Backdraft diff. output flange

travisallen1985 · #1 (**permalink**) 12-20-2020, 10:34 AM

Hello this is my first post.

I currently own Backdraft build number 906 build completed in 2010. Problem I'm running into is the seals for the diff. are leaking at the out flanges (where the seal rides there is pitting). I've ordered two different output flanges using year model 1993 BMW 325i and the 6 bolt going to the axels is too large. Mine has a adapter as my 6 bolts have a smaller center to center. Any help in the right direction would be appreciated. Thanks

travisallen1985 · #2 (**permalink**) 12-20-2020, 10:46 AM

Pictures of output flange

spdbrake · #3 (**permalink**) 12-20-2020, 03:44 PM

1.) Can you post picks and part#s of the output shaft you rec'd?

2.) Have you changed the lip seals on the output flange side covers?
If not I do that 1st before changing the flanges. Although yours are pitted there is not a lip seal burnish line showing any contact with the seal. My guess is they are shot. The since the Diff is a oil bath and the resting oil level is below the side cover seals, there is not a whole lot of pressure to cause a leak. But if someone filled the diff while only the rear of the car was jacked that would add to the leak rate.

Side cover oring
https://www.eeuroparts.com/Parts/324...g-33111214144/
Output shaft seal and snap ring
https://www.eeuroparts.com/Parts/168...ial-152941101/

3.) It looks like you have BDR axles spacers installed on your flanges as well. From your axle bolt spacing it appears your output flanges have a smaller bolt pattern when compared to the BDR spacer on the website.
https://www.iconicparts.com/axel-spacers
Can you dissemble the spacer and flange and get a On-center measurement? it would really help. compare yours to the Ebay link I posted below, there are 13 pics in that listing showing ALL the various measurements.

4.) On this used set you can see the wear line from the seal.
https://www.ebay.com/p/1422198240

5.)The flange PN should be 33131214102
https://www.ebay.com/p/1422198240?iid=163891704505
https://www.pelicanparts.com/More_In...-1-214-102-BOE

Last observation and its not a slam. Those output flanges are what I'd call severely pitted and appear to have been exposed to the elements (read that not installed in a diff that has oil in it) for an extended period. Even the snap ring groove and splines are corroded.