Looking to get rid of the torque tube 50 sedanette,
Published on 01-17-2014 08:34 AM
Go to a salvage yard and find a 50+ Olds/Pontiac with the 3 speed tranny. Get one with 5 bolts on the top cover and the same shifter inputs on the driver's side of the tranny as your Buick's. It's the same gearbox as what you currently have except it has an open drive on the tail shaft end. The input shaft may be a different length than your Buick's 3 speed. Swap most of the guts from your Buick's tranny inside the Olds/Pontiac gearbox case, retaining the latter's output shaft and tail shaft housing. You'll need the Olds/Pontiac driveshaft and rear axle as well. The 49-51a Olds 88 has coil sprung rear axles. You'll want the short cross member that is riveted/bolted to the Olds frame (just behind the X member) and the trailing arms as well. Basically you're converting the Buick to an open driveline using similar Olds rear suspension. It's often called a Nascar suspension and was used in 60's Chevy trucks as well.
Manual transmissions come in multiple flavors, and like the Automatics, Pontiac did not make their own, rather acquiring them from the Buick, Chevy or Oldsmobile Divisions until 1958, at which time Borg-Warner also became a supplier.
1937* - 1955 = Buick Light-duty 3-speed w/5-bolt top cover
1956 - 1957 = Buick Heavy-duty 3-speed w/6-bolt top cover
1) 1937-38* floor-shift tops bolt to the later trannys, the Light-Duty stick using 5-bolts, the Heavy-Duty stick using 6-bolts. It is not necessary to remove the column-shift selector mechanism, only the stamped-steel top cover...
2) Although the Buick manual gearboxes are the same as those used in Pontiac and Oldsmobile, the extension housings are different. Buick used a torque-tube (closed) driveshaft, while Pontiacs and Olds used an open drive shaft. To switch between, you need the open drive mainshaft and the rear extension housing. The case and the gears are the same, within types...
3) Attempting to use the "good" 1956-57 Buick trans or one of the B-W's in a 1956-56, requires a modified driveshaft, as the big transmissions are a couple of inches longer than than the little ones, AND the 1949-56 Olds rear end is much smaller than the big 1957-64 Olds/Pontiac unit...
Like the automatics, the manuals come in different lengths as do the driveshafts, and the front yoke needs to be a 10-spline item, which are pretty scarce these days. Of all the manuals, the 1956-57 units are by far the strongest (and nosiest!), with gear width(s) nearly double that of the Borg-Warner T85 or T10 units...