Picking a rear gear .....

shaune

shaune

Well-Known Member
Supporting Member
Math isn’t my forte so I shy away from anything with math. I am wondering how you choose a rear gear ratio for a build ? I know factors will be intended use, transmission ratios and tire size ... again, math :confused:
What would be a ratio for my 9” in my 52 Ford truck. A fuel injected 428, thinking a 4R70W trans, highway cruiser but still want to peel some rubber off the back tires when the girls are watching. Thinking 3.0 or 3.25 ..... thoughts ?
 
Well, I personally love the 3:54 ratio, that’s what I’m running in the 60 for my Satellite and I just changed my model A over to 3:54’s as well. With the ratios that are in the 727 for the Satellite, RPM’s are somewhere around 3000 @ 120km/h. I personally would rather have the higher torque and the set ya back in your seat lanch then the go fast. But that’s just me. If you’re planning on doing lots highway cruising 3:54’s, I think, would be good with an overdrive, with out, might be a bit much. I’m by no means an expert though lol.
 
Shaune I have 3:55's in my delivery without an overdrive, not a bad gear at all for around town but a tad low for highway driving (it can be done but rpm's are up there) like Taggart says with an overdrive I think it would be just right. Wish I had the room to put one in. :(
 
In my 56 F100, I had 3:50 LS and a 5-speed with a 0.64 fifth gear with a dual quad 429. Worked like a charm on the highway but found more times than not I was always dropping down into fourth due to congestion or getting around slower vehicles.


With the '52, installed 3:55 posi as that's all I could find on short notice to replace a broken 2:78 open. Rev's somewhat higher but better than running 3:73 or lower.

My preference was for 3:25's or 3:31's.
The '52 has a 360HP 350 teamed with a turbo 400 tranny.
Looking at going to a a 200 or 700R that has an overdrive would help.

3:00, 3:01 or 3:08 are great for the highway but poor on the launch.
 
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