Author Topic: Third member gear ratio (Read 2294 times)

Quadromaniac · « **on:** January 18, 2015, 08:21:34 AM »

I just discovered that my 53 Allstate has the 4 cylinder without overdrive rear end Gear tag 47/11. The car came to me 4 cylinder, with an overdrive installed. I now have a 6 cylinder with overdrive in the car. Will that gear ratio present any kind of a problem?

kaiserfrazerlibrary · « **Reply #1 on:** January 18, 2015, 10:29:49 AM »

It's simple. First verify the ratio by dividing the larger number by the smaller number; that gives you 4.27:1. While the B-W overdrive was set up to work with 4.55:1 past "tests" with Kaisers indicate a bit better gas mileage, otherwise the engine won't wind quite as much.

joefrazer · « **Reply #2 on:** January 18, 2015, 01:50:27 PM »

My 50K Traveler has a 4.27 rear axle and was originally equipped with a standard transmission. I added OD and the results are lower engine rpms and a bit better gas mileage. I won't beat anyone off the line in a drag race, but I will go farther on a tank of fuel!

Fid · « **Reply #3 on:** January 18, 2015, 04:09:52 PM »

The four cylinder has a much longer stroke than the six and can be wound out to a higher RPM. The six does not work well at all with the 41/9 (4:55) unless it has an OD transmission. The 41/10 (4:10) works well in the six with or without OD. The 47/11 (4:27) may not work well with a six. It's a much higher ratio and the six has a short stroke so it's likely not going to be very good off the line. There are plenty of people making hot rods out of Js, so it shouldn't be too difficult to find a 41/9 or 41/10. I would keep looking for one. There's a 41/10 that keeps reappearing on ebay. Watch for it.

Corsairdeluxe · « **Reply #4 on:** January 18, 2015, 05:00:00 PM »

My experience in winding up a 4 cyl. was an expensive one!

Quadromaniac · « **Reply #5 on:** January 22, 2015, 09:03:00 PM »

Thanks for the information. I guess I am going to try it as is, and I did pick up a complete rear end axel assembly with the correct gears if I don't like what's in there now. I just don't want to change it out if I don't have to.