[DIY] Torn Rear Shock Tower Repair

[jworms]

long story short: i recently found that my rear shock tower tore (for what it's worth, my setup is stock suspension and recently replaced RSMs with no RSM reinforcements - lesson learned ). in my searching for a repair tutorial, or general guidance on what to do i found lots of people mentioning how much they paid for a shop to fix it (upwards of $500-$800) and only one thread that detailed some of the process for a diy fix (thread here: http://forums.bimmerforums.com/forum....php?t=1283649). this one diy fix thread helped me greatly and i want to build on that with my own experience. this whole process cost me about $50 (note: you will need access to somebody with a welder). that said, let's start off with the before pictures...

from inside the trunk:


from under the tower, where the shock connects to it:



the part to fix this is easily obtainable at the dealer for around $8. here's the part number and diagram from realoem (41148169027 - left, 41148169028 - right), number 17 here: http://www.realoem.com/bmw/showparts...42&hg=41&fg=25

first things first, jack up the car, remove the wheel, then remove the shock. the shock is only attached at the tower (top - see pictures above - 13mm for both sides, no need to remove the center nut yet) and behind the brake caliper (at the bottom - see picture below - i believe this bolt is 17mm):


next, clean the area up and inspect the damage. proceed to kick yourself for not installing the RSM reinforcements. try to see the outline for the stock piece (identical in shape to the one you picked up at the dealer). you will need to use a sander/grinder/razor/wire brush/etc. to remove the underside coating so you can see the factory spot welds (see picture):
from this:


to something like this:


notice the small circles on the shiny metal that you just exposed. these are the spot welds. the one at the bottom center is probably the most noticeable in the picture. once you have exposed/marked ALL 16 of the spot welds you can start drilling them out. yes, drilling...i know

all 16 welds drilled out (i used a 3/8" drill bit):

(use this as a guide to find them on your own - make sure you get all 16!)

here's a picture of what it will look like from the trunk:


see all that stuff slathered on the tower (brush strokes)? you need to figure out where the shock tower pokes through the chassis and remove that stuff to free up the torn shock tower. a razor is helpful for this step. next, remove the shock tower. this is where i think somebody might be able to improve upon my process. in the other diy thread i linked to above, it seemed like the shock tower just kind of popped out for him with a couple of hits from a small sledge...this was not the case for me. i basically used a flat head screw driver and pried the shock tower out, little by little. this was a tedious process and it ended up stretching the already pretty thin metal chassis somewhat. here's what the end result of that looked like with the shock tower removed:


here's a picture showing the old shock tower and the new one from the dealer:


prepping the new tower for welding: we test fit the new tower and marked the holes on it. it was then sanded down in those areas to allow for welding.


next step is to prep the hole in the trunk for welding. the areas around the drilled holes were sanded down to bare metal:


the new tower was then put in place and spot welded (as you can see, i purchased the RSM reinforcements ):


i bought some primer for $3 and sprayed it over the exposed metal areas in the trunk and underneath, in the wheel well.
trunk:


wheel well (underneath):


the next step (and the most expensive part) was to slather seam sealer on the underside to protect the area from debris and to give it that factory look. I found this 3M seam sealer online for $20:


bought a couple of paint brushes and went to town on it:



i bought some paint from a website online that will sell you factory colors in a spray can (http://www.automotivetouchup.com i think was the website). i haven't painted it yet. i'll probably do that in the next couple of days.

i also haven't slathered the seam sealer in the trunk yet. i'm waiting to see how this holds up before sealing that up. with how thin the chassis metal is (i was kind of shocked), i might end up welding little reinforcements onto the chassis to ensure i don't have any issues down the line. that said, i have been driving the car around for a couple weeks and haven't had any issues. i even went for a little twisty run in the local canyons and everything has held up fine. i'm pretty pleased with the repair.

the real lesson to be learned here is that EVERYONE should buy RSM reinforcements. it is literally a 5 minute fix to prevent this ordeal i went through. i even took a picture of my other tower to show how easy it is...

before RSM reinforcement:


after (spending as little as $10 and removing/reinstalling two 13mm nuts):


i ended up buying the UUC Meyle HD RSMs (even though my old RSMs were fine, i figured i might as well replace them) and the reinforcements came with them. it's really a no-brainer to install the reinforcements, though many shops don't do so. if you feel like you might be one of those people, i highly suggest you request that your shop install these asap!

i'm sure i could have done things better which is part of the point of this thread -- to help anybody who has to deal with this in the future. i invite you to suggest better methods for doing this, but please don't post frivolous comments that contribute nothing to the thread.

[Mad Dog 20/20]

Sorry to hear/see that.



Congrats - you are the poster child for RSM reinforcement plates.

[sivikvtec]

You cannot bolt it in like that. That is fatigue critical structure, not designed to have loads concentrated on fasteners like that. The replacement plate will start to fail at the fastener attachement points and tear out.

[libravcs]

Amazing. All of the expensive engine and performance mods...but $5.00 RSM reinforcement plates that could have prevented this werent used. Priorities. SMH.

[jworms]

Sorry to hear/see that.



Congrats - you are the poster child for RSM reinforcement plates.

yeah, i know

hopefully people will learn through my experience and buy the reinforcement plates.

You cannot bolt it in like that. That is fatigue critical structure, not designed to have loads concentrated on fasteners like that. The replacement plate will start to fail at the fastener attachement points and tear out.

that's the other guy's thread. i welded mine in.

Amazing. All of the expensive engine and performance mods...but $5.00 RSM reinforcement plates that could have prevented this werent used. Priorities. SMH.

lesson definitely learned on this one. like i mentioned before, hopefully this thread will save a few shock towers in the future.

[NotSoAverageJoe]

Thanks for the diy. Fingers crossed that my rsms dont fail...

[Brent 930]

Good job!

[Mad Dog 20/20]

that's the other guy's thread. i welded mine in.

I just peeped that link. Oh man, that bolt-in repair is hilarious!!

[alanilil]

I just peeped that link. Oh man, that bolt-in repair is hilarious!!

I agree, how hard can it be to find somebody to spot weld it (or seam weld it) to do it right.

Nice write up. I hope I never have to do it, but it's nice to see it documented!

[m3luckyoo]

Very nice- this happened to me as well and I took it to Mieneke for a quick fix but yours is so much cleaner. Mine is SLOPPY! lol. Miracle it hasnt failed yet. The only thing I do like about it is that they welded on a fat metal plate for strength. =P

[langley]

Thanks for the diy. Fingers crossed that my rsms dont fail...

Dont cross your fingers, it wont do you any good. Add reinforcements and put it out of your mind.

Jworms, thats a boss DIY. This kind of thing really helps the forums.

[MasterKwan]

Is the replacement panel thicker than the old one?

[Brent 930]

I was wondering that too, but I doubt it knowing BMW.

[racer m]

Nice write up!
When are you going to make another jab at the fastest quarter mile NA E36 record?

[TTstealthRR]

Very nice DIY!

[jworms]

Thanks for the compliments all. i wish i didn't have to make this thread, but i feel a little bit better about it knowing that others might benefit from it now

Is the replacement panel thicker than the old one?

i'm honestly not sure. i really think they are about the same thickness. it's kind of surprising that this happens because the shock tower is pretty thick metal, especially when compared to the chassis metal that it's welded to.

Nice write up!
When are you going to make another jab at the fastest quarter mile NA E36 record?

hah! as soon as the weather gets colder i'll give it another shot. probably towards the end of the year, around november.

[KnudsonsM3]

looks really good man!

[KGB M3]

Excellent work man! Glad you got it taken care of. I ripped the stuff out of my trunk yesterday to inspect, seems ok. Placed an order for the Mason strut brace to help prevent this from happening. I'm amazed how clean it turned out for you, great thread!

[95s52]

Was wondering about the process of your shock tower repair. Glad to see you tackle to job. It came out great. Props on documenting it for the community!

[Moron95M3]

Sticky!

great write up, I'm going to go look at mine and see if they're reinforced.

[CMG]

I thought this was going to be fail when you referenced that other thread, but it looks good. Now to see how it holds up.

[Xiphos]

Nice write-up, added to the DIY guide.

[Badgtho is back]

nice.. done the correct way

[m3mobbin]

Beautiful work on the repair John. I'm surprised you, of all people, would overlook the RSM plates. Well at least it won't happen again lol.

[328iJunkie]

Where else you buy the RSM plates