6066 (1960-1966) GMC Truck Club

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

Clarke July 17th, 2013 05:07 AM

Problem with clutch disengaging
 
I have a '62 3/4 ton with a 305D and SM420. The guy I bought it from said the orig clutch fell apart so he replaced the pressure plate and clutch disk. He also said he flipped the starter ring gear over because it was grinding. I don't think he ever fixed or replaced the starter, because when I bought the truck the starter was grinding again.

I put up with it for several years... A year or two ago I replaced all the brake and clutch hydraulic components, except for the clutch line because I couldn't find a replacement. I noticed there was no slack in the clutch petal or clutch fork, so I added the recommended slack. As a result, the clutch would not disengage. So I took all the slack back out and the clutch would disengage, but barley.

Over the winter, I decided to install a new ring gear. Pressure plate and clutch disk looked good, but I wasn't sure about the pilot and release bearings, so I took them into NAPA and bought new. I compared/measured old with new and they matched. While I was at it, I had a new clutch line made to replace the original. After putting all back together, I couldn't get the clutch to disengage, even after taking all the slack out. I bled the line multiple ways, replaced master and slave cylinders, reinstalled the original line, bled the line multiple ways again and again with no luck.

Fed up, took the truck to the dealer, they quickly told me I had good travel, but I had the wrong release bearing. They said there is a short and long, I had the short and I needed the long. Fed up, I let them do the work. I picked it up the next day and it was driving fine.

Approx 100 miles later on my way home I'm not able to shift; clutch is not disengaging again... I have to stop the engine, shift into gear, restart, drive, repeat... I rolled under the truck tonight, hoping to find slack in the clutch fork, readjust and be back on the road. I noticed the adjustment nut was approx in the middle of the adjustment rod (with the longer release bearing vs. towards the end with the short release bearing), but after I released the clutch fork spring I found there was no slack. I readjusted it several times (both directions), bled the system several times and no luck!

Any suggestions??? I'll be calling the shop tomorrow, but I'd like to pass on any suggestions the group may have to minimize the drama.

Thank you in advance.

David

FetchMeAPepsi July 17th, 2013 03:27 PM

Re: Problem with clutch disengaging
 
I havent dug into clutch stuff yet but are you sure he put the right plate and disk in? They dont have the right disks anymore from what I have heard. You have to have the old one resurfaced because the springs are on the wrong side and it makes it too big or somesuch.

I know that doesn't help much, but maybe someone with knowledge of the borg-warner clutch disks (discs?) will reply and clear it up some. It has something to do with the diaphrams.:confused:

David R Leifheit July 17th, 2013 04:09 PM

Re: Problem with clutch disengaging
 
The last time I had to deal with a clutch the discs were still available, but had to be ordered. Now I understand you can't get them..

I have a clutch disc in my office, I am pretty sure it is a GMC since I don't actually have any Chevrolet... And the spring pack and "nose" are on the same side of the disc, which means on the Chevrolet disc they are on opposite sides. There isn't enough clearance for it to work with the Chevrolet disc. The recess in the flywheel is just enough for the bolt heads.

There are two different release or throwout bearings, a long and a short so the shop was correct on that. I found out the hard way... An important part to look at when working with the clutch is the input shaft bearing cover. It doesn't just cover the bearing but also the input shaft and the throwout bearing "rides" on this. With the wrong bearing or improperly adjusted bearing, this can break off. My first 4-speed didn't have this and it took me quite a while to find a cover that was intact.

The clutch adjustment rod should have two nuts on it, so once adjusted it doesn't change. I had mine back out on a lonely stretch of road. -funny story, when it did that and I got the truck stopped, there was a nut of the same size and thread on the shoulder of the road-

As of late I haven't been the most active or the "best" source of information. But if you have questions and need to look at manuals, http://www.oeltd.net/doc/6066.htm is the site for my trucks and there is a link at the top to my manuals. Some of the manuals have had sections scanned in, so take a look and see if I have scanned in what you need. If not, email me and I will try to scan in whatever information you are looking for.

Andice July 20th, 2013 03:29 AM

Re: Problem with clutch disengaging
 
Having learned from previous "experts" concerning clutches and pressure plates I have my old parts rebuilt now. It may cost a little more up front but I've been happier in the end.

Funky61 July 20th, 2013 04:50 AM

Re: Problem with clutch disengaging
 
1 Attachment(s)
Quote:

David R Leifheit Re: Problem with clutch disengaging

The last time I had to deal with a clutch the discs were still available, but had to be ordered. Now I understand you can't get them..

I have a clutch disc in my office, I am pretty sure it is a GMC since I don't actually have any Chevrolet... And the spring pack and "nose" are on the same side of the disc, which means on the Chevrolet disc they are on opposite sides. There isn't enough clearance for it to work with the Chevrolet disc. The recess in the flywheel is just enough for the bolt heads.
Here is a photo

Clarke July 27th, 2013 01:40 PM

Re: Problem with clutch disengaging
 
Update:

My local dealership has decided they are not going to trouble shoot the issue, so I guess I'm stuck trying again myself...

To clarify, I did not change the clutch disk or pressure plate when replacing my starter ring gear, so these are the same parts.

I believe it's a hydraulic issue... When reviewing the service manual, appears I'm supposed to have a "fluid damper valve" installed between the slave cylinder and clutch line (1500 Series with SM420)? Does anyone else have this on their truck? Is it possible this can be the issue, or add to it?

I'm going to remove the master cylinder and bench bleed it to verify it's good.

raycow July 27th, 2013 07:13 PM

Re: Problem with clutch disengaging
 
Are you saying that this "fluid damper valve" is a separate external component which is installed in the line between the master cylinder and slave cylinder? If yes, I don't have one and I have never heard of such a thing before now.

Ray

David R Leifheit July 27th, 2013 08:58 PM

Re: Problem with clutch disengaging
 
Quote:

Originally Posted by Clarke (Post 49538)
Update:

I believe it's a hydraulic issue... When reviewing the service manual, appears I'm supposed to have a "fluid damper valve" installed between the slave cylinder and clutch line (1500 Series with SM420)? Does anyone else have this on their truck? Is it possible this can be the issue, or add to it?

Just curious, what service manual are you using?
You should have the X-6223 manual.
1000-5000 series trucks.

http://www.oeltd.net/doc/GMC_Manuals...6223-5-299.jpg
through
http://www.oeltd.net/doc/GMC_Manuals...6223-5-309.jpg
Are scans of the clutch section of the manual.
Or you can just go here:
http://www.oeltd.net/doc/GMC_Manuals/X-6223/
To see which sections I already scanned in out of the manual.

Each scan is numbered by the manual-section-page

http://www.oeltd.net/doc/manual.htm
The manuals list, ones I own and as well as an overview of all the manuals for the 60-66 trucks. Any that I have scanned in any pages for will have a link. For clarity purposes, any manuals listed in italics are ones I do _not_ own but have found referenced in other manuals or have seen for sale.

Clarke July 28th, 2013 02:49 AM

Re: Problem with clutch disengaging
 
1 Attachment(s)
Yes, I'm using X-6223; the fluid damper valve is noted in Section 5, Page 302. It is also noted on Page 301. I'm curious to know if anyone has this installed on their truck...

David R Leifheit July 28th, 2013 04:57 AM

Re: Problem with clutch disengaging
 
Quote:

Originally Posted by Clarke (Post 49546)
Yes, I'm using X-6223; the fluid damper valve is noted in Section 5, Page 302. It is also noted on Page 301. I'm curious to know if anyone has this installed on their truck...

Now I am going to have to go and crawl under my trucks. I have never noticed this before, and I have changed the transmission on my '61 and have pulled and put back in the trans/clutch lines on a couple others.

I don't think I have seen this valve... or even knew it was a valve.

After all these years and I still learn something...

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.

Ray

Clarke October 15th, 2013 04:27 AM

Re: Problem with clutch disengaging
 
Update:

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
 
Quote:

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
 
Ahhh....
Success at last.

Clarke December 9th, 2013 04:02 AM

Vintage Camper
 
Quote:

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.

Clarke December 10th, 2013 03:43 AM

Re: Problem with clutch disengaging - 12" Clutch Kit Photos
 
9 Attachment(s)
Quote:

Originally Posted by Clarke (Post 51425)
I took several pictures of the clutch kit and will post them soon.

Photos of the 12" clutch kit I installed...

Jim A May 15th, 2020 04:50 PM

Re: Problem with clutch disengaging
 
I wonder if this whole discussion is still open.
I have had a problem with failure to completely disengage for years and have tried everything.
If there is anyone reading this, let me know so I can pose specific questions.
1960 3/4 4 spd, 2 wheel drive. Purchased 50 years ago, runs good.

Funky61 May 16th, 2020 02:24 AM

Re: Problem with clutch disengaging
 
Go ahead and ask Jim, I'm sure someone will respond.

Clarke May 16th, 2020 04:35 AM

Re: Problem with clutch disengaging
 
Quote:

Originally Posted by Jim A (Post 72536)
I wonder if this whole discussion is still open.
I have had a problem with failure to completely disengage for years and have tried everything.
If there is anyone reading this, let me know so I can pose specific questions.
1960 3/4 4 spd, 2 wheel drive. Purchased 50 years ago, runs good.

Hello...

Mine was related to a weak pressure plate. I proved it by adding washers as shims between the pressure plate and flywheel, then it disengaged.

Anyway, ended up upgrading all clutch components from 11Ē to 12Ē and all has been good. Since then Iíve driven about 12K miles with no issues. Most of those miles was hauling a load.

Jim A May 16th, 2020 05:02 PM

Re: Problem with clutch disengaging
 
I replaced the clutch assembly sometime in the last century, probably in the '80's. It worked fine for years.
The current problem would seem to be one of adjustment, where I have never been able to get full release without what I assume is constant wear on the throwout bearing.
I have recently put in an new master cylinder with an eye to small leaks in both the clutch and brake systems. It did not seem to improve the clutch drag, which of course is most notable in granny and reverse.
I use the truck so seldom now that I really don't want to pull the tranny. The release is not a problem while moving, but the TO bearing is.
I have the release rod in the middle (second) hole without a "wedge." Are either of those a possible cause?
Thanks for ideas.

Funky61 May 16th, 2020 05:25 PM

Re: Problem with clutch disengaging
 
3 Attachment(s)
I hope this might help you.

Clarke May 17th, 2020 02:16 AM

Re: Problem with clutch disengaging
 
I also have mine set up in the middle hole with the recommended slack.

With my old pressure plate I had to adjust the rod tight, which caused the throw out bearing to spin all the time. Thatís when I added washers to shim the pressure plate out, but that didnít fix it. I was just trying to get by a little longer to allow for more garage time.

So I pulled the tranny and upgraded to the 12Ē clutch assy.

Clarke May 17th, 2020 02:29 AM

Re: Problem with clutch disengaging
 
I forgot to mention the previous owner had replaced the clutch assy only a few years before I purchased the truck from him, but he didnít drive it much and at the time I had only driven it 5K Miles. Therefore, pressure plate didnít last long.

The pressure plate I removed had lots of fingers; whereas, the new one I installed only has three.

Jim A September 17th, 2021 11:29 PM

Re: Problem with clutch disengaging
 
After taking up all the slack on the throw-out rod (and then some), things worked fine for the next several trips. I knew this set-up would finish off the throw-out sooner or later.
This week hauling hay, it disengaged fine with no complaints even in granny and reverse.
Then it quit disengaging almost completely. requiring killing the engine and starting in gear with up shifts really difficult, but worked to get home and hay in barn.
I think the pressure plate or disc has failed but will have to pull to find out.
Since I haven't pulled the tranny for 30 years or more and lost my manuals since then, I could use some help with the steps of the procedure to pave my way.
A link to directions or ideas from personal experience both would be useful.
Thanks

Jim A October 2nd, 2021 05:43 PM

Re: Problem with clutch disengaging
 
This is turning out poorly so far.
Upon pulling the clutch I think I found the problem of failure to release was the grinding off of the finger tips!
I am not sure how thick they were where they engage the throw-out bearing, but it looks like 1/8" plus is gone. Of course every bit of loss reduced the amount of disengagement.
This wear had to come from the throw-out bearing face, but it shows no damage and the bearing itself works as it should.
The flywheel and pressure plate surfaces look new.
So I am temporarily stumped and not sure of the main problem.
Kits are not available, custom rebuilds expensive, correct t/o's hard to find.
If there are replacement fingers available, I would try that route.
Any ideas are welcome/

Jim A October 3rd, 2021 01:29 AM

Re: Problem with clutch disengaging
 
Just talking to myself here.
Even though the throw-out bearing turns freely and quietly under testing (standing on it and spinning), the only thing that could have caused the release fingers and the big lever to have worn where they did as a much as they did was if the bearing froze for an extended time.
If I can find three new fingers and a correct t/o bearing, I will have hope for a fix.

Funky61 October 3rd, 2021 02:21 AM

Re: Problem with clutch disengaging
 
Jim, have checked this page for part numbers

http://6066gmcguy.com/partnumbers.html

or even PM Lewis Matkin as heís the parts number Guru

Jim A October 15th, 2021 05:44 PM

Re: Problem with clutch disengaging
 
I am having no luck finding the three release levers (fingers) that I think will put my '60 1500 back on the road and pasture.
They carry the number C-4B-200-F; the B could be an 8.
They have two holes for pivots at .475 diameter, with a weird plug in the outer one.
I am hoping someone has a pile of (or even one) pressure plates with good levers.
I don't need the plate and the levers would be easier to ship.
Thanks

Funky61 October 15th, 2021 07:12 PM

Re: Problem with clutch disengaging
 
Is this the part with the fingers you are looking for?

https://www.ebay.com/itm/11504617354...EAAOSwwMZhXywc

Jim A November 22nd, 2021 05:17 PM

Re: Problem with clutch disengaging
 
I think the control shaft broke at the clutch pedal years ago and was carelessly welded back in the wrong position relative to the adjusting rod clamp.
A modification seems to allow both free play at the t/o bearing and proper disc release.
Details on request.


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