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50 Merc Overdrive, How Strong?

Discussion in 'The Hokey Ass Message Board' started by 87Heaven, Jan 6, 2011.

  1. 87Heaven
    Joined: Dec 20, 2009
    Posts: 71


    I am in the process in building a strong 276" 8BA.
    I have available to me a good 3 speed overdive from a 50/51 Merc.

    How much horsepower or torque can this tranny take?

    I'm thinking 411 rear end, 9" Clutch, medium sized tires (not too sticky)
    The OD would be nice if its strong enough..

    It would be in a 40 ford deluxe coupe.

    I'm not expecting 4000 rpm clutch popping starts but I would like to get on it from time to time
    without worry about picking up the pieces:)

  2. used to say as long as you can break the tires loose you don't have to worry. had a friend with a 450 horse nailhead in his merc with stock trans. didn't dump the clutch and never speed shifted even when racing. probably still running skinny bias ply tires today
  3. It'll be fine.
  4. Dale Fairfax
    Joined: Jan 10, 2006
    Posts: 2,585

    Dale Fairfax
    Member Emeritus

    The '49-'55(?) Ford /Merc transmissions and Overdrives were Borg Warner T-86/ R-10. Back in the day we abused a lot of Ford drivelines and never hurt an O.D. unit but we sure trashed a lot of transmissions. You're probably O.K. but if you have real concerns, look for the T-85/ R-11 combination as used in '49-'51 Lincolns and later ('57(?)-'62 Fords and Mercs. Somebody out there knows the exact years for each.

  5. Fred A
    Joined: May 3, 2005
    Posts: 288

    Fred A
    from Encino, CA
    1. Upholstery

    In the sixties, my '40 coupe ran a '42 Zephyr side shifter with a R10 overdrive in front of V8-60 rear gears. Was a wonderful set of ratios for the J-2 Olds. Worst part was having to modify the crossmember for the overdrive. I twisted an axle and knocked out the trans a couple of times while acting up or offroad abuse. With bias plies the tires would break loose easily and protect the weaker trans. The 25 tooth gear also softened the shock of bad clutch work. Good Luck: Fred A
  6. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,307

    from Quincy, IL

    I agree with both recommendations for consideration.........while the stock trans would probably be okay for most of your driving, I remember guys "back in the day" ripping cluster gears out of stock Fords and Mercs with some regularity when they got on it. The T85, with or without OD is a stout box, but Skidmarks is correct that a T-5 is a more readily available and less complicated install and offers plenty of strenght to boot. Your call. Have fun whatever you deceide.


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