# Clutch size



## orelog (Dec 21, 2011)

I would like some opinions on clutch size. 10.4 vs 11" I have a 400 bored .30, with a good street cam, tri-power, mildly ported 061 heads, Keith Black flat top pistons, brand new muncie 4 speed, rebuilt 4 pinion posi with 3.55 gears. I thought the bigger diaphragm would give a softer pedal feel and still give good clamping force. What are you guys using?


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## Chris-Austria (Dec 23, 2010)

I have another link for you  GMFlywheel
I've run a 10.4" clutch before (428cui, 4 speed) and never had problems with slipping.


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## orelog (Dec 21, 2011)

Great information! Thanks.


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## leeklm (Mar 11, 2012)

Good article, thanks. I just purchased the 10.5" Ram "muscle car" series clutch to fit a Hays flywheel that came with my core motor. I am bringing the clutch & flywheel into my motor guy to be sure everything balances up ok. My stocker 400 had an 11" disc, and has quite a lot more surface area than the smaller unit. I was a little worried that the small clutch may be an issue, but does not sound like it!


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## allpawl66 (May 9, 2008)

If flywheel will accept it , go with the 11" . Just like brake surface the bigger the better .


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## leeklm (Mar 11, 2012)

allpawl66 said:


> If flywheel will accept it , go with the 11" . Just like brake surface the bigger the better .


Unfortunetly, the "virgin" flywheel that came with my motor core only had mounting holes for 10.5", so I spent $50 to have it resurfaced and bought the smaller clutch. Hopefully I will not regret it later!!


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## orelog (Dec 21, 2011)

I have done the same. The car (1965 GTO) will be a cruiser and not for racing of any kind.


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