The Stovebolt Site Forums The Shop Area Engine Shop How do I adjust my clutch?

Hi guys, I have a manual but it isn't to clear on how to properly adjust my cluth. I can put it into gear but can't pull it out without rocking the truck. I have a '46 GMC 2 1/2 ton (canuck) it hasn't ran it 20 years but does now and I want to be able to drive it in and out of the shop, oh it is a 4 speed also. Any help would be appreciated, thanks.

Scott :confused:

Hy 46GMCanuck Can you put the truck into gear with the engine running and the clutch pedal depressed? Your adjustment is accomplished by loosening the two nuts which hold a threaded rod in place on the transmission throughout arm, you should soak the threaded portion with the penetrating oil of your choice before you start. Do you have any freeplay in the clutch pedal, does the pedal feel like its pushing on something immediately or does it move a bit before it starts to do something? If it does start to do some thing immediately it needs adjustment if it doesn't it doesn't {does that make sence} The other thing that might be happening is the clutch disc may be stuck to the flywheel, so you can't really disconnect it by depressing the clutch pedal. In your manual it will give you a spec. on how much freeplay the pedal should have. You should also have a return spring on your clutch linkage, trucks that old sometimes the springs rust and break.

hey 3B, the manual states one inch freeplay by hand not foot, i believe the spring is still there. Now I'm not sure if I feel it doing anything or not, how stiff should it be and if the clutch plate is stuck to the flywheel how do I fix that without wrecking anything; or having to take the thing apart.

'46,

Maybe I don't understand your post. If the engine is running, can you put the transmission in gear.....without grinding. I am not sure if the '46 has a "crash" box or synchros. If you can run the rig, depress the clutch and put it in gear, without grinding, you should be able to pull it back out of gear. Is there some part of this tale that's missing? If the clutch were stuck to the flywheel, you would never get it into gear..running!

Stuart

Hy 46GMCanuck, Stuart is right,we need to know can you put the truck into gear with the engine running?

Stuart,

I believe the 46 should have a crash-box.

Eric,

I'm not even sure I know what a crash box is. Is it a old style straight cut, no synchro transmission? Does it have to be double clutched when shifted.

I had a '38 Chevrolet car, with a "top loader" three speed, and I would swear it didn't need to be double clutched.


Stuart

Hi guys, sorry for the delay when I run the truck i cannot put it into gear it just grinds. A fellow not to far from me has the same truck and he needs to double cluth so the the assumption would be that I would need to as well. I adjusted the clutch as much as I can and I still can't put it into gear, there is a lot of racket coming from the bell housing, the pressure plate springs? or release bearing? Do I need a new clutch?

Scott

Scott,

It sounds like you need something. If you can crawl under the truck with a trouble light, I think you can take the gravel guard off the bottom of the bellhousing. You can actually look up into the clutch/flywheel area and should be able to asses disc wear and turn the throw out bearing by hand (if adjusted properly).

It's sort of like open heart surgery. Your diagnosis doesn't sound promising, but adjusting a clutch can sometimes be confusing. The bottom line is, if adjusted properly, you should be able to put the rig in gear with a minimum of
clashing. Crawl and take a peek!

Stuart

Thanks Stuart I'll definately remove that plate and have a look I'll even adjust the clutch the other way just to see if I have things basackwards.

Scott

Hy 46GMCanuck, If you adjusted the clutch and removed the freeplay the throughout bearing will be forced to turn all the time, I hope that is the noise that you are hearing now. That throughout bearing is probably worn who knows how old it might be. By your description I would say the clutch disc is stuck to the flywheel, try this trick to unstick it, with the engine off put the truck into either 1st or reverse depending on which direction has more space to allow the truck to move, now depress the clutch pedal and try to start the engine, if the engine starts without the clamping force of the pressure plate it might break the disc free BE CAREFUL MAKE SURE YOU HAVE SPACE AROUND THE TRUCK BEFORE YOU TRY THIS!!! you may have to repeat this trick a couple of times for it to succeed.

Hi guys, I crawled under the truck and removed the clutch inspection cover; what a freakin mess. I never realized all the different places mice will call home, the disc was definately stuck to the flywheel and very rusty, some springs loose and some tight. The release bearing almost seized and very rough to turn and twenty odd years of muck. So I put it into first gear started it up and all hell broke loose, no brakes and a brick wall in front of me, to make a long story short the cluth is NG. I hope I wasn't being rash but I removed the tranny and dropped the cluth and ordered a new release brg, disc, pressure plate and pilot brg.

Scott,

I hope you cleared all this with the mice first.

Don't forget to appraise the condition of the flywheel itself. Nothing tops off a clutch job like a freshly surfaced flywheel.


Stuart

Hi Stuart, I inspected the flywheel and there is no visible cracks or heat checking. Is there anything else I should be looking for?

Scott,

If there are no grooves worn in it, and as you noted, no cracks or checking, it is probably fine. I always felt as long as you were into the middle of the beast, why not go a little more and make sure the flywheel was dead flat and had a nice new "tooth" to it. It's a personal preference...your doing it right!

Stuart

Right on thats good to know, if I were to get the flywheel mackined would it have a surface really any different than what it is now, also I should put a staright edge across it and see maybe if it is warped?

Scott