Page 1 of 1

difference in brake drums with different wheel bolts?

Posted: Sat Apr 02, 2016 6:02 pm
by TvdWerf
My MM has at the front other wheel bolts as rear, but I have a complete front suspension with the right ones.
I ordered new bolts at ESM, but am wondering if only the drums are different, or the complete suspension?
Are the brake cylinders and shoes also the same?

Re: difference in brake drums with different wheel bolts?

Posted: Sat Apr 02, 2016 11:45 pm
by mike.perry
Early brake drums had BSF threads, later drums had UNF threads
See http://seriesmm.mmoc.org.uk Technical info, front suspension stub axle and wheel bolt threads

Re: difference in brake drums with different wheel bolts?

Posted: Sun Apr 03, 2016 12:03 am
by TvdWerf
I know the drums have different threads, but to get the other drum on the car, do I need to change only the drum, or also the other suspension parts?
My rear axle has the UNF bolts, and front the BSF, my spare suspension has also UNF bolts.
I like to drive with front and rear the same bolts.
When not need to change, I like to keep the good working brake cylinders, and wheel bearings :D

Re: difference in brake drums with different wheel bolts?

Posted: Sun Apr 03, 2016 11:19 am
by TvdWerf
At ESM I see 2 different bearing Kits, from 1948-1949, and 1950-1954, is this the difference also between BSF and UNF?
The only other way to check is take the drums from the car, and when possible, I do this at a later moment, not now..

Re: difference in brake drums with different wheel bolts?

Posted: Sun Apr 03, 2016 11:04 pm
by mike.perry
The drums should fit on either side, you just have to keep the bolts to the matching brake drums.
Change BSF to UNF threads car LHD 126725, RHD 131858

Re: difference in brake drums with different wheel bolts?

Posted: Mon Apr 04, 2016 8:19 am
by smithskids
You only need swap the brake drums. I have changed axles in the past and the only difference was I had to re-adjust the brakes as the older drums were slightly more worn. Apart from the thread size for the wheel bolts they are identical. :D

Re: difference in brake drums with different wheel bolts?

Posted: Mon Apr 04, 2016 6:35 pm
by TvdWerf
my (LHD) chassisnumber is 122061, but rear UNF, Front BSF.
I got the car with an extra front suspension with UNF, so this means the actual BSF is original?
I will start the job in a few weeks, maybe first to order 2 new bearingsets at ESM...