Dana/Spicer overdrive question

[1951 Mack LJ]

I am working on my other truck which is a 1958 Pete. The main box is a Spicer 8051 and the Aux box is a Spicer 8341C. When I was looking up the ratios for both of these the main had a 0.67 od and the aux has a 0.84 od. So don't you just multiply the two numbers together to get the combined ratio which comes out to 0.56 I have still to look for the axle ratio but thought 0.56 double over seemed like a lot. What is your thoughts?

[fifth wheel]

Or you can do it this way,

1.00 divide .67 = 149.2

149.2 divide .84 = 177.6

1.00 divide 177.6 =.563

FW

[57 bcr]

The overdrive gear in my T2070 was .60 : 1.With 5.55 rears, 2100 rpms,11R22.5 rubber,I still topped out at 72mph. I believe the double-over quads were real close to that (.60+or-).Not impossible,for sure! Al

[David]

I am working on my other truck which is a 1958 Pete. The main box is a Spicer 8051 and the Aux box is a Spicer 8341C. When I was looking up the ratios for both of these the main had a 0.67 od and the aux has a 0.84 od. So don't you just multiply the two numbers together to get the combined ratio which comes out to 0.56 I have still to look for the axle ratio but thought 0.56 double over seemed like a lot. What is your thoughts?

Yes. You multiply the ratios to get the final ratio.

[1951 Mack LJ]

OK. Thanks for the info guys. I don't see this old truck needing to go faster then 60 if even that. I am waiting on getting the radiator back. Of the two cores I had neither were worth fixing so I am forking out $950 for a new one.