10" or 11" Clutch Disk?

[Martin64]

1964 Chevy C10 Long/Fleet, 230 cu in motor and 3 speed manual transmission. Kragen lists 2 different diameter clutches for it. Which one is right, or are they both right? And if they're both right, what are the different applications for?

[aerotruk63]

10 inch is standard clutch, 11 inch is heavy duty.

[markeb01]

They're not both right for your application, you have one or the other depending on which flywheel you have. Generally, the smaller clutch is fitted to the 153 tooth flywheel. The larger clutch mates with the 168 tooth flywheel. This many years since the introduction there are exceptions in the performance aftermarket. Since you have the small six with a standard 3 speed, it's most likely the 10" version, however it's best to pull and measure it, then you don't have to deal with returning the wrong parts.

[Martin64]

I was afraid of this. I'll basically have only one day to change the clutch when I pull it apart. Working on vehicles here is frowned upon harshly and I don't want to put out $300 for both sets then return the ones I don't use.... I'd hate to test their "1 day delivery" and miss the cut-off time. Of course if I pulled it apart on a Friday afternoon and ordered it on Sat morning when they open I could feasibly have it by Sunday morning. That'll give me time to change the output seal and clean up the transmission on Saturday....I really need to have it back together (or looking innocent) by Monday morning.

[markeb01]

One last suggestion - pull the tin inspection cover from under the flywheel, and do the best you can to measure the diameter of the flywheel. The outside diameter of the ring gear on the 153 tooth flywheel is 12.835". The O.D. of the 168 tooth flywheel ring gear is 14.096.

If you have the 153 tooth flywheel you have the 10.4" clutch. You might also be able to count half of the ring gear teeth that are showing: half of 153 = 76 teeth, and half of 168 is 84 teeth.

[Martin64]

Thanks, I didn't consider those options. I don't think it's going to happen this week end though. It's freakin' hot outside and I don't need to drive that truck around for a while nor do I want to lay under it in the hot sun right now. Yesterday was 106 and today's forecast is 109, even though it's only 101 out there now. I'm going to watch the weather and look for a cooler weekend forecast coming up. This is our typical hot time of year, but in the last 14 years I've lived here, they haven't lasted long. As long as the Santa Ana's don't whip up, we're usually pretty good.