New master cylinder for HUP

[Malcolm Towrie]

We needed a new master cylinder for our HUP restoration. The old one had a badly corroded bore. I agree resleeving is the way to go, but money is tight for a museum in these Covid times. So one was ordered from LWD in Holland. We ordered the wrong one. It did not have the bottom mount design of the original, the bore was 1-1/8", not 1-1/4", and the piston had a much deeper hole for the actuating rod than the original. I can live with all of these discrepancies so we used it.

Searching showed the bottom mount design is now hen's teeth rare and I can see why. Not only because of the unusual bottom mount, but the two feet are different heights to angle the m/c to suit the pedal mount! GM's buying power, I guess.

We made an adapter to allow fitting the side-mount m/c to the bottom-mount frame bracket. And I figure the 1-1/8" bore giving a bit more brake pressure for a bit more pedal travel is a reasonable compromise.
The deeper rod hole in the piston was filled with a machined rod, so we now have a working m/c.

Now onto finding rear wheel cylinders that have starwheel adjusters, because the popular 4511 replacement cylinders don't!

Malcolm