Rear axle ratio

AzBob

AzBob

Senior Member
Today, I removed the floor plate above the transmission for inspection and lube purposes on the '34. On the speedometer gear turtle, I see 11-39. Does this mean I may have a 3:54 rear axle ratio? Are there any other tell tale signs such as a stamping on the rear axle?
 
yep; on the underside of the pinion casting -the tooth count is usually stamped. Newc
 
ring and pinion and/or turtle may have been changed at any time over the years, and in addition, a different turtle gear may also have been installed into the turtle case. A simple confirmation of turtle ratio and use of a GPS while on the road to compare with your speedo can be useful.
 
If you can turn the motor with a crank you can jack up one rear wheel and with 3rd gear selected, turn the motor with the crank as the raised wheel does exactly 2 turns. The number of turns of the crank handle will be the same as the axle ratio.

I show the principle here in this somewhat old video.

https://youtu.be/bkvp3Fq21ZM

Mart.
 
Thanks all for the replies. I will be verifying using the methods suggested. I did check the underside of the pinion area as suggested and it appears 11-39 is stamped on the rear axle. Photo below.

If it is indeed a 3:54 axle ratio, I guess no need for an overdrive. As most of my driving will be around town and rural. :)
 

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AzBob said:
Thanks all for the replies. I will be verifying using the methods suggested. I did check the underside of the pinion area as suggested and it appears 11-39 is stamped on the rear axle. Photo below.

If it is indeed a 3:54 axle ratio, I guess no need for an overdrive. As most of my driving will be around town and rural. :)
Click to expand...
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