440 Clutch Recommendation.

Big Block A body Tech

  1. Mark Strader

    Mark Strader Member

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    Hello! I dont have an a body but thought i might get some good feedback on this forum. I'm building a 440 for a 1967 D100 2wd short utiline pickup. It is your standard 1978 rv 7.8:1 compression low milage motor. Summit 6400 cam, template ported 452 heads, factory dual plane 4v intake with egr stuff brazed shut, holley 750dp, truck headers. Pretty mild. This is a basic drive for fun, no racing, weekend truck. No heavy towing...maybe a 2500lb boat at the most...maybe. According to factory specs, the truck's curb weight should be around 3600lbs. Rearend is an 8.75 sure grip with 3.55 gears. I have an A833 OD iron case transmission I'm putting behind an American Powertrain bellhousing. Hydraulic clutch. This accepts both 10.5" and 11" flywheel/clutches. I want to use a good oem grade clutch such as luk, exedy, sachs, etc. Any reason why I should go 10.5" over the 11"? I've heard the bigger clutches are harder on synchros when shifting because of the extra weight inertia. All the factory stuff was 11" in the trucks, but that was a long time ago and new clutches seem to hold better than the older stuff. Would a 10.5" be a better choice? The price difference is just about a wash but the 10.5 seems better supported. Any info would be much appreciated. Thanks!
     
  2. Garrett Ellison

    Garrett Ellison Amateur driver on public roadway, do not imitate..

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    I have read and heard a lot of good things about advanced clutch technology, if you call their tech line they will build a clutch to spec out to your build. Definitely worth a look. One drag racer trick in the past was to run the smaller 10-1/2 inch disc on an 11 inch (Or Larger!) flywheel to add inertia to the launch but use a 10-1/2 inch or smaller clutch disc with a crap ton of spring pressure to reduce inertia on the synchros. This is definitely a combination that would be better served by the close ratio heavy duty NP 445 four speed truck transmission, but if your not going to be power shifting it and do a good job scuffing a cross hatch on the synchro brass and gear cones with some 400 grit, it should handle an 11inch clutch with ease, just like the Hemi A 833.
     
    Last edited: May 15, 2019
  3. famous bob

    famous bob mopar misfit

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    Don't over do it , I had a 1969 440/4 speed coronet, that I blew the clutch on in just a short time. I had a clutch built for it at Tulsa brake and clutch (way back) , that clutch is why I switched to my first automatic , sure sucked in city driving----
     
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    • Mark Strader

      Mark Strader Member

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      I checked out ACT's web site. I noticed their 10.5" clutch was rated for 620ft/lbs torque which they say is 32% above stock oem. This would suggest that the stock 10.5" clutch is rated for about 475ft/lbs. ACT didn't list an 11" clutch for a mopar so I can't compare. I did check out there GM 10.5" to 11" clutches and the 11" was rated about 12% higher which is about what I would expect.

      Either size should work for my application when using an oem clutch. My gut tells me the difference in size might be relevant when shifting at 7-8k rpm, but maybe not be too noticeable with a 3-4k shift. My power band should be done not too much above 4-4.5k. Does anybody have direct comparison between a 10.5" and 11" clutch when using an A833 as far as shifting feel/engagement goes?

      I'm probably overthinking this whole thing, but I just don't want to go 11" and get that "heavy" feel if I can avoid it by going the 10.5" route.
       
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      • sireland67

        sireland67 Well-Known Member

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        I used a RAM HDX clutch kit in my last truck, the pedal was moderately stiffer, than the old wore out stock clutch, but not hard at all to push, my wife actually drove the truck more than me.
        It is a borg n beck design, so it bolts right in.
         
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        • Garrett Ellison

          Garrett Ellison Amateur driver on public roadway, do not imitate..

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          At your power level and vehicle weight, as long as you properly use the clutch as intended and not excessively slip it while towing, a 10-1/2 inch will have negligible difference in wear over time. Clutch disc weight really isn't going to be that big of a factor between those two sizes of disc unless your trying to rip shift at 6500 plus rpm. Use good EP gear oil and about 15 percent Lucas oil stabilizer in your 833 and you'll never know the difference. Keeping the wear minimized on the synchro rings and cones by keeping the oil changed at the first sign of thermal breakdown is the best thing you can do to keep your transmission shifting properly.
           
        • Mark Strader

          Mark Strader Member

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          After more reflection and research, I think I'm going with a 10.5" luk 05029. It's listed as an oem replacement for a 413 in a chrysler 300. I think it will hold up to my non-racing, mild combo. If it doesn't, I can always change it out. Thanks for the insight!
           
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