[Max Well]

Originally Posted by Kevin_The_Clean1

I'm getting pretty lost too & this thread should come with a bag of free popcorn. It's funny that MaxWell has an X3 MC with 40k on the clock & 40-50 launches (conservative estimate) & yet his factory bolt was just fine / straight as an arrow...

One of the main reasons I started this compilation was that I also had trouble keeping track of these different 'solutions'. I appreciate everyone sharing their thoughts on the pros and cons of these different approaches (strength/stability vs NVH/downstream force issues).

To be fair, my factory bolt was bent some as an image in my OP shows, but agreed that I was pleasantly surprised it wasn't worse given the reports from others and my number of trips to the Strip.

As I've also taken my wife's X3MC to the Strip a few times with about 10 or so launches, I'm thinking about ordering an OEM bolt and nut from the Dealer and having them just replace those on hers (leaving the bushing alone) - 33326775040 Hex bolt with washer, 33326760380 Combination nut. Knowing my front bushings and bolts were fine I'm not concerned about those on hers.

Will be interesting to see what they quote for the labor since both of ours don't have the vertical bracing as we don't have a pano, so it should be a quick and easy process.

[Stereolab42]

Originally Posted by Stereolab42

What a mess... decided to bite the bullet and just get the Einhorn installed next week (along with low-dust brake pads). Seems to be reports of noise with all of these solutions so I may as well use the strongest one. And noise doesn't bother me unless it's really bizarre. Guess we'll see.

Shop took one look at the instructions and said labor would be up to 2k so I just noped out lol. He works with people who track Ms and thought this was overkill if you're not drag racing the thing, and was worried about the noise introduced. Maybe I'll get one of the less extreme solutions installed instead, but for now I will wait until the year mark in August then pull and inspect the OEM bolt. That I can do at home.

[TacosRule!]

Originally Posted by Stereolab42

Shop took one look at the instructions and said labor would be up to 2k so I just noped out lol. He works with people who track Ms and thought this was overkill if you're not drag racing the thing, and was worried about the noise introduced. Maybe I'll get one of the less extreme solutions installed instead, but for now I will wait until the year mark in August then pull and inspect the OEM bolt. That I can do at home.

WTF, thats obv the "dont want the job" rate. I just hope none of the few ones I have around here dont pull the same crap.


Ugh

[joebie3]

Originally Posted by Stereolab42

Shop took one look at the instructions and said labor would be up to 2k so I just noped out lol. He works with people who track Ms and thought this was overkill if you're not drag racing the thing, and was worried about the noise introduced. Maybe I'll get one of the less extreme solutions installed instead, but for now I will wait until the year mark in August then pull and inspect the OEM bolt. That I can do at home.

LOLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL LLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLL

Wow.

[Stereolab42]

Originally Posted by TacosRule!

WTF, thats obv the "dont want the job" rate. I just hope none of the few ones I have around here pull the same crap.


Ugh

I mean, if you go religiously by the instructions, it's a ton of work. Drop the brace under the exhaust, drop the exhaust, drop the diff, and reverse all that. They thought their press tool might not have enough room so they said they might have to drop the rear subframe too, that's what they thought might cause it to reach $2k. Ehh. In the end, I have to agree that this is the most extreme solution and it's probably only applicable to the most extreme drivers -- dedicated racers who don't blink at these type of costs to prep an M and/or do their own work.

[Max Well]

For spatial reference here is how my 2020 X3MC (top) and my wife's 2022 X3MC (bottom) rear diff bolts appear on images taken directly behind and midway underneath the bumper, both sans pano. I just leaned down and reached underneath with the iPhone.

[Kevin_The_Clean1]

Originally Posted by Max Well

For spatial reference here is how my 2020 X3MC (top) and my wife's 2022 X3MC (bottom) rear diff bolts appear on images taken directly behind and midway underneath the bumper, both sans pano. I just leaned down and reached underneath with the iPhone.

Thank you Max for taking these. Someday I want to by another X3 MC with the pano roof delete & turn in into an absolute track monster & drag strip warrior. Wish MotorTrend & all the other mags could test this lighter & stiffer version of the platform that only a few people have & even know about.

[Max Well]

Received the new OEM bolt and combination nut yesterday which we'll eventually use for my wife's X3MC. Comparing to the Sep 2019 versions which I had replaced in Feb, it appears the bolts are identical. The only difference I can see is the combination nut which has a different size and shape, which is maybe the 're-design' discussed earlier?

Not in a rush to change hers out, but it'll be interesting to see if its bent if/when we do, given it's only had 10 launches over two Strip outings...

[TacosRule!]

Originally Posted by Max Well

Received the new OEM bolt and combination nut yesterday which we'll eventually use for my wife's X3MC. Comparing to the Sep 2019 versions which I had replaced in Feb, it appears the bolts are identical. The only difference I can see is the combination nut which has a different size and shape, which is maybe the 're-design' discussed earlier?

Not in a rush to change hers out, but it'll be interesting to see if its bent if/when we do, given it's only had 10 launches over two Strip outings...

Interesting finds. Thanks for sharing.

[Kevin_The_Clean1]

That looks like a slightly strong nut. That bolt (like you said) appears identical in all dimensions. Wonder if the new revised nut will improve things. With 40 or so launches on your X3 M & many of those at the strip, still surprised your was bent more

[Kevin_The_Clean1]

Originally Posted by Max Well

Received the new OEM bolt and combination nut yesterday which we'll eventually use for my wife's X3MC. Comparing to the Sep 2019 versions which I had replaced in Feb, it appears the bolts are identical. The only difference I can see is the combination nut which has a different size and shape, which is maybe the 're-design' discussed earlier?

Not in a rush to change hers out, but it'll be interesting to see if its bent if/when we do, given it's only had 10 launches over two Strip outings...

That looks like a slightly stronger nut. That bolt (like you said) appears identical in all dimensions. Wonder if the new revised nut will improve things a bit. With 40 or so launches on your old pre-LCI X3 MC & many of those at the strip, still surprised yours was bent more.

[Jnat]

Is this the correct bolt size?
M12X1.5 Fine Hex Bolt
Steel Class 10.9 Hard

[Max Well]

Originally Posted by Jnat

Is this the correct bolt size?
M12X1.5 Fine Hex Bolt
Steel Class 10.9 Hard

In post #171 Th3Walrus shows how realoem describes it (M14x1.5x148) - https://x3.xbimmers.com/forums/showp...&postcount=171

In the next post (#172) Bimma360 indicates he measured with his digital calipers which showed, 'the factory bolt at 12.9X mm. It's a cheap caliper, but right under 13mm looks to be about right. Yeah in theory an M14 bolt should be 14mm.'

I ordered the BMW OEM hex bolt and washer and the combination nut direct from a BMW Dealership using the actual part numbers, and as my images showed I measured 13mm but my calipers aren't digital.

The bolt size is confusing, though, for online searching the part number 33326775040 as BMW hex bolt, at least three BMW parts suppliers (of Monterey, Stratham NH and Northwest in Tacoma) also describe as the M14 size, yet bmwpartspros, bmwofsouthatlanta and getbmwparts show it as M12x1.5 .

Personally I felt more confident ordering by the actual OEM part numbers so regardless of what its described as, I figured I'd be getting the correct item. Just one more confusing variable to add to the mix.

[Kevin_The_Clean1]

Originally Posted by Max Well

In post #171 Th3Walrus shows how realoem describes it (M14x1.5x148) - https://x3.xbimmers.com/forums/showp...&postcount=171

In the next post (#172) Bimma360 indicates he measured with his digital calipers which showed, 'the factory bolt at 12.9X mm. It's a cheap caliper, but right under 13mm looks to be about right. Yeah in theory an M14 bolt should be 14mm.'

I ordered the BMW OEM hex bolt and washer and the combination nut direct from a BMW Dealership using the actual part numbers, and as my images showed I measured 13mm but my calipers aren't digital.

The bolt size is confusing, though, for online searching the part number 33326775040 as BMW hex bolt, at least three BMW parts suppliers (of Monterey, Stratham NH and Northwest in Tacoma) also describe as the M14 size, yet bmwpartspros, bmwofsouthatlanta and getbmwparts show it as M12x1.5 .

Personally I felt more confident ordering by the actual OEM part numbers so regardless of what its described as, I figured I'd be getting the correct item. Just one more confusing variable to add to the mix.

I found a great digital caliper for only about $25-30 bucks Max. And that revised nut looks a touch more stout than the previous one does. Not sure about the revised bolt though. LOL

[Max Well]

Originally Posted by Kevin_The_Clean1

I found a great digital caliper for only about $25-30 bucks Max. And that revised nut looks a touch more stout than the previous one does. Not sure about the revised bolt though. LOL

Thanks, Kevin_The_Clean1. I'm convinced the bolt wasn't changed - just the combination nut. Unless they changed the strength from 10.9 to 12.9 (which by appearance it doesn't seem to be), my Aug 2019 OEM bolt has exactly the same dimensions and washer as the May 2024 replacement.

For final reference I measured M12 and M14 bolt diameters and compared with the BMW OEM bolt which has been described as both M12 and M14. I purchased M12x80x1.75 Str 10.9 and M14x90x2.0 Str 10.9 bolts at a local hardware store and measured by calipers. What is clear in the images - the M12 is 12mm, the M14 is 14mm, and the BMW OEM rear diff bolt is 13mm. Next I wanted to get real measurements on the bushing's central ellipse - 14.5mm x 17mm. I then placed each bolt into the ellipse to show the available spacing remaining.

Given the engineering expertise of BMW M, that there remains space between the ellipse and even a(n) M14 bolt still implies this is purposeful IMHO. When they re-designed the combination nut, and left the actual bolt unchanged there must be a basis for their decision, right? NVH only, or is this focal point acting as a fuse to be broken to spare downstream components when exposed to extreme forces, or ?

They clearly assessed forces which the average F97/98 components might encounter and designed around such it seems.

[95wildtt]

Given the engineering expertise of BMW M, that there remains space between the ellipse and even a(n) M14 bolt still implies this is purposeful IMHO. When they re-designed the combination nut, and left the actual bolt unchanged there must be a basis for their decision, right? NVH only, or is this focal point acting as a fuse to be broken to spare downstream components when exposed to extreme forces, or ?

This is my belief as well...

[AshtonPJT]

8 Week old bolt with 2 "launches"

I started working on my own custom bushing a few weeks ago and finally finished the project last night, So far shift and downshifts feel much crisper. The car also feels a little more planted on launches.

The kit consist of:
85A shore polyurethane bushing
Grade 12.9 M14 bolt
Nylon locking nut

[knali8]

Originally Posted by AshtonPJT

8 Week old bolt with 2 "launches"

I started working on my own custom bushing a few weeks ago and finally finished the project last night, So far shift and downshifts feel much crisper. The car also feels a little more planted on launches.

The kit consist of:
85A shore polyurethane bushing
Grade 12.9 M14 bolt
Nylon locking nut

Nice work! Keep us updated on how the kit holds up.

[AshtonPJT]

Originally Posted by knali8

Nice work! Keep us updated on how the kit holds up.

So far I'm happy with it and it seems to be holding up well, I put about 300 miles on it yesterday, 20 launches and a 5ish 2nd gear rolling antilag launches and it feels amazing. Going to try and find a way to add a gopro under the car to see how much movement it has.

I really can't speak on the NVH as I kept the exhaust off and its open downpipe at the moment but I'd say its a very slight increase if any at all.

[Y0jjimb0]

Originally Posted by AshtonPJT

So far I'm happy with it and it seems to be holding up well, I put about 300 miles on it yesterday, 20 launches and a 5ish 2nd gear rolling antilag launches and it feels amazing. Going to try and find a way to add a gopro under the car to see how much movement it has.

I really can't speak on the NVH as I kept the exhaust off and its open downpipe at the moment but I'd say its a very slight increase if any at all.

Were your ears bleeding after?

[AshtonPJT]

Originally Posted by Y0jjimb0

Were your ears bleeding after?

Honestly Im kind of use to it, I daily it open dump for 3 months only put it back on since I was doing a road trip. With the B58 its not that bad and the chassis soaks up a lot of the drone and NVH, I had a M235 N55 before my X3 and I did open dump the drone and NVH would cause an instant headache every time I drove it had to put the exhaust back on shortly after.

[Max Well]

One more reference point - my wife's 2022 LCI X3MC no pano, 25K miles, 2-3/4 yrs old, bone stock, 10 launches total during 2 outings to the Strip.

Actually more bent than my bolt...

Added to the bottom of the compilation photos -