Perkins Diesel Cj Axle Ratios

Working on a story for Diesel World magazine on the Perkins powered CJs. I have never found any literature that lists what axle ratios were used in CJ's with the Perkins diesel. One brochure say the axle ratio was changed due to the lower rpm capability of the diesel vs the gas but doesn't specify. Had to be taller than 5.38:1 or even 4.27:1 or the thing could only do 45 mph. The Parts Peculiar book doesn't list anything. I know there are a couple of "Perkies" here so maybe someone can give me a quick answer. And it need to be quick, as my deadline is almost up. I was counting on someone who claimed to have literature on it.... but didn't. Many thanks.

 

I don’t see any specific ratios for the diesel. I’ve just seen 4.27’s and 5.38’s listed during those years the Perkins was offered.

 

This calls the drivetrain to be the same.
Remember the 134 isn't any faster.

1966 Jeep CJ-5 Perkins Diesel - Jeep Encyclopedia

 

I didn't even notice they had the same name.

Personally I *thought* they had 4.27s but it's been 10 years since I looked closely at one in person.

 

When I got mine it had 3.73, but the previous owner stated he'd had the ratio changed. I assumed it came with 5.38 due to his description of how slow it was. I've since swapped in 4.27's with an overdrive and I think that ratio with an overdrive is about as good as it gets. Slightly lower would be nicer (T98 option), but if I went lower gears, highway driveability would suffer. They have a pretty narrow RPM range.

I've never taken a sample from any of the owners that have one (very few at any rate) of what gear ratio theirs had. Mine will likely forever be an unknown regarding what ratio it left the factory with.