Transmission Output Flange Seal Replacement

[Rus]

Hello everyone!

I'm in the process of changing the O2 sensor (done :)) on my 535i and am also planning to replace the center bearing. After removing the exhaust system today, I found that my transmission output flange seal has been leaking slightly. This is evident by a thin ring of transmission fluid on the heat shield surrounding the area. From various sources I've gathered that to replace the seal I'll need to find a thin-wall 30 mm socket. I do not have the tools to machine down a regular socket, although I do have a die grinder. Is there a source for these sockets either in regular retail stores or online? I believe Armstrong Tools made/makes a socket that works for this with a part number 12-238. I can't however find anyone who sells these sockets to the public. :( It would be disappointing to have to let this leak continue just because I can't find the right tool for the collar nut. All advice and suggestions are appreciated!

Best wishes.

[gale]

Sears might have something close. You could use one of their 1/2" drive thin-wall/deep sockets. You'll still have to shave a token amount of material off the o.d. ~.025", but you should be able to do that with a grinder. You only have to shave about 1/4" to 5/16" from the end if it's an automatic. The manual yoke recess is deeper if I recall.

Here's one I did on a lathe with a 3/4" regular depth socket:

http://www.nmia.com/~dgnrg/1_1875socket.jpg

unfortunately it split when I tackled one that was on too tight with an impact wrench. If you can't get one locally, e-mail me off-line & I'll be happy to buy a cheapie at Harbor Freight and mail to you for cost plus a couple dollars.

[shogun]

http://www.technictool.com/bmwtable.htm
http://www.sirtools.com/bmw_tools.htm
http://www.samstagsales.com/bmwtools.htm
http://www.skywaytools.com/
http://www.zdmak.com/wbstore/main.asp?LowCt=0&action=cat&cat=BMW+TOOLS

[Rus]

Just a small update. I found a standard length 1-3/16" socket at Sears and it works perfectly for the flange nut. The part number is 50734. I found the flange nut to be very easy to loosen...too easy. It was nowhere near the proper torque. Also, the fluid leak was not from the seal, but from underneath the nut itself. I suspect that the petrified remains of the thread sealant had something to do with this. I replaced the seal anyway. How square should the seal be installed? I pressed in the new seal and by running my finger around the circumference I can sense a very slight variation (a fraction of a milimeter) in the seating. It appears to be seated completely. Am I being too anal? Could it be just the casting around the seal that is creating this sensation. Visually the seal appears to be squarely seated.

Also, I believe I found the cause of my ticking noise in the center console. The center bearing not only had a large tear in the upper portion of the rubber (very dry at this point), but also sounds like a can of marbles when shaken.

One last question. Can regular lock nuts be used for the drive shaft? I do not remember ever seeing BMW-style locknuts without the nylon inserts anywhere, although I suspect the dealer may have some on hand. Is it ok to use automotive grade locknuts with a nylon insert?

Hopefully I'll have my baby running again tomorrow. :) Thanks to Gale and Shogun for the wealth of info provided.

[The Bigfella]

Sounds like you got out of this a lot cheaper than me. It cost me just over $400 to get mine fixed by my mechanic - mostly because whoever tried to do it last time over-torqued it. He broke one of his tools in the process.

Ian

[Rus]

Final update:
Car is finally back together :) I ended up reusing the locknuts for the drive shaft with a little blue locktite on the threads. The exhaust system is a bear to install in one piece. Car drives well and the whining and ticking sounds that bothered me at highway speeds are gone now. I used Permatex Thread Sealant on the transmission flange nut and I'm wondering if I should have let it sit for longer. It indicates that it cures in 4 hours. I drove the car more than 4 hours after application of the sealant. I guess I'll just have to be on the look out for a leak. The car idles much better with the new oxygen sensor. Engine vibration is less pronounced inside with the new motor and transmission mounts as well. It seems as if now during acceleration the engine drone is more pronounced. I know the exhaust pipes are installed properly and torqued to the exhaust manifolds so I'm ruling out a leak there. The exhaust and transmission are now mounted with new stiffer rubbers, so perhaps they simply transmit more noise and vibration from these components into the cabin? All opinions and advice are welcome :)