The case of the mysterious clutch. (71 C10)

[jowwel]

Hi All,

This is my first post here. I recently bought a 71 C10 and just love it. I'm new to working with trucks, but I'm pretty well mechanically inclined and I want to do as much of my own work as possible. That said, I'd like to tell you all about my problem and get some feedback.

In a nutshell, I think my clutch is going bad. Here is why.

Basically, the clutch pedal has back pressure and feels like it's operating normally, but when I push the pedal down, the clutch itself is not engaging.

If I turn the engine off, I can put it into whatever gear I want. When the engine is running, I can only put it into reverse or neutral (from whatever gear I had it in).

So I guess that firstly, I'd like some confirmation that my clutch is going bad (or other suggestions) and secondly, a little help on what I'd need to do to get to the clutch to work on it/replace it if it is going bad. Thanks!

Other things to note:
- The guy who had it before me put in a 3 speed transmission with a hearst shifter and linkage.
- I have a 1 ton hoist to pull the engine if I need to.

[MARKDTN]

I would adjust the clutch before I assume it is bad. Sounds to me it could be a clutch linkage issue.

[LockDoc]

-
I guess the first thing I would do is to check the adjustment. There is an adjustable rod that goes from the clutch linkage cross shaft to the clutch fork. The end that connects to the pivot is threaded and is the adjustment for the clutch. Lengthen the rod and see if that helps. Don't get carried away with it, just go 2 or 3 turns at a time and try it.

Also check the linkage under the dash. The splined shaft that rotates as the pedal is pushed could be stripped and letting the arm slip. It would move the linkage but not far enough to really do anything.

LockDoc

[68gmsee]

First check the above carefully and then remove the bottom dust shield so you can observe the action from under the truck. Be sure and use parking brake and chock the truck tires.

Depressing the pedal forces the throwout bearing into the pressure plate fingers and releases or dis-engages the clutch disc. If this is not happening then more than like the pressure plate is bad or clutch disc is badly worn.

If you do find you have to replace parts be sure and get both the disc and pressure plate asm and have the flywheel turned. Also be aware that new parts from local auto parts are not what they used to be and may be new defective. If you can afford it, buy from a reputable parts place that hopefully has parts made in the U.S.

One more thing, make sure all of the shift linkage bushings are in place and not worn.

[Shyguy]

I too think it is a linkage adjustment problem. Changing the clutch on a truck with a 3 speed is not real complicated and does not require removing then engine.

It is not a two person job, but a second set of hands helps. A transmission jack is helpful but not necessary.

I normally buy a clutch kit when I replace a clutch, they are not real expensive and includes every thing you need, matched. I also check the pilot bearing in the end of the crank shaft, most times I just go ahead and change it since it is part of the kit.

[jowwel]

So the end that I should adjust is the end connected to the "Cross shaft", or down at the other end?

[jowwel]

Originally Posted by 68gmsee

First check the above carefully and then remove the bottom dust shield so you can observe the action from under the truck. Be sure and use parking brake and chock the truck tires.

Depressing the pedal forces the throwout bearing into the pressure plate fingers and releases or dis-engages the clutch disc. If this is not happening then more than like the pressure plate is bad or clutch disc is badly worn.

If you do find you have to replace parts be sure and get both the disc and pressure plate asm and have the flywheel turned. Also be aware that new parts from local auto parts are not what they used to be and may be new defective. If you can afford it, buy from a reputable parts place that hopefully has parts made in the U.S.

One more thing, make sure all of the shift linkage bushings are in place and not worn.

Thanks, if I had to replace the clutch, I was going to get all my parts from LMC Truck catalog. Is that a good reputable source?

[webfoot]

You can see a nut on the end of the "clutch rod", in the pic, the part sticking out beyond that is threaded and this is the adjustment.

[jowwel]

Originally Posted by webfoot

You can see a nut on the end of the "clutch rod", in the pic, the part sticking out beyond that is threaded and this is the adjustment.

Thanks a lot. I'm excited to go try it out.

On a side note, thanks for all of the help. I'll be hanging out here quite a bit I think. Cheers!

[RenoKeene]

Welcome from Central Florida! I see you have already figured out that this forum rocks. I am an automatic kinda guy so I'll leave the manual advice to the experts, I just wanna see a picture of your truck.

[lil hoodlum]

Originally Posted by jowwel

Thanks, if I had to replace the clutch, I was going to get all my parts from LMC Truck catalog. Is that a good reputable source?

No need to pay for shipping! Just about any auto parts store should be able to get what you need. Last time I replaced mine I got it from O'rielys.

Welcome from North Texas.

Keith

[LockDoc]

Originally Posted by jowwel

So the end that I should adjust is the end connected to the "Cross shaft", or down at the other end?

The adjustment is where the arrow is pointing that says "Clutch Rod" Just remember it is easy to go too far with it....

LockDoc

[68gmsee]

re. LMC: I've bought stuff from them before and overall I wasn't dissatisfied. However, it was not major components. Some parts providers try to get the cheapest they can so they have them imported from Taiwan or China. I haven't done a clutch in a long time so I don't know for sure the best place to get one. These days, it seems sort of a crap shoot.

Re. buying from local auto parts: Many years ago I bought a new pressure plate from a local auto parts and it wouldn't release the clutch properly. It was a pain because you don't know how it works until you install it. I didn't want to take the chance on redoing it so I got my money back and got one from NAPA. Not sure if NAPA's quality is still the same though.

Forgot to say welcome... Welcome from semi central Texas.

[PAWS 72]

Welcome to the board. DO NOT buy the assembly from LMC.Go to your local car quest or napa parts store to get it.No need of getting it from them it will take to long to ship it

[jowwel]

Update:

I tried to adjust the linkage to no avail. I threaded it down about a half an inch and nothing changed at all. That said, it's still got more space to get shortened up. But considering that this issue just abruptly started happening and nothing has changed in the half in of shortening that I've already done, would you guys think that I would be wasting my time to go under and tighten some more?

Also, unrelated to this, after I had fired it up to test the clutch and then turned it off again, I noticed that antifreeze was literally streaming out of the engine. It seemed to be coming from an area directly behind the fan. It pissed antifreeze for a good 30 seconds after I shut it down until it slowed to a trickle and eventurally stopped. Any thoughts?

[jowwel]

Originally Posted by LockDoc

The adjustment is where the arrow is pointing that says "Clutch Rod" Just remember it is easy to go too far with it....

LockDoc

Considering my latest update, do you think that I should keep going farther or do I have a bigger problem on my hands? I don't want to go to far like you warned.

[GASoline71]

Get a service manual... it will show you exactly how to do the job.

Gary

[Shyguy]

The anti-freeze coming out sounds like the water pump shaft seal.

If you are not sure of the clutch and are going to keep and drive the truck quite a bit it is not that hard or expensive to change out the clutch. I think the last kit I bought from a local parts store was right at $150. Like I said in a previous post it is best to get a kit, that way every thing is matched.

[68gmsee]

Originally Posted by jowwel

Considering my latest update, do you think that I should keep going farther or do I have a bigger problem on my hands? I don't want to go to far like you warned.

First check the hoses and/or replace the water pump. You won't be going far without that first.

Were you able to do any of the things I mentioned in my first post. If adjustments won't help, you need a pressure plate, clutch, throwout bearing pilot bearing and have the flywheel turned all at the same time or you won't be happy with it. Trust me.

[LockDoc]

Originally Posted by jowwel

Considering my latest update, do you think that I should keep going farther or do I have a bigger problem on my hands? I don't want to go to far like you warned.

First off from what you said in your first post you need to lengthen the rod between your cross shaft and clutch fork, not shorten it. Also 1/2 inch adjustment at a time is WAY too much. Put it back where it was when you started and lengthen it 1/8 inch at a time, AND NO MORE. Then try it.

LockDoc

[jowwel]

So, an update for everyone. I finally got around to pulling out the clutch. I tried shortening the linkage, to no avail.

The good news is that I found the problem. Two fold really, one, the throwout bearing just fell out of the thing when I got it out and two, the springs in this picture were just bouncing around in front of the pressure plate.

I have a new clutch already and will be putting it in once I get the flywheel machined down.

Any tips for the process of putting it back in?

[jowwel]

Oh and here is my truck, not the best shot of it, but it's all I got.


And here is me!

http://a6.sphotos.ak.fbcdn.net/hphot...97694780_n.jpg

[mrein3]

Originally Posted by jowwel

Update:

I tried to adjust the linkage to no avail. I threaded it down about a half an inch and nothing changed at all. That said, it's still got more space to get shortened up. But considering that this issue just abruptly started happening and nothing has changed in the half in of shortening that I've already done, would you guys think that I would be wasting my time to go under and tighten some more?

Also, unrelated to this, after I had fired it up to test the clutch and then turned it off again, I noticed that antifreeze was literally streaming out of the engine. It seemed to be coming from an area directly behind the fan. It pissed antifreeze for a good 30 seconds after I shut it down until it slowed to a trickle and eventurally stopped. Any thoughts?

If you're new to older vehicles, and it isn't too late, verify that your antifreeze isn't just peeing out of the "pee" tube. On these old time religion systems the antifreeze was allowed to equalize by just going out a pee tube into the environment. If it doesn't do it a 2nd time, don't worry about it. If the antifreeze continues to leak out you need to find the source.

If you end up determining that it came out of the pee tube, note the level in the radiator when everything is cold. That is the proper level for your system.

[camrycurt]

Originally Posted by jowwel

Any tips for the process of putting it back in?

If you get some good tips or figure it out on your own, I'd be interested in hearing what you end up doing to get everything back together. I'm not as mechanically inclined as you are and think I'll be needing to replace my clutch soon as well.

[lil hoodlum]

Originally Posted by jowwel

So, an update for everyone. I finally got around to pulling out the clutch. I tried shortening the linkage, to no avail.

Not that it matters much now but you want to legnthen the linkage not make it shorter.

Good luck!

Keith