70 c10 clutch adjustment question

[1970C10truck]

Hi, I'm new to the 67-72 trucks and the manual 4 speed that came in it. My truck is a 1970 C10 with a 350 and sm-465 transmission. I bought this truck about a week ago for a project. I noticed the clutch pedal has to pushed all the way to the floor before it disengages and also seems like it fully engages after the pedal is let up about 1/2-3/4 of an inch. Will an adjustment of the linkage cure this and if so can someone explain how to do it? Or does it sound like it needs a new clutch?

Also the clutch pedal almost never returns back up all the way on its own. It seems to hang up a little bit before it gets to the stop. Thanks in advance for the help.

[LockDoc]

-
There is an adjustment rod between the clutch arm on the bellhousing and the pivot on the frame. Lengthen this rod with the adjustment nuts on the front of the rod. Go a little bit at a time and try it.

LockDoc

[1970C10truck]

Thanks for the reply I was hoping you were going to suggest the opposite. My rod looks like it doesn't have much adjustment left in it. I have been a little nervous to do any experimenting after talking with my brother. I don't know if it was coincidence or not but he adjusted the one on his old truck and the next day his clutch had a major come apart. I think I see TH-400 in my near future.

[68gmsee]

Worn clutch or weak pressure plate can cause the problem you describe. As the clutch wears down it takes more pedal to disengage.

The problem with adjusting the rod too far is that it forces the throwout bearing to put more pressure on the pressure plate spring fingers and eventually the problem gets worse.

The clutch return problem may be a weak spring or it could be the sliding surface of the throwout bearing retainer needing lubrication. It could also have a wear spot preventing the bearing from sliding smoothly.

[1970C10truck]

There Probably isn't a way to look at the throw out bearing with out pulling the trans is there? The truck is a project that I want to be able to drive while under construction if I really want too. I guess I should invest a decent lower price clutch to get by with for now and hopefully that will make me start wanting a to find an automatic for it.

I'm still in the planning phase and don't really know what I want to do with it yet. The one thing I do know is the sm465 doesn't really match my possible out comes. Is there a good 4 or 5 speed that can be easily and inexpensivly swapped in? I have a feeling I'm going to be eventually be changing the motor out for a 450-500 HP small block.

[68gmsee]

I'm not sure if you can get a good look in there by removing the dust cover on the bottom of the bell housing but you can check.

Not sure which trans would be your best one for your project. You may get a better answer in the engine and driveline forum.

[gregg72340]

Originally Posted by LockDoc

-
There is an adjustment rod between the clutch arm on the bellhousing and the pivot on the frame. Lengthen this rod with the adjustment nuts on the front of the rod. Go a little bit at a time and try it.

LockDoc

Im having the same type of problem, which way do you adjust the clutch rod, towards the front or the back of the truck? y clutch releases about two inches into the pedal push and doesnt engage until the pedal is relased almost all the way out, does it sound to anyone like mine may be shot as well?

[jamie72]

Originally Posted by gregg72340

Im having the same type of problem, which way do you adjust the clutch rod, towards the front or the back of the truck? y clutch releases about two inches into the pedal push and doesnt engage until the pedal is relased almost all the way out, does it sound to anyone like mine may be shot as well?

mine is just like that,but its a 3sp... so i need to know as well...

[68K30]

If the linkage is all good and the engine mounts are in good shape there should be about 1" of free play at the top of the travel, which translates to 1" of pedal travel without the throw-out bearing moving the pressure plate fingers. The reason for checking the engine mounts is the inner end of the Z-bar [bellcrank] is attached to the engine. If you get 1" of free play and the clutch takes hold in the upper third of it's travel the clutch is nearing the end of it's useful life; a new, properly adjusted stock type clutch will take hold [start moving the truck] in the lower third of the travel up from the floor.

Hope this helps
Bill

[1970C10truck]

I pretty much figured with my luck that the clutch is probably wasted. Can anyone recommend a decent replacement that isn't going to totally break the bank. At this point it is Probably going to be kept for a temporary long term solution until I can come up with an automatic. My last truck was only driven about 200 miles in 3 years so its not like I need something for a hard used daily driver. Also checking out clutch kits I noticed there are several sizes available from 10 to 12 inch. What's the easiest way to determine the size I need? Sorry to sound so dumb but this whole manual transmission thing is all new to me

[red71cheyenne]

Originally Posted by 68K30

If the linkage is all good and the engine mounts are in good shape there should be about 1" of free play at the top of the travel, which translates to 1" of pedal travel without the throw-out bearing moving the pressure plate fingers. The reason for checking the engine mounts is the inner end of the Z-bar [bellcrank] is attached to the engine. If you get 1" of free play and the clutch takes hold in the upper third of it's travel the clutch is nearing the end of it's useful life; a new, properly adjusted stock type clutch will take hold [start moving the truck] in the lower third of the travel up from the floor.

Hope this helps
Bill

Is there a different push rod(the part you can adjust) for three speed and four speed? When I went to the 4 speed, I noticed that my pedal play is like the OP's. This is with all new mounts, clutch, throw out bearing everything. I have to have the pedal to the floor and it takes hold about a half inch or just a little more once I start letting it out.

[1970C10truck]

I don't know about the rod but that Sounds exactly like what mine is doing.

[Jacfourteen]

The easiest way to tell if the rod is adjusted right is to have the pedal all the way up then step on it and see how far it moves before you feel resistance, like stated above it should be about 1" or so. If you have more than 1" then you need to loosen the nuts which will in effect make the rod longer, if you have less than 1" then you need to tighten the nuts which will make the rod shorter. Make sure to lock the nuts after any adjustments by turning them towards each other so they won't vibrate and change the adjustment. If you have the correct amount of freeplay and the clutch still isn't working right then you probably have bigger issues like a worn clutch disk or weak pressure plate. If you are interested in the shape of your clutch disk you can pull the dust sheild/inspection plate at the bottom of the bell housing and look inbetween the flywheel and the pressure plate and see how much material is left, some have grooves in the friction disks and when the grooves are gone that means that they are about worn out (kind of like tires). Hope all this makes sense, if you have any questions let me know.

[1970C10truck]

Jacfourteen thanks clarification on that I think I can figure it out now. I just haven't had a chance too look at it yet. Hows Oroville doing? Last time I was there we had all the streets tore up and made everyone pretty mad at us.

[red71cheyenne]

So, how far from the floor should the clutch take hold? I just don't know if I have enough rod left to move it very far from the floor. Right now, I'd say the clutch engages about 1/2 inch from the floor. Here is where my rod is at:

[1970C10truck]

That looks right about the same as mine and having the same problem. I haven't had a chance to pull the dust shield and inspect it yet. I would be curious to see what you find because I think we are both in the same boat.

[bonestock70]

I know this is an old post, but I wanted to revive it to find out what the root cause was for these problems. I just completed an engine and tranny rebuild and put a new clutch in also. When reattaching the clutch pedal yesterday, the pedal went all the way to the floor before encountering any type of resistance. I reviewed old pictures and everything seems to be connected up properly. I am wondering if I got the wrong pressure plate or something. Definitely don't want to pull the tranny unnecessarily.

Anyone know what to look for? Did I forget to pull out a keeper in the clutch or something?

Thanks for all the info in previous posts.

[LockDoc]

-
Maybe the wrong throwout bearing for the pressure plate you have? There is a long and a short.

LockDoc

[bonestock70]

Doc,

Thanks for the info. I will take some pics and compare the TO bearings. I didn't know there were two different units and trusting this to the Autozone experts may have been too much. Either way it sounds like I will have to pull the tranny out. I try to post some pics if I get that far this week.

Regards

[Jacfourteen]

Originally Posted by LockDoc

-
Maybe the wrong throwout bearing for the pressure plate you have? There is a long and a short.

LockDoc

That was the first thing that came to my mind too.

[rsavage]

Often times, the #3 push rod nut is missing which shortens the length beyond adjustment range. Is yours still there?
See page 124 of the LMC catalog "clutch linkage" section.

[bonestock70]

Thanks again guys. I just found the old TO bearing and it looks like a "short" one. Overall length measures 1.283'' using my trusty $16 Harbor Freight calipers. Now I am stumped as to what this could be. Same motor, tranny and bellhousing back in the same truck and it doesn't fit. Maybe a wrong pressure plate? The only things that were changed are the pressure plate and TO bearing and it doesn't appear to be the bearing.

More research necessary...

[rsavage]

Just two additional thoughts - you don't have the throw out bearing in backwards do you? Is the clutch fork cracked/bent?

[bonestock70]

I crawled under and checked the TO bearing and it is in properly. Also the clutch fork worked fine before it was removed and didn't suffer any catastrophic injuries while it was out. I am gonna try to post a pic, but don't know if it will help at all, just show the pressure plate. I did check the bearing with an inspection mirror, hard to get a picture of.

[heyjoe]

Was the pressure plate you took out a Borg & Beck or a Diaphragm? Did you swap the same for the same?
Like LockDoc already said, one takes the long T/O bearing and the other takes the short.