Gear Advice.

[grimhelm]

I have a 2000 Cherokee I recently put a 4.5" lift, 33" tires and a hack and tap SYE. I'm about to take out the Dana 35 and put a Chrysler 8.25 in the rear with gears, Detroit True-Trac, and rear discs out of Grand. Its a daily driver with weekend fun. It also pulls a pop-up tent trailer that can weigh around 3500lbs when loaded for the weekend. I drive to Reno about 35 miles on the freeway quite a bit. My question is with 4.56 gears and an auto trans what rpm does the engine rev doing 75? Also with 4.10 gears and auto what rpm does the engine rev doing 75? I'm stuck at what gears to have put in soon. I'll have to do the rear first then the front at the beginning of the summer. Probably change to High Pinion on the front axle, upgrade the ball joints, axle seals, u-joints, and an E-Locker in the front. Later might put coil spacer and leaf spring shackle to get me close to 6" lift and run 35" tires. Any advice on what rpms the motor runs at or gears would be best would be appreciated.

[Mudderoy]

I have a 2000 Cherokee I recently put a 4.5" lift, 33" tires and a hack and tap SYE. I'm about to take out the Dana 35 and put a Chrysler 8.25 in the rear with gears, Detroit True-Trac, and rear discs out of Grand. Its a daily driver with weekend fun. It also pulls a pop-up tent trailer that can weigh around 3500lbs when loaded for the weekend. I drive to Reno about 35 miles on the freeway quite a bit. My question is with 4.56 gears and an auto trans what rpm does the engine rev doing 75? Also with 4.10 gears and auto what rpm does the engine rev doing 75? I'm stuck at what gears to have put in soon. I'll have to do the rear first then the front at the beginning of the summer. Probably change to High Pinion on the front axle, upgrade the ball joints, axle seals, u-joints, and an E-Locker in the front. Later might put coil spacer and leaf spring shackle to get me close to 6" lift and run 35" tires. Any advice on what rpms the motor runs at or gears would be best would be appreciated.

4.10's would be the proper gear ratio for best fuel mileage. 4.56 for 35's.

[OrangeXJ]

If you are in hills or mountains and going to pull a trailer I would use 4:56. The chart I looked at shows 2565 rpm @65 for 4:10 and 2845 rpm @65 mph. with 4:56 @ 75 I would guess with either gear it would be between 3100-3500 rpm.

[Mudderoy]

If you are in hills or mountains and going to pull a trailer I would use 4:56. The chart I looked at shows 2565 rpm @65 for 4:10 and 2845 rpm @65 mph. with 4:56 @ 75 I would guess with either gear it would be between 3100-3500 rpm.

80 mph is 3k rpm in over drive. This causes excessive engine cooling temps on my 4.0l if air temps are high. I have quite a bit of additional weight on mine, but I believe 4.10s would drop the rpms and the 4.0 would run a little cooler.