Which Clutch Do I Need? - The 1947 - Present Chevrolet & GMC Truck Message Board Network

sixtyfour · 12-22-2007, 05:31 PM

Getting ready for the new motor, replacing the old 305 with a new 350. Anyway, was trying to order a clutch set up from JEGS and they were asking questions I didn't know the answers to. Oh, and this is for a 64 C10 with a 4 on the floor...

Tranny Spline Count, 18 or 10?

Clutch Size (Diameter)?

The dude on the other end of the line was saying that these old trucks didn't use a standard brand of tranny? Is this true? I'd like to know what tranny I have, may have to wait till the motor is out to find out for sure...

62 short step · 12-22-2007, 06:29 PM

Most likely your tranny is the sm 420, and that is a standard brand for this year of truck. I would go with an 11 inch clutch, thats what I had with my 283 with the sm 420. It should be a 10 spline shaft, but when you tear it apart just count the splines. Hope this helps you some.

rss396 · 12-22-2007, 06:45 PM

62 Short Step. If he goes with the 11 inch clutch will his bell housing have enough clearance inside? Not sure on these old trucks but cars (early camaro, nova etc.) require the larger bell housing for the large clutch. The larger housing for the cars bring good cash at the swap meets.

62 short step · 12-23-2007, 02:28 AM

Thats what my truck had, if you look at LMC website they offer a 10 and 11 inch clutch. I'm pretty sure I had just a regular ole bell housing.

rickf · 12-23-2007, 10:10 AM

Mine stock was a 230 with 3-speed, it had a tinly little clutch, 10 inch maybe, I forget exactly.

I put in a 12 inch clutch, that's what the guys at the parts store said a real truck ought to have.

It fit the stock bell housing fine.

sixtyfour · 12-23-2007, 03:25 PM

I should have the motor pulled tomorrow so I'll know for sure then. This new motor I bought is rated at 290hp, so if I have room in the bell housing to go bigger does this mean I need to change out the flywheel or can I use the same flywheel I have now?

Also whats a good brand clutch and pressure plate to go with? I deal with alot of traffic here so I wouldn't want something that's crazy hard to push.

Thanks

12-22-2007, 05:31 PM	#1
sixtyfour Zombie Killer Join Date: Dec 2007 Location: Texas Posts: 317	Which Clutch Do I Need? Getting ready for the new motor, replacing the old 305 with a new 350. Anyway, was trying to order a clutch set up from JEGS and they were asking questions I didn't know the answers to. Oh, and this is for a 64 C10 with a 4 on the floor... Tranny Spline Count, 18 or 10? Clutch Size (Diameter)? The dude on the other end of the line was saying that these old trucks didn't use a standard brand of tranny? Is this true? I'd like to know what tranny I have, may have to wait till the motor is out to find out for sure... __________________ 1964 C10 Long Step

12-22-2007, 06:29 PM	#2
62 short step Senior Member Join Date: Aug 2005 Location: Greenwell Springs, Louisiana Posts: 2,882	Re: Which Clutch Do I Need? Most likely your tranny is the sm 420, and that is a standard brand for this year of truck. I would go with an 11 inch clutch, thats what I had with my 283 with the sm 420. It should be a 10 spline shaft, but when you tear it apart just count the splines. Hope this helps you some. Last edited by 62 short step; 12-22-2007 at 06:30 PM. Reason: spelling

12-22-2007, 06:45 PM	#3
rss396 Registered User Join Date: Nov 2006 Location: Amity Oregon Posts: 70	Re: Which Clutch Do I Need? 62 Short Step. If he goes with the 11 inch clutch will his bell housing have enough clearance inside? Not sure on these old trucks but cars (early camaro, nova etc.) require the larger bell housing for the large clutch. The larger housing for the cars bring good cash at the swap meets. __________________ 1950 Chevy 1/2 ton 283 Mustang II 1961 SWB 2x4 235 six 2007 Silverado 1/2 ton Z71 4x4 1968 Camaro SS 396 / 502

12-23-2007, 02:28 AM	#4
62 short step Senior Member Join Date: Aug 2005 Location: Greenwell Springs, Louisiana Posts: 2,882	Re: Which Clutch Do I Need? Thats what my truck had, if you look at LMC website they offer a 10 and 11 inch clutch. I'm pretty sure I had just a regular ole bell housing. Last edited by 62 short step; 12-23-2007 at 02:29 AM.

12-23-2007, 10:10 AM	#5
rickf Registered User Join Date: Dec 2005 Location: Lake Oswego, OR Posts: 318	Re: Which Clutch Do I Need? Mine stock was a 230 with 3-speed, it had a tinly little clutch, 10 inch maybe, I forget exactly. I put in a 12 inch clutch, that's what the guys at the parts store said a real truck ought to have. It fit the stock bell housing fine.

12-23-2007, 03:25 PM	#6
sixtyfour Zombie Killer Join Date: Dec 2007 Location: Texas Posts: 317	Re: Which Clutch Do I Need? I should have the motor pulled tomorrow so I'll know for sure then. This new motor I bought is rated at 290hp, so if I have room in the bell housing to go bigger does this mean I need to change out the flywheel or can I use the same flywheel I have now? Also whats a good brand clutch and pressure plate to go with? I deal with alot of traffic here so I wouldn't want something that's crazy hard to push. Thanks __________________ 1964 C10 Long Step



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