What is the stock gear ratio on a 94 YJ with the 2.5L engine? I have been told they were 3:88 and also 4:11. Any one know for sure? The gears in my rear are going out, since they have to be fixed anyway might as well do it correctly to run the 31" tires. If 3:88, goin to 4:45. If 4:11 going to 4:88.
Gear ratio
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Bounty__Hunter
Super Moderator
Go with 4.88, swapping from 4.11 to 4.56 isn't enough of a change to warrant the time/money spent. Do it once and do it right.
jfrabat
New member
Stock ones on a '94 are 4.10
I disagree; I ran 4.88 on 31's and was REALLY happy with that setup. Now that I stepped up to 33's, I wish I could go to 5.13 to keep that same ratio I had before...
Numerically speaking, you will have more torque than stock, but keep in mind the Jeep is lifted for 31's tires (ie. mode wind resistance), and larger, heavier tires also have more rolling resistance.
With 4.88 and 31's, you'll be able to stay in 5th at highway speed going up overpasses even with a head wind. The Jeep will be at around 3,200 RPM's at 70 mph, and although it may seem a bit high, the 4 banger really likes to be in that range... Whn I had the 31's, I used to get up to 65mph, put on the cruise control (I installed an aftermarket one on mine) and forget about the gas pedal until I reached the destination.
I agree; not much difference between 4.10 and 4.56. If making the change, go to 4.88...
HAHA Going over a over pass is not a hill :lol: he lives in washington it appears, we're talking elevation changes over 20 feet are hills.
jfrabat
New member
I understand; my point was that with 4.10, you cannot maintain speed even in the slightest of hills, or in headwinds, whereas with 4.88, you can stay on 5th for small hills even with a head wind.
If it is a DD, I suggest a selectable locker on both ends. If you have the D35 on the rear, though, you need to be careful, as it can go KABOOM if locked on 31's unless you upgrade the shafts...
BS.. I've had 3.07 with 33 for years, when going up verticle elevations in the hundreds, at elevations way above sea level so the air is a little thin to begin with, then I would have to down shift, but not small hills. When I went to 4.88 with 36, my rpm's were higher, but I still had to down shift on those hills that I did with the old set up.
While it is opinion based 4.56's with 31" tall tires will keep him close to stock range for rmp's, plus still be able to maintain some of the fuel economy.
While it is opinion based 4.56's with 31" tall tires will keep him close to stock range for rmp's, plus still be able to maintain some of the fuel economy.
Bounty__Hunter
Super Moderator
Jeep Ratio Calculators is a common chart. Compare the RPM's with 27" tires and 4.11 gears, then find a similar RPM range for 31" tires. It's in between 4.56 and 4.88, with 4.88 being ideal for the increased wind resistance, the increase in rolling mass of the larger tires, etc.
jfrabat
New member
You have a 4-Banger that came with 3.07 and it went uphill with 33" tires without downshifting? It sounds more like you have the I6... $-Bangers came stock with 4.11/4.10 IIRC for most all years.
Yes, but it does not consider the additional wind and rolling resistance of the bigger and wider tires; 4.88 will make him happier I feel based on my own experience. But, as you say, it IS a matter of opinion.
never said I had a 4 cyl, yes I have a 6, The point that I have been trying to make which I think you are failing to get, He is going to have to down shift anyways, you could put a 6.32 gear ratio in there if it were possible, the inclines are still going to require down shifting, so... I suggested to stay with a ratio that will keep him as close to stock as possibe for fuel economy
Regardless. let us know what gearing you choose, and while your at it, toss a locker at the axles if you don't already have one.
Regardless. let us know what gearing you choose, and while your at it, toss a locker at the axles if you don't already have one.
Bounty__Hunter
Super Moderator
We wouldn't be driving jeeps if we were all that concerned about fuel economy. Knowing that many jeepers would prefer performance over economy, I think one would side with the ratio that improves performance.
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