Re-Gear?

[97JadeTJ]

Hey you gearheads…. My new 97 tj has the I6 rh32… build sheet says it originally had 3.07 gears with 30” tires… it currently has 33’s on it and drives ok so I figured it had been re-geared so I did some math and it appears that it has been re-geared to 3.55… would it be worth it to re-gear it to 4:10 or 4:56 from 3.55… i realize I’m driving a brick but I’m only Getting about 10 mpg, I figured on at least 13-14, he’ll the 4 banger got 14…

That is all…

 

[Jerry Bransford]

4.10 would be the correct ratio for 33's with your 3-speed automatic. Personally I'd regear but while slightly better mpg is likely it certainly won't be enough extra to pay for the regearing lol in most people's lifetimes lol. I would not even consider 4.56 due to your particular transmission, the highway rpms 4.56 it would produce would be excessive.

 

[97JadeTJ]

4.10 would be the correct ratio for 33's with your 3-speed automatic. Personally I'd regear but while slightly better mpg is likely it certainly won't be enough extra to pay for the regearing lol in most people's lifetimes lol. I would not even consider 4.56 due to your particular transmission, the highway rpms 4.56 it would produce would be excessive.

sounds Like a plan… build sheet says it has a trac-loc rear axle so that’s a plus also…

 

[97JadeTJ]

While I’ve got your attention… it also has a 4” pro comp suspension lift with non adjustable pro comp LCA and stock UCA and a 1” transmission drop… i had a 2.5” suspension lift and a 1.25” body lift on my 4 banger and didn’t have any vibrations… if I take the transmission 1” drop out will it more than likely have vibes and is a sye the fix if i do? And do I need adjustable Control arms?

 

[Jerry Bransford]

While I’ve got your attention… it also has a 4” pro comp suspension lift with non adjustable pro comp LCA and stock UCA and a 1” transmission drop… i had a 2.5” suspension lift and a 1.25” body lift on my 4 banger and didn’t have any vibrations… if I take the transmission 1” drop out will it more than likely have vibes and is a sye the fix if i do? And do I need adjustable Control arms?

Yes you'll get vibrations with your 4" lift if you remove the tcase drop. A SYE and DC driveshaft is the cure but you'll also need adjustable length control arms for the rear so the pinion angle can be raised for the DC (double-cardan) driveshaft. If you can't afford both upper and lower adjustable length arms go with uppers. They'll help move the axle back some when you lengthen them to raise the pinion angle. That helps to partially compensate for the 4" lift having shortened the wheelbase by pulling both axles slightly closer to each other.

 

[97JadeTJ]

Yes you'll get vibrations with your 4" lift if you remove the tcase drop. A SYE and DC driveshaft is the cure but you'll also need adjustable length control arms for the rear so the pinion angle can be raised for the DC (double-cardan) driveshaft. If you can't afford both upper and lower adjustable length arms go with uppers. They'll help move the axle back some when you lengthen them to raise the pinion angle. That helps to partially compensate for the 4" lift having shortened the wheelbase by pulling both axles slightly closer to each other.

Thanks!