drum brakes with single booster

Brakes discussion.

drum brakes with single booster

by ss2fly [old] » Sun Oct 27, 2013 9:35 am

Hi team,
I am trying to get my car back on the road for summer as cheaply as I can... not a lot of money round here with 4 kids....

I have a Wagon with the standard front end at the moment with standard drum brakes all round.

A while ago, I fitted a brake booster off a Subaru with a VN Commodore Master cylinder adapted to the end of it. I made a new pedal box to operate it all....

What I want to do it make this work with the standard drum brakes if possible...just for the summer until I strip the car for the rebuild...

As the booster is before the master cylinder, I will only need one. Can I split the brake circuit so there is one circuit for each side, or front to back???

Do I need to modify the master cylinder at all to accommodate the drums as it was originally off a disc braked car???

Any help appreciated.

As I said, it is only a temporary solution till I rebuild it.

Andy in NZ
Posts: 106
Joined: Thu Jan 01, 1970 11:00 am

Re: drum brakes with single booster

by peter_ejeh » Sun Oct 27, 2013 4:46 pm

Disc brake masters are different as they don't have a residual valve. Tandem dual circuit masters are different as they have a proportioning valve. The Subaru disc brake booster and the Commodore master will not work with drum brakes.

With the standard 4 wheel drums originally only a small booster was fitted and it was all one circuit front and rear. The master had no proportioning valve as it was single circuit It did have a residual valve, which drums need.

If you have standard drums all round, there are brake masters available brand new that are not expensive when you consider how important brakes are.

The other option is to leave the car off the road until you rebuild it.
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Joined: Mon Apr 28, 2014 11:50 pm

Re: drum brakes with single booster

by ss2fly [old] » Sun Oct 27, 2013 7:13 pm

I was planning to fit a couple of 10lb residual pressure valves, one on the front and one on the rear circuit (possibly 2, one on each side at the rear) plus an adjustable proportioning valve on the rear.

The subaru booster is nowhere near the size of a Commodore unit. I chose it as it fitted next to the hinge and spring nicely.

I think this setup will work well enough. I can then reuse most of the parts when i get round to rebuilding it anyway.

Posts: 106
Joined: Thu Jan 01, 1970 11:00 am

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