The Stovebolt Site Forums The Shop Area Engine Shop Clutch Question

Need to do some work on the clutch but have not pulled it yet. I was under the impression that on my 61 C20 with a 235 engine it is a 10 inch clutch. When I called to order parts the parts guy stated that it is 12 inch. Anybody know for certain? Also, what kind of job am I looking at to replace the throwout bearing, pressure plate and disk? I've never worked on a clutch before.
Thanks!

You almost have to pull it out to be shure.
measure the dia. of the disk. Its a really
simple one to do if it,s a 3 speed. Alittle harder
on a 4 speed. Dont forget the pilot bushing.
It will probably need replaceing too.

If it is a four speed you will probably need a transmission jack unless you are a lot stronger than I am.Pay attention to how the throw out bearing and the disc are oriented. You can get them in backwards but they wont work that way.

I've found the 12" clutches are usually on the heavy-duty rigs, 1 ton and above. There is an 11" option that's available, and also a 10". Your best bet is to take it out and measure before ordering parts. Be sure and remove the flywheel and get it resurfaced, and replace the pilot bushing in the end of the crankshaft. The clutch plate can be installed backwards, and the center hub will drag the flywheel attaching bolts and prevent the disc from releasing fully.

Use an alignment shaft during reassembly to align the clutch and pilot bearing, and it's also effective to use a couple of long, headless bolts screwed into the bellhousing to guide the transmission back into place during reinstallation. Tighten the pressure plate bolts a little at a time to avoid distorting the clutch cover or misaligning the clutch plate on the flywheel. Good luck!
Jerry

On my '65 w/ SM420 4 spd, it's an 11" clutch. It's not all that difficult. I replaced mine earlier this year and had never done one. Took the whole day but, was up running by evening. You'll definitely want a jack if it's a 4spd. I didn't use a jack but, my buddy we affectionately call Shrek helped me. He's 6' 5" and 290 lbs. The truck was on a lift and even with his strength and size it wasn't easy gettin' that thing outta there. As you're disassembling, try to take mental pictures as your takin' stuff apart. Use a digital camera if you have to. Then reassemble in the same order.
One thing we forgot to do was drain out the old oil and that made it a bit heavier (not to mention messier) when removing. When it's back together, don't forget to adjust your pedal. You need to have an inch or so of freeplay.
Good luck,
David

Thanks for all the input.

The easy way to deal with a SM420 is to use an engine hoist through the passenger door to hold it up from the top.

Ditto. The extra time required to pull the seat and floor pan is well worth it. These things can be a real pain to line up, esp. with a new pilot bearing, so anything that makes this job easier is worth it in my opinion!