Mz rear brake caliper ?

[Ian]

My rear brake caliper was binding so I bought a seal kit and fitted it .

But where the caliper splits in half it's now leaking !

I've tried the old seal back in it , another new seal and an o ring seal and it's still leaks .
As far as I can tell it's because it has very fine lines on the mating surfaces form being machined during manufacture .

Is it wise to use a gasket type sealant on it ? 


 

[themoudie]

Aye xbrmz,

Did you torque the bolts or just tighten them?

Did you get rid of every scrap of white aluminium oxide?

Have you tried laying the caliper body mating faces on a piece of plate glass and trying to put a 1thou feeler guage between the the glass and the caliper body? Shouldn't be able to. If you can maybe warped castings. How much feeler gauge you can push between, will determine whether you can salvage or have to bin the castings.

Anybody any other ideas or factory tolerances to help?

Regards, Bill

[Ian]

Torque the bolts ... It's a MZ ,no torque settings are supplied for anything other than the engine ,
that I'm aware of ,bent the 9" long allen key about the same doing up as undoing .

There was no aluminum oxide to scrape ,clean as a new pin .

Will try them on a piece of plate glass tomorrow ,If they have warped I would of though that they would warp together ? maybe.
When placed together you can't see light between the joins .

Thanks for the suggestions Bill ,Other than buying a new caliper it's got me baffled .

[guest27]

Useless comments dept...

I would guess that if they were not leaking before it is something that has happened in taking them apart.  Assuming you are not ham-fisted like me and the mating faces are not damaged, is there any male/female junctions, locating pin, raised edge etc that is either not locating or has a small scrap of dirt stopping proper mating.  There is a pretty high pressure in the caliper when in use so any very small compromise to the seal will cause a leak.  Is there a componant that can go in either way but sitts lower one way than the other?  Just thoughts, cant see you warping the castings taking them apart - mind the bolster chisel and lump hammer did not help.

Have pulled a number of calipers apart in the past and had occasional leak probs - usually because of some small bit of grit behind one face etc.

Best of luck and enjoy the smell of brake fluid.

R

[Ian]

Ham-fisted .. me ,that's a very polite description .
On a bad day I can mangle anything ,that's why my bikes are all ways in bits ,
I take them apart on a good day for a simple job and then I don't have another good day for weeks
so I don't touch them .

The two parts of the caliper are dead flat no locating pins ,just the two allen bolts that hold it all together and a little cut out on both parts for the O ring to sit in.
I've striped them down today and put a new O ring in with a very light smear of silicon gasket sealant .
I'll bleed it tomorrow and see if it still leaks .

I prefer the smell of petrol ....