78C20Reaper
Registered Member
Would I check it just by trying to shake it? Or is there a different way? I did mess with the springs and they are still springy but I dont think they were stout enough in my opinion.
CK5
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Clutch problems
- Thread starter 78C20Reaper
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78C20Reaper
Registered Member
Is there a way to tell if I have a 11 or 12 inch clutch setup without taking it out and measuring? This is my daily so the less downtime it has the better off I am I just dont want to be stuck truckless for a week or however long itll take to get a new clutch kit in and installed
I would think that you have the 12" being in a truck, and also being a 3/4 ton. But check the starter mounting bolts, if they are diagonal, that would mean the large flywheel. The should be the larger clutch. But I can't say that I am a 100% expert on these.
78C20Reaper
Registered Member
What's the difference between the raised and the flat style diaphragm other than the obvious? Why is there so many options to just get a clutch kit? 11 or 12 then raised or flat plus HD or "race" or DD and then clutch material too. Why cant parts stores websites just say "hey this is what you need for your application"
It's been 25 years since I had a manual trans in a K5,but when I converted mine from a TH350 to a SM465,I got the complete setup off another '72 K5 a guy had he totaled,from the flywheel back..
I put a 12" clutch setup in it ,it had an 11" originally,and wished I had just used the old clutch,this was the truck I had three of the 3 finger pressure plates fail in short order (Borg-Warner rebuilt ones that sucked)--I ended up using a used Centerforce 11" diaphragm type clutch in it I found for $30 like new,used,from a swap meet..
The flywheel accepts both 11" and 12" far as I know,the bolt patterns are the same,the bell housing I think is larger for trucks though with 12" clutches,some of the 11" bell housings wont fit a 12" clutch setup..---the starter in that truck had the diagonal bolt pattern--only a few old 307's and 283's,and straight sixes used the "straight across" bolt pattern starter noses,and a 10.5" diameter clutch in some applications,usually three speed manuals in 2wd trucks..
There are a lot of different clutches--disc diameter,number of splines,the flat diaphragm ones are lighter duty,usually used on the engines with 3 speeds I listed above--the throwout bearings are different lengths to compensate for the height difference also..
--you can get a "oem" disc,or a variety of heavy duty or race only discs,the ones with 3 ceramic pucks that look like a fan blade are the most rugged,but they engage harsh,its more like an on-off switch than the ones with full faced linings that you can "ride" without getting clutch chatter..
I hated the 12" 3 finger pressure plates,the pedal effort was very high,it was like pumping a universal gym with your left leg at every shift,and holding the pedal down at a stoplight got tiring fast--when I switched to the Centerforce 11" diaphragm type the pedal effort was so low I thought something was wrong,it was like going to a hydraulic clutch from a mechanical one..
I put a 12" clutch setup in it ,it had an 11" originally,and wished I had just used the old clutch,this was the truck I had three of the 3 finger pressure plates fail in short order (Borg-Warner rebuilt ones that sucked)--I ended up using a used Centerforce 11" diaphragm type clutch in it I found for $30 like new,used,from a swap meet..
The flywheel accepts both 11" and 12" far as I know,the bolt patterns are the same,the bell housing I think is larger for trucks though with 12" clutches,some of the 11" bell housings wont fit a 12" clutch setup..---the starter in that truck had the diagonal bolt pattern--only a few old 307's and 283's,and straight sixes used the "straight across" bolt pattern starter noses,and a 10.5" diameter clutch in some applications,usually three speed manuals in 2wd trucks..
There are a lot of different clutches--disc diameter,number of splines,the flat diaphragm ones are lighter duty,usually used on the engines with 3 speeds I listed above--the throwout bearings are different lengths to compensate for the height difference also..
--you can get a "oem" disc,or a variety of heavy duty or race only discs,the ones with 3 ceramic pucks that look like a fan blade are the most rugged,but they engage harsh,its more like an on-off switch than the ones with full faced linings that you can "ride" without getting clutch chatter..
I hated the 12" 3 finger pressure plates,the pedal effort was very high,it was like pumping a universal gym with your left leg at every shift,and holding the pedal down at a stoplight got tiring fast--when I switched to the Centerforce 11" diaphragm type the pedal effort was so low I thought something was wrong,it was like going to a hydraulic clutch from a mechanical one..
78C20Reaper
Registered Member
Wow that's alot of info, thank you! So that kinda helped my decision I think. If I'm wrong please tell me but i think I'm gonna go with a 12 in HD clutch kit with a raised diaphragm.
Not that you can do much about this atm,
When/if the pilot bearing in the crank gets dry or rusty, this will cause the input shaft to continue to turn no matter condition of clutch or how it's adjusted.
You'll want to inspect it to see if there was an issue, before you replace it.
Also inspect the input shaft nose for rust, gaul, grooves. Hit it with Emery cloth regardless, then light coat of grease before installing trans.
Lots of ways to remove pilot bearing from crank, some easier than others.
If you don't own a good universal clutch alignment tool. You should either rent one form auto auto or similar, you could also source a actual input shaft form a core sm465, best in my opinion.
If you rent, get a pinion bearing puller this is the easiest.
After clutch and flywheel are removed use a little rust penetrate, smack bearing/bushing with brass drift and dead blow, it may not move any, but oil will start to work in between bearing and crank. Then use the puller.
I have successfully filled cavity with heavy grease, and used my alignment tool as plunger with dead blow. The grease will force the bearing out, if the alignment tool is a tight fit in bearing.
When you order your parts get a throw out fork and pivot ball, since is your daily, don't want truck down for these parts.
Light coat of grease on ball, tips of forks, and face of throw out bearing.
Man this getting long, have you ever done a clutch before?
I have more tips but don't know how much detail to provided
When/if the pilot bearing in the crank gets dry or rusty, this will cause the input shaft to continue to turn no matter condition of clutch or how it's adjusted.
You'll want to inspect it to see if there was an issue, before you replace it.
Also inspect the input shaft nose for rust, gaul, grooves. Hit it with Emery cloth regardless, then light coat of grease before installing trans.
Lots of ways to remove pilot bearing from crank, some easier than others.
If you don't own a good universal clutch alignment tool. You should either rent one form auto auto or similar, you could also source a actual input shaft form a core sm465, best in my opinion.
If you rent, get a pinion bearing puller this is the easiest.
After clutch and flywheel are removed use a little rust penetrate, smack bearing/bushing with brass drift and dead blow, it may not move any, but oil will start to work in between bearing and crank. Then use the puller.
I have successfully filled cavity with heavy grease, and used my alignment tool as plunger with dead blow. The grease will force the bearing out, if the alignment tool is a tight fit in bearing.
When you order your parts get a throw out fork and pivot ball, since is your daily, don't want truck down for these parts.
Light coat of grease on ball, tips of forks, and face of throw out bearing.
Man this getting long, have you ever done a clutch before?
I have more tips but don't know how much detail to provided
78C20Reaper
Registered Member
Replaced a clutch on something this old, no. Replaced clutches on fiat spiders (Mazda miata) and HD ram trucks, yes. I've just never messed with a mechanical/manual clutch system before, it's always been hydraulic.
Is all the same, then. You just need to make sure the linkage moves freely.
The z bar mounts to frame and motor has 2 ball studs, remove frame side ball studs, clean and grease z bar pockets, and ball studs.
When you do the initial adjustment, remove the spring/s from clutch fork
And adust rod at fork so there is @⅛"
Movement, by hand, at rod end of fork. This should get you very close. Install springs and give it a go.
You shouldn't need to adust pedal side. Unless it has been messed with.
The z bar mounts to frame and motor has 2 ball studs, remove frame side ball studs, clean and grease z bar pockets, and ball studs.
When you do the initial adjustment, remove the spring/s from clutch fork
And adust rod at fork so there is @⅛"
Movement, by hand, at rod end of fork. This should get you very close. Install springs and give it a go.
You shouldn't need to adust pedal side. Unless it has been messed with.
78C20Reaper
Registered Member
Thanks for the info. I was hopeful it would be roughly the same but I bought a book also just in case. I picked up my clutch kit and the wallet decided against the HD setup but I'm hoping I can get it done by sunday evening. I'll post how it turns out and what I find when I'm in there
78C20Reaper
Registered Member
Well sunday evening was a major bust finally got the old clutch and pressure plate off and noticed something that might pose a future issue. I lack the funds to get a new one so I'm gonna have to run it for now but I got a 400 in a parts truck I'm getting so I think I'll wait. I couldn't figure out how to post a picture of it but my pressure plate was the three finger style and one of the fingers was stuck about halfway down. I also noticed a few little micro cracks maybe or just some stubborn clutch material on the flywheel in the same area as the messed up finger. Also there was enough clutch material behind the release fork I could have made a small birds nest but the disk didnt look to terrible and no I'm not reusing it before anyone assumes.
Low pressure plate arm usually denotes broken spring/s in plate assembly. What is it you have to run for now?
78C20Reaper
Registered Member
My flywheel looks like it has some micro cracks and maybe a hot spot on it where the one finger was messed up. I looked at the pressure plate after removal and noticed both springs beside the messed up finger looked to be slightly crooked. If I could figure out how to post a picture I'd put it up so you could see
I would expect that after you have described what it was doing and what you found. I would get it resurfaced and put it back in. Tell them that you want just the minimum cut off to clean it up. ( It's to try and preserve as much material as possible. )
But if you have already put it back together as is, then don't worry about it too much. I guarantee that lots have done the same thing before. And it has to be better than before!
78C20Reaper
Registered Member
I thought about taking it off and having it cleaned up but my wallet says I can take it to the sandpaper shop. But hopefully the 350 wont be in it to much longer
I understand that!
Just as frame of reference, my boss wanted me to "toss a clutch " in on of the mixer trucks 2 years ago. We put a brand new Eaton clutch in with just a quick scuff on the flywheel. The truck was back hauling concrete with only one day downtime. It's still going without problems, well except for the loose nut behind the wheel...
If there was no clutch chatter on take offs,I'd just sandpaper the flywheel smooth and leave it as-is--I used to turn flywheels at work back in the day,and often they ended up being problematic,often they came out not true ,at first we were using a brake lathe,then we got a big surface grinder,which worked a lot better..
When you remove material from the surface the clutch rides on ,that makes the flywheel further way from the pressure plate and reduces the clamping force some--they sell shims to put between the crankshaft and flywheel to compensate for this,but them you have less bolt threads in the crank flange..the thinner flywheel is,the more likely it is to warp also,just like a brake rotor thats been shaved down..
When I put the SM465 in my 72 K5 ,the flywheel I got from a donor truck looked like its surface had a "crackle" pattern,and a few blued spots..
I was in a hurry to get the truck back together,I had to drive it with "no clutch" (it refused to release!) 75 miles to my parents house and rent a transmission jack on a Saturday afternoon,then get it back together by Monday morning to get to work by 10 am.
I just put the flywheel on,started the engine up,and held a sanding block with coarse emery cloth against it till it was shiny and the blue spots were gone--only took less than a minute..after it was all assembled the clutch had no chatter and worked fine over 2 years I had the truck..
When you remove material from the surface the clutch rides on ,that makes the flywheel further way from the pressure plate and reduces the clamping force some--they sell shims to put between the crankshaft and flywheel to compensate for this,but them you have less bolt threads in the crank flange..the thinner flywheel is,the more likely it is to warp also,just like a brake rotor thats been shaved down..
When I put the SM465 in my 72 K5 ,the flywheel I got from a donor truck looked like its surface had a "crackle" pattern,and a few blued spots..
I was in a hurry to get the truck back together,I had to drive it with "no clutch" (it refused to release!) 75 miles to my parents house and rent a transmission jack on a Saturday afternoon,then get it back together by Monday morning to get to work by 10 am.
I just put the flywheel on,started the engine up,and held a sanding block with coarse emery cloth against it till it was shiny and the blue spots were gone--only took less than a minute..after it was all assembled the clutch had no chatter and worked fine over 2 years I had the truck..
78C20Reaper
Registered Member
How bad of an idea is it to reuse the pilot bushing? I'm only asking because I've been under this lovely money pit of mine for about 4 hours with different styles of pilot pullers and none have even budged it
You would want the bushing to be in decent shape to reuse it. Check the inside dimension of it, or look to see how much it is worn by looking into it. Usually there is some down in the hole that doesn't get worn by the shaft. This should give you an idea of how much is gone.
There are several ways to pull a brass bushing. You can pack the hole with grease and then drive a rod into the hole which pushed it out with hydraulic pressure. If it doesn't work the first time, put more grease in. The rod or punch has to fit the hole decently.
Another way is to run a tap into it until it bottoms out on the crankshaft and then it will jack the bushing out.
There are several ways to pull a brass bushing. You can pack the hole with grease and then drive a rod into the hole which pushed it out with hydraulic pressure. If it doesn't work the first time, put more grease in. The rod or punch has to fit the hole decently.
Another way is to run a tap into it until it bottoms out on the crankshaft and then it will jack the bushing out.
I've used a tap as described and they came right out..
Tried using the "pack it with grease and use a dowel and a hammer" method only once..it may work for others,if the bushing has no wear,but the time a friend & I tried getting his pilot bushing out using that method resulted in both of us getting splattered with grease !-
-the bushing was ovaled out inside,and nothing we had handy fit tight enough..
We got it out by screwing in a large lag bolt we borrowed from a beam in his garage using his air impact gun..it didn't pull it out very far,but we were able to use a pry bar under the bolt head and got it to come out the rest of the way..
I didn't bother replacing the pilot bushing in my '72 K5 when the two 12" three finger clutches failed after a month or so of use,I had put a new one in and it was still perfect..
I'd also discourage anyone from using a needle bearing type pilot bearing,those do not last,the needles can rust,or get dirty and come loose from the cage and chow the input shaft on the trans..
Tried using the "pack it with grease and use a dowel and a hammer" method only once..it may work for others,if the bushing has no wear,but the time a friend & I tried getting his pilot bushing out using that method resulted in both of us getting splattered with grease !-
-the bushing was ovaled out inside,and nothing we had handy fit tight enough..We got it out by screwing in a large lag bolt we borrowed from a beam in his garage using his air impact gun..it didn't pull it out very far,but we were able to use a pry bar under the bolt head and got it to come out the rest of the way..
I didn't bother replacing the pilot bushing in my '72 K5 when the two 12" three finger clutches failed after a month or so of use,I had put a new one in and it was still perfect..
I'd also discourage anyone from using a needle bearing type pilot bearing,those do not last,the needles can rust,or get dirty and come loose from the cage and chow the input shaft on the trans..
