I don't know the specifics on that thread, but remember there is a difference between a tap that cuts new threads and a tap for chasing threads...

You don't want to use a cutting tap for thread chasing, as it will remove additional material. The end result will be an even sloppier fit of the bolt, and lower ultimate clamping force.

-G

 

Btt

Are there any symptoms besides the "dead body thump" that are attributed to broken subframe bolts?

I've had 3 alignments in the last few months and still can't seem to 100% resolve a "wiggle" in the rear end under full-throttle. It's there up through 80mph and can quite disconcerting... At moderate throttle I don't notice anything... Occasionally I think I hear a minor bump out back... But so far it's only rarely there.

Thanks guys!

-G

 

Greg

You can peak under the rear off the car without a jack and you will be able to see all 4 mounting points

 

Thanks Shardul!

So if one of the bolts is broken will the bottom half of the bolt have probably fallen out, or is it likely to still be in there? I'm just curious how easy it will be to see actual breakage if it happens inside that bushing area with the subframe possibly blocking the view?

 

it may be missing the bolt and you when you compare it to the other side the sub frame will be lower. you will be able to put your fingers between the chassis and the sub-frame.

 

Cool... Thanks. Sounds like it will be easy to recognize if there's a problem.

Does the squirminess I described sound like a symptom of a broken bolt based on your own experience?

-G

 

not really I had the same issue and it was solved after alignment

 

I'd have your toe link bushings checked out if your car feels like it is "steering" from the rear.


-Oscar

 

If these bolts do have a torque spec followed by a degree turn they are torque-to-yield and should not be reused. That would explain the failures after removal and reinstallation. I worked in a service shop for 20 years and I could count the times on one hand I saw a tech use the correct torque method on this type of chassis bolt. 99% of the time they simply hammer them in with a impact.

 

Here in Germany every nut or bolt that has a torque spec is always properly tightened with a torque wrench.

 

What's weird I'd that I now have a new set of MBArts toe links in there....(solid heims and round tubular links) so the stock rubber bits aren't there anymore to cause toe changes.

At first when my car was lowered, I thought the excessive negative camber might be complicating things. But this last go around with alignments I disabled the ELM and put the car back to factory height before the alignment.

Puzzling...

-G

 

Here's some pics I took yesterday. This is the second time this has happened to me; first time was on passenger side, this time on drivers side. The bolt ripped out of the frame both times.

Went to the most awesome local hardware store (Marshall's Industrial Hardware) with the old MB bolt in hand. Measured the thread pitch and diameter and picked up a hardened steel version a little longer than the stock bolt. Also picked up several heavy duty washers and some nuts for the bolt.

Remove the wheel and the plastic fender liner and then you can access the frame. My mechanic used two plates of steel with a hole drilled for the bolt. He did it in less than 30 minutes. Parts cost was around $6. I paid $11 because I always buy extra when I go get little pieces of hardware.

 

How hard is this to do as preventive maint?

 

Not too bad. Cut an access into the frame like pictured, get a good look around, remove the bolt, reinforce the area, install new bolt. Don't reuse old bolt. It's a torque-to-yield (a.k.a. stretch bolt) designed for a one-time use. Like the crank pulley bolt.

I'd say an hour tops per side for the handyman with the correct tools and materials.

 

Is there any other symptom of this issue besides a terrible noise?

Would one side of the rear suspension be hanging lower when the car is off the ground?

 

When my passenger side went, the right rear of the car was way up in the air, like the bag had fully inflated. Nothing like that on the left until I raised the car with the button.

Both instances were met with a fairly loud pop. Definitely something you would notice.

 

Good all,

I'm flabbergasted. A quick recap. I have 07 W211 E350 sport (staggered wheel layout) with OE specs. 2 days ago, an incident took place on my driveway. As I was driving home, approaching my driveway, I heard and loud "thud" as if I ran over a pothole. no potholes where I live nor did I ran over anything. After inspecting the car, noticed that the rear is low, 1/4 of the rear top of the tire is tucked in the wheel well and negative camber to the extreme. Jacked up the rear and to my surprise, 2 bolts long bolts fell, seems to have sheared off. It came from rear sub-frame bushing. Another member here in the forum, ECsquared has experience this issues. I do not carry any heavy loads, I have a toddler I shuttle around. I do not race, track the car in anyway, it's currently at the dealership and I just got their labor and part quote for, get this, $1450.34.... WHAT!!! for 2 bolts that are designed to hold a rear subframe, price seems extreme. I'm very disappointed with this brand...Any insights?

 

it is a 1 hr fix per side if you know what you are doing and about 10 dollars in parts

 

I've been following and reading all inputs from this forum regarding this issue and I'm confident with my know-how that I can do it with the guidance from this forum. Unfortunately time is not on side. I did buy an extended warranty and hoping this is something they cover....I still in awe on how that happens. It's not reassuring, particularly for this brand, and I'm very disappointed.

 

You keep referring to "this brand" hope you now that this brand does have reliability lower than a GM in a lot of cases right?

 

 

Sub frame has come away twice.


first time was the worst and caused a fair amount of other damage, both cavity threads were ripped out.


https://mbworld.org/forums/w211-amg/...y-chassis.html




second time bolt snapped

 

touché my friend

 

Lol good responses!

 

C32 has joined the club. Torn at subframe (lefthand side) . Cutting an access area to weld a replacement. Only plus is quaife will go in as the whole back end is off. lolz.