1964 SM420 Clutch question
 

Hey guys - need your advice again. As most of you know I have a 64 3/4 ton truck w/ 305E in it, and SM420 trans. So I take it to the mechanic shop to see about getting a new clutch put in, and they remove what is believed to be the original clutch (only 89K original miles on this Jimmy) and find it to be an 11" clutch. So once that was identified for me, I knew what size to ask for, so I went to 3 different parts stores and every single one said their computer systems only show a 12" clutch for this 305E equipped truck - same for 1000 series, 1500 series and 2500 series according to them.

So, what in the world have all of you been putting in your SM420's for replacement HD clutches? (and where did you order or buy it from)

Re: 1964 SM420 Clutch question
 

The problem is nobody sells the 11 inch clutch for light duty GMC V6applications. The only difference between the clutch used on V8 and inline 6 engines vs the V6 is the center splined hub is reversed other than that the clutch disc and pressure plate are the same, if there's a local clutch remanufacturer in your area they can come up with what you need. Otherwise you will have to go with a 12 inch clutch, I'm also running a 12 inch clutch in my 68 V6 powered truck but that's a different story too.

Re: 1964 SM420 Clutch question
 

....so doesn't a 12" clutch feel a lot stiffer at the pedal though?

Re: 1964 SM420 Clutch question
 

I switched to the 12 inch clutch back in 1985 because it was an upgrade and a GM pickup trucks at that time came from the factory with 12 inch clutches. As far as stiffness goes it's hard to tell from a change I did 29 1/2 years ago but I felt the aftermarket clutch and pressure plate from "Webber" was a smoother setup than stock.

Re: 1964 SM420 Clutch question
 

I just switched to the 12 inch and there's no noticeable difference. It's a good clutch and bolts right up. Come on over to the heavy duty clutch side

http://windypix.com/?dm=6H8Z.jpg

Re: 1964 SM420 Clutch question
 

OK - thanks guys - I guess if this is the will of the force there is no fighting it so I will go to a 12" clutch as well...

Re: 1964 SM420 Clutch question
 

:lolsmack2:

Welcome to the Dark Side! Your hat and scary Vader outfit are in your new locker. Let us know how the replacement goes, model number and all that. I put a bunch of links up in the transmission forum to online places to get them.

Re: 1964 SM420 Clutch question
 

Well, O'Reilly Auto Parts, Autozone and others here in town seem to have these in stock, so currently planning to just go with one of them - most of these parts seem to be fairly generic branded so not sure if its worth chasing a better brand or not

Re: 1964 SM420 Clutch question
 

That's good news. My local Autozone said, "You want a what?"
:lol: