E92 M3 broken differential bolt

[V8FunNaturally]

Originally Posted by Dackelone

You could use four jack stands to make the car level up in the air(and safe to go under it) and then check the diff oil level. Or maybe have an indi shop/of your original dealer check it.

When BMW has a diff that makes noise then will change the fluid first to this SAF-XJ+FM and then the tech will take the car to a parking lot and do 20 tight turns(full lock) left and then right. This will heat up the diff clutches and the fluid will get up in there. Then you won't have any more noises. But the noise is a different sort of noise from what you describe. Its more of a wobble or vibration type.

The next time you hear the noise make a video of it so you can show it to your dealer.

Good Luck,
Dackel

Thanks for these ideas, thinking of it, that turn must have been the first hard slow turn after the 1200 mls service. Could it be the new SAF-XJ diff oil had not gotten up yet to lubricate the diff similar to what you describe ?
Yes the noise is not a wobble noise. I will be on the watch. Probably will do 10 tight turns on a parking lot next time with full wheel lock and report back.. Without sound present I feel there is nothing wrong. I think what i heard was the discs inside the differential because the oil had not layered everything yet. but that is pure supposition.

PS: I don't have 4 jack stands. Does it have to be absolutely level, what about 5-10% incline ?

[Dackelone]

Originally Posted by sunsweet

PS: I don't have 4 jack stands. Does it have to be absolutely level, what about 5-10% incline ?

Yes, it does have to be completely level. Otherwise you will have too much/little oil in your diff(or trans) when you remove the fill plug.

[JFlo]

Man! Finally made it through all 8 pages... so I am left with a couple of questions.

1) Wheel hoping: I wasnt aware of this term, and read up on and now have a pretty good understanding what actually happens. However, what I am uncertain about is whether or not this can only happen during a launch/hard accelerating? The reason why Im asking is cause sometimes when I change gears mid turn, pretty hard on the throttle (we're obviosuly not talking a sharp turn here), when I change gears (especially with the MDM on) the car kinda jumps/skids. So far I have assumed that's just a result of changing gears mid-turn while going pretty hard on the throttle and you are borderline about to experience somewhat of an oversteer. However, reading through this makes me wonder if that is also a type of "wheel hop"?

2) Just having bought an 09 M3 DCT (picked up 6/1/13) I am of course shitting bullets right now, hoping this will not happen to me. However, there seems to be a trend on newer, 6MTs. Is that just a coincidence or is it just me. I just hit 50K on the odometer, so I would like to do some pro-active work if possible.

3) What can we do? I guess could be a summary post somewhere else (possibly sticky?) which summarizes what we can do in order to prevent this from happening. Both for the people that have been through this already and have had parts replaced under warranty, and the ones that have gotten by so far. So for example, replace bushings, periodically check torque levels on XYZ bolts with x-amount of torque, replacement of any other parts that might assist with this issue etc.

Like alot of you I am pretty disappointed/scared over these stories. I certainly didn't buy an M3 to drive like a granny around town and never drive the car the way it was "meant to be driven!" That being said there's a difference between abuse and driving the car it was "meant to be driven" IMO.

[jjw2331]

Switching to solid diff bushings and/or using a defiv differential brace is a solution to prevent wheel hop (maybe the cause of broken diff bolts) and broken diff bolts. However, there is increased NVH. A gear whine as some have described it. Switching to solid subframe mounts are also recommended.

[squartus]

Had this happen to me yesterday, dint think id make it home.





This is deff a dam problem with these cars

[neerredd1]

@stE92M3
Did this happen because you where driving it hard??

[MrAdams]

Thank God for this forum and all us nerds in here.


so..... I just had my bolt break last night.

I think it was slowly breaking or broken and holding on by a thread because I always had a little trouble getting in 1st at a stop and I could feel a clunk when I would put it in gear.
Last night I came out of a driveway with a crazy angle and heard some popping, at the next light I heard the clunking sound of a bad diff mount w I tried to accelerate. So I safely drove it home ( about 1/2 mile ) and the next morning I drove it to work with the hazards on ( about 1.5 miles ) Lifted it up and sure enough the bolt was broken.

I swapped on my lunch break today, took about an hour. it was a bishhh tho.

it feels a lot smoother and sturdier than I have ever felt it ( which leads me to believe something may have always been wrong back there....
Das Germans....

[e46m3tony]

BAM! on point! herd a clunk last night.... drove.... it went away.
drove the car again today... was stuck in traffic then the noise came back with a vengeance! started rattling and etc.
went on this forum looking for answers....
came upon this thread.
checked my car.
and what do ya know......
broken screw

[e46m3tony]

Originally Posted by MrAdams

Thank God for this forum and all us nerds in here.


so..... I just had my bolt break last night.

I think it was slowly breaking or broken and holding on by a thread because I always had a little trouble getting in 1st at a stop and I could feel a clunk when I would put it in gear.
Last night I came out of a driveway with a crazy angle and heard some popping, at the next light I heard the clunking sound of a bad diff mount w I tried to accelerate. So I safely drove it home ( about 1/2 mile ) and the next morning I drove it to work with the hazards on ( about 1.5 miles ) Lifted it up and sure enough the bolt was broken.

I swapped on my lunch break today, took about an hour. it was a bishhh tho.

it feels a lot smoother and sturdier than I have ever felt it ( which leads me to believe something may have always been wrong back there....
Das Germans....

hey where did you get another bolt from?

[e46m3tony]

the broken bolt and the new bolt

[templarklimek]

I'm no expert but those bolts BMW is using looks the same as I can get from the local hardware store for 35 cents.... that's what holding the diff together, yikes!

[e46m3tony]

Originally Posted by templarklimek

I'm no expert but those bolts BMW is using looks the same as I can get from the local hardware store for 35 cents.... that's what holding the diff together, yikes!

Cost me 5 bucks at BMW 😭 bought 2 extra ones just in case it happens again 😔

[Dackelone]

Originally Posted by templarklimek

I'm no expert but those bolts BMW is using looks the same as I can get from the local hardware store for 35 cents.... that's what holding the diff together, yikes!

Bolts sold at your local hardware store are 4.1 grade, IF they are marked/graded at all. BMW's bolts are 10.9 grade. Yes, they can break, but its rare. I suspect what's causing some of these bolts to break is launching hard from a stop or getting crazy axle hop doing 0-60 mph runs.


Dackel

[aussie2u]

Originally Posted by Dackelone

I suspect what's causing some of these bolts to break is launching hard from a stop or getting crazy axle hop doing 0-60 mph runs.
Dackel

In retrospect, I agree 100% with you. The 1-2 shift with clutch dump will shear it if the axle starts to hop.

[Vybz]

Just had this happen to me last week. Wheel hop is a bitch, but then again I guess you'd imagine that the car would be able to handle it. I lucked out though, cause at least in my case it wasn't the main bolt, but one of the smaller supporting bolts. Wish I had known about this earlier, would've reinforced the rear sub frame from the start.

[kamber]

Resurrecting this with a quick question:

Does anyone have the part numbers for all 3 differential bolts? Im going to be replacing my diff bushings with powerflex purples and would like to replace the bolts themselves while I'm at it, incase they have been warped or fatigued from knocking around due to soft/hollowed out oem bushings.

Edit: Checked last night and saw that my rear 2 diff bolts are perfectly fine. Which one of the three bushings is the foam bushing? I'm assuming the front? I didn't know exactly where this was (shrouded by a heat-shield, I'm guessing?), so I didn't get to take a look at it.

[wyatth]

Bumping this up. Searched around and couldn't find the direct answer to my Q.

I just picked up an E90M ZCP/DCT with 48K. Differential feels good and passed a PPI at EAS. That said, I am coming from an E46M and they had a similar issue. Few cars are affected (and it seems more common on 6MTs), but it's cheap insurance to replace bolts/bushings preventively. So I'd like to do it for the peace of mind.

Question: What's the exact PN list for someone who wants to address this preventively? That is, assume no collateral damage like the subframe. Is it just the rear/foam diff mount, or should I replace all 3? And does the diff have to be dropped completely either way? And then 1 bolt, or 3?

I'm thinking this:

1x 33312283384
2x 33312284019
1x 33306785433
2x 33176760343

[pbonsalb]

It’s not a common problem on the E9xM3 like it is on hard driven E36M3. The E36 has one front and 2 rear bolts. The E9x has two front and one rear.

Dropping the diff should give room but that rear bolt is tucked up in there. You icould also lower the subframe 6 inches. Use M12x1.5 threaded rod in place of the subframe bolts. You will have to undo the rear brake lines in the subframe and loosen up some other lines and wiring but it can be done. You also need tools or devices to press bushings out and pull new ones in.

The foam bushing is actually solid aluminum with maybe a 1/8 thick foam sleeve around it. There are aftermarket solid and poly bushings, but beware of diff whine if you use a hard compound.

[wyatth]

Thanks for that feedback.
I'm not interested in aftermarket bushings at this time or in this car. The current setup feels nice, I was just interested in replacing the bushings/bolts with OE preventively to avoid any issue. But that labor sounds like a drag. Overkill on a DCT car with 50K?

[pbonsalb]

Probably overkill unless you like drag racing. There are a few reports of broken diff bolts, somersaulting in diff cover and/or subframe damage, but not many such reports. If the theory is that the bolt fatigued or gets tweaked and then fatigues and breaks, find out which bolt is most likely to break and just replace it or replace all 3 bolts but leave the bushings in place. That would be easier but I remember that rear bolt being tucked up high—it may not come out unless you lower the subframe at least a bit (maybe just loosening the subframe bolts would be enough but I don’t know for sure).

[Scharbag]

All 3 diff bolts are really easy to change in the car. Just drop the muffler to access them.

BMW recommends that you replace the "stover" nut on the big bolt too.

Here is some good info.

[Norm_701]

I bought a 2011 e92 m3 with 39k miles. Have driven it to florida from Virginia and back. everything with the car is great. Except the fact that I've sheared 3 bolts already, causing the differential gearbox to drop from one side and even leaked fluid. not cool. am definitely gonna try and find a fix for this