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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > Suspension | Brakes | Chassis > Front strut mounts for lowering 335xi



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      11-28-2019, 11:13 AM   #1
relative4
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Front strut mounts for lowering 335xi

I just installed Bilstein B8s and Dinan springs on my '08 E90 335xi. The ride and handling are great, but the front is way too high. I think I've figured out why. The AWD strut mounts have extra-long studs and a 10mm spacer on top of them, between the strut mount and the body. I just realized that RWD strut mounts have shorter studs and no spacer. Simply removing the spacer is not an option, because the studs on the AWD mount would stick up too far, and one would hit the strut brace.
So I believe I need strut mounts for a RWD car to eliminate the spacer and get the height right. I see two part numbers:
31306775098 all pre-LCI, LCI Sports, M Sports, Performance, Poor Road
31336760943 LCI standard suspension

Looking at pictures online, I can't tell the difference. Can anyone help figure out how to choose?
Or am I barking up the wrong tree? Will this cause problems?
Thanks!
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      11-28-2019, 12:23 PM   #2
Soravia
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Get both, return the ones you don't like. They are not that expensive. Takes more effort and time to work them in. I imagine they fit the same holes, but difference will be with smaller dimensions.

Be sure to get replacement 22 mm locking strut nuts for Bilstein. They are single use.
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      11-29-2019, 02:52 AM   #3
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Is taking off the spacer and grinding off some of the excess length of the studs an option?
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      11-29-2019, 03:08 AM   #4
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https://translate.googleusercontent....xdc-ERZjDxBmvA

Switching to rwd top mounts won't help you, since they're ~10mm taller. I'd remove the spacer and cut the stud(s).

It's the first I've heard of there being a 10mm spacer on xd top mounts... Are you sure you don't have the poor road package and corresponding top mount?

Last edited by Tambohamilton; 11-29-2019 at 03:14 AM..
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      11-29-2019, 03:54 AM   #5
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Quote:
Originally Posted by Tambohamilton View Post
https://translate.googleusercontent....xdc-ERZjDxBmvA

Switching to rwd top mounts won't help you, since they're ~10mm taller. I'd remove the spacer and cut the stud(s).

It's the first I've heard of there being a 10mm spacer on xd top mounts... Are you sure you don't have the poor road package and corresponding top mount?
I'd say try switching to RWD top mounts then adding Supreme Lowering Perches.. but if the RWD too mounts are 10mm taller, its not going to help much when adding lowering perches that only lower about 11-13mm
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      11-29-2019, 09:22 AM   #6
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Literally no point in switching to rwd mounts; they're taller than the xd ones. You've got nothing to lose by cutting the necessary studs on the xd ones. I measured an xd one I have here, and the studs are 3/4 long...that doesn't look like it would hit the strut braces? This mount is a Sachs 803 006.

Lowering perches is another good call though, if removing the spacer doesn't get you where you want to be (I don't think it'll be enough on its own!)
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      11-29-2019, 10:12 AM   #7
relative4
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Quote:
Originally Posted by Tambohamilton View Post
https://translate.googleusercontent....xdc-ERZjDxBmvA

Switching to rwd top mounts won't help you, since they're ~10mm taller. I'd remove the spacer and cut the stud(s).

It's the first I've heard of there being a 10mm spacer on xd top mounts... Are you sure you don't have the poor road package and corresponding top mount?
Thanks for finding that page! Your google-fu is strong.

I pulled the old xi mounts out of the trash, and comparing them to online pics of RWD mounts, yep - the xi mounts are substantially lower. So RWD mounts are out, but I already ordered a pair of sport mounts, so I will post pics and full measurements when they come in.

I was able to roughly measure the spacer while installed, and it's actually about 6mm. There's currently about 6mm of clearance between the stud and the strut brace, so minimal grinding would be needed to make it work.
However, a 6mm drop isn't really worth the effort. I'll do it next time I'm in there.
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      11-29-2019, 10:18 AM   #8
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Although Supreme Power does not list the perches on their website, it appears they do stock and sell them if you contact them directly. But I'm hesitant - what sort of changes in ride and handling can I expect from changing the springs' rest compression that way?

Also of note - the stock spring perches for AWD and RWD have different part numbers. So Supreme's perches may not be applicable to AWD. I can ask them.
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      11-29-2019, 10:48 AM   #9
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I can never find stuff when I actually need it so I rely on bookmarking useful stuff as/when I come across it!

Ride and handling will be the same as they are now, with the lowering perches in...if anything slightly better because of the increase in negative camber that you'll get from lowering the front a little. Tiny gain though.
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      11-29-2019, 11:48 AM   #10
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Quote:
Originally Posted by relative4 View Post
Although Supreme Power does not list the perches on their website, it appears they do stock and sell them if you contact them directly. But I'm hesitant - what sort of changes in ride and handling can I expect from changing the springs' rest compression that way?

Also of note - the stock spring perches for AWD and RWD have different part numbers. So Supreme's perches may not be applicable to AWD. I can ask them.
They're not compatible with awd, I wanted to do the same thing awhile ago and asked them myself. They said I'd need rwd top mounts. And for as little of a difference as it is I doubt you'd notice a change in ride quality
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      11-30-2019, 09:56 AM   #11
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Quote:
Originally Posted by relative4 View Post
I pulled the old xi mounts out of the trash, and comparing them to online pics of RWD mounts, yep - the xi mounts are substantially lower. So RWD mounts are out, but I already ordered a pair of sport mounts, so I will post pics and full measurements when they come in.

I was able to roughly measure the spacer while installed, and it's actually about 6mm. There's currently about 6mm of clearance between the stud and the strut brace, so minimal grinding would be needed to make it work.
However, a 6mm drop isn't really worth the effort. I'll do it next time I'm in there.
Interesting footnote - I just noticed that LCI xDrive cars have a different part number (31306785962) for the strut mount. From the pictures, it appears to be the same mount as the pre-LCI xi mount (31336775097), but with shorter studs. So they eliminated the 6mm spacer for LCI.
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      11-30-2019, 12:46 PM   #12
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Well spotted, good info!
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      12-01-2019, 09:37 AM   #13
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This is what I got from Turner Motorsports for my LCI xDrive wagon
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Last edited by Soravia; 12-01-2019 at 10:37 AM..
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