SM465 Questions - Help!

[andhar]

My Clutch is slippling and I am trying to figure out what brand/type of clutch to buy.

First question , Between the types of clutches which is best for an almost daily drivin truck? Metallic , organic or iron/organic?

how do I find out what size the clutch is apparently there are 2 sizes, 11" or 12"

Do you guys have a particular brand that you think is best?

Truck has a 350 4bbl , SM465 w/ NP205 w/ 3.73 gearing...


thanks yall

 

[diesel4me]

what NOT to buy!!

When I put an SM465 in my 72 K5,I used what I thought would be an indestructible clutch,a 12 inch 3 lever type pressure plate and disc--well,it lasted about a week,when one lever broke at a redlight while sitting there with the clutch pedal to the floor,it leaped forward into the car in front of me!

I put another one in (it was waranteed for 90 whole days! )--and a month later that one would not release fully either--I finally got an 11 inch diaphram style clutch setup(I think it was a "Centerforce" ,"Hayes"or some other hi-performance one from a speed shop a friend runs)--the pedal effort was so easy compared to the 12 inch 3 finger style I thought there was something wrong with it!--but it worked perfectly for over 5 years,and I never got it to slip once-they do make a 12 inch diaphram one now too,-I'd say 11 inch is enough,and the diaphram type outlasts the other style by far--and your left leg wont look like its on steriods either with a diaphram type clutch...thats what I'd put in if I had a manual tranny truck..

 

[diesel4me]

almost forgot!!

They have a clutch disc available that looks like a fan blade with disc brake pads on the blades--they are called a "ceramic puck" disc in some brands--I sold them to a local DPW garage that had some international trucks that ate clutches every snowstorm(probably the drivers fault!)--those discs lasted them 3 years!!--but be aware they are very "grabby",you cant "slip" them like a normal clutch,there either engaged or disengaged--not sure if it would be the right choice for off roading,or rock climbing,but they do NOT slip!!

 

[mechted]

When i asked this, i was told to look at a Luk ProGold Diaphragm clutch... same quality and performance as Centerforce, but 2/3 the price (will be getting one for the K5 when i do manual swap, eventually)
and when i found some papers on my DD, i found that that is the exact clutch set that was in it. The clutch has been very good to me, taken some abuse, and it still feels good 4 years later, so I cant complain about it

 

[big83chevy4x4]

everytime i put a clutch in a full size truck, its a 12". i perfer the diaphram over the three finger. easier on the leg and doesn't chatter. never heard of them breaking though.

the last remanded i bought, on the pressure plate was stamped the LUK logo, not sure on the disk.

 

[dyeager535]

Yes, difference in clutch size is based on the ring gear count as I understand it, and the only two I am aware of are 153 teeth or 168 teeth. Maybe brand new stuff or pre '73 had different size clutches, but 70's/80's for our purposes were all 11 or 12".

I believe the small clutch WAS available some years in the C/K's, but the 12" is by far the most common. (you can find that info in the Blazer Brochures that dremu has on his site) Starter bolt pattern will also tell you which clutch size you have, but for the life of me can't recall if 12"/168 tooth is staggered starter bolts or straight across.

They aren't even a true 11 or 12", so you can run into difficulties measuring one by itself as well.

 

[diesel4me]

yup--

The "12" inch clutch is actually 11-7/8 or so,and the 11 inch is closer to 10-7/8 inches,but they "round it off" to the nearest inch I guess...

In reality,the "dinky" 10-1/2 inch clutch used in 6 cylinder GM cars and some trucks has nearly the same or slightly more surface area than even a 12 inch--more "meat" on the disc surface where it contacts the flywheel...I've seen nova's use those small clutches and drag race with few failures!...,I guess "bigger" aint always better,except in the bedroom...

 

[big83chevy4x4]

the biggest clutch ive seen on the small flywheel (153 tooth) is a 10.5", never seen one of those in a fullsize truck, but i bet there were some made with them.

the 168 tooth flywheel will take a 11" or a 12" clutch. the pattern for the pressure plate is the same. in fact my truck has a flywheel off my dads 85 k5 305 with the factory 11" (he took mine when we put a clutch in it)