Mixing boosters and Master Cylinders

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Apr 2, 2006
Heres what i have. A chevy hydroboost setup and a stock LC master. I drilled the master to fit on the booster. Does anyone know the difference in stroke length of a chevy or toyota master cylinder? Is the toyota stroke length longer than most? I may try lengthening the internal rod?

My problem is I am getting no rear brake pressure. All new lines and the front works. I can stop very well with the petal all the way to the floor. When I try to bleed the rear...nothing. No air, no fluid, nothing. The lines are not blocked.

Does anyone know of a setup like mine? I'll post pics tonight or tomorrow.

Thanks in advance.
I've been using a Hydroboost, Chevy truck 1 1/8" bore master, 4 Runner front calipers, stock prop valve setup for a few years with perfect results.

Bought another 60. Lots of pedal travel, Stopping power was bad, especially working them hard on the trail, pedal travel would increase and pedal feel spongy. Thought the master was bad. replaced it. Same results. thought I bought a bad master. Took it back, got another. Same results.
Now I'm convinced the 7/8 bore is too small.
I just put on a Hydroboost 1 1/8" GM master and am now satisfied.

You may have a bad or clogged proportioning valve as you should get some fluid flow at the rear.
Yeah, i am more and more thinking it's the master to booster combo that is messing me up. I may pick up a corvette master for a disk drum setup and see what results I get.
I just put on a Hydroboost 1 1/8" GM master and am now satisfied.

FL Cruiser: Could you elaborate on what's involved in swapping the GM master & booster? Is this a direct bolt in or what customization is needed? Pics? What year and model for the GM parts?

I have 4 runner calipers with a stock booster & MC & have been pretty happy with the results. But, after reading your comments, I wonder if things could be even better.

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