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Allison Transmission Question

8569 Views 5 Replies 5 Participants Last post by  pera730
I just finished rebuilding the 6-71 for the TDH 4512 listed in my Sig. The Allison V-Drive (pretty much the most bullet proof transmission I've ever seen) is in excellent shape and doesn't need any work.

However, it still has the original fluid in it from god knows when in the '70s. The GM manuals, which date from 1955, call out a GM part number for the fluid that is now meaningless. The trans fluid looks like clear hydraulic oil, and I'm wondering if anybody knows what a good replacement for it would be, or whether Dexron III would work as well.


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OK going from memory here back in the 70's the Allison V-drive used straight 30 weight motor oil. I don't remember if it was regular or Non-detergent. Yep a very bullet proof tranny. Kinda like a powerglide for transit busses. Had 2 speeds forward, low was to get you moving and then when it got to 20-30 mph (depending on gov. setting) it shifted into direct drive and locked up the torque converter. The only down side of the V-drive was getting them in gear with an ice cold tranny. Lots friction with that cold oil and some gear teeth grinding until they all stopped. Another trick on the 70's vintage units, there was a switch in the shifter that was activated when the lever went into the F or R slot. The clutches didn't engage until the switch was closed. You could release the clutches without taking it outta gear. Kinda fun playing with a rookie driver, just slip the lever out of the slot when he wasn't looking and the bus doesn't go anywhere. Spent a few years going around in circles at the wheel of a transit bus back in the 70's.
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