Ring and Pinion gears?????

[kufd]

can I have some opinions/advice? I have a 1976 CJ7 with 33inch TSLs on Dana 30 and AMC20 axles. currently have stock gears of 3:54 and both axles are open (no lockers, as of yet) I wanted to do a lower ring and pinion ratios: availible to both axles are 3:04, 3:73, 4:11, 4:56, 4:88

I was torn between 4:56 and 4:88!?!?!?!

my engine is a 283 Chevy small block V8, with TH350 trans and dana 300 Tcase. I dont do rock crawls, just sand, mud, and mountain trails. I also plan in future to someday run 35inch tires.

thank you for the feedback.

 

[CJ]

Well, I can say this... This question will most likely get five different answers from five different people... It's kinda subjective...

You left out one very important thing, how much highway and at what speed? If you plan on doing any highway driving I would go with 4:11.

I have 4:56's in my CJ with 33's and it is purring at 70! From my experience, I won't be going lower at all.

 

[kufd]

sorry, I forgot about the highway stuff. anyhow im from Hawaii so our roads dont go very far, and 50 MPH is usually the fastest you can go. LOL

for reference I drive about 10% of my time on road, just to get to the trails. and 90% is off road. while on the road for short time, I usually go 40-45mph and my current rpm is 2100.

 

[CJ]

By using your numbers. With 33's @ 45 mph, 3.54 gears and turning 2109 rpm you final gear ratio is around 1.3

By changing to 4.56 = 2716 RPM
and 4.88 = 2907 RPM

Change the tire size to 35's
3.54 = 1988 RPM
4.56 = 2561 RPM
4.88 = 2741 RPM

You can see how the ratio affects the rpm by the above list. If you are only doing 10% on road, IMHO - I would go with 4.88. As long as that 10% is realistic...

 

[kufd]

thanks alot bro, that is some good feedback for me to look off of. nice rpm calculations/chart.

aloha

 

[coolman009]

Hey that was a cool RPM chart calculator. Dint knew we had such great stuffs out here.
Well I personally use 4:56's in my CJ and really roaring at 60.!
Newaz, nice detail info.!