Gear ratio ? For 4.2's w/T5 & 35" tires

[Jnjcj7]

83 CJ7 shackle reverse kit, w/AMC 258 i6 / 4.2l & Dana 300 , T-5 , AMC20 , 1 piece axels, 35" tires. I know this is not a strong set up at all. This is my 3rd CJ in my 52yrs. I don't rock crawl or go mudding anymore. I just want my gears to fit the job of driving down the interstate and able to pull a fishing boat at 60mph in OD. With the stock 3.30's It barely could pull 2-lane hwy's in 5th gear w/gps saying 55 mph. There's no way it could pull a trailer or even itself at interstate speeds. So here's where I need y'all's help. I do plan on trussing the rear tubes and better tranny in near future. I drive fire roads and hook up to my boat and go fishing a lot so really looking for nice hwy speed "60-70. I'll always have low range for the tech stuff.
So anyone out there w/AMC 258 i6 / 4.2l & T-5 and running 35-36's and actually running 4.11 or 4.56's THANKS!!!!!

 

[BusaDave9]

I'd run 4.56
I have 36 inch tires and 4.88
Your right that is a very weak drive train. That T 5 has got to go. Put in a ford T-18 with granny low. Start out in 1st and top gear would be like an Overdrive .

I had a similar setup. Mine was a '82 CJ7 with a T-5 and Dana 300 . When the T-5 went out I got a ford T-18 kept tall gears in the axles but I only had 33 inch tires.

 

[Lumpy Grits]

I'm run'n 4:88 w/33" BFG A/Ts.
Love the set up.
Your axles will not last, if your hard with the fun-pedal w/35" tires.
LG

 

[Lumpy Grits]

I'd run 4.56
I have 36 inch tires and 4.88
Your right that is a very weak drive train. That T 5 has got to go. Put in a ford T18 with granny low. Start out in 1st and top gear would be like an overdrive.

I had a similar setup. Mine was a '82 CJ7 with a T5 and D300. When the T5 went out I got a ford T18 kept tall gears in the axles but I only had 33 inch tires.

That chart is for a 1:1 top gear as in 3 or 4 speed.
The OP is run'n a T-5 with OD 5th gear.
Chart really doesn't apply here.
FWIW: I'm run'n about 2700rpm at a true 65mph.
LG

 

[BusaDave9]

That chart is for a 1:1 top gear as in 3 or 4 speed.
The OP is run'n a T-5 with OD 5th gear.
Chart really doesn't apply here.
FWIW: I'm run'n about 2700rpm at a true 65mph.
LG

True, the chart is for 1:1 gear. (4th gear). When a manufacturer puts in an Overdrive Transmission they don't lower the axle gears. 4th gear is high gear and 5th is Overdrive and therefor lowers the rpm even further.