Hi I have a 94 yj 2.5L with 31x10.5 tires and 3 inch lift. i have 4.10 gears as of now. my truck is on its last leg so i need to start using the yj for daily driving, so it will be getting alot more hwy miles on it. im running about 3000 rpm at 65 now but like all others i cant get it in 5th. what dirrection should i go with new gears 3.73 or 4.88 i read different sites and just get more confused. like i said im not mudding or hill climimng with it.
05-09-2013 07:47 PM
4.88. You don't need those gears though unless you get 35s
05-09-2013 08:26 PM
4.56 would be a good highway gear for the 31's. 4.88 for 33's.
3.73 would make it worse than it is now.
But you have to realize that you have a 4cyl. the 4.10's in it stock, are designed for stock tires which are about 27-28 inches tall. The 31's are not only taller but also heavier to haul around. Moving up to a 4.56 will allow you to use 5th gear more often, but you will have to downshift on any slight grade (only a 4cyl).
05-09-2013 09:48 PM
I would go as high as you can, so 4.88.
Cant be as fun as what I am doing now with 3rd gear at 3100rpms on the freeway haha
05-09-2013 11:51 PM
Are you trying to get better gas mileage? Or, are you just concerned that you can't use 5th gear? I run 31's on the stock 4.10's at mile hi altitude and have no complaints. Although, soon I am upgrading to 33's and will definately be gearing to 4.88's. But I wheel up to 2 mile high altitudes and get 20 mpg's.
05-10-2013 06:09 AM
better gas milage would be nice, but i do understand what im driving. Im more concerned with putting to much stress on the engine while driving on the hwy/interstate in 4th. as of now 5th is usless to me all the way around. even at 50-55 i can feel the struggle the engine is taking in 5th. by the way i live in south ga so its mostly flat
05-10-2013 06:27 AM
I am running 4.88's with 33" tires. Your 94 should do a little bwttwr than my 90 as afr as power due to mine being throttle body still.
I am at 3000 rpm in 5th gear at 70-72 mph. Just keep in mind no matter what you do to it the motor will still be gutless. The. lower gears do help a lot, but probably not as much as you think it will.
I am in the process of building another set of axles and 5.34 ratio to run 37 Hummer wheels. At this point it will be an off road only vehicle so then I will not get passed by angry people with mopeds on the road anymore