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rear axles options

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  • Rear Axle: rear axles options

    I need some help making a decision. Backround- the car is a 64 GT Hawk, stock 289 4 barrel, 4 speed. I am going to change the stock open rear to a Twin Traction and I have 2 options.
    First is a Dana 44 3.54 TT - 45C 45 degree rear out of a 64 GT R1 auto/ parts car
    Second is a Dana 44 3.31 TT -T 30 degree rear, no idea what it is out of but I am sure its early 56/58? It does have a drain directly in the bottom and it was drilled for grease fittings on the axle bearings.
    I am not worried about the ratios as much as which is the better rear or if there is any big difference between the 30 degree and the 45 degree models.
    Also is there a way to test the TT units , both rears have the fluid drained now.
    Is parts availability the same or is 1 more better for parts ?
    Any advice or info is greatly appreciated.


  • #2
    IIRC, the 30-degree Twin Tractions are the very early models and were superseded by the 45-degree. That Dana changed to the 45-degree would lead one to infer there is some advantage to that design. AFAIK, if you plan on rebuilding the TT and swapping gear ratios, probably should go with the 45-degree.

    There's no reliable way to bench test a TT dry. I've known people to try by blocking on axle with a bar and turning the pinion with another bar. It gives an indication of the holding torque of the clutch pack, but what actually will happen when the pack has hot lube in it is always different. No way to simulate what 300lbs/ft of torque x 2.54 low gear x 3.31 rear gear is going to do in there.

    If both rears are operational, switching them in and out is not an irreversible decision. Maybe, put them both to work and see what happens and which gear ratio you like best.

    jack vines


    • #3
      If you need new clutches, I have a source for new ones, and shipping is very fast too.
      Bez Auto Alchemy

      "Don't believe every internet quote" Abe Lincoln


      • #4
        I got some more info on the early and later TT rears today. And again I am asking for your input. I am told by a reputable shop who specializes in the older rears that the 45 degree series are the better of the two. I am also informed that the older "T" 30 degree units can be brought up to the 45 degree standards by substituting one of the early flat discs with one of the later dished ones.
        Does anyone have any experience with this before I order parts?

        Thanks, Mark