Gear ratio

[Rotorhead907]

Hello. I did a 4 inch lift on my cj5. It originally had a 2 inch lift with 31 inch tires. I put 37 inch tires and they clear the front pretty good. No rubbing. It has an AMC 20 rear and a Dana 30 front. The rear axle is stamped "A" meaning it came with a 3.54 gear. The P O. I bought it from said he changed it out to 3.73. I took the rear diff cover off and counted the teeth. Yup, 3.73. So with the 37 inch tires, I know I have to re gear. Question, what kind should I get? The engine is a rebuilt 258 with a 2 barrel Ford motocraft 2100 carburetor. The transmission is a 4 speed manual T-18 transmission with a granny 1st gear. I will be using it as a daily driver and will be 4 wheeling in the dirt, sand, and hills. Nothing wild. I saw the chart and I could go up to 4.88. Any advice will be great. Oh, and where can I get a rebuild kit for the front and back axle? A full kit, no just the ring and pinion. Thanks, Mark.

 

[Rotorhead907]

Oh, forgot. It is a 1980 cj5 Renegade with the narrow AMC 20 axle and Dana 30 front axle. Thanks, Mark Feuerherdt.

 

[Jeepergeo]

That's a lot of tire diameter for those axles. I'd be more concerned with stopping power and axle strength than gearing.

Assuming you have the braking issues addressed, those 4.88s will sure help over the 3.73s. Steeper would be better, but it sounds like 4.88s are your limit.

 

[Rotorhead907]

Thanks for the info. 4.88 ok. What do you mean by steeper, and why? My brakes are ok. Front disc's and drums in rear. No problems with stopping. I do plan on doing a rear drum upgrade with new shoes, etc. Thanks, Mark.

 

[JPNinPA]

The D30 lowest ratio that will fit is 4:88. Lower will give you more torque at the tire. 4.88 is just enough.
I’d price out a axel rebuild and compare against a swap to bigger axels. With disc brakes all around. The D30 is weak for 35s and wheeling. 37s do not maje it easier. You could do some searching and save/avoid trouble of rebuilding broken axels.



Sent from my iPhone using Jeepz.com mobile app

 

[Rotorhead907]

Thanks for the reply. I have one piece axles that the P.O. had changed out from the original 2 piece that it came with. I rarely go over 65 mph as this is my daily driver in the summer, and I plan on having it shipped by barge to Costa Rica in 2020. Any place where I can look up to purchase 4.88 gear kit for front and back? I need the rebuild kit not just the pinions only. Thanks, Mark.