Rear Brakes

Hello again all,
Can anyone advise where I would be able to get a rear brake master cylinder kit for an '82 A4 1300.

Thanks in advance.

Unfortunately only in the land of Unicorns & Fairies !!!

They are very hard to find as no longer available from K

MCG Z1300 in Germany do them............if you got too much money !!

Pete F

If you know exactly what parts need rebuilt in the cylinder I don't think it would be impossible. The rubber parts in the cylinder are usually just o-rings and those can be matched and replaced easily...
A specific "kit" may not be easy to find due to the low demand of them, but those kits can be assembled piece by piece if you take the time to match everything up. Plus one assembled by hand is always cheaper in the long run than having someone else assemble it for you. In the end all you're paying for are the o-rings lol.

Just be sure that whatever you're using won't be affected by the brake fluid

Mikez

All good advice I would second !

Its well worth having a good look inside the cylinder at the bore once stripped, as they often have damage which leads to the leaks......scratches or wear marks. This makes replacing the seals a waste of money as it will only leak again.

You should also find somewhere on the cylinder body the BORE SIZE of the part.

Once you know the size of the original bore, you can actually use a slightly larger size drill to RE-BORE the cylinder (VERY CAREFULLY) & use a piston & seals from another bike of the new size. These should be more available & cheaper.

Needs Must !!

Pete F

Nice idea Pete!

If you know where to look, another suggestion would be to find a dealer that sells o-rings in bulk and see about getting a variety of sizes.

I did a quick google search and found that Ethylene Propylene o-rings are what you need for brake fluid resistance. So whatever you do make sure that's what you're getting .
Found the info here:
www.marcorubber.com/materialguide.htm

Mikez

You will find you will need more than just o rings for the job.

The end seal is a tapered type seal which is pretty specific. Also the seals used in most master cylinders are flat profile as they have to move & retain fluid at the same time whilst normal o rings just hold fluid back & would wear very quickly if constantly moving.

You need to remove the piston & take seals off & have a look to see what I mean.

Pete F