31pickemup (9/6/2014)
I'm putting a 292 in my 32 3-window and am wanting to stay with a period transmission. Which Borg Warner T-series 3spd OD transmission should I be looking for? Also any specific ratios?
Ted's covered this pretty thoroughly. The T-85 is THE 3 speed w/ od that jumps out in my mind as a '50s, '60s period RUGGED unit. I'm not sure on this point, but somewhere I picked up that not all B-W manufactured T-85 ods had the R-11 overdrive units. Some T-85 ods used in other make vehicles may have had the R-10 overdrives. I don't think that FoMoCo used any of the T-85s with R-10 overdrives behind them.
The R-11s have four planetary gears while the R-10s only had three. The R-11s are a more rugged unit.
The T-85s with R-11 overdrives used in post (?) '57 (?) FoMoCo cars used a 23 spline input shaft and a 31 spline output shaft. The earlier FoMoCo cars used the 10 spline input shaft and a 16 spline output shaft. IF you go with a Ford application T-85, I don't think that there is any variation in gear ratios available. Also, across all vehicle applications, none of the T-85s have a synchronized 1st gear.
The earlier Ford application 16 spline output shaft has historically given people a fit finding a driveshaft yoke to mate with it. The original Spicer unit has been out of production for a long time. About two years ago, I learned from an old time salvage yard operator (LOL, likely my age or younger!) that the driveshaft yoke for '55, '56, and '57 Mercs were the same for the T-85 (3 speed OR 3 speed w/ od) and the '55-'57 Mercury auto trans. In looking at a friend's '56-'58 Mercury parts book, I verified that the '56 and '57 yokes are the same '56 number. I haven't verified the '55 yoke interchangeability. I think that this information increases the chances of locating the appropriate 16 spline driveshaft yoke significantly.
Just to muddy the waters, I was told by a fellow Forum member that one of our members had accomplished mating a Ford application T-10 (4 speed) with an R-11 overdrive unit. I don't know how that was done nor do I recall who I was told the Forum member was.
With the lightweight vehicle you're building, three, four, or even five gears forward is likely immaterial. Those of us with heavier vehicles like the four or five speed transmissions for the windy roads and varied terrain we travel to improve our vehicle's performance and driving enjoyment.
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Here's something from an earlier posting that is somewhere in our Archive:
Feature Article from Hemmings Motor News
December, 2006 -
Jim O'Clair Few transmissions can claim to be as popular with American manufacturers as the Warner T-85. From the mid-Fifties into the early-Sixties, you were likely to see it mounted behind the engines of most U.S. car makers. The helical-cut gears offered in the T-85 made it a much quieter transmission than its predecessors, which lent to its popularity as standard equipment in many three-speed applications during that time period. Some manufacturers such as American Motors and Ford added an electric overdrive, also designed by Warner, to the tail housing to make this transmission more reliable at highway speeds and more fuel-efficient. The T-85 was also the transmission that Warner tinkered with to build its most popular four-speed transmission, the T-10. The T-85 is popular with many classic car enthusiasts because it can be installed behind just about any engine size and can handle the higher torque and horsepower engines with ease. Although not used in any Chevrolets as original equipment, the T-85 will replace the weaker Saginaw three-speed with minimal installation problems.
The T-85 has a 9-bolt D-shaped side cover to access the gears and side-shifting linkage so the T-85 shares those same features with the T-10. The case is 9 1/2 inches long and made of cast-iron, making the T-85/T-89 transmission both very strong and very heavy. [A '57 'Bird T-85C-1A w/ overdrive weighs ~ 140 lbs.!] Its initial use was in performance V-8 engine applications such as 1955 Packards, Mercurys,1956 Studebakers, and the supercharged 1957 Ford Thunderbirds. First gear was not synchronized, although second and third gears were, using 36-tooth bronze synchronizer rings. The T-85/T-89 uses a four-step cluster gear.
The major difference between the T-85 and T-89 transmissions is the mainshaft; the T-85 uses a helically cut mainshaft, whereas the T-89 has a straight-cut mainshaft. When Warner built the T-85 into the T-10, it put the fourth gear in the reverse position in the gear case and moved reverse back to the tailshaft. The high-ratio non-synchronized first gear allows you to shift into second gear at a higher rpm, but this also makes it very difficult to downshift from second to first at speed. Shift ratios were either 2.53 or 2.49:1 for first gear, 1.59:1 for second gear, and 1.00:1 for third gear. The reverse ratio was 3.15:1. Truck ratios were 2.99 or 2.97:1 for first, depending on year and model with 1.75:1 for second and 1.00:1 for third. Reverse remained at 3.15:1. The input shaft is 1 1/8 inches in diameter in most passenger car applications and 1 3/8 inches in the Ford trucks, and has 10 splines. The clutch outside diameter varies between engine sizes and manufacturers, but both the friction disc and pressure plate were available between 9 1/2 and 12 inches.The casting number on the passenger side of the transmission is another easy way to identify the T-85. The transmission model is part of its casting number, usually with an additional letter designation after the T-85.
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Hope this helps.
a.k.a. Charlie Brown
near Syracuse, New York