'03 540/6 w/New Eibach ProKit/Koni Yellow Setup - Second Failed Rear Shock Mount

[peter540]

Recently, I upgraded the suspension in my '03 540/6 to the Eibach ProKit/Koni Yellow setup. Twice within 1,000 miles, the right rear shock mount, which was new and was, I believe, Lemforder, has failed (broken). Every other suspension component is new.

In this most recent instance, I hit a sharp, but not big, bump, and the right rear bottomed out a little. I drive the same route every day and hadn't bottomed out anywhere on that route before. In fact, there hasn't been a single instance of bottoming out before this occurrence. (I'm not driving hard or overly fast.) It was after the bottoming out that the clunk/rattle began.

What on earth could be causing this to happen? I don't think the Eibach/Koni setup requires anything special in terms of the type of shock mount or how it's installed -- is that right? We did cut the OEM bump stops to avoid premature bottoming out (not sure how much my indie, who did the install, shortened the bump stops). I can't imagine that could be causing the shock mount to fail.

Couldn't be more frustrated!

Any thoughts from you folks?

--Peter

[peter540]

In further researching this issue, I found a good comment from 540 M-Sport on the Bimmerfest forum (http://www.bimmerfest.com/forums/sho...php?t=882981):

#10 and #6 need to be properly positioned, or the rubber insert will separate (above or below) from the metal mount. In my case the tech installed #10 below, instead of on top, and the bushing pulled through below. I took the shock assembly out myself, and pressed the rubber insert back in with a press and re-assembled in the correct order...no further issues......been over 140k miles (Bilstein B14 coilover kit). Had to re-assemble the other side too, before it came apart...If the rear shock mount is assembled in the correct order, this shouldn't happen.

Here's the ReamOEM image to which he was referring:

http://www.realoem.com/bmw/enUS/show...diagId=33_0448

Any thoughts from all of you with this additional input?

--Peter



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[StephenVA]

In the original assembly configuration #10 would allow the impact to push on the shock mount directly with no impact spread from the top nut washer allowing the #10 (assembled incorrectly) to punch it way through the mount.
The strut needs #5 & #6 in correct order as well as the washer #10 on top to spread out the load impact on the mount at full compression.

The bump stop needs to there to stop the metal to metal impact so hopefully the shorting cutting was not way too aggressive. There are short high density bump stops out there. Dinan sell them as do others.

Helpful?

[peter540]

Thanks, Stephen! I'm not sure what brand of shock mount was used -- the invoice for the work doesn't specify brand. The invoice does seem to include just about all the required parts, but the terminology used for some of the parts (below) was generic, so it's hard to tell what they included in the install kit.

• Rear strut/shock bellows
• Rear shock mounts (not sure if they were Lemforder, but they were about $39 each -- less than the BMW original part. Lemforder rear shock mounts don’t seem to be available from anyone any more.)
• Upper rear coil spring shims
• Lower rear coil spring shims (there were two line items on the invoice -- two of these per side; I’m assuming these were different parts associated with this job?)

I've just emailed the mechanic to make sure we know exactly what parts were installed new (or reused), and in what order, and I've asked how much they shortened the bump stops.

--P

In the original assembly configuration #10 would allow the impact to push on the shock mount directly with no impact spread from the top nut washer allowing the #10 (assembled incorrectly) to punch it way through the mount.
The strut needs #5 & #6 in correct order as well as the washer #10 on top to spread out the load impact on the mount at full compression.

The bump stop needs to there to stop the metal to metal impact so hopefully the shorting cutting was not way too aggressive. There are short high density bump stops out there. Dinan sell them as do others.

Helpful?

[Jason5driver]

I would guess that the rear shock mount assembly was installed wrong.

[peter540]

I would guess that the rear shock mount assembly was installed wrong.

I'm beginning to suspect you're right about that...

--P

[BMW540san]

In my many years with owning and messing with BMW suspensions, I think it's quite likely something was installed wrong. With every BMW I ever purchased or worked on, I found signs of incompetence or laziness when replacing something. More often than not, it was done " specially trained technicians". I just want to puke.

Anyway, I'm about to redo suspension on my newly purchased 03 M5 and I actually ordered German Vaico rear mounts. I'm not sure I'm following the logic behind cutting oem bump stop. I always install new ones when I redo rear suspension.

[peter540]

In my many years with owning and messing with BMW suspensions, I think it's quite likely something was installed wrong. With every BMW I ever purchased or worked on, I found signs of incompetence or laziness when replacing something. More often than not, it was done " specially trained technicians". I just want to puke.

Anyway, I'm about to redo suspension on my newly purchased 03 M5 and I actually ordered German Vaico rear mounts. I'm not sure I'm following the logic behind cutting oem bump stop. I always install new ones when I redo rear suspension.

Hi, Z, you lucky M5 owner, you!

Cutting the rear bump stops is recommended when going with springs that are lower than OEM. That's what I have with my setup -- Eibach ProKits, with Koni Yellow shock/struts.

Thanks for the tip on the German Vaico rear mounts. Are they supposed to be better/more robust? I'll search for them, but in the meantime, where did you source them? FCP/Euro?

BTW, I agree -- almost every time I outsource work on my car, I find that there's a lack of eye for the details. I couldn't send out work the way many do. Even the little things matter -- no missing bolts, everything cleaner than when it came in (at least what's been worked on), etc. Puke.

--P

[peter540]

BTW, perhaps it's just the princess-and-the-automotive-pea me, but now that the shock mount (or whatever it is) problem exists, the car's handling feels off. And I'm driving it cautiously and gingerly. Seems to make sense that if the shock isn't firmly mounted, it would impact handling.

Thoughts?

--P

[Jason5driver]

BTW, perhaps it's just the princess-and-the-automotive-pea me, but now that the shock mount (or whatever it is) problem exists, the car's handling feels off. And I'm driving it cautiously and gingerly. Seems to make sense that if the shock isn't firmly mounted, it would impact handling.

Thoughts?

--P

Yes, your car will handle erratically IMO.
I have seen pictures of guys installing the rear mount washers incorrectly and tearing out the rubber completely from the mount.
I wouldn't drive the car until the rear mounts are replaced and installed correctly.
I do all my work myself.
If it is something big (hopefully not...), then I take the car into my trusted local BMW independent mechanic.
Most of the time, I only trust me, myself, and I...

[peter540]

Yes, your car will handle erratically IMO.
I have seen pictures of guys installing the rear mount washers incorrectly and tearing out the rubber completely from the mount.
I wouldn't drive the car until the rear mounts are replaced and installed correctly.
I do all my work myself.
If it is something big (hopefully not...), then I take the car into my trusted local BMW independent mechanic.
Most of the time, I only trust me, myself, and I...

Thanks -- glad to know I'm not crazy in terms of what I'm feeling with the car's handling.

I agree -- I used to do all my own work until this past year. Life's been extremely busy on all fronts, and I needed to keep my car's downtime to a minimum, so off to the shop it went. The upside of all this is that it's on the shop, instead of me, to make right anything that goes wrong with recent repairs, upgrades, etc.

[computiNATEor]

Most of the time, I only trust me, myself, and I...

Seriously. The flat rate system does not promote careful repairs.

[peter540]

We installed Lemforders today. Guess what we found?

- No support cup (sits under the shock mount and above the bump stop -- a CRITICAL part)

- No bump stop (they were supposed to have been installed, having first been cut shorter)

- Wrong washer at the top of the assembly (too small to prevent the shock from pulling out with downward movement)

The shop corrected everything for free and admitted their mistake. When they first installed my Eibach/Koni setup, they pulled out my Fortune Auto coil-overs, which didn't feature any of the OEM parts needed for the new setup. They should have known what parts to source, of course, but at least they were honest about everything.

Lucky for them, this time I thought to bring the original rear spring/shock assemblies, which I'm glad I'd kept when I'd put in the FA coil overs. They served as a reminder/example of the proper setup, and they also provided side of the parts we needed today.

Here's hoping this is the last I have to deal with this for a LOOOONG time.

--P