E92 M3. BROKEN drive Axle. Pictures inside

[Malek@MRF]

As we all are coming to learn, the E9x M3 has its short comings when it comes to some aspects of the driveline. In this case, we will be discussing the axle half shaft (passenger side).

For a very long time, I have been recommending that the rear sub-frame & differential mounts be upgraded, especially in the 6MT vehicles where shifts are more harsh and deflect the rear end more aggressively. The car with the softer factory rubber bushings deflect enough to cause catastrophic failure of rear end components. In some cases it will even be as bad as the sub-frame actually being irreparably damaged and requiring replacement, a failure which I have experienced as well.

Unitizing the rear end would prevent this deflection which would prevent these type of failures.

For those of you wondering, BMW will NOT cover this under warranty if the vehicle is lowered even by the slightest amount. Please keep in mind this has occurred on my personal E92 M3 which is still N/A. The axle can fail with no warning at all and will give out under moderate lateral load. The rear differential can be moved up and down approximately 3/4" with a small pry bar with less than 15 pounds of arm pressure.

Attached are some pictures of the failure. The CV joint literally exploded and most of the ball bearings shot out and the internal parts shattered to more than a dozen pieces.







Malek

[Sandye90m3]

What are the options to have the rear diff "upgraded"? I feel like the M has slight hesitation when letting off the throttle, or getting on the throttle fully as well as a slight "bump" noise from the rear.

Is that something that you heard/felt before your M went out?

M3 E90 DCT

[Tim B.]

Yes, i'd love to hear specific products to get for this too. I've read about the Delran bushings from Turner, Defiv brace, control arm bearing kit from Bimmerworld, etc. but there always seems to be some negative involved too.....noise, ride quality, $$$. I have a 6MT and am recently SC'd so i'd really be interested in doing something for reinforcement in those areas. Thanks.

[Malek@MRF]

Originally Posted by Sandye90m3

What are the options to have the rear diff "upgraded"? I feel like the M has slight hesitation when letting off the throttle, or getting on the throttle fully as well as a slight "bump" noise from the rear.

Is that something that you heard/felt before your M went out?

M3 E90 DCT

If the rear end mounts are going bad, there will a prominent thud coming from back there during gear shifts and throttle application/release. You should check the bolts and the weld joints for the differential to make sure they are still in tact.

Originally Posted by Tim B.

Yes, i'd love to hear specific products to get for this too. I've read about the Delran bushings from Turner, Defiv brace, control arm bearing kit from Bimmerworld, etc. but there always seems to be some negative involved too.....noise, ride quality, $$$. I have a 6MT and am recently SC'd so i'd really be interested in doing something for reinforcement in those areas. Thanks.

The solid sub-frame bushings and delrin differential bushings are all that is needed to solve the issue. The brace kit that is made by Defiv is a nice addition to add further security, however when the bushings are unitized to the sub-frame and unibody, deflection is eliminated (unless the hardware is not torqued properly).

[PrometheusM3]

Originally Posted by Malek@MRF

The solid sub-frame bushings and delrin differential bushings are all that is needed to solve the issue. The brace kit that is made by Defiv is a nice addition to add further security, however when the bushings are unitized to the sub-frame and unibody, deflection is eliminated (unless the hardware is not torqued properly).

What about the subframe bushings alone? Some reviews indicated that the differential bushings introduce a significant amount of NVH. The Delrin subframe bushings seem to be more tolerable. In light of this, would the solid subframe bushings alone, without the differential bushings, be sufficient to prevent this type of failure in your opinion?

[AlpineE92M3]

The solid sub-frame bushings and delrin differential bushings are all that is needed to solve the issue. The brace kit that is made by Defiv is a nice addition to add further security, however when the bushings are unitized to the sub-frame and unibody, deflection is eliminated (unless the hardware is not torqued properly).[/QUOTE]

Do you have a link to what parts are needed and where to purchase? I might do this as a precaution, even tho I only have 1200 miles on mine. Sounds like a good preventative measure to take.

[Malek@MRF]

Originally Posted by PrometheusM3

What about the sub-frame bushings alone? Some reviews indicated that the differential bushings introduce a significant amount of NVH. The Delrin sub-frame bushings seem to be more tolerable. In light of this, would the solid sub-frame bushings alone, without the differential bushings, be sufficient to prevent this type of failure in your opinion?

Both are needed. The sub-frame bushings are required to prevent axle deflection which could cause a very severe failure (far more severe than axle breakage and diff mount failure) such as weakening and possibly tearing the uni-body. Sub-frame bushings also make the rear end more stable, predictable and reduce wheel hop.

I will update this thread periodically as well showing what would need to be done in order to address these issues. I have about a half dozen E9x M3's that are getting this work done in the next month or so. Some of them are 6MT, some DCT. This set of modifications is absolutely crucial for the supercharged M3's. I will update with installation pictures, before and afters and I am sure you guys will hear from the owners themselves as to the massive difference doing this makes.

[Tim B.]

Originally Posted by Malek@MRF

Both are needed. The subframe bushings are required to prevent axle deflection which could cause a very severe failure (far more severe than axle breakage and diff mount failure) such as weaking and possibly tearing the unibody. Subframe bushings also make the rear end more stable, predictable and reduce wheel hop.

Sent you a pm

[pbonsalb]

What do you think about harder poly subframe and diff bushings instead of aluminum and delrin? Should keep NVH to a civilized daily driver level.

[dereksM3]

It looks as if Powerflex now makes Poly bushings for our application? Is that a worthwhile upgrade?

[Malek@MRF]

Originally Posted by pbonsalb

What do you think about harder poly subframe and diff bushings instead of aluminum and delrin? Should keep NVH to a civilized daily driver level.

The sub-frame should be unitized, as in no poly, no delrin, just straight solid billet aluminum. The sub-frame does not need to have compliance, that is never a primary source of NVH.

The differential should be delrin or aluminum or a combination of both. Poly has the possibility of squeaking and needs occasional maintenance.

The most common and obvious source of NVH into the cabin is spherical joints in suspension links, stiffer/solid engine and transmission mounts.

Malek

[vinniechin]

I've tried Delrin differential bushings and the poly. Delrin tightens it up great (actually AMAZING) but loud and you feel all driveline clunks, shifts, rattles and gear whine. The poly (95D) is almost as loud in whine but slightly softer on driveline clunks. Definitely a difference in feel but both provided a more soild feel during gear changes...sound is annoying with either. I would have stuck with Delrin but as DD it was too much for my wife. The poly still annoys her but I told her its precautionary and to deal with the whine since the clunks are not as prominent.

I have solid delrin subframe bushings as well. Definitely a must do as this didn't add much of anything other than a more solid planted feel in the rear end.

Unfortunately I trust Malek's views as his posts are alway informative and based on fact. So does that mean We should all go with aluminum subframe bushings as a must and delrin doesn't help as much as a preventative? Who sells solid aluminum sub frame bushings? I still have the Delrin differential bushins...should I put those back in and deal with the driveline clash? BTW, you can't hear the poly diff bushings over the gear whine! :-)

Thanks for the informative post and keep us updated.

[pbonsalb]

If you go with aluminum subframe bushings and delrin diff bushings, there is no isolation of the diff. I need a civilized daily driver.

In my E36M3, I have poly subframe and poly diff bushings. Neither squeak and I think it is because those are really mounts more than suspension bushings and do not move much. I also have poly rear trailing arm bushings and those do squeak despite being well greased. I have had the poly RTABs in there for about 6 years and am pulling them right now to replace with heavy duty rubber bushings and limiting shims.

Also in the E36M3, I have run both delrin and poly front control arm bushings. No squeak from the poly. I first ran poly for a couple of years, then delrin for a couple of years, and no poly again. I pulled the delrin because they took away some of the suppleness from the front suspension and made it bang a bit more. I like a little compliance.

I will wait to read more about the experience of others with the E90M3, but my inclination would be to run poly diff bushings if I run aluminum subframe bushings, since my car is my primary driver and I want it to be civilized.

[Tim B.]

Originally Posted by pbonsalb

If you go with aluminum subframe bushings and delrin diff bushings, there is no isolation of the diff. I need a civilized daily driver.

Are you saying going this route will make the car "uncivilized"?

[dereksM3]

I believe I can't cross link but PowerFlexUSA just released their full line of Poly bushings for the E9x M3 chassis...including all suspension, diff, and subframe bushings. Reading the literature they offer either an 80A durometer (street) or 95A durometer (race) on all the M3 applications. Also they have grooves they say helps retain the grease which they also claim negates the need for frequent greasing. Seems to be a very good option...

[aussiem3]

Originally Posted by Malek@MRF

The sub-frame should be unitized, as in no poly, no delrin, just straight solid billet aluminum. The sub-frame does not need to have compliance, that is never a primary source of NVH.

The differential should be delrin or aluminum or a combination of both. Poly has the possibility of squeaking and needs occasional maintenance.

The most common and obvious source of NVH into the cabin is spherical joints in suspension links, stiffer/solid engine and transmission mounts.

Malek

What kind of load are we looking at for this type of failure? I am sure for a DD that sees the occasional track day this shouldn't be an issue. I think the way Malek described it, if you're consistently launching the car then I think you can anticipate this failure in combination with other mods such as lowers and adding spacers. I am prompting a discussion with this.

[Malek@MRF]

Originally Posted by aussiem3

What kind of load are we looking at for this type of failure? I am sure for a DD that sees the occasional track day this shouldn't be an issue. I think the way Malek described it, if you're consistently launching the car then I think you can anticipate this failure in combination with other mods such as lowers and adding spacers. I am prompting a discussion with this.

Both failures that have occurred on my E92 M3 have been during normal street use with moderate loads laterally. The car has never been launched or drag raced.

The main point here being that the differential and sub-frame deflect enough under lateral load on the passenger side to greatly affect half shaft pinion angle and cause the CV joint of the axle to wear. When analyzing the internals of the failure carefully, there were a lot of heat ligature marks found on the ball bearings, enough to make them out of round! Some of them were even scoured and the rest of them were simply lost because the CV joint exploded and they are now victim to a gutter somewhere on the street.

This axle failure occurred at 20 MPH loading the car up laterally, but not to any excessive amount.

Also, please keep in mind, if the car is lowered, this could further exacerbate the issue because lowering the car will slightly change half shaft pinion angles, and in combination with the excessive deflection that occurs on the passenger side, it can fail.

[thekurgan]

Here's a link to the powerflex USA site if anyone is interested:

http://powerflexusa.com/e9xm3.aspx

[sterile stork]

Originally Posted by thekurgan

Here's a link to the powerflex USA site if anyone is interested:

http://powerflexusa.com/e9xm3.aspx

As a long time user of powerflex components, I was greatly disappointed to see the lack of product offerings for the E9X M3. Thank you for making my day with this announcement. A foresee a big order in the near future!

[pbonsalb]

Originally Posted by Tim B.

Are you saying going this route will make the car "uncivilized"?

I don't know. Need to read more from those who have done it. If I read the responses correctly, at least one person said his wife complained enough that he removed the delrin diff bushings and replaced them with poly.

[Mr. 5]

From my experience, wheel hop is the biggest contributer to broken half shafts, which means that if you are not launching at the drag strip or going for your best 0-60, then I don't know if it's really needed to upgrade.

[s65e90]

Originally Posted by Malek@MRF

Both failures that have occurred on my E92 M3 have been during normal street use with moderate loads laterally. The car has never been launched or drag raced.

The main point here being that the differential and sub-frame deflect enough under lateral load on the passenger side to greatly affect half shaft pinion angle and cause the CV joint of the axle to wear. When analyzing the internals of the failure carefully, there were a lot of heat ligature marks found on the ball bearings, enough to make them out of round! Some of them were even scoured and the rest of them were simply lost because the CV joint exploded and they are now victim to a gutter somewhere on the street.

This axle failure occurred at 20 MPH loading the car up laterally, but not to any excessive amount.

Also, please keep in mind, if the car is lowered, this could further exacerbate the issue because lowering the car will slightly change half shaft pinion angles, and in combination with the excessive deflection that occurs on the passenger side, it can fail.

was just talking about this today; no one really mentions this; overlooked. I haven't (1st hand) seend any direct problems though and still would be premature to worry about issues such as this on the e9x platform. Although, like anything else, as the car ages, so do it's mounts/bushings and this may be a bigger issue down the road. that being said, I will be doing all Poly mounts in the suspension as I have always used them in the e46 and never had any issues/noises etc.