1940-41 Overdrive trans and rear...how do you tell???

[Rolf]

Hi Dave, love these softball questions, for once I can be reasonably certain I am right, the only OD the '40 and '41 shared, was the Columbia 2 speed axle, the drive shafts and transmissions were the standard 3 speed column shift unit with the 26 tooth cluster gear instead of the later 25 tooth gear, in 1941, you had the option of 2 OD's, the afore mentioned Columbia and the new that year Borg Warner electric transmission Overdrive, both were optional in 1941, giving you a choice of 2 transmissions, and 2 differentials. The '41 BW OD trans differed only slightly from the '42-'48 units, except for one model of the later ones that required a wider mounting than the earlier type, both types are clearly pictured in the chassis parts catalog, the trans OD requires a shorter drive shaft and torque tube, but are all the same '41-'48, think that covers it, let me know if I can be of anymore help, interesting bit of trivia on this subject is that LZ won a national economy run for it's class in '41 by using BOTH the BW and Columbia, must have had a gear ratio close to 1 to 1 with both in OD, Rolf

But how do I tell by looking at it?

[Rolf]

Check the attachment here, or if that does not work, e-mail me at rolf@sasquatch.com and I will send you a pic of an OD transmission, OK? Rolf

Thanks got the pic of the trans. Mine looks much smaller. Do you have a pic of a 1940 regular trans?

[Rolf]

No, but it looks just like the front half from the back edge of the cover to the front of the trans, same trans gears and shift cover, just the longer tail housing and the actual front case are different, if you have ever seen a '40-'48 Ford transmission, you have to look twice to distinguish it from a conventional Lincoln, curious why you want to know?? R

We did not get the car with a transmission in it and have to guess which goes in it by the distance available.

[Rolf]

Ok, wish you had relayed that info at the start, take your trusty measuring tape, and measure the distance from the front end of the torque tube to the back end of the bellhousing, this should tell the tale, and this will only be critical in a '41, if it is a '40, it should only be a standard 3 speed transmission, with no OD, if your car is indeed a '41, there should be tell tale signs of whether it was an OD car or not, an ivory knob on the left side of the steering column, under the dash with an O on it, and a kickdown switch under the gas pedal, and a OD relay, resembling a voltage regulator on the engine side of the fire wall, if you need either of these transmissions, I can provide sources, Rolf

This is a mid-engine race car so please understand the drive shaft was shortened and need to figure out what tranny came in it.

[CBoz]

If it's that heavily modified, I'd say all bets are off as to what was in it. But I can't imagine a race car with an OD?