The Stovebolt Site Forums The Parking Lot '60-'66 Trucks Master cylinder leaking

Hi guys,

Ok, so it seems I finally figured out why my clutch weakens when i hold it down too long. (hydraulic clutch, it's a 61) Took my buddy to point it out, actually. We were driving home this morning, and he said that it looked pretty wet around the pedals. Sure enough, there's brake fluid peeing on the floor from where the brake and clutch pedals enter the master cylinder. I held the brake down for a while, no fluid came out. But after holding the clutch down for a while, fluid started dripping slowly out from where the brake pedal goes in. So I'm thinking there's some seals that are shot? Is there a rebuild kit for these master cylinders, or should I just replace the whole thing? Ixs it easy to do? (Man I have to get that shop manual...think I'll order it today.)

Ok, well, I just found out that there is rebuild kits available. I'll likely do that. But I'd still appreciate some input from the Stovebolt gurus out there if you guys have any, which I know you do:)

Hold on a minute. The clutch works off the brake master cylinder? Are you sure? That would be a first as far as I know. You should have a separate clutch cylinder, and that sounds like what your problem is. Your clutch "weakens" because you have a hydraulic leak from the clutch master cylinder. That's what you need to rebuild.

Or did I completely misunderstand what you said?

When you rebuild it, be sure to clean the cylinder with clutch fluid and hone it carefully to clean up the bore. Should be a fairly simple job.

Yes, the clutch and the brakes work off the same master cylinder. When the fluid gets really low in it, it affects the brakes and the clutch. On the 60 to 62, with manual tranny, the clutch is hydraulic. Two lines come out the master, one goes to the brakes, one goes to the clutch slave cylinder.

There's a rebuild kit for the brake side, and for the clutch side. Parts are identical. And there's only one reservoir, for both systems. Yup, kinda odd, I know:)

Wow, that's weird. I didn't know that.

I made the mistake of assuming an NOS master would do the job. It worked at first but the spring of it's first storage with oil in it , it leaked oil out the back down the firewall inside and out and stripped the paint real well. Fresh rebuild is in order.

That's what mine is doing right now, leaking on the inside of the firewall. But it only seems to leak when the clutch is pressed in.