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410bn 410bn is offline
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Default Can 8mm rear main seal replace 12 mm? - 03-13-2020, 08:26 AM

I'm about to install a SPEC stage 3+ clutch today and I want to replace the rear main seal while I'm in there but I haven't found conclusive information on which rear main seal(s) I'm able to use. My car is a 2007 E92 335i (Pre-LCI).

There are two available seals - an 8 mm thick one that came in the 09+ cars and the 12 mm thick one that came in the pre-09 cars that requires the $70 sealant from BMW.

Real OEM lists both but it's not clear if they're interchangeable for pre-09 cars. If looking at the 12 mm seal (11117584398), it has the 8 mm seal (11117587168) listed under "superseded by" but also says nonexchangeable retrospectively. If you're looking at the 8 mm seal, it has the 12 mm seal listed under "supersedes" and also says "Exchangeable retrospect. in connect. w".

I'd prefer to use the thinner 09+ seal as the sealant and primer from BMW appears to be hard to come by. It seems like many have used the thinner seal on the older cars but I haven't seen any long term updates on those installations.

Does anyone have any definitive information on this? My local dealer couldn't tell me much besides the fact that there are two seals listed for my car and I need to pull it out and see which one is currently installed.

Last edited by 410bn; 03-13-2020 at 08:32 AM..
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Maximum996 Maximum996 is online now
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Default 03-21-2020, 05:30 AM

08 n54 here, replaced with 8 mm, had leak, replaced with 12 mm, (used red silicone around seal) no leaks as of yet...I believe difference 09 + had 8 bolt main [which shouldn't make a difference I would think] .

08 535Xi - jb4 iso w/mhd flash, Bms dci, AR ********* DP, er cp with forge dv, second *** delete, muffler delete, xhp trans flash, ets fmic, bms oil tstat bypass.
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ReforMatt ReforMatt is offline
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Default 03-21-2020, 07:17 AM

I believe with either seal you would still need to use the BMW sealant n primer or like sealant. When I replaced mine I used the bigger seal..I believe I was able to order the primer an sealant from FCP they are expensive compared to the amount you will actually use. But do you actually wanna drop a trans an do it twice?

2017 Mercedes E300-Daily
2010 E92 335i-Smiles
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