6066 (1960-1966) GMC Truck Club

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-   -   Problem with clutch disengaging (https://6066gmcclub.com/showthread.php?t=47661)

Funky61 July 28th, 2013 03:52 PM

Re: Problem with clutch disengaging
My 61 does not have this extra valve either.

raycow July 28th, 2013 06:24 PM

Re: Problem with clutch disengaging
Ok, now I get it. I thought that part was just a tube fitting/adaptor. In fact, I still do, because that's what it looks like from the outside. I won't know for sure until I disconnect the line and remove the part from the slave cylinder.


Clarke October 15th, 2013 04:27 AM

Re: Problem with clutch disengaging

Okay, after pouting for the last several months, I finally got motivated over the weekend and start over on trouble shooting...

I came up with a couple of items: my master cylinder had fluid between the primary and secondary seal cups (this was working before, but I tried so many different things I'm sure I blew the seal). My master cylinder is under warranty, so I replaced it, bench bled, reverse bled the system, and seems to be working okay, but my clutch still isn't disengaging. I took all the slack out of the clutch fork, removed the lower clutch housing pan, asked my wife (nicely) to hold the clutch down while I was under the truck and verified I have good travel, but clutch disk is still tight. Just for kicks, I shimmed the pressure plate away from the flywheel using 0.050" thick washers, readjusted clutch fork, asked her to hold the clutch down (nicely again) and I noticed the disk did relax some. I also noticed one of the liners was not centered with the other, so I took a screw driver, pushed on the edge of the suspect liner and it moved about 0.25".

Okay, so now I'm really pissed and suggested to my helpful wife she'd better go back in the house. The reason I'm pissed, I had new liners put on the disk in the spring after changing out my starter ring gear. After picking up the disk from the shop I noticed the edge of one liner was cracked about 0.50" wide X 3.0" long, so I asked them to replace the damaged liner. A week later I went back, they told me the rivet pattern didn't match, so they bonded the new liner on. I questioned this attachment method and even stated I prefer the mechanical fasteners and I was willing to wait for the correct liner. They assured me this was fine, they do it all the time on the 2 and 3 ton trucks. Whatever!!! Now I have to pull the transmission again! Hopefully, the disk was not damaged by spinning on the liner...

I'm also wondering if my pressure plate is weak? I'm going to call around to see if someone can test the springs/etc on it for me. The prior owner replaced the pressure plate a couple of years before I bought the truck. It's always been sensitive and with the new liners (increased thickness compared to worn liners) I'm nervous if it's going to disengage.

I read a quote from Edwin on the old forum "I recommend the Center Force CF165552 11 inch pressure plate to replace the Borg and Beck unit." Anyone have experience with this part? Pros and cons? I put one on my JEEP years ago, but didn't notice any difference, except maybe a little stiffer. I don't care, I just want good travel.

dthela October 16th, 2013 02:05 AM

Re: Problem with clutch disengaging
62 also, no valve

George Bongert October 17th, 2013 01:47 AM

Re: Problem with clutch disengaging
Howdy everyone!

Now I've heard just about everything. A fluid damper valve in the line between the Master and Slave cylinder? Never saw one much less hearing about their existence. Since my conversion of my '63 Chevy from inline 292 to a 305 V-6 from a '62 GMC, I had to use all of the components from the GMC, and there was no such valve anywhere in that system, just the Master cylinder, fluid line, and Slave cylinder. I would look for some form of mechanical interference (wrong clutch components) as the cause of your problem of the clutch not releasing. Someone out there somewhere has to have the right clutch components for these old trucks. I guess it's just a matter of hunting them down and finding them.

BarryGMC October 21st, 2013 02:42 AM

Re: Problem with clutch disengaging
Sound like you have problems with the disk. Why don't you get a 12 inch kit for the truck and call it good.

Clarke December 8th, 2013 10:10 AM

Re: Problem with clutch disengaging

Originally Posted by BarryGMC (Post 50792)
Sound like you have problems with the disk. Why don't you get a 12 inch kit for the truck and call it good.

Thanks to Barry's suggestion, my truck is back on the road. I replaced my 11" clutch with a 12" kit. I looked at several 12" kits around here locally and the center hub on the forward side of the clutch disk stuck out about .25", so I ordered the same one that FetchMeAPepsi ordered/installed (Rhino Pac - Part# 04-528 - through WWW.AUTOPARTSANDSTUFF.COM for $177.00 delivered). The center hub only sticks out about .06", so there is ample clearance to the flywheel. It was three weeks before they could ship the kit out, as they did not have it in stock.

Turns out my old pressure plate was weak enough that it would not disengage the disk, but was strong enough to pinch the disk. I now have the recommended clearance/slack between the adjustment rod and clutch fork.

Now I have to take my rebuilt 11" clutch (that fell apart) back to the shop and get my money back.

Thank you all for the feedback.

I took several pictures of the clutch kit and will post them soon.

This weekend I'm installing an electric brake controller and 7 way RV connector, so we can tow our camper that is currently being built.

BarryGMC December 8th, 2013 08:07 PM

Re: Problem with clutch disengaging
Tell us about this camper. Curious curious. Barry

Rockdriller December 8th, 2013 10:15 PM

Re: Problem with clutch disengaging
Success at last.

Clarke December 9th, 2013 04:02 AM

Vintage Camper

Originally Posted by BarryGMC (Post 51430)
Tell us about this camper. Curious curious. Barry

I've been looking for a single axle early-mid 60's camper for several years to pull behind the GMC... I got tired of looking, so I decided to go with a custom build. A few months back I bought a frame off a 13' 63 Winne in MO. I'm doing the design/drawings and someone is doing the hard work.

It'll be green and white like my truck. Should be done in the spring.

Been trying to get my truck in good enough shape to take out of town and be reliable. It's getting there.

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