AFFsoc2586

Hey guys, im knew to this whole forum thing. But i hope i posted this in the right area, if not please let me know. Well here goes, im in college right now im very hands on when understanding what im dealing with. I guess my question is i have a 1994 cherokee 5sp 4.0, and i have several questions. First off what the rear axle are in these, what gear ratio do they come with. And with the rise in gas prices and from reading some other posts, im looking for a new gear ratio setup for better mpg. I currently get around 13-16 highway with factory gear ratio and larger diameter tires, not a huge jump in tire diameter, but a little bigger. Now what gear ratios are there, whats the install like, prices oh and i do a little towing of a trailer max load of about 1 1/2 tons at max, but never really put that much in it. And maybe only used a hand full of times for towing. Mostly highway and local driving. Thanks for help and if you have any questions that you need answers to let me know.
THanks again
Also what how does the whole gear ratio work. as in the lower the number the samller the gear, which makes it longer for the enginer to gain speed.. etc.

AFFsoc2586

Hey guys, im knew to this whole forum thing. But i hope i posted this in the right area, if not please let me know. Well here goes, im in college right now im very hands on when understanding what im dealing with. I guess my question is i have a 1994 cherokee 5sp 4.0, and i have several questions. First off what the rear axle are in these, what gear ratio do they come with. And with the rise in gas prices and from reading some other posts, im looking for a new gear ratio setup for better mpg. I currently get around 13-16 highway with factory gear ratio and larger diameter tires, not a huge jump in tire diameter, but a little bigger. Now what gear ratios are there, whats the install like, prices oh and i do a little towing of a trailer max load of about 1 1/2 tons at max, but never really put that much in it. And maybe only used a hand full of times for towing. Mostly highway and local driving. Thanks for help and if you have any questions that you need answers to let me know.
THanks again
Also what how does the whole gear ratio work. as in the lower the number the samller the gear, which makes it longer for the enginer to gain speed.. etc.

Bustedknuckle

I merged your threads. Asking the same question in 2 sections won't net you a faster answer, it'll just attract the attention of the staff, and may annoy other users.

For any questions related to O.E.M (Original Manufactures Equipment) aka questions or problems about stuff that came with the Jeep from the factory, use the "OEM Cherokee Tech" section. For anything aftermarket, or stuff you add to the Jeep, use this section, the "Advanced Cherokee Tech". Since you were asking about gears, and about UPGRADING gears, this is the better section for it.

Anything else, just ask. Thanks!

93gc40

You should have 3.07 gears now. What size tire are you running, because that is what is going to determine the answer? In general best MPG will be 30-31" 3.55 or 3.73, 32 3.73 or 4.10, 33" 4.56. But in general the best ratio will be that which maintains MPH to RPM ratio closest to stock. Gearsets cost about 150 per axel and install will cost about $500 per axel. Gears are not really a DIY job, for most of us, special tools and knowledge required. I have the tools and training, but will pay to have gears done, because I want a warranty for when it goes wrong and it often does.

AFFsoc2586

well is the differential separated from the axle, can i go to the junyard and find a jeep model with a 3.73 and swap it for mine...Im not really sure how the diff case and carrier are connected to the rear axel, is it all one piece. i am not by the car its back home

rollingstone

Well if you're running 31's, you could just get the axles out an automatic from a junkyard or find someone that's parting out an auto on craigslist. That will give you 3.55's. If you're running 32's or 33's, you could try to find an xj with a towing package that will give you 3.73's. Or if you're really lucky, find an xj with a 4 banger in it and take the axles with 4.10's and run.

93gc40

axel housing is 1 piece, differential is inside the housing. You would need both the front and rear COMPLETE axels to do that. And you will not normally find 3.73 in a XJ, unless somebody did it themselves, aftermarket. 3.73 gears were available, from Jeep in XJ's by special order ONLY. You Might find 4.10s in some older 4cyl models and 3.55 in 99% of those with an auto tranny.

WHAT SIZE TIRES?

loosenut

Make a bigger difference with a good tune up run higher tire pressure (max pressure printed on tire) shift up early, even skip shift 1 3 5 and stay out of the gas. You will never recover your costs changing your gears out and possibly do some walking due to cheap axle options. 4.0 is not a frugal motor but the 5 sp can be close if you drive it right.