I've got a 81 CJ7 that I want a 5 spd tranny in to get better MPG because I have the 4 spd. I found a AX-5 tranny but arn't they just for 4 bangers? And i read something about the T-5 only fitting 82-86 cjs? Any opinions on a tranny and how much of a difference it'll make to my MPG?
Alright, sorry bout that and i've got 33"s on 4.10s and the 258 6 cylinder. Never heard of the term R&P?
R&P = ring & pinion.
What RPMs are you seeing at 65mph. TRUE 65mph. NOT what your speedo sez. You'll need a GPS for true ground-speed.
My '85 CJ-7 has 4:56 R&P, 33" BFG's and a T-5.
I start out in 2nd on the street and at 65mph in 5th. I'm run's 2550-2600rpm's
My tach stopped working but I top out somewhere around 60 mph, I'm guessing 2900-2800 rpms lol I went from a 2.73 R&P to the 4.10s and lost like 10 mph and some mpg. I don't get it lol Only thing I could think of was the tranny.
Don't hit kids, no seriously they have guns now.
Get your tach fixed, then you will know for sure of what you are talking about.
The 4.2L, 6 cly. 'red-lines' at 4500rpm.
Your 'topping out' could be ign. timeing or carb. or BOTH.
My stock 6cly, 4.2L, 'pulls' all the way to red-line, and that is with 118K miles on it.
I have 33's, 3.31, T-5 and 258 and cruise down the fairly level highway in 5th at 65mph and at 1500rpm. After getting timing, plug gap and carb better tuned, it does fine against some incline and 20mph wind with room left to pass while still in 5th. Feels more like a diesel now with more lug. I go from 1st to 4th pretty quick.
Read all about the T-5 and its weaknesses. It's been doing alright but over the past year it's slowly been doing some strange things and I wonder how much longer before a rebuild.