e34 540i Bilstein B6 front shock fitment issue.

[Sankekur]

Good day everyone.

So I recently ordered a full set of Bilstein B6's for my 540i, and while I was at it I ordered new top mounts from the dealers seeing as I will be pulling it all out in any case. However before doing anything fitment related I just decided test the front top mounts over the front shocks, and found they don't actually fit, the stud of the shock that is supposed to go through the center of the top mount has a larger diameter than the hole it is supposed to fit through. I don't have the exact number with me, but diameter of the stud is about 15.1mm and the hole in the top mount is something like 14.4mm. With the difference so small it is obviously an option to just drill/ream open the top mount, but it still doesn't make sense that there are issues like this with fitment. I have checked the part number of the shock and according to Bilstein's site it does look to be the right one, part number is 34-030226. The part number on the top mount also looks to be the right one 31331134096. (This is the part number that the car's serial number returns)

I am wondering if anyone else has ever run into an issue like this?

Thanks for reading, any comments/input appreciated.

[moroza]

Not that I blame you, because it's very long, but you didn't read the FAQ stickied in this subforum.

There were three different front strut mounts used in the E34. 096 is version 1, the early one, and no 540i (except maybe some eastern European bad-roads package) came with it. You want 31331139437, version 2. Or keep the 096 and swap shocks for early-style, if Bilstein still makes them.

Oh, but ZA E34 were built as knock-down kits in Rosslyn? Then maybe your car did come with the 096 after all. Regardless, exchange either the mounts or the shocks, whichever is more convenient (there's no meaningful difference in function).

Totally unrelated, just curious - does your car have extra-wide front armrests?

[Sankekur]

Thank you for the feedback it is much appreciated. I certainly didn't read the FAQ, I mean why would I do that I already know everything and all my issues are unique . Jokes aside I had a look through it and there is a lot of really good info there, definitely something that would have helped had I read it before buying anything, also had I known I had to do reading up before buying shocks. After posting I searched the part number (31331134096) and actually found that it was superseded by 31331139437. The strange thing about it is usually dealer's system is pretty much on top of these kinds of things. This led me to think maybe something strange happened with the ZA assembled e34's, something that made them stick with an older version mount, something like rough road package, or they only bought the old version mount in so that is what they ended up using on all e34's.
I will have to see what is easier to swap mounts of struts.

Thank you again.


Regarding the armrests, I have sport seats in mine so no armrests, but I do have two comfort seats that I can measure the armrest on for you.

[Sankekur]

Quick follow up question, is the bearing ID from 14mm to 16mm the only change between the version 1 and version 2 mount? (I can get the version 2 from the dealers, but it will be on back order) My thinking is that is if it is only the id that is different I might still be able to just ream open the version 1 mounts I have to 16mm.

Also having a closer look at the FAQ, it would seem that the part numbers for bilstein shocks have changed or the HD, sport and touring versions have different numbers from the B4, B6 and B8 versions. On the B6 side of things, would it be correct to assume that this is the version 1 B6 and that this is the Version 2 B6 The latter matches the part number that I have, the former the stem diameter matches the 14mm bearing ID of the version 1. That said the stem length is also different 70 mm on version 1 vs 73 on version 2.

[moroza]

"Superceded" usually means the fit is the same and some minor details (not affecting fit) were changed. In this case, physical compatibility with the shock cartridges changed. The only difference between 096 (v.1) and 437 (v.2) mounts is the middle hole. Reaming is an option.

B4 = Touring, B6 = HD, B8 = Sport. A few (5?) years ago, Bilstein redid all their part numbers to a different format. Furthermore, some parts were updated throughout production while staying in the same format. I don't know what's up with the different stem length but 3mm is inconsequential.

[Sankekur]

Thank you I appreciate all the help. My next step will be to strip the current struts out just to measure everything length-wise, should be fine as the version 2 has the longer stem in any case. Then I will probably modify the mounts I have. Exchanging the shocks won't be an option as the supplier has never bought the version 1 fitting shock in.
Also just going to check if there is anything decent aftermarket available in terms of the mount.

[Sankekur]

Just out of the sake of closure for this thread, I ended up having the top mounts reamed open so the studs could fit.


While I was at it I also had the machine shop make up some taper spacers to fit over the studs so that the taper on the shock shaft could properly mate with the top mount that has a flat bottom.








Thanks for reading, I hope someone finds this of use.