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Heavy Duty Clutch

Discussion in 'Early CJ5 and CJ6 Tech' started by oblvnnwtnjhn, Aug 21, 2022.

  1. Aug 21, 2022
    oblvnnwtnjhn

    oblvnnwtnjhn Member

    North Alabama
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    I assume it’s more so for the plow packages etc? Any inherent advantage for the average CJ?
    About to reinstall my engine, rather address now than later but only if there’s an advantage for everyday use.

    With the limited information out there, it seems best suited for rigs with plows and PTO attachments. You need to locate a specific heavy duty flywheel for the HD kit to mount to?
     
  2. Aug 21, 2022
    danielbuck

    danielbuck Uncle Buck

    USA
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    Jan 22, 2013
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    140
    on my 46, I put a small diesel engine in it, and broke a few factory 8.5" clutches (cracking the areas where the springs are located, as well as cracking springs). I have moved up to a slightly larger diameter clutch disk and pressure plate, and haven't had any problems since then.
     
  3. Aug 21, 2022
    oblvnnwtnjhn

    oblvnnwtnjhn Member

    North Alabama
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    What kind of torque is that diesel putting out??
     
  4. Aug 21, 2022
    danielbuck

    danielbuck Uncle Buck

    USA
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    I don't know exactly to be honest. More than the original flathead, for sure, but not a crazy amount. I see specs online that say about 40hp and 140 newton meters of torque (100 ft lbs?). but I think that's the specs for no turbo, I put a turbo on mine and have messed with the fuel governor a bit.
     
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  5. Aug 21, 2022
    kenb

    kenb Cleverly disguised as a responsible adult

    Detroit
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    Jan 22, 2019
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    Early flywheels were drilled for the 8-1/2" clutch only, later were drilled for both. There is a different clutch cross tube for the heavy duty clutch. If you use the heavy duty clutch with a standard cross tube it makes it harder to release smoothly.
    When I replaced my clutch I went from heavy duty to standard and was happier with it. It drove much better.
     
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  6. Aug 21, 2022
    oblvnnwtnjhn

    oblvnnwtnjhn Member

    North Alabama
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    Good feedback Ken. Thanks for the real world application review.
     
  7. Aug 21, 2022
    oldtime

    oldtime oldtime

    St. Charles,...
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    I put a T98A in my last build along with a genuine oem 9-1/4” Auburn clutch cover assembly.
    Wanted a HD clutch because the Jeep is set up with rear boom that can be used among other things for log skidding.
    The 9-1/4 puts out 216 pound feet of plate pressure compared to 165 pound feet for the 8-1/2”
    I find the 9-1/4” Auburn to be every bit as smooth as the various oem 8-1/2” clutches.
    The 8-1/2” clutches were standard from 1942-1963.
    In 1963 - 1971 the standard was changed to 9-1/4”.
     
  8. Aug 21, 2022
    oblvnnwtnjhn

    oblvnnwtnjhn Member

    North Alabama
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    Standard on the F-134 before the 66’ release of the Dauntless? Interesting
    I may pursue this later, I’ve been down with my daily rig for nearly 4 mo, I had to repair some boondoggles by the machine shop assembly, just tapped/reamed my NOS crank and OEM flywheel for the 9/16 straight dowel upgrade outlined in the FSM when using a new crank and/or flywheel other than what was balanced at the factory.

    Plus, in my NOS bundle, I got a clutch in the deal, may as well use it and circle back around to this later if I feel the need. Or spend this money on the Buick 266 stroker build that I have yet to decide which vehicle to install it in. But first, the F head, then on to the 71’ Triumph T120 woods sled my engine builder is waiting for me to return with lower engine installed and the bike as roller. Plan to ride and show it at Barber Vintage Bike Fest in October.

    all great feedback and use cases presented.
     
  9. Aug 21, 2022
    oldtime

    oldtime oldtime

    St. Charles,...
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    “Standard” implies that an item was designated in compliance with the “factory service standards”
    Service Standards were provided for all models and all vintages of jeeps.
    The V-6 cj’s we’re not standard. They were an option from 1966 -1971. That said a separate set of v-6 standards were provided for those optional equipped cj’s.
    I have a set of nos oem factory straight taper dowels if your interested.
     
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  10. Aug 22, 2022
    kenb

    kenb Cleverly disguised as a responsible adult

    Detroit
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    I think I probably wasn't clear in my post, the experience I had with the 9-1/4" clutch was on a Jeep where it was mismatched with a cross tube designed for the 8-1/2" clutch. My experience likely would have been different if I had the correct cross tube. I was getting the flywheel machined anyway and at the time could source a 8-1/2" clutch kit much more easily so that's what I went with as opposed to sourcing both a cross tube and a clutch.
     
  11. Aug 22, 2022
    oldtime

    oldtime oldtime

    St. Charles,...
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    Yes the clutch control item referred to as the “ lever and tube” makes a difference. Jeep had several versions that were used for various applications.
    Dependent upon the the engine, the clutch itself and even the transmission.
    Also after market clutches like a genuine Borg Beck 9-1/4” cover plate assembly can be extremely stiff at the pedal with very high plate pressures.
    But the 9-1/4” Auburn is certainly a winner in my opinion.
     
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  12. Aug 22, 2022
    oblvnnwtnjhn

    oblvnnwtnjhn Member

    North Alabama
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    I bought mine of eBay from NOS seller, thanks for the offer though.
    Do you keep some NOS odds and ends on hand? I like to document parts sources.

    Thank you for taking the time to share your knowledge.
     
  13. Aug 22, 2022
    oldtime

    oldtime oldtime

    St. Charles,...
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    Yes and thank you for exposing your Jeep addiction.
    More Jeep data seems to ease the affliction but, OEM NOS always seems to be the best remedy.
     
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  14. Aug 22, 2022
    Oldpappy

    Oldpappy A.C. Fults - Curmudgeon at large 2022 Sponsor 2021 Sponsor

    East Tennessee
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    It is all part of J.A.S. (Jeep Acquisition Syndrome), once infected there is no cure, only treatment.
     
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  15. Aug 22, 2022
    oblvnnwtnjhn

    oblvnnwtnjhn Member

    North Alabama
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    For posterity, if I decide to upgrade my stock 61’ setup to HD, what is needed beside the disc and pressure plate?

    PO added later Cherokee pedal with Wilwood cylinder to actuate. So not sure control lever is stock, I haven’t really inspected it closely.

    I assume as Parts Manuals says #922076 Lever & Tube for 9-1/4, HD disc and HD pressure plate. And it's possible the 61' flywheel has the correct mounting taps spaced as needed though they may need to be tapped and threaded larger?

    [​IMG]

    Shows current: https://walcks4wd.com/Cross-Shaft-C...1960-1971-4-Cylinder-CJ3B-CJ5-CJ6_p_1695.html
     
    Last edited: Aug 22, 2022
  16. Aug 22, 2022
    oldtime

    oldtime oldtime

    St. Charles,...
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  17. Aug 23, 2022
    CHUGALUG

    CHUGALUG Member

    Silverton, OR
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    May 11, 2019
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    I built my 48 CJ-2A with a 9.25" clutch and improved Clutch tube and its so easy to depress I can do it standing outside the jeep with my hand. I love it. I did it as I plan on towing a 1500lb trailer including some off road stuff so the stronger engagement of the bigger clutch will be a plus.
     
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