71 LT1 Clutch

[David K.]

Is there some way to find out what size clutch is correct for a 1971 LT1?

I need to replace the clutch on mine but all the part suppliers show clutch kits of 10.4" or 11" with 26 splines the the 71 SB. Is there a way to find out what came in my car without pulling the transmission first? I would like to have thet parts ready so I can pull the tranny, replace the clutch and get it all buttoned up the same day to minimize down time.

Thanks.

[Joe L.]

Re: 71 LT1 Clutch

David----

For some reason, there is some confusion in aftermarket parts books rearding the 1971 Corvette clutch. What I think happened is that an application involving only a handful of cars caused this problem.

Basically, all 1971 Corvettes with 4 speed used the same clutch with a few minor exceptions. This was an 11" unit that was used in conjunction with the 14" flywheel and GM #3899621 bellhousing. The exceptions were 1971 Corvette with LS-6 and 1971 Corvette with ZR-1. The LS-6 used a 14" flywheel with 10" dual disc clutch. The 1971 ZR-1 (i.e. LT-1 with HD chassis package) used a lightweight 12-3/4" flywheel with 10-1/2" clutch and GM #3858403 bellhousing.

ALL original 1971 clutches were 26 spline, regardless of clutch size or application.

The easiest way to confirm what you need is to look at the casting number on the side of the bellhousing. If it's 3899621, then you have a 14" flywheel and require the 11 inch, 26 spline clutch. If it's 3856403, then you require the 10-1/2", 26 spline clutch. I'll bet you find a GM #3899621.