Transmission / Overdrive: Changing to overdrive Transmission

[joenj]

Hello, I am going to change my 1950 Champion

[irish]

It's been done many times. As long as it's from another 170/185 6 cylinder it's a direct bolt-in. DO NOT switch the bell housing, just install your O/D transmission in place of the one you have in the car now. You'll need a shorter drive shaft and the other little items to operate the O/D. That's all their is to it!

Joe

[RadioRoy]

I did it to both of my 51 Champions years ago.

Everything mechanical forward of the transmission is the same (clutch, flywheel, release bearing, everything).

All you have to do is swap the transmissions and drive shafts, hook up the electrics and the cut out cable, and you are set.

If you have the overdrive transmission and driveshaft, all you need is the electrical parts, wiring harness (simple enough to make your own) and the cut out lever/cable.

Your car probably has a 4:10 rear axle and that was an optional ratio for the overdrive. The standard overdrive ratio is 4:56.

[jclary]

As far as I know, all you do is disconnect the drive shaft at the tail of the transmission...remove the four transmission to bell housing bolts... disconnect the gear shift rods, and slide the old transmission out.

Next is install the overdrive transmission. The tricky part is aligning the pilot shaft to slide through the throwout bearing, clutch spline, and into the pilot bearing (bushing) in the flywheel. Install the four major mounting bolts. Connect the shift linkage, the shorter OD drive shaft, and install your overdrive electrical wires/hardware. If your clutch, pressure plate, and throwout bearing is in good shape...you shouldn't have to mess with them. Enjoy.

[RadioRoy]

From my experience, it is safe to not worry about it and just change the parts that everyone said to change.

I will venture a guess that the difference in the clutch disks comes more from the rear axle ratio than from the overdrive. With a 4:10 ratio, the clutch is a bit fussier about engaging without chattering at a stop light than it would be with a 4:56. Maybe, just maybe, the disks have different torque absorbing springs in them, or maybe the thicknesses of the friction material are different. I welcome some discussion on that.

It's good that you looked at the parts manual, though. You are one of the very select few in forum history who ever did.

[RadioRoy]

I left the 4:10 in both of my 51's, but wished I had a 4:56 in them. 50-51 Champions are not the fastest cars around and it seems like they might benefit from a little more revving at highway speeds than a 4:10 with overdrive gives. You can drive yours for a while and decide for yourself.

[Tom Bredehoft]

Smithville, Tennessee.....hilly? you might benefit from the 4.56, with overdrive that would have a 3.17 final ratio, whereas your 4.10 will have a 2.87 final ratio, Ok in flat territory, but you'll be downshifting on the hillls.

[rockne10]

When I changed the trans in my '60 LarkVI and '63 Cruiser to overdrive I did not need to change the driveshaft but, those later T96 transmissions had the long tail shaft.
I agree you should live with your old ratio for a while before you decide its value. It may work just fine for your purpose and give a couple extra miles per gallon.

[Tom Bredehoft]

Downshifting with the OD is simple, just put the accellerator to the floor and push. Instantaneously the engine will quit, the transmission will downshift and the engine will start again. All you will notice is the dowhshift. Interstate grades may not be a problem anyway.