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73-87 Chevy _ GMC Trucks => Engine/Drivetrain => Topic started by: FritzA on December 20, 2009, 11:52:29 pm

Title: clutch size help
Post by: FritzA on December 20, 2009, 11:52:29 pm

Hi all,

I am getting ready to pull the 350 in my 77 C20 with SM465. a 14 bolt rear end and swap in another 350. I want to replace the clutch and want to have parts ready to go.

I understand there were 2 sizes of clutches. Was the larger clutch an option I'd see on the glove box sticker? I don't see one. I would think I have the heavier duty cluitch with it being a C20 with a 14 bolt rear.

Ant thoughts how to tell before I pull it?

Thanks

Title: Re: clutch size help
Post by: Irish_Alley on December 21, 2009, 12:51:43 am

on my 465 when i pulled the engine i got a new clutch and all the two diffrent choices i think or for the fingers on the clutch one has only 3 the other has like 8 or something well the clutch i pulled off the trany was the 3 finger one the clutch i put on was the 8, still a year later no problem thats with some mudding and playing in the snow

Title: Re: clutch size help
Post by: hotrodpc on December 21, 2009, 10:38:50 pm

IF that is the case, you should be able to look up insde the bell housing and possibly see enough to tell if you have the borg&deck 3 finger, or the diapharm type pressure plate. I would agree, you likely have the heavy duty clutch if you have the heavy duty rear end. So which 14 bolt do you have? The 9.25in semi float or the 10.25 Full Float?

Title: Re: clutch size help
Post by: Irish_Alley on December 22, 2009, 12:45:01 am

the way to tell from 9 or 10.5 is on the pinion you can see six bolts around the yoke
hard for me to tell you lol but look at the bottom right corner of this pic
(http://www.pirate4x4.com/tech/billavista/14b_bible/images/Design-2_small.jpg)

Title: Re: clutch size help
Post by: Captkaos on December 22, 2009, 10:05:55 am

The way to tell full float vs semi-float is the full float has a hub on the end of the axle.  Semi-float look like your standard diff.

If the truck has a factory clutch it is a 3 finger.  You can replace it with a diaphragm clutch though, I would...  It could be 11" or 12"

Title: Re: clutch size help
Post by: FritzA on December 23, 2009, 04:50:26 pm

The 14 bolt is a full float, another reason I was anticipating a heavy duty (12") clutch.

Title: Re: clutch size help
Post by: Blue 82 on December 23, 2009, 05:34:49 pm

What is your GVW?
Do you have Hydroboost brakes?
Most of the non-hydroboost trucks I've worked on have 11" clutches
Hydroboost brakes = 12" clutch

Title: Re: clutch size help
Post by: Longshot379 on December 23, 2009, 08:42:30 pm

My 78 K25 with 350, SM465, FF14 Bolt 7300 GVW came with a 12' clutch.