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What size is your SM465 clutch?

Discussion in '1973-1991 K5 Blazer | Truck | Suburban' started by sled_dog, Jan 14, 2003.

  1. sled_dog

    sled_dog 1 ton status

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    I have been swapping out my now cooked 305 for a 350 and when I pulled my clutch I was amazed to find it was cooked as well. This is amazing to me cause it felt perfectly fine and I figured it was somewhere around like half worn not just gone. Anyway the only clutchs I have in my garage are too big for my pressure plate. So I went to Autozone to pick myself a shiny brand new clutch. I did so but forgot my old one for the core. I went to put my new clutch on(which happens to be the last step before installation of my freaking engine) to find that this clutch is the same too large size as the ones I have. I think mine is about an 11" clutch plate and the ones I have and was given are 13". Sound about right? What size is stock? Did they just give me the wrong clutch or did someone before me change the setup?
     
  2. Muley

    Muley 1/2 ton status

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    Not sure on teh 350 for that year, but on my 305 there are two different clutchs listed. A 10 3/4 and a 11 5/8. A friend of mine that works at the GM shop says you really want the bigger clutch if it will fix. Infact if you can fit on off of a 3/4T that is better. The reason being that the throw out bearings are bigger and tend to last a lot longer. Since the engine is not in I would suggest that you take the old clutch as well as the fly wheel in. That way you know it will fit on the fly wheel as well as you will be able to check and make sure the splines on the new clutch match the old clutch.
     
  3. sled_dog

    sled_dog 1 ton status

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    Taking in my old clutch and pressure plate, see i am just replacing the clutch disc not the pressure plate or throwout bearing. I have a zoom pressure plate with barely a 1000 miles on it in the garage just gonna use that. could note I had the 305 but I am puting in a 350, I will see if they have different sizes for the 305.
     
  4. BowtieBlazer

    BowtieBlazer 1/2 ton status

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    I think my two options were 11" and 12" I went with the 12" and like it alot!
     
  5. CaveBlazin

    CaveBlazin 1/2 ton status Premium Member

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    I believe mine was the 12 too my truck came with a 305(V6 trying to be a V8)And when I put in the 350 I just went for the bigger clutch. WARNING WARNING!!! The clutch I bought from autozone only lasted like 1500 miles and it was toasted. I went and bought one of them centerforce and its still going strong and that was ohhhh about 200k ago so Im pleased with it... Just my 2 cents
     
  6. sled_dog

    sled_dog 1 ton status

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    Think I should replace my 11 with the 12? That would require a new pressure plate too right? I could see if I can just get the pressure plate at autozone and use the 12" I have lying around. I think the clutch I have sitting in the garage is from my dad's old tow truck which was an early 80s 1ton chevy with a tow truck back end, 350, and SM465. Would make sense since when I went to autozone I told them my engine was a 350 and not the 305 that came with it. New pressure plate time I guess.
     
  7. sled_dog

    sled_dog 1 ton status

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    Will the 11 7/8" pressure plate bolt up to my flywheel?
     
  8. madmike

    madmike 1/2 ton status

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    I sort of went through the same thing 11 years ago when I pulled the 250-I6 out of my truck and swapped in a 305. My clutch was the smaller (11") and wasted, so I replaced it with the larger 12" clutch. If you have the 168 tooth flywheel, you can run either 11 or 12. If you have the 153 tooth flywheel, I think you can only run the 11, if I remember correctly.

    If you can go big, do it, it's worth it. I've got 11 years on my Zoom 12" clutch, don't know the mileage, but its been abused, and it is still going strong. I'll be doing another engine swap this summer, so I'll replace it then.
     
  9. R72K5

    R72K5 Banned

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    im 75% sure that 12" wont bolt to 10 or 11" flywheels

    10" was std equipment on 250, 11" was std for 292, and 11" for LD like 305, 307, 283, etc, most 327 back in the days got 11" std, 350 11", 12" optional and with BB engines

    good luck
     
  10. TopOff

    TopOff 1/2 ton status

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    Go to www.centerforce.com

    Or here is the link - click on C K G (blah blah blah).

    http://128bitencrypted.com/centerforce/2001catalog/centerforcemodel.tpl?db=2001catalog.txt&eqmakedatarq=CHEVROLET%20LIGHT%20TRUCK

    I got their 12" disc, and CFII clutch, and a CF Throw-out bearing.

    I also had to get the flywheel for a 400 SB. No one could tell me if the 12" would fit or not, but I got it anyway. The disc was a little too big and the outside of the disc covered up some balancing holes. But it has worked fine.

    Good luck.
     
  11. dyeager535

    dyeager535 1 ton status Premium Member

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    I thought I had seen it somewhere:

    http://brochures.slosh.com/1976/blazer8.jpg

    Of course, that means nothing for other years as often as GM changed that sort of stuff, but I knew I had seen that 12" was required for V8's somewhere /forums/images/graemlins/smile.gif

    I have yet to see even a 350 truck engine that DIDN'T have a 12" clutch. Of course, there were a few "lesser" transmissions than the 465 offered in the trucks for quite a few years, those may have been a reason for smaller clutches, along with the smaller displacement engines.
     
  12. sled_dog

    sled_dog 1 ton status

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    You should take notice that the 305 wasn't available that year. I got a brand new 11" clutch(only $20 compared to the 36 for the 12) and used the Zoom 11" pressure plate I had. I was gonna go about switching to the 12" because I found some 12" pressure plates in the garage but they had a different spring style and I didn't know if I needed a new throwout bearing and if so what one or any of that info. And I just wanted it done. The 12" plates I have have the 3 levers instead of the group of springs. I think its called lever style vs the diaphram style, diaphram being what I have and had. I am not even sure my motor is in any type of good condition so I am not very worried about how the clutch holds up yet.
     
  13. dyeager535

    dyeager535 1 ton status Premium Member

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    </font><blockquote><font class="small">In reply to:</font><hr />
    You should take notice that the 305 wasn't available that year.

    [/ QUOTE ]

    No, I noticed it, but I know that the later year dealer brochures didn't cover that. The earlier year brochures are the only places you'll find that info, outside of the parts or service manual.

    The 3 finger style is called Borg &amp; Beck as I recall, the other is a diaphram style. I'd have to run them back to back in my own vehicle to tell you which I liked better...my dad has the 3 finger style with mechanical linkage, and its horrible to drive, mines hydraulic with diaphram, and its awesome.

    3 finger has more "clmaping power" as I understand it, and are less likely to "chatter" on engagement than a diaphram style when you are trying to do something thats hard on a clutch (getting something heavy moving when towing, racing), but with some light towing (maybe 2000lbs) I haven't had any problems with the diaphram style.

    In your situation, if the 11" has been working for you, I'd go whichever route was cheaper. I picked up a 12" flywheel at the last swapmeet for $10, and had it turned for $25. /forums/images/graemlins/smile.gif Of course, I think the clutch set (complete) ran me $150 or so a couple of years ago, so that was additional cost to the "swap", although I had nothing to start with.
     

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