Hard Brake Pedal

[trb41]

Installed organic frt brake pads. Brakes were okay for awhile now brake pedal very hard to push to make car stop. Feel like my foot is going to go through the floor to get car to stop after I use brakes during in town driving. Car is 77 TR7 with 32K original miles. Replace frt brake hoses a few years ago to solve a brake pulling to the right problem. Caliper pistons move freely. Replaced rear wheel cylinders and frt organic pad a couple of weeks before this problem started. Has original master cylinder that has never been touched.

Any advise?

[saabfast]

Sounds like a servo problem. When you stop the car (engine off), if you press the brake pedal it should go down normally, then harden up and go down less with each subsequent push. Check the non return valve in the vacuum hose connection, otherwise could be the diaphragm.

If the servo is OK it could be the master cylinder with one of the seals breaking up. It does not take too much to put new seals in - if the lower shaft for the failure warning is not frozen in and the bore is OK. Mine was frozen and I ended up changing for an uprated servo and master cylinder - works well.

Alan
Saab 9000 Stg 1
Saab 9000 2.3 FPT Auto
Saab 2.3 LPT Auto
'81 TR7 DHC

[Hasbeen]

A couple of easy tests for servo problems.

With the engine stopped apply the brakes reasonably firmly. Start the engine. As the engine applies vacuum to the servo the pedal will sink an inch or more towards the floor, as the boost comes in.

Take the hose off the manifold & suck on it. If you get air the hose has failed, or the diaphragm in the booster has failed. You should not get any flow of air.

Eat a chocolate to get taste out of mouth. [:D]

Hasbeen