dual master cylinders?

[reg of the overflow]

This is a serious question.


I have a 1961 SWB with a Holden engine, hence it has 11'' LWB brakes at the front and SWB 10" at the back. It never had great brakes, by normal standards but whilst rebuilding her I have overhauled the brakes. New everything -shoes, pipes, lines, cylinders, everything! And it has the CB type LWB master cylinder as well, as it had before.


now, I have bled the brakes -over and over, in every way possible as the book tells me, as people on here told me. Pumped like billyo, used a syringe and reverse bled from the slave cylinders, etc. When I clamp off the front brakes you couldn't ask for a better pedal, rear works awesome. When I clamp the rear brakes off, I get half a pedal - damn fine by LR standards, but, when I unclamp both, the pedal goes almost to the floor then pumps up on the second and third pump. I am over it!


I got to thinking though, that it would be possible to put another master cylinder on next the existing one and connect them together, it wouldn't really be hard to do. That way, one could operate the rear brakes and the other, the front brakes.


Think this would work?

[Blknight.aus]

nope, youd have all sorts of problems with it.

youd be in with a shot if you converted all the brakes to the same size, fitted balance rods to keep the pressure even on both MC's and ran split hydraulics for the brakes.

your issue is worn snail cams or the shoes are in the wrong way round along with a potential side serve of over size drums and incorrectly radiused shoes.

[reg of the overflow]

worn cams............. not thought of that. I didn't replace the drums as they are relatively new - perhaps a year old. might get them checked. Thanks

[JDNSW]

What master cylinder do you have? If you are trying to operate 11" two leading shoe brakes with a swb master cylinder you will never get a pedal.

John

[reg of the overflow]

it's the LWB master cylinder........ still working on it, when I get time

[Homestar]

As Dave mentioned - is the radius of the shoes wrong? This caught me out once before. Used new drums and new shoes, could never get a pedal. Turned out the shoes were only touching in a couple of spots. A bit of work later - shoes off and on a dozen times I managed to put a radius on them that contacted almost all of the drum - got a great pedal after that.

Not sure what the correct method is, but I got there in the end.

Decided to do it a bit easier with the Series 3 I'm helping my son rebuild at the moment and stick Cookeys disk brake conversion on it.

[gromit]

As Dave mentioned - is the radius of the shoes wrong? This caught me out once before. Used new drums and new shoes, could never get a pedal. Turned out the shoes were only touching in a couple of spots. A bit of work later - shoes off and on a dozen times I managed to put a radius on them that contacted almost all of the drum - got a great pedal after that.

Not sure what the correct method is, but I got there in the end.

Decided to do it a bit easier with the Series 3 I'm helping my son rebuild at the moment and stick Cookeys disk brake conversion on it.

Had the same with my Series I, radius was wrong.
Rubbed chalk on the linings, drum back on, applied the brake gently while someone spun the drum, then filed off the high spots.
Eventually got good contact, adjusted up the brakes and had a good pedal. Brakes are still average and you do have to plan ahead.....


Colin