Heartbreak-broken rear shock mount

Stevehose

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So I pick up Luis A because he's in town and we're going to cruise to dinner but on the way we hear a loud bang from right rear, first sounded like a flat tire but then realized it's likely the shock. Pulled over and verified. Limped home. Am bummed most about the elephant skin cover which was original and mint, now torn apart. I knew this is an issue with our coupes from back in the 80's (I welded my first coupe's towers preemptively and should have done these) and when I installed my Bilstein's a couple years ago I checked the integrity of the metal and added washers to spread the load but obviously no workee. No rust at all up there. The sub zero temps the last 2 days may have had something to do with it but on the bright side better now than in the middle of nowhere on the way to Amelia Island in March. I don't think I'll find another mint elephant tower cover so will try to repair as best possible. But more important things in life, yes?

So what is the best way to weld these back? The old CS Register has articles about this which I will research but does anyone have modern day tips on how to do this given the difficult access of the tower? What do I tell a welder to do?

Bottom line guys and gals: no matter what condition your car is in, get your towers welded asap if you haven't already done so!

Party crasher:





 
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MyFemurHurts

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Ouch! Anyone have a few pictures of what the reinforcement welds look like? I have some family that's super talented with a welder, so this is on my to do.

Sorry for the bad luck. :(
 

rsporsche

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Steve,

so sorry ... i am bummed for you and your wonderful coupe. keep us posted, and i am now curious about the preemptive welding. and will add that to my ever increasing list of things to do.

scott
 

bert35csi

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Very unfortunate Steve...I feel for you and your lovely coupe. My driver's side shock tower failed back back in 2006. The shock tower was repaired by my BMW shop (Phaedrus in SF) by welding a steel plate over the cracked and punctured top portion of the tower. It was a pretty straight forward repair, but obviously, it depends on the severity of the damaged metal.


This was the damaged left shock tower. note the repair is barely noticeable. See the raised welded plate sitting below rubber mount.


This was the 'insurance policy' repair done to the right shock tower.

Good luck with the repair Steve.
 

Stevehose

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Thanks for this. Will bring these pics to the shop tomorrow to show them to see if they have the desire/skills to do same.

Very unfortunate Steve...I feel for you and your lovely coupe. My driver's side shock tower failed back back in 2006. The shock tower was repaired by my BMW shop (Phaedrus in SF) by welding a steel plate over the cracked and punctured top portion of the tower. It was a pretty straight forward repair, but obviously, it depends on the severity of the damaged metal.





This was the damaged left shock tower. note the repair is barely noticeable. See the raised welded plate sitting below rubber mount.





This was the 'insurance policy' repair done to the right shock tower.



Good luck with the repair Steve.
 
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w. chen

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so sorry about the busted tower

mine happened while touring the ghost town of bodie in the sierras in the mid 80s. it was a torture hearing the clunking sound for 250 miles. it is a 74 model and that would make it only 10 years old when the metal fatigued. hope you find a good welder to do a good job. the welds has lasted 30 years, longer than the factory metal. sometimes, i wonder if the coupes shock mounts were suppose to handle the bilstein shock stiffness. it shouldn't make a difference but then most of us have these mounts issues. good luck.

w. chen
74 3.0 cs
 

deQuincey

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hi steve, i am so sorry about this
thank you for your recommendation
elephant skin covers can be found at bmw dealers, not the same as the originals, but,...
 

restart

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Oh man, I am sorry to see that.

I noticed on one of the recently posted coupes for sale that the shock towers were welded. Originally I thought it was shock repair, maybe it was pre-emptive. I only remember them because the welds were atrocious and unpainted and of course starting to rust in an ugly way. no way as nice as bert35s are...
The welds in berts pics are to strive for! Hoping yours come out as nice!

Bilsteins, beefed up diff and various other mounts, a bunch of extra ponies, Extra traction,l spirited driving, fat tires, wide wheels, maybe some corrosive cleaners, wrong torque, mount a little loose, a little,tight, more spirited driving...what could go wrong?

Part of the fun! Oui?

I am sure a trunk liner will make its way to you.

Bravely forth;)
 

Kizilsakal

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It hurts to see that. Does tower braces help to prevent this? I just got mine painted, so i don't want to weld anything if i can..
 

Stevehose

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The old Registry articles point a finger at the Bilsteins as, if not the cause, certainly the accelerator to this problem. Either way, after all these years the metal is even weaker now after being weak to begin with. And yes it's a horrible noise!

Thanks for the advice.

sometimes, i wonder if the coupes shock mounts were suppose to handle the bilstein shock stiffness. it shouldn't make a difference but then most of us have these mounts issues. good luck.

w. chen
74 3.0 cs
 

NewSixCoupe

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The old Registry articles point a finger at the Bilsteins as, if not the cause, certainly the accelerator to this problem. Either way, after all these years the metal is even weaker now after being weak to begin with. And yes it's a horrible noise!

Thanks for the advice.
I had been on the fence as to whether I should replace my Bilsteins, now after hearing about your misfortune any hesitation I might have had is gone...

Good luck with the repair work!
 

Bwana

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Ouch! Sorry to see that Steve! You should be able to get that repaired before Amelia. I had the same thing happen but I caught it about 10 seconds before it came loose. I think it was still connected but took very little effort to pull the top completely off.

The original problem



I cut out a new support mounting plate from 3/16" steel (I think) and drilled a hole thru it.



Note the highly professional weld splatter shields :lol:



With the fine welding skills of 61Porsche, he was able to weld the plate onto the top of the remaining shock tower. He was even able to get around the backside somehow for a complete weld. It may not look very glamourous but it works!



Alternatively, you could cut out the whole cylindrical section out and replace it with a new, stronger one. More work but probably better. Just depends on how much is left in the sub-structure to weld to.
 

Peter Coomaraswamy

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I may not have this in time but I'm working with my neighbors who build custom instrumentation for oil pipelines and they have a pretty extensive machine shop across the parking lot from us here at work. I want to develop a brace that solves this problem without any welding, however will require 2 holes to be drilled in the trunk floor at the base of the shock tower and be tightened around the smaller cone that the rear shock attaches to. It will also include a ring around the top where Steve's tore. This will transfer the stress to the floor, which can be braced from below. I will check on the progress later today after a meeting I have. I started working on this when I noticed that the Polaris coupe had no additional welding on top and I think the Bilstein shocks do cause additional stress there because they are harder to compress and the springs take less of the burden.
 
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