[Heybuck]

As part of my brake rebuild on my '66 Grand Prix, I wanted a new master cylinder.

Actually I was going to get my original one stainless sleeved but the cost is prohibitive. Here it is anyway.

So I called my friendly American Car Parts supplier who has been around forever. He asked all the expected questions, make, model, year, booster or no booster etc and yes he has one on the shelf. But then he threw me by saying his book tells him it has a 7/8th inch bore.

I say no, mine is a 1 inch bore. He asks if I'm sure, I say yes it is and I think his book is wrong. So he is sending me one with a 1" bore.

But am I correct? Is my cylinder correct? I've had the car for 25 years since i imported it and I know I put new rubbers in all the cylinders when I bought it but never touched it since.

The workshop manual does not specify the size of the rubbers.

Just wondering?

Ian