1972 Corvette Clutch Size ??

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Apr 25, 2008 | 12:22 PM

GT-1 Corvette

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1972 Corvette Clutch Size ??

Hello,

I cannot get the same answer twice for what size clutch goes in a 1972LT-1 Corvette.

How many splines on the front shaft? 26 Fine? Can anyone tell me for sure if the 10.4" or 11.0" is corect?

Will the 11"clutch bolt up the same as the 10.4"? Is the only differance the clutch disc size?

Thank you,

Apr 25, 2008 | 01:57 PM

Gordonm

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From: Forked River NJ

The 72 LT1 used an 11 inch clutch. The input shaft is a 26 spline shaft. The 10.4 uses a different flywheel, disc and pressure plate. Some after,arket flywheels are drilled for both 11 and 10.4 inch.

Apr 25, 2008 | 01:58 PM

0Willcox Corvette

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From: Jeffersonville Indiana 812-288-7103

St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15

In 1972 the GM parts book list

71-72 Corvette (H.D. 4-Spd.
w/Sp H/Per.) (350) . . . 3991428 1 PLATE ASSY.. driven (10.4" O.D.) (26 tooth spline)

71-72 Corvette w/Sp. H/Per.
(350) (exc. H.D. 4-Spd.) 3989030 1 PLATE ASSY., driven (1 1" O.D.) (26 tooth spline)
(black paint mark) . . . . . . . . . . . . . . . . . . . . . . . . . . . .
71-72 Corvette( 350) (exc. Sp.
H/Per., H.D. 4-Sad.). 3989030 1 PLATE ASSY., driven (1 1" O.D.) (26 tooth spline)

The first one, 3991428 is the application for the LT-1 with h/d 4sp trans.

Last edited by Willcox Corvette; Apr 25, 2008 at 10:47 PM.

Apr 25, 2008 | 02:26 PM

Solid LT1

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From: Fremont CA

ZR-1 option with M-22 4 speed uses 10.5" clutch and regular LT-1 has 11" clutch with 26 spline disc.

Apr 25, 2008 | 04:04 PM

GT-1 Corvette

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2 Out Of 3

well now you see the problem....2 say 11" and 1 says 10.4"
I wanted to buy this AC delco Clutch that is 11" and this is why I was asking without pulling out my clutch a seeing for myself.

Thank you

GT-1 Corvette

Apr 25, 2008 | 04:51 PM

Gordonm

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From: Forked River NJ

Quote:

Originally Posted by Solid LT1

ZR-1 option with M-22 4 speed uses 10.5" clutch and regular LT-1 has 11" clutch with 26 spline disc.

You most likely have a standard LT1 with an 11 inch clutch. The ZR 1 was a very low production car and it is doubtful you have one of these.

Apr 25, 2008 | 09:24 PM

LT-1 kid

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From: cary Il

i just did my clutch on my 72 lt-1 its a 11 '' and 26 spline, i used center force II very nice clutch.

Apr 25, 2008 | 10:54 PM

0Willcox Corvette

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From: Jeffersonville Indiana 812-288-7103

St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15

I should have been more specific and filled in the details that are lacking in the GM parts publication. Even in 1971 they made things hard to read and I apologize.

The first listing from GM is for the HD 4 speed tranny and yes the ZR-1 optioned sp h/per car.

The correct listing for your car would be:

71-72 Corvette w/Sp. H/Per.
(350) (exc. H.D. 4-Spd.) 3989030 1 PLATE ASSY., driven (11" O.D.) (26 tooth spline)

Sorry I did not mean to add confusion to this. I was in a hurry today trying to deal with my own issue on a camshaft.