The Stovebolt Site Forums The Shop Area Driveline Hard Brake Pedal

Hi All,

My 59 3200 has been sitting for 14 years or so. I've just started trying to get it drive-able.

The brake pedal is really stiff. I really have to stomp on it and then it only gradually stops. It rolls freely, so I don't think the brakes are stuck or anything. Not talking about stopping on the road, just rolling a little in the driveway.
I had replaced all the wheel cylinders, shoes, lines and hoses and I think the master cylinder years ago, and the lines and hoses all look okay. I flushed the fluid, to no effect. I haven't pulled the drums to look at the insides. I don't remember it ever being so stiff, and I don't think it was even like this a couple months ago.

Any ideas what could be wrong? Is there a troubleshooting sequence to follow? The manual doesn't even mention hard pedal as a potential problem, so isn't very helpful! And everything online I can find is about systems with boosters.

Thanks!

Make sure you have a bit of play (1/8”) in the plunger rod from the pedal to the M/C. This is important because the fluid needs to bleed off a little as you release the pedal. Make sure fluid flows freely through all the lines.

Since the truck rolls free and releases the problem isn't with the drums, it's the MC

How did you flush the system? If you open one of the wheel cylinder bleeders while you have someone pushing on the pedal does the pedal go to the floor easily? If the pedal is still hard it's time to remove the MC and see why it's not working.

Mike B

Thanks for the replies.

I'll check for play at the plunger arm. Is that adjustable? Is that the toeboard clearance adjustment in the manual?

I flushed the system with the wheel cylinder bleeders. The pedal still seems hard with the bleeders open, though after a few pushes it would go most of the way easily then get stiff maybe 75% of the way. I'm trying to remember if that happened only on the rear wheels.

What would I check on the MC?

Disconnect actuator rod from pedal to master cylinder--- if moves freely not in the linkage.
Remove banjo bolt from rear of mc---if moves freely the mc is okay.
Reinstall banjo bolt and block front brake lines---check.
Block rear brake line---check.
Should isolate problem area.
Last thought, do the new wheel cylinders have the same bore as the old. Smaller wc or bigger mc makes for hard pedal.

Check and/or replace the rubber flex lines between the frame and the suspension parts- - - - -two up front and one in the rear. They deteriorate and collapse from the inside, and restrict fluid flow. "New" doesn't necessarily mean "good" since a lot of replacement parts for stovebolts are made offshore with poor or nonexistent quality control.
Jerry

I just completely replaced the entire brake system on a truck that had been sitting for over 20 years. I started by trying to bleed the brakes. I could not get an fluid to flow from the wheel cylinder bleeder valves. I did open the brake line at the T on the rear axle and had good brake fluid flow. I discovered the 20+ year old brake fluid had actually gelled. It was about the consistency of Vaseline. I did not have to change the brakes lines but I did have to rebuild or replace all 4 wheel cylinders and the master cylinder.