Regearing Time

Robert_Strausberg · #1 (**permalink**) 01-03-2004, 01:13 PM

Hey folks,

It's about time to re-gear my TJ. Its the 2.5L (auto blah), sadly, currently running 32" tires.

What would you say are the best gearing ratio I ought to go for? I believe I'm running 3.73 gears right now (although I could have sworn the SE's all came stock with 4.10 gears... but my buildsheet says otherwise).

Thanks for the imput.

-Rob

phatyaspen · #2 (**permalink**) 01-03-2004, 01:30 PM

depends on how big of tire you are gonna run...32"s id say 4.56 i run 4.88s w/ 33's and have a 3000rpm at 60 mph

Bounty__Hunter · #3 (**permalink**) 01-04-2004, 12:47 AM

Go with the 4.56 for 32" or 33" tires with the 2.5L auto.

All 2.5L autos came with 3.73, the 2.5L 5spd came with 4.10 gears.

Junkpile · #4 (**permalink**) 01-04-2004, 06:27 AM

Snitty · #5 (**permalink**) 01-04-2004, 01:23 PM

you'll use too much gas with the 4.88.. unless its only for offroad...

Robert_Strausberg · #6 (**permalink**) 01-04-2004, 03:54 PM

Im looking for something that'll be good on the road (afterall, it is my daily driver). She see's mud about two or three times a month...

YJnamedTJ · #7 (**permalink**) 01-08-2004, 09:55 AM

All 2.5L autos came with 3.73, the 2.5L 5spd came with 4.10 gears. bounty

does that count on yj's too cause i have a yj with a 2.5l and an ax5 transmission and i was always told that i have 3.73 gears ...... but i dunno ive never torn the front or rear diff of to look? because i want to regear to 4.11's or 4.10's and thats another question to all whats the difference between the to i mean other that one has a diff number.

outerbeachyj · #8 (**permalink**) 01-08-2004, 10:21 AM

I could use some clarification on this topic too, hope you all don't mind my butting in on this thread. I am going to be running my new 32" tires on a 1995 2.5 L YJ also. Mine is a manual 5 speed trans, so does this mean I definalty have 4.11 gears? If so, I should be ok with the new 32" tires. It sounds like it is o.k. to run 32s on a manual 2.5 L but an auto 2.5 L needs to be re-geared then? Thanks for your help on this one, I already got the tires and lift to be installed in the spring, but I don't want to re-gear.

redrooster · #9 (**permalink**) 01-08-2004, 10:37 AM

There should be a metal tag on one of the cover bolts that will tell you what gear ratio you have. Sometimes it will say the ratio and sometimes it will give you the number of teeth on the gears. Divide the higher number by the lower and it will give you the ratio.
To answer the question: 4.56 if you are going to run the road.

redrooster · #10 (**permalink**) 01-08-2004, 10:40 AM

Quote:

but i dunno ive never torn the front or rear diff of to look?

10 year old vehicle. Maybe it's time you at least open it up and change the gear oil.

YJnamedTJ · #11 (**permalink**) 01-08-2004, 10:50 AM

i bought the jeep from a family friend who is like a god when it comes to vehicles...he had an s-10 for like 30 years and it had close to 300thousand miles on it and it still ran fine....he kept up on keeping everthing changed and in good running order. but i will tear it off when i get a warm day and take a look ...plus i want to regear and put lockers in so ill have to do it some time soon.

hi_c · #12 (**permalink**) 01-08-2004, 01:13 PM

If you got an older jeep (>10yrs) then your "axle tag" is missing too. To verify that I had 4.10 gears, I just put the jeep on a flat surface, wrapped a piece of tape around the driveshaft, put a mark on it, marked my tire with chalk, then pushed the jeep slowly and counted the number of driveshaft revolutions for one revolution of the tire. It was just over 4. This confirmed my 4.10 gears. If you do this and get just under 4, you probably have the 3.73. I know this is a redneck method, but it get's it done.

C

GreenReaper93 · #13 (**permalink**) 01-08-2004, 02:19 PM

Awsome Idea C. I think I'll try that when I get home.

Bounty__Hunter · #14 (**permalink**) 01-08-2004, 02:41 PM

It's a little easier to count if you have the jeep jacked up off the ground.

Yes, it applies to TJ's and YJ's, the 2.5L auto has 3.73 and the 2.5L manual has 4.11.
For Jeep, rules are meant to be broken so there is an exception to every rule. Always double check your jeep to be sure, jeep will surprise you sometimes as they were known for using whatever parts were on hand.

4.10, 4.11 same thing. That slight of difference does not matter.

If you have 4.11 stock and you go to 32" tires you'll want to regear to 4.88 to get near stock performance back. Keep in mind that regearing accounts for the change in tire height, but not for the added weight and rotating mass. I recommend going slightly lower if there is ever a choice.

I'm running 32" tires with my 2.5L 5spd and 4.11 gears, it's okay. I can still use 5th gear on flat roads with no headwind, but I've got some engine mods that help. I'll be regearing to 4.88 first chance I get and running 34" TSL's.