[Max Well]

As my Sep 2019 early production 2020 X3MC no longer has a warranty, I wanted to preemptively head off potential rear diff bushing issues considering my many runs at the Strip. It took quite a while searching for relevant threads in our F97/98 forum so thought I might as well share this list (by OP posting date, earliest to latest). Appreciation to those who shared their experiences in these earlier threads.

I decided to have done at a BMW Svc Ctr with OEM parts since they come with a two-year warranty which should cover issues that might later arise. I also replaced the other two connections in addition to the rear diff bushing/bolt. I’m including images of the old parts which revealed slight bending of the main bolt but no apparent issues with the two smaller ones. Was encouraged that it wasn’t more prominent considering my 47 LCs at the Strip and >4-year-old age.

Close inspection of both bushing types reveals complex designs which suggest intent to allow motion within these connections. Having zero engineering background I’m unable to comment on the pros or cons of such constructs. Will be interesting to read others’ experience using some of the alternative solutions being produced, especially with regards to noise, vibration, and harshness [‘NVH’] given their more solid designs.

“For all those whos Differential bolt failed”, OP Dawgz 06/07/2023, last post 1/18/2024 https://x3.xbimmers.com/forums/showthread.php?t=2023722
“Snapped axle and diff bolt”, OP D-Pat Murph 06/06/2023, last post 07/05/2023 https://x3.xbimmers.com/forums/showthread.php?t=2023357
“Rear diff toast?”, OP Vinnief96 09/16/2022, last post 07/27/23, https://x3.xbimmers.com/forums/showthread.php?t=1955142
“Rear differential bushing/bolt reinforcement *** making pre order list***, OP Dawgz 08/27/2023, last post 11/08/2023 https://x3.xbimmers.com/forums/showthread.php?t=2044095
“x3m & x4m Solid rear diff bushing Rear diff bolt issue fix”, OP 0vrwtm3 10/05/2023, last post 01/10/2024 https://x3.xbimmers.com/forums/showthread.php?t=2053091
“Einhorn Industries Diff Bushing Upgrade”, OP Commanderwiggin 11/02/2023, last post 12/01/2023 https://x3.xbimmers.com/forums/showthread.php?t=2059199
“Rear Diff Bolt Movement Video”, OP R0ot.Us3r 01/06/2024, last post 1/16/2024 https://x3.xbimmers.com/forums/showthread.php?t=2073149
“VTT Rear Diff Bushing Insert Kit”, OP s58.bill 01/18/2024, last post 2/5/2024 https://x3.xbimmers.com/forums/showthread.php?t=2076072
"X3M Diff Bolt", OP Sammy17 03/4/2024, ... https://x3.xbimmers.com/forums/showthread.php?t=2087269
"Ryan's 14mm Rear Diff Bolt Kit - Review and Install", OP Bimma360 05/05/2024, ... https://x3.xbimmers.com/forums/showthread.php?t=2102344

Edit 28 Apr 2024 0840AM - a list of 'solutions' for this issue can be found in post #113: https://x3.xbimmers.com/forums/showp...&postcount=113 . This will be updated as more options are shared.

[Kevin_The_Clean1]

Max Well You are simply awesome & a stout resource. I alway admire the way you collect data & keep us all well informed. This is very encouraging & I'm impressed you kept track of how many LC's you used. Wish that was stored in a secret menu screen for us F97 guys!

[Max Well]

Originally Posted by Kevin_The_Clean1

Max Well ...This is very encouraging & I'm impressed you kept track of how many LC's you used. Wish that was stored in a secret menu screen for us F97 guys!

Many thanks, Kevin_The_Clean1. We're all a group of BMW performance Enthusiasts who appreciate max performance and precise handling (and dependability), so the more we can share our experiences and research with each other, the better in my mind. Much as you've done with your 265/295 and brake threads.

I'll be honest - I suspect BMW and M probably have staff following forums and social media for trends, ideas, issues, marketing, ... Would seem a reasonable stance to take for a global firm. So hoping some of what we share here ultimately makes it up the chain to allow improvements down the road.

[Jnat]

Max Well /// So you replaced the bushings with stock units also (self evident by the pic's but just confirming)... pretty encouraged by the amount of launches and only the slight bend...thanks for all you do!

[Max Well]

Originally Posted by Jnat

Max Well /// So you replaced the bushings with stock units also (self evident by the pic's but just confirming)... pretty encouraged by the amount of launches and only the slight bend...thanks for all you do!

Thanks, Jnat. Yes, OEM replacement parts for everything. My reasoning was based on being bone stock (except lighter weight BC Forged wheels but in OEM specs and tire sizes) - if the bolt fractures within the next two years and drops the diff etc then it should be covered by BMW's 2 year warranty.

And that the bolt seemed to be only slightly angled (despite my numerous hard launches at the Strip and my X3MC's 4+ year age) was indeed encouraging and factored into my decision. Granted it wasn't seeing forces which occur during high-end St1 and St2 launches, but with the added plus of the warranty being there, this path seemed to make the most sense for me.

Will be interested in hearing comments from those choosing the more solid solutions as time passes, though, to see if NVH or downstream force issues develop. Intuitively those designs make sense, but since we don't know why BMW/M developed the complex bushing designs we currently have, we're left with selecting what works best for us individually.

[Bimma360]

Originally Posted by Max Well

Thanks, Jnat. Yes, OEM replacement parts for everything. My reasoning was based on being bone stock (except lighter weight BC Forged wheels but in OEM specs and tire sizes) - if the bolt fractures within the next two years and drops the diff etc then it should be covered by BMW's 2 year warranty.

And that the bolt seemed to be only slightly angled (despite my numerous hard launches at the Strip and my X3MC's 4+ year age) was indeed encouraging and factored into my decision. Granted it wasn't seeing forces which occur during high-end St1 and St2 launches, but with the added plus of the warranty being there, this path seemed to make the most sense for me.

Will be interested in hearing comments from those choosing the more solid solutions as time passes, though, to see if NVH or downstream force issues develop. Intuitively those designs make sense, but since we don't know why BMW/M developed the complex bushing designs we currently have, we're left with selecting what works best for us individually.

The "why" on the stock designed bushing will always be a mystery unfortunately. And like anything else, design and/or manufacturing error could very well be the reason for this. I think EVERY single M model has some sort of a design flaw, there are numerous examples for this. Some of these BMW confirms are flaws and others they don't.

At the same time the internet sometimes tends to be an echo chamber, and the bad experiences get amplified (which could actually be few relative to the total production run). Not saying that this is the case here, but sometimes I always take into account.

Your experience is really encouraging, and is not something people will usually post. So thank you for that. Also, good thinking on the warranty! Do you know for a fact the BMW will cover any peripheral damaged caused by a failed bolt under this two year warranty? I personally wouldn't hold my breath that they would. I would honestly be shocked if they did, even though I agree that they should.

Having said that, my car goes in next Friday for an end of warranty check and another issue I'd like to have addressed before the warranty does expire. I am debating having them replace the bolt. Curious what the labor rate on that is.

For now I am thinking I may just pull the trigger on the VTT lockdown kit. It is something that looks really easy to DIY and also looks like a robust option. I am weary of removing all flex from the diff, but I do like how the kit would distribute the force across a larger area. Whereas the solid bushing solution from other sources will concentrate the stress at a single point. Both might end up being non issues. Lots of people run urethane and solid bushings in their cars without damage to peripheral components, so perhaps most solutions would be just fine.

[Jnat]

Originally Posted by Max Well

Thanks, Jnat. Yes, OEM replacement parts for everything. My reasoning was based on being bone stock (except lighter weight BC Forged wheels but in OEM specs and tire sizes) - if the bolt fractures within the next two years and drops the diff etc then it should be covered by BMW's 2 year warranty.

And that the bolt seemed to be only slightly angled (despite my numerous hard launches at the Strip and my X3MC's 4+ year age) was indeed encouraging and factored into my decision. Granted it wasn't seeing forces which occur during high-end St1 and St2 launches, but with the added plus of the warranty being there, this path seemed to make the most sense for me.

Will be interested in hearing comments from those choosing the more solid solutions as time passes, though, to see if NVH or downstream force issues develop. Intuitively those designs make sense, but since we don't know why BMW/M developed the complex bushing designs we currently have, we're left with selecting what works best for us individually.

All makes sense. I'm running MHD Stg2 E30/95oct and bought pre owned at 15k now at 21k. I drive hard but haven't launched yet because of the bolt issues. I bought the unicorn and there it sits on my desk yet to be installed because of feedback on NVH. I am now leaning towards either the Ryan Morad or Cliff Hightower solutions (maybe even the Vargas)... I will post when i finally decide and again, thanks for your contributions which have been many!

[Max Well]

Originally Posted by Bimma360

...Your experience is really encouraging, and is not something people will usually post. So thank you for that. Also, good thinking on the warranty! Do you know for a fact the BMW will cover any peripheral damaged caused by a failed bolt under this two year warranty? I personally wouldn't hold my breath that they would. I would honestly be shocked if they did, even though I agree that they should.

Having said that, my car goes in next Friday for an end of warranty check and another issue I'd like to have addressed before the warranty does expire. I am debating having them replace the bolt. Curious what the labor rate on that is.

For now I am thinking I may just pull the trigger on the VTT lockdown kit. It is something that looks really easy to DIY and also looks like a robust option. I am weary of removing all flex from the diff, but I do like how the kit would distribute the force across a larger area. Whereas the solid bushing solution from other sources will concentrate the stress at a single point. Both might end up being non issues. Lots of people run urethane and solid bushings in their cars without damage to peripheral components, so perhaps most solutions would be just fine.

I think BMW would probably have a tough time negating a warranty claim on a new OEM bushing/bolt if it fractures and if I keep it stock, but you're right - nothing is guaranteed. For my situation, though, it just seemed the most prudent course to take.

And the labor costs are tough to predict as there seems to be wide variability in pricing depending on your locale. Certainly doesn't hurt to ask for a quote at your specific Svc Ctr.

Doubt we'll ever get more than anecdotal briefs on these various options. So many variables at play for each Driver/Vehicle that it will never reach statistical relevance, but as an Enthusiast community we can at least try to share our experiences.

Originally Posted by Jnat

All makes sense. I'm running MHD Stg2 E30/95oct and bought pre owned at 15k now at 21k. I drive hard but haven't launched yet because of the bolt issues. I bought the unicorn and there it sits on my desk yet to be installed because of feedback on NVH. I am now leaning towards either the Ryan Morad or Cliff Hightower solutions (maybe even the Vargas)... I will post when i finally decide and again, thanks for your contributions which have been many!

Its a tough call for all of us as we don't have alot of concrete data to go on, but the more experience that's shared with the different solutions should at least provide some background support for each of these. Thanks for your input and let us know what you decide.

[Jnat]

Originally Posted by Max Well

I think BMW would probably have a tough time negating a warranty claim on a new OEM bushing/bolt if it fractures and if I keep it stock, but you're right - nothing is guaranteed. For my situation, though, it just seemed the most prudent course to take.

And the labor costs are tough to predict as there seems to be wide variability in pricing depending on your locale. Certainly doesn't hurt to ask for a quote at your specific Svc Ctr.

Doubt we'll ever get more than anecdotal briefs on these various options. So many variables at play for each Driver/Vehicle that it will never reach statistical relevance, but as an Enthusiast community we can at least try to share our experiences.



Its a tough call for all of us as we don't have alot of concrete data to go on, but the more experience that's shared with the different solutions should at least provide some background support for each of these. Thanks for your input and let us know what you decide.

Absolutely correct, totally agree with more feedback is needed.

[stefan]

Why the hell wouldn't they just recall this for the 3hr of labour and $5 in parts?

[Edgar_FriendlyX3M]

Originally Posted by stefan

Why the hell wouldn't they just recall this for the 3hr of labour and $5 in parts?

Probably because there isn't a big enough subset of reported issues to be the case. In other words, there aren't enough people being towed to bmw dealers to have their drivetrain fixed due to the bolt/bushing failing.
The tech I was chatting with yesterday said in the last 3 years, he's had one x3m with an issue like this.
I'm not saying this isn't a design oversight or something that could be an issue, but for most people, if it never breaks or is never inspected, then it's a non issue.
Another example (which I think I used in another older post) is the Jeep Grand Cherokee Trackhawk...with 700hp...uses the exact same shitty stamped steel rear control arms used in their V6 base model with under 300hp.
Many guys reported twisting them since they are only stamped steel. I don't ever recall seeing a TSB or recall for this but there is plenty of aftermarket support options to replace with a solid steel unit.
Sorry if this was long winded but it's my theory on why BMW hasn't officially recognized this as a recallable item. Or tsb even.

[Bimma360]

Originally Posted by Max Well

I think BMW would probably have a tough time negating a warranty claim on a new OEM bushing/bolt if it fractures and if I keep it stock, but you're right - nothing is guaranteed. For my situation, though, it just seemed the most prudent course to take.

Oh sorry, I didn't mean negating a warranty claim on the bolt and bushing (the parts that were replaced). I meant covering under the same warranty any damage a bolt failure causes to other components (say an axel and/or diff). I was just saying I could see them trying to weasel out of replacing a diff for example.

[Max Well]

Originally Posted by Bimma360

Oh sorry, I didn't mean negating a warranty claim on the bolt and bushing (the parts that were replaced). I meant covering under the same warranty any damage a bolt failure causes to other components (say an axel and/or diff). I was just saying I could see them trying to weasel out of replacing a diff for example.

Thanks. Yes, that's exactly what I thought you were inferring. In the case of a brand new bolt and bushing failure which then directly (and verifiably) caused a downstream cascade of failures which can logically and understandably have been caused by such an integral failed warrantied part, then yes, I would expect full coverage of the other parts/systems which were damaged.

[Max Well]

Originally Posted by Bimma360

... Having said that, my car goes in next Friday for an end of warranty check and another issue I'd like to have addressed before the warranty does expire. I am debating having them replace the bolt...

For now I am thinking I may just pull the trigger on the VTT lockdown kit...

Curious about results of your end-of-warranty check and your decision on the bolt issue?

[Bimma360]

Originally Posted by Max Well

Curious about results of your end-of-warranty check and your decision on the bolt issue?

Nothing exciting. I ended up not even brining up the bolt, and their end of warranty check didn't really catch anything of note. Car got fixed for the issues I brought it in for under warranty though (passenger occupancy sensor, sunroof shade motor, hvac blower motor check and ultimate recalibration).

I did decide I was going to go the VTT lockdown kit route, and figured if the current bolt was even a little bent the lockdown kit would make it a moot point anyway. I ordered the lockdown kit yesterday, so I'll report back!

[Jnat]

Originally Posted by Bimma360

Nothing exciting. I ended up not even brining up the bolt, and their end of warranty check didn't really catch anything of note. Car got fixed for the issues I brought it in for under warranty though (passenger occupancy sensor, sunroof shade motor, hvac blower motor check and ultimate recalibration).

I did decide I was going to go the VTT lockdown kit route, and figured if the current bolt was even a little bent the lockdown kit would make it a moot point anyway. I ordered the lockdown kit yesterday, so I'll report back!

Please do!

[joebie3]

Originally Posted by Bimma360

Nothing exciting. I ended up not even brining up the bolt, and their end of warranty check didn't really catch anything of note. Car got fixed for the issues I brought it in for under warranty though (passenger occupancy sensor, sunroof shade motor, hvac blower motor check and ultimate recalibration).

I did decide I was going to go the VTT lockdown kit route, and figured if the current bolt was even a little bent the lockdown kit would make it a moot point anyway. I ordered the lockdown kit yesterday, so I'll report back!

Get that lockdown kit installed yet?

[Bimma360]

Originally Posted by joebie3

Get that lockdown kit installed yet?

Nope. It's been sitting here waiting. I ended up having to bring the car back to the dealer for out of warranty, warranty work. I decided not to install it as to not rock the boat with the dealer at the time.

I'll install it very soon! Going through the install instructions, this looks to be incredibly straightforward.

[///LBB Rav]

I might chime in here..I went from OEM to the Einhorn solid bushing and was met with some copious amount of NVH and clunking that was unsettling for a daily car. I had weird vibrations that seemed to feel like fuel cutting out at 3k rpm in 2nd gear for 0.5 seconds on acceleration and similar in third gear at lower RPM. This was nerve-wracking and so took it to the stearlership who suggested a fluid change in the Tcase and front diff oil. Not surprised that this didn't fix the problem so the next step in finding the cause was to replace the OEM bushing back in. This fixed all the issues that I had with clunking and NVH and the acceleration vibration. BMW did not apply the spline fix again which was done initially before the Einhorn. No spline clicks or clunk was apparent with the new OEM rear bushing after the Einhorn was pulled out. I ordered the VTT full lockdown kit and a JXB carrier. The NVH is marginal - not audible with music on soft volume or with windows. Both solutions had diff whine which you can't escape. If I was to compare the different configurations I'd say that OEM is best for stock cars if you're not launching etc (mine was stock but bushing collar was worn and visible bolt thread marks were cutting into it). If you're running stage 1 or 2 and the car is a daily, the VTT full lockdown kit and JXB add about 10-15% more NVH than stock. The Einhorn (in my opinion) is over engineered for a daily car but have no doubt its just as strong if not stronger than the VTT kit for really high HP cars. The Einhorn re-introduced loud clunk which was easily audible even with music on, windows down and my akra catback open valves and vibration was too much for me. If running really high HP, I'd suggest to just install the einhorn and perhaps the VTT front bushing inserts, tcase bushing as well as a JXB centre carrier to be sure but adding the VTT diff brace wouldn't hurt too much more from a NVH perspective.

[joebie3]

Originally Posted by Bimma360

Nope. It's been sitting here waiting. I ended up having to bring the car back to the dealer for out of warranty, warranty work. I decided not to install it as to not rock the boat with the dealer at the time.

I'll install it very soon! Going through the install instructions, this looks to be incredibly straightforward.

Definitely understand that first statement, I have downpipes and I don't plan on putting them on before my June service because I don't want any 'marks' on my record LOL

Originally Posted by ///LBB Rav

I might chime in here..I went from OEM to the Einhorn solid bushing and was met with some copious amount of NVH and clunking that was unsettling for a daily car. I had weird vibrations that seemed to feel like fuel cutting out at 3k rpm in 2nd gear for 0.5 seconds on acceleration and similar in third gear at lower RPM. This was nerve-wracking and so took it to the stearlership who suggested a fluid change in the Tcase and front diff oil. Not surprised that this didn't fix the problem so the next step in finding the cause was to replace the OEM bushing back in. This fixed all the issues that I had with clunking and NVH and the acceleration vibration. BMW did not apply the spline fix again which was done initially before the Einhorn. No spline clicks or clunk was apparent with the new OEM rear bushing after the Einhorn was pulled out. I ordered the VTT full lockdown kit and a JXB carrier. The NVH is marginal - not audible with music on soft volume or with windows. Both solutions had diff whine which you can't escape. If I was to compare the different configurations I'd say that OEM is best for stock cars if you're not launching etc (mine was stock but bushing collar was worn and visible bolt thread marks were cutting into it). If you're running stage 1 or 2 and the car is a daily, the VTT full lockdown kit and JXB add about 10-15% more NVH than stock. The Einhorn (in my opinion) is over engineered for a daily car but have no doubt its just as strong if not stronger than the VTT kit for really high HP cars. The Einhorn re-introduced loud clunk which was easily audible even with music on, windows down and my akra catback open valves and vibration was too much for me. If running really high HP, I'd suggest to just install the einhorn and perhaps the VTT front bushing inserts, tcase bushing as well as a JXB centre carrier to be sure but adding the VTT diff brace wouldn't hurt too much more from a NVH perspective.

Excellent review! Thankyou!

[TacosRule!]

Originally Posted by ///LBB Rav

I might chime in here..I went from OEM to the Einhorn solid bushing and was met with some copious amount of NVH and clunking that was unsettling for a daily car. I had weird vibrations that seemed to feel like fuel cutting out at 3k rpm in 2nd gear for 0.5 seconds on acceleration and similar in third gear at lower RPM. This was nerve-wracking and so took it to the stearlership who suggested a fluid change in the Tcase and front diff oil. Not surprised that this didn't fix the problem so the next step in finding the cause was to replace the OEM bushing back in. This fixed all the issues that I had with clunking and NVH and the acceleration vibration. BMW did not apply the spline fix again which was done initially before the Einhorn. No spline clicks or clunk was apparent with the new OEM rear bushing after the Einhorn was pulled out. I ordered the VTT full lockdown kit and a JXB carrier. The NVH is marginal - not audible with music on soft volume or with windows. Both solutions had diff whine which you can't escape. If I was to compare the different configurations I'd say that OEM is best for stock cars if you're not launching etc (mine was stock but bushing collar was worn and visible bolt thread marks were cutting into it). If you're running stage 1 or 2 and the car is a daily, the VTT full lockdown kit and JXB add about 10-15% more NVH than stock. The Einhorn (in my opinion) is over engineered for a daily car but have no doubt its just as strong if not stronger than the VTT kit for really high HP cars. The Einhorn re-introduced loud clunk which was easily audible even with music on, windows down and my akra catback open valves and vibration was too much for me. If running really high HP, I'd suggest to just install the einhorn and perhaps the VTT front bushing inserts, tcase bushing as well as a JXB centre carrier to be sure but adding the VTT diff brace wouldn't hurt too much more from a NVH perspective.

Well shit, now i'm really on the fence on installing mine.

Thanks for the review, good info to have.

[AshtonPJT]

X3m40i