70 c10 clutch adjustment question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

1970C10truck · 08-13-2010, 03:40 PM

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** · 08-13-2010, 06:15 PM

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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

gregg72340 · 08-15-2010, 09:41 PM

Quote:

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** · 08-15-2010, 10:13 PM

Quote:

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 · 08-16-2010, 10:36 PM

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

red71cheyenne · 08-16-2010, 10:59 PM

Quote:

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 · 08-14-2010, 11:46 PM

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 · 08-15-2010, 10:41 AM

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 · 08-15-2010, 02:12 PM

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 · 08-15-2010, 03:14 PM

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.

1970C10truck · 08-16-2010, 10:58 PM

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

1970C10truck · 08-17-2010, 07:24 PM

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

Jacfourteen · 08-17-2010, 07:42 PM

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 · 08-18-2010, 08:49 AM

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 · 08-19-2010, 11:08 PM

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 · 08-20-2010, 07:13 PM

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 · 01-30-2011, 06:22 PM

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** · 01-30-2011, 11:11 PM

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

LockDoc

Jacfourteen · 01-31-2011, 03:59 AM

Quote:

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.

bonestock70 · 01-31-2011, 01:11 AM

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

rsavage · 01-31-2011, 07:28 AM

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 · 02-01-2011, 12:54 AM

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 · 02-01-2011, 07:37 AM

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

bonestock70 · 02-03-2011, 12:56 AM

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 · 02-03-2011, 02:44 PM

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.

08-13-2010, 03:40 PM	#1
1970C10truck Registered User Join Date: Aug 2010 Location: Redding California Posts: 72	70 c10 clutch adjustment question 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.

08-13-2010, 06:15 PM	#2
LockDoc The Older Generation Join Date: Aug 2006 Location: Montezuma, Iowa Posts: 25,896	Re: 70 c10 clutch adjustment question - 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 __________________ Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 -

08-16-2010, 10:36 PM	#5
68K30 Registered User Join Date: May 2007 Location: Pennsylvania Posts: 99	Re: 70 c10 clutch adjustment question 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

08-14-2010, 11:46 PM	#7
1970C10truck Registered User Join Date: Aug 2010 Location: Redding California Posts: 72	Re: 70 c10 clutch adjustment question 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. __________________ 1970 C10 swb 350 4spd under construction

08-15-2010, 10:41 AM	#8
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: 70 c10 clutch adjustment question 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.

08-15-2010, 02:12 PM	#9
1970C10truck Registered User Join Date: Aug 2010 Location: Redding California Posts: 72	Re: 70 c10 clutch adjustment question 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. __________________ 1970 C10 swb 350 4spd under construction

08-15-2010, 03:14 PM	#10
68gmsee Active Member Join Date: Jul 2007 Location: Centrally located between Houston, Austin and Waco. BCS area. Posts: 7,947	Re: 70 c10 clutch adjustment question 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.

08-16-2010, 10:58 PM	#11
1970C10truck Registered User Join Date: Aug 2010 Location: Redding California Posts: 72	Re: 70 c10 clutch adjustment question 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 __________________ 1970 C10 swb 350 4spd under construction

08-17-2010, 07:24 PM	#12
1970C10truck Registered User Join Date: Aug 2010 Location: Redding California Posts: 72	Re: 70 c10 clutch adjustment question I don't know about the rod but that Sounds exactly like what mine is doing. __________________ 1970 C10 swb 350 4spd under construction

08-17-2010, 07:42 PM	#13
Jacfourteen Big Red - Now its a SWB! Join Date: Jun 2009 Location: Oroville, Ca Posts: 1,624	Re: 70 c10 clutch adjustment question 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. __________________ 68 3/4 ton (Project)-350 Small Block, .030 over, 10:1 comp, 3998993 heads, C3BX edelbrock intake, comp cams XE268, Holley 670 SA, long tube headers, dual flow 40's, E-fan, Alum rad, currently under the knife getting shortened and bagged build thread 41 3/4 ton (wife's)-flatbed, fully restored to original 01 Tahoe LT 4WD (my daily driver)-Magnaflow Muffler, Rollin on 22's 02 Ford Mustang Convertable (Wife's Car)-Flowmaster 50, Clear corners, Intake, sittin on 18's Last edited by Jacfourteen; 08-17-2010 at 07:45 PM.

08-18-2010, 08:49 AM	#14
1970C10truck Registered User Join Date: Aug 2010 Location: Redding California Posts: 72	Re: 70 c10 clutch adjustment question 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. __________________ 1970 C10 swb 350 4spd under construction

08-19-2010, 11:08 PM	#15
red71cheyenne Back in the sticks Join Date: Jan 2001 Location: Fordland, MO Posts: 3,188	Re: 70 c10 clutch adjustment question 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: Attached Images __________________ 1971 Cheyenne C-10 w/700R4 and Tuned Port Injection 1969 K5 Blazer w/Tuned Port 2010 2SS/RS Flaming Orange Camaro 2011 K1500 Suburban 2014 K1500 Pickup 2008 Nissan Altima? The wifes' hoopty

08-20-2010, 07:13 PM	#16
1970C10truck Registered User Join Date: Aug 2010 Location: Redding California Posts: 72	Re: 70 c10 clutch adjustment question 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. __________________ 1970 C10 swb 350 4spd under construction

01-30-2011, 06:22 PM	#17
bonestock70 Registered User Join Date: Sep 2010 Location: Yorba Linda, ca Posts: 9	Re: 70 c10 clutch adjustment question 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.

01-30-2011, 11:11 PM	#18
LockDoc The Older Generation Join Date: Aug 2006 Location: Montezuma, Iowa Posts: 25,896	Re: 70 c10 clutch adjustment question - Maybe the wrong throwout bearing for the pressure plate you have? There is a long and a short. LockDoc __________________ Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 -



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01-31-2011, 01:11 AM	#20
bonestock70 Registered User Join Date: Sep 2010 Location: Yorba Linda, ca Posts: 9	Re: 70 c10 clutch adjustment question 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

01-31-2011, 07:28 AM	#21
rsavage Registered User Join Date: Aug 2009 Location: Alden NY Posts: 2,705	Re: 70 c10 clutch adjustment question 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. __________________ 1961 C1 Corvette 1959 El Camino 350 TPI, 9" 4 w disc 69 Blazer K5 - sold July '20 2021 Durango RT 5.7 Last edited by rsavage; 01-31-2011 at 07:30 AM.

02-01-2011, 12:54 AM	#22
bonestock70 Registered User Join Date: Sep 2010 Location: Yorba Linda, ca Posts: 9	Re: 70 c10 clutch adjustment question 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...

02-01-2011, 07:37 AM	#23
rsavage Registered User Join Date: Aug 2009 Location: Alden NY Posts: 2,705	Re: 70 c10 clutch adjustment question Just two additional thoughts - you don't have the throw out bearing in backwards do you? Is the clutch fork cracked/bent? __________________ 1961 C1 Corvette 1959 El Camino 350 TPI, 9" 4 w disc 69 Blazer K5 - sold July '20 2021 Durango RT 5.7

02-03-2011, 12:56 AM	#24
bonestock70 Registered User Join Date: Sep 2010 Location: Yorba Linda, ca Posts: 9	Re: 70 c10 clutch adjustment question 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. Attached Images

02-03-2011, 02:44 PM	#25
heyjoe Registered User Join Date: Apr 2003 Location: New Orleans area Posts: 198	Re: 70 c10 clutch adjustment question 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. Attached Images __________________ '67 C20 small window Fleetside - 250 inline 6 - 3 on the tree - heavy duty clutch, brakes, rear springs - 17.5 wheels w/bias ply tires - AM radio - heater.

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