adjusting Series III clutch

[adkrover]

I have a series III clutch master and slave cylinder in my truck. I recently changed the master cylinder for a new, non leaking one. It was an exact match and is a new unit, not rebuilt. My IIa manuals (most of my truck is a IIa) don't cover how to adjust the linkage or pedal freeplay on a Series III. The book suggests a 1/16" freeplay on the IIa master cylinder pushrod but I can't get it to have ANY play in it. Even with both adjusting nuts backed completely off, it doesn't wiggle in or out at all without pushing on the cylinder. It acts as if the rod is fixed to the piston. Is that typical of a Series III master cylinder?

I've completely bled out both cylinders but the clutch still requires about half of it's travel before it really starts to dissengage the clutch. The old cylinder had a much firmer pedal. I could adjust the master cylinder pushrod to decreade that travel but there I'm afraid it will cause the cylinder to hold some pressure. What's the general rule for adjusting the pedal at the master pushrod if there is no freeplay detectable?

Thanks

[adkrover]

amazing what you find when you read

OK, so with the help of searching previous posts, I've answered my own question. Just in case anyone is interested in the solution, here goes.

1) While my cylinder does not have 1/16" of freeplay, there is a very minute but noticable freeplay so I was able to set the pushrod length so that it is not applying any pressure.

2) A previous post suggested that Series III clutches are especially hard to bleed properly but didn't list any explaination beyond that. I assume because of the extreme vertical drop and the large diameter of the fluid line (larger than a brake line) and the relatively small amount of fluid you get from one shot of the pedal that the bubbles keep rising in the tube faster than you can expell the fluid doing a regular bleeding procedure. Another post suggested the best way to bleed it was to route the bleed tube back up to the master cylinder res., open the bleeder completely and pump the pedal repeatedly until all of the air is out of the system. This overcomes the bubbles want to rise in the tubing and assures total elimination of air. This only works of course after you've shot enough fluid into a jar that you are not recirculating old fluid.

So after that, my old clutch is back and the pedal feels just right.

[Tim Smith]

I'm guessing that you either have air still trapped in the system or your flex hose is starting to bulge under pressure. If it were me, then I would probably re-bleed the system after I replaced the flex hose (it's a cheap item) and then try to get everything in order.

I don't know much about adjusting the peddle/master position.

Hope this helps.

[Tim Smith]

Oops! Looks like I too so long to write my response that you already answered your own question. Oh well. Glad you figured it out.

Cheers!