HYDRO BOOST MASTER CYLINDER

lenray

Well-known Member
Have this 70s style tractor called a DO MOR made out of some component truck parts etc. Made in Manistee, Michigan.

I don't have any brakes and very little brake fluid comes out of the bleeders.
New master is 750.00 and a repair kit is 320.

Any chance I can get something newer to replace the master cylinder. Hydraulic oil goes into the cylinder somehow but the reservour is brake fluid.

You guys had any luck with repair kits on these????
 
Check out some of the mid 1970s Chev one ton pickups. There where some of them that had the hydro brake setup. My Grand Dad had a 1976 that had it. It would slide the rear wheels loaded. They where wicked empty.

I have a 1985 Chev 3/4/C30 ton diesel pickup and it has the hydro boost setup too.

Look real close at your setup. On the 1985 truck the master cylinder and the booster where just bolted together. You could replace the master cylinder without the booster. I have replaced it twice and it was under $150 each time. The booster never has given any trouble.
 
As JD said, hydroboost is real common on the C/K one ton GM trucks. My 86 dump has it also. It is on the curren trucks too.

Not sure of the changes through all the years, hopefully you can match something up.

Rick
 
JD and RICK what is that unit that the master cylinder is bolted to called. It has the plunger from the foot pedal attached to it.
 
I would call it the hydro boost section. If yours is two pieces you have the master cylinder half and the booster half. The not having any fluid at the wheel cylinders would involve the master cylinder part. If you can get them bleed but the pedal just pushes hard then that is a booster issue.

The units we are talking about are different than the vacuum booster units that are all made in one piece. You need to look at what yours has. Even better take us a picture. We are just shooting in the dark on this with out seeing what you have.
 
Yeah it is a two piece unit--the master cylinder is bolted to it and it rec. its power fluid from the power steering unit.
JD SELLER had a pic of a tractor like mine not sure if he can put it on here.
Was told by another owner of a DO MOR that the master cylinder goes out about every two years and that it is very under powered for the use it has.
Was told if you install a rebuild kit or go with a new unit--the service life is near two years.

750. was a price on a new unit and 320. was the price for a rebuild kit.
Doesn't sound like a good unit for service life.
This is a 1970's tractor with a Detroit and 4x4 and 4 wheel steer and a funk tranny.
 

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