Ok so this all starts with a rear differential that was repaired by a very known shop in West Los Angeles. They did a Mickey Mouse job in that a couple days after picking up my car, my diff was leaking again. I had to take it back for a second time to get it sealed. Some 3-4 days pass after the second seal and I start getting this awful noise coming from the rear right of the car. It sounds like it's coming from the back seats and so I take her in to the dealer. My buddie calls me and tells me that it does not look good and I have a broken sub frame bolt.







My warranty denies the claim on the basis that they do not cover bolts. Fine, its right there in the contract. They do however add that I should take it back to the shop that serviced the diff. They said that they most likely did not put the sub frame back together properly and the improper install lead to the bolt failure. They of course could not prove it but the tech said he is almost 100% sure as it is not the first time he has seen a broken sub frame shortly after rear end was dropped.

I took the car back to the shop that did the diff. Not only did I spend $35 on a new bolt from the dealer, I bought the tech the MOST expensive authentic German beer I could find in hopes they would have a soul and just help me assemble the new bolt. Boy was I wrong. After a week of finger pointing and complete BS, I just picked up my bolt (unfortunately they drank the beer) and started to look for a shop that would do the work.

I found a local shop down the street from Disneyland that did my diff and caused the bolt to break. The mechanic was absolutely a stand up guy and it took him all of 35 minutes to get the old bolt out and install the new one. He used vice grips and a wrench to pry the old bolt out and we did have to cut a small hole in the frame of the car to fit a washer and nut. They welded the hole back and took a grinder to it after. A+++ work and again it took him all of 35 minutes to do. The best part? He charged me $120!! I paid him and tipped his guy $30. I was thinking it would cost closer to $250 anyway. Which brings me back to the shop that butchered the install to begin with. Instead of just putting the car on a lift and attempting to tackle the problem, the owner just fed me a bunch of BS about who's to blame, how he doesn't have time, bla bla bla. This all knowing mechanic had no clue how simple of a job he was turning away. What could have taken 35 minutes of his time to right a wrong has instead earned him a disgruntled customer.

Also, big huge thanks to Shardul. I don't know where I'd be if he wasn't ready to troubleshoot problems any time day or night. Oh yeah, we live 1500 miles apart and I've never met the guy. That folks is a gentleman and a TRUE enthusiast.

 

Glad its sorted, there is no shortage of dishonest people with no integrity. I find it hard to trust any mechanic. I do as much as I can myself.

 

Glad you got it easily sorted out, it's a shame the shop who did the diff remains unnamed... With that service, I would gladly post their name and their ways to high heavens. And if there's ever a vote for "Most helpful person on the forums", I am voting for Shardul as well. He has helped me countless times, and I too have never met him. Just phone calls/ emails/ and PMs. I hope one day to meet him, just have to see what God has in store for me first.

 

Glad you got everything sorted out

 

Had the same issue months ago. Mine was much worst though. I heard a thud at the rear right door for some time and did not realize what it was until I hit a pot hole. The rear part of the subframe separated from the car. Had to get it towed. With the help of Shardul, I cut the side out, got longer, stronger bolts from the dealer. Very labor intensive job without a lift.

 

For the same problem I had to pay 752$ for labour and 85 for the rubber mounting and 3.80$ for the bolt at the benz dealership. They said "cuz the bolt had to be drilled out"

I didn't even know what the hell was happening until Shardul told me the "dead body thump" is broken subframe bolt. My warranty also refused to pay for it.

 

OMG wow, THAT'S what it is?!!! Damn, my last E320 CDI had the dead body thud and all the time I thought it was the airmatic strut on the rear!

Holy wow, awesome info for sharing. The amount of stories I've read about the thud and people not being able to work out what it was.....

 

FWIW - One friend got MBUSA goodwill cover a broken subframe bolt on his 03 E500, while another friend managed to get a broken subframe bolt covered by warranty on his E55...

 

[QUOTE=03'55AMG;5634737]Glad you got it easily sorted out, it's a shame the shop who did the diff remains unnamed... With that service, I would gladly post their name and their ways to high heavens. And if there's ever a vote for "Most helpful person on the forums", I am voting for Shardul as well. He has helped me countless times, and I too have never met him. Just phone calls/ emails/ and PMs. I hope one day to meet him, just have to see what God has in store for me first.[/QUOT
Shardul is the man , never met him....same phone calls ,pm's, emails .....saved big money on my air strut.....this guy is the man....glad to hear that you got your car all buttoned up....another piece of information to put in the memory bank of the 55's ....thanks again for everything Shardul
-Chris-

 

Just so everyone knows, whenever the subframe bolts are removed you should always!!! install new ones. If a shop that does it for you says they can reuse the bolts, promptly ignore them and pay to have new bolts put in!

 

Same **** happened to me.

 

I think I am just going to go ahead and replace mine.
Anybody know where to find them at a fair price?

 

i have two sitting in my trunk, i bought them for that reason as a preventive kind of sittuation and still havent done em... wounder if i should

 

Does anyone know what the PSI rating is on the factory bolt? I'm assuming it's a metric, like 10.9 (~150,000 psi) ???

Is this a standard type bolt that could be replaced with something stronger? I was thinking something like those F911 type bolts

http://www.f911.com/

Modded cars are clearly putting more stress on those factory bolts, so swapping in a stronger set of bolts BEFORE they break could be money well spent...

-G

 

Greg, what's interesting is every story I've heard of where someone has broken a bolt they had recently had the bolts out. I'm not saying it couldn't just happen, but it seems like the problem is just not putting in new ones when you take out the old ones.

 

I may do mine as preventive maintenance.. Is it as simple as pulling them out and installing new ones?

 

+1 on that answer would like to know

 

What breaks, is it always the bolt or do the threads shear out of the frame?

The appropriate torque might stretch the bolts similar to head bolts which are not reuseable. Otherwise all I can think of is the mechanic installs one bolt at a time, does them up one at a time and the last bolt(s) is not perfectly centered. Going around all the bolts in several passes while tightening will help get even alignment.

 

the bolt snaps in half and you have drop down your whole sub frame down to drill it out and all that crap.......... ITS a B!itch

 

In that case it makes sense to buy new ones and make sure they don't just bang them in one at a time. I wish there was easier access to bolt torques, I have a nice full pdf repair manual for my 350z but the benz repair cd makes you want to kill yourself and everyone else when you try to find specific information.

 

The mechanic at benz dealership told me that "bolt" alone can take 2 tons of stress. If our car weighs 4200 lbs that is 2.1 tons and the bolt itself can handle 2 tons and in real terms that 4200 lbs of weight is shared by numerous components.

He said it's the side ways or diagonal stress on it which can reduce the life. I asked him like what ? He said "Donuts, burnout, cornering while in comfort mode cuz the car leans more in that mode than sport 1 or 2"

 

I only do occasional burnouts, not much else.. So I am good there.

 

I believe it's 90nm(66ft lbs) and then a 60* turn. Don't forget to chase the threads before putting the new bolts in.

 

what size tap should be used to chase the threads?

 

Most likely the bolt will rip out the housing that is welded to the "frame" of the car. It's what happened to me.

What you want to do is buy a front suspension bolt.



If you look at the pic, the bolt on the left is the current rear sub frame bolt. The one on the right is the front suspension bolt. It's a sledgehammer compared to the rear sub frame one. **The fix is that it comes with a washer and nut, you are "sandwiching" the sub frame to the frame of the car. I don't know why it wasn't done like this to begin with.

Also, this happens like you guys mentioned, from hard driving but most of all from launching the beast!

** R&D credit goes to my hero Shardul.