1980 1000sp rear master cylinder

[snobear]

Having some confusion on my rear master cylinder for my 1980 1000SP.
What all I am finding online is part number 29667000B replacement for original 29667000 which is a 15mm piston size.
My actual rear master cylinder is stamped 18D9 which is a 19mm piston size?  This I have confirmed with my caliper.

Has mine been replaced?  Just trying to source the proper rebuild kit.

[Antietam Classic Cycle]

Stock SP master cylinder is a PS15 which has an actual bore size of 5/8".

[snobear]

The part number 29667000B is the ps15 master cylinder so my 19mm must be a replacement, looks like I might be replacing rather than rebuilding

[n3303j]

Stock SP master cylinder is a PS15 which has an actual bore size of 5/8".

Thought that metric to fraction conversion was interesting. When I bought my T3 both master cylinders were heavily pitted after sitting for 18 years. Both converted to a US fractional inch bore dimension. I reamed each out with a 1/32" oversize reamer and lined them with thin wall brass K&S fractional dimension tubing. Then installed standard rebuild kits in the relined bore.  It's been 16 years so far.

[snobear]

Do you know if your rear was a 15mm or 19mm?
That is an option I had not considered but I would like to retain the 19mm master cylinder if possible with the linked brakes.
Where were you able to find a standard size rebuild kit to fit the Brembo's?

[n3303j]

That was the magic. The metric cylinders were exact fractional bores. I bought the brass tubing at the local hobby shop. I used the standard rebuild kit for the original cylinders. It all fit admirably. That was 20 years ago. When I get home I'll check if my logs contain the original bore dimensions fir my '76 T3.

[wirespokes]

Thought that metric to fraction conversion was interesting. When I bought my T3 both master cylinders were heavily pitted after sitting for 18 years. Both converted to a US fractional inch bore dimension. I reamed each out with a 1/32" oversize reamer and lined them with thin wall brass K&S fractional dimension tubing. Then installed standard rebuild kits in the relined bore.  It's been 16 years so far.

As far as I know, all brake parts (at least master cylinders) are made in inch sizes.
Ron - how did you line the bore? Did the brass slip in or was it an interference fit? If it was glued in, what glue was used?

[snobear]

 Well I mislead everyone, the part number kept telling me a 19mm piston but when I took it apart this morning it is a stepped down bore to about 15.8mm so it will be the standard rear master cylinder I have.
I was measuring the bore from externally for the seal which is about 19mm

[n3303j]

As far as I know, all brake parts (at least master cylinders) are made in inch sizes.
Ron - how did you line the bore? Did the brass slip in or was it an interference fit? If it was glued in, what glue was used?

Loctite RC680 bonded the brass well. Just be quick about it as it can set up quickly if you dawdle. Cross drilled holes from reservoir afterward and polished off the burr in the bore.