to the plastic cap on the body so that it stays stuck in there.

[FRFNUGN]

Turns out the bump stop supporting cup is different as well between EDC and non-EDC. The diameter of the hole is smaller for non-EDC to not allow the shock shaft to pass through. This cap positively captures the shock so that it doesn't simply shoot up into the trunk. So for anyone going from EDC to non-EDC shocks, you need new upper shock mounts ("Guide supports" upper part: 33506771737; lower part: 33506771738) as well as bump stop supporting cups (33526764418). As the others mentioned, the bump stop/dust cover itself will ride on the shaft just fine (a little loose), but the top mounts and cups are what you really need.

[marconi118]

the hole is smaller for non EDC cars

nothing to do with E90 or e92

[feuer]

Originally Posted by marconi118

the hole is smaller for non EDC cars

nothing to do with E90 or e92

Exactly,10 vs 12mm