Auburn Columbia 2-speed rear axles

Auburn transmissions were 1-1 in high gear If an overdrive is installed between the transmission and the rear differential there will be a greater than 1-1 going into the rear differential. There is no overdive in the rear differential. When the high range of the dual ratio is engaged, ratio will be lowered approxmately one point.

the ratios are:
51-10 5.1 652-850Y
41-9 4.55 851 (ser 1772-2745)
47-10 4.7 653
43-10 4.3 851 (after 2743)

So the highest ratio when the dual ratio is engaged is roughly 3.3

Ratios vary. and those printed in my owners handbook are not quite accurate, but high range is an overdrive.
Cheers, Bill Snelson.

What are you planning on using it for?

I don't know the exact answer to your question and some else will help but I can say that a 35/36 Auburn in "high" range will cruise at 65 with fair comfort.

Is the Auburn Columbia two-speed rear axle's final drive in the high range an overdrive or is it a 1:1ratio. If it is not an overdrive, was an overdrive unit available for it that could be added on to the differential as used on Fords and Lincolns ?

Thanks,

Gary