550 k0 1974 front brake master cylinder

[Mark sharman]

Hi all
Thanks for your kind welcome into the group.
I have a couple of questions regarding my master cylinder that i  have just managed to disassemble.
the plunger check valve and rubber were stuck fast but managed to free eventually but this has left a small amount of pitting in the chamber .This is such a shame as once cleaned the out side looks like new.
1.can this be repaired(I'm thinking not)but not sure?
2.if not does anybody know the best place for a replacement?

Also on the under side of the master cylinder is a small plate which holds the rubber cushion for the clutch lever is this zinc plated or painted.
it was so rusted a couldn't tell.   
TIA
Mark

 

[mickwinf]

Would probably leak before long. There is a possibility of having it lined with stainless, I have seen companies advertising this. Personally I ended up getting a repro from silvers as could not get a good feel with rebuilt original.

[McCabe-Thiele (Ted)]

I fitted the DS one as my old unit seemed to have a lot of free play before anything moved inside the master cylinder itself.

The DS one I found was brilliant with hardly any free play at the lever end.

[deltarider]

Most of us opt for the repro which performs even better than OEM. Cost is about the same as a rebuild set. In my case: €55,- instead of €46,50. The lid of the old OEM can be used on the new repro.

[Bryanj]

If you have one of the nicro(ball) hones of a small enough size you could try a very light hone as long as you already have the kit, otherwise as others said get the Dave Silver one.
I would suggest checking the flexi hoses, the first US one i did the hoses were so solid i had to push a welding rod through to clean them, outside was perfect with no cracks or i wouldnt have bothered.
Strip and clean the caliper as well, if piston pitted replace with stainless plus scrape out the seal groove with a dental pick

[Mark sharman]

Hi All
Thanks for the information .
I did think there may be a possibility of honing and shimming but wasn't sure. I have a couple of engineering company's near me so I might have a try.
I looked at the DS one and its different to the original call me pedantic but just trying to keep it as original as I can .
I have serviced the calliper and brake switch union and changed all hoses + the metal pipe and ordered a new set of EBC pads.

Did anybody have any joy with the plate that holds the damper rubber in for the clutch lever .
is it painted or zinc plated?
Thanks again
Mark

[mickwinf]

The little plate underneath is plated as I have a nos one.

[Mark sharman]

Thanks Mickwinf
 sorry I meant brake lever( senior moment ) but you knew what I was talking about
Thanks again