SM420 clutch replacement parts
 

I have an SM420 in my C-50 and it needs a new clutch. Went to the auto parts store and they said it could be either a 10" or a 10.5" plate.

This will be my first time ever opening up a transmission so having the right parts the first go round would be very helpful for my confidence level. I've got a buddy helping me who has done it a lot in the past but he said its been 14 or so years since the last time he worked on one. I feel we are the blind leading the blind. Youtube and a few kind words from you fellas are sure to get me through.

Looking for help on part numbers and /or any advice. Thanks!

Re: SM420 clutch replacement parts
 

I'm sorry I'm not much help, but I was told it could be a 13" on my SM465, and basically will have to wait until it's all apart to figure out which I need. PITA, but it is what it is.

Re: SM420 clutch replacement parts
 

Blue, I would bet on it being a 13" clutch. You may have to go to Napa or a M/D truck shop to get what you need. What year is your truck?

Re: SM420 clutch replacement parts
 

I would bet 11" with a 420 trans

Re: SM420 clutch replacement parts
 

If it is a 13 inch then there would be an adapter plate between the engine and the bell housing. The bell housing required for the 13 inch clutch set up is too big to bolt directly to the engine block.

I have the NP 542L and engine that came out of a 72 C50. It came with the 13 inch clutch.

Re: SM420 clutch replacement parts
 

1960. I don't think its that big judging from the outside. I was hoping t get a definitive answer but I guess I am going to have to pull it before I have parts. Oh well.

Re: SM420 clutch replacement parts
 

Like Lynn Said, look for the adapter plate, that is as solid of an answer as you're going to get from the outside.

Re: SM420 clutch replacement parts
 

It is just a 1/4 inch thick plate. I will try and get a pic of mine and post it tonight.

Re: SM420 clutch replacement parts
 

Here you go. Easy to see as there is no distributor in the way. I am using these parts to mock up the engine swap. Putting the 72 Chevy C50 engine & trans into my 49 Studebaker 2R16A farm truck.

The adapter is just a 1/4 inch thick plate. You can see it between the engine and bell housing.

Another way to tell: if your starter bolts go in from the bottom, you probably don't have a 13 inch clutch.