I think the high torque number is wrong & details (archive)

I called around to a couple of friends with BMW shops or mechanics on Friday and Saturday because I couldn't believe the quoted number of 347ft-lb. This seems like and incredible amount of torque on the rear bearings etc. The information that I got was that you should do the old tighten the nut down lightly, spin the the wheel, back the nut off a 1/4 turn, re-tighten and turn the wheel again a couple rotations, then back off a 1/4 turn. This is the method that I used which is almost no torque. You spin and tighten the nut a couple times to make sure the hub is seated correctly. FYI when I took off the passenger side nut the first time, it seems like it was under very little torque and spun right off. The drivers side was another story but it was rusted on from driving around with no center cap.

Several parts are required for this modification. You will need a pair of the rear trailing arms from a 323i. In the US this is the most difficult and costly part of the upgrade. If can get the whole trailing arm with all the brake parts then you are all set. Otherwise you need to purchase the emergency brake parts, rotors, calipers and other associated bits. For my project I decided to substitute E30 325i rear calipers because it was my understanding that there are not many brake pad choices for the stock 323i calipers. Using the E30 325i calipers requires some machining to get them to fit and the use of non-factory (some VW lines) or custom brake lines. I just finished this project yesterday. Overall it was a very simple bolt-on job, but time intensive. I spent about 16 hours replacing front and rear braking systems and doing some other repairs "while I was in there."
I can't say much about the performance part of the upgrade yet. The brake pedal is now very firm, but before the brake system was in pretty sorry shape.

For now I haven't changed the master cylinder. I am unsure whether or not I really need to do this. There is probably a proportioning valve somewhere in the system needs to be removed but I haven't looked into this yet. The car stops pretty well the way it is right now.

I have lots of pictures and will be putting up a web site in the near future.

Mike Matison
'83 320is with disk brakes
Hello Mike,

I think you are in the process of upgrading the rear brake system of your 320i. Could please indicate me what are the modifications you made to change the drums into disks. (what size, what kind of calipers, did you have to change the master cylinder, or perform any other drilling and/or welding stuff on the trailing arms). My 320 is a 76 european model... :-))

Thank you very much in advance for your help

Jean-Louis (Belgium)

Follow Ups:

Thanks a lot for all these usefull info (eom) JL 04:57 12/05/2000 (0)
Re: I think the high torque number is wrong & Ed Walker 09:31 12/04/2000 (0)

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