AX-15 and gearing

A number of you had some great advise on gearing for the auto transmission. What would you guys do with the 5 speed? I'm running a 89 with the 6 cylinder, D30 front, D35 rear. Weather or not I keep the D35 rear is questionable. I'm running highways 30-35%, trails and some rock 65-70%. Sand trails (Arizona desert and high country, Arizona, Nevada, Utah, no mud or snow, just sand and hard pack. Tires will be 32" or 33" with 41/2" lift, 15X8 wheels, 41/2 - 43/4" backspacing. I will be changing gears and going to a limited slip rear, air or electric selectable front. What gears are working for you guys with 5 speeds? Thanks!

I had a ax-15 in my 91' wrangler with 33's and it really sucked. I got stuck in a mud/water hole at the Badlands off-road park in Indiana and blew my motor. Any gear numerically higher than the pathetic 3.08 gearing with the 6 cylinder/5 speed would be good. If you want to get new axles, then you can find 4.10 gears in the 4 cylinder/5 speed xj or yj from 87' on I believe. The 4 cylinder/auto had 3.73 gearing & the 6 cylinder/auto had 3.55 gears. I highly suggest getting a ford 8.8 from a 95' or newer explorer then you get a heavy duty axle with disc brakes, 31 spline axles and you might be able to find one with 4.10 gears and a trac lock limited slip. Depending on where you look you should be able to get one for $350-650. I have the ford 8.8 in my wrangler with 33" tsl's & 4.88 gears and a 95' chevy vortec v-6 and love the power. I run about 3200 rpms at 80 mph, which isn't too bad. If you are going to just do the gears and not do a whole swap of your axles, then I'd suggest 4.56 or 4.88 gears with your 33" tires and low to moderate highway driving. I have a 4l60e auto tranny with overdrive in my wrangler which has a .79:1 4th gear I believe. Your 5th gear in your ax-15 is around .85:1 I believe so 4.56 gears should work nicely. It's not cheap to have your gears done, so you should do it once and be done with it.

I ran 31x10.50 MT/Rs with a 5spd and 4.10 gears for 3 years. Great gearing. I just mounted a set of 33x12.50 MT/Rs this week, and the power is still good.

3.07 gears just plain suck for anything, especially any tire larger than stock.

I'm running 4.10's with the 5spd and 31's. I think it's a little low for the highway but great for everyting else. The motor is around 2,800 on the highway at 65 now.

Go 4.56, you won't be sorry. Anything higher (like 4.10) and you might be.

4.56 GEARS AND 5SPD

I have a 92 XJ 5spd 6 cyl 32" tires. I just installed 4.56 gears and love them. I'm told that I should have gone 4.88 by my buddies but I think that would have been to low. I run about 3000 rpm at 75-80 mph in 5th. When I go bigger tires 35-37" , I will loose some power but I dont think It will be too bad. I will just get the 4 low kit for the 231 or the atlas 2 to make 4 wheeling the big tires easier!

I just upgraded from 3.07's to 4.10's in mine with 31" tires. The gearing is great off-road and around town but too low on the highway IMO. I'm planning on putting on 33's in another few months once my 31's wear out though and that should be just about right. I swapped the axles for junkyard axles that came with 4.10's, and after selling my old axles, the entire swap only cost me about $200-$250.

xj92 said:

I just upgraded from 3.07's to 4.10's in mine with 31" tires. The gearing is great off-road and around town but too low on the highway IMO. I'm planning on putting on 33's in another few months once my 31's wear out though and that should be just about right. I swapped the axles for junkyard axles that came with 4.10's, and after selling my old axles, the entire swap only cost me about $200-$250.

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I agree, 31's and 4.10 with the 5-speed is great offroad, on-road too high. I have 33's and 4.10, great on-road, and it does pretty good offroad, better than stock. If you plan on keeping the D30 up front, 4.56 is what I would recomend for 33's. That should even leave you some room for 35's if you decided to go bigger later.

IMHO, gear for the road and Highway, get a lowered T-case for crawling.

I'm running 31s, AX-15, I6 with 3.73 and it's great for the street and highway, which I do 98% of the time as it's a DD.

At least 4.56, I'm still kicking myself for listening to those to told be to go 4.56s when I installed my 4.10s.

4.56..... I got 4.10's and 31's and 4.56's with 33's won't be too bad.... I drove 4.10's on 235's and that was liveable!

Kejtar

4.56s and 33 won't be too bad?!?
That's what I have with my AX15 and I get 20MPG on the highway @ 70MPH.
I'm actually going to regear to 4.88s when I put on 35s just to retain how it "feels".


Jes

I had the AX15 on my 4.2L YJ with 32's and found that 5th gear was basically useless on the highway unless I had a tail wind or was going downhill. I was always shifting into 4th gear. I had the factory 3.73 diff gears. Go higher than 4.10's, since that was the stock 4 cylinder gearing. If I still had the YJ, I would put 4.56's in it.

Send me your Email if you want and I’ll send you a spreadsheet that will clear it right up, clear as mud. It will let you put 3 set ups side by side and graph the speed over RPM for each gear inall three set ups.

Spreadsheets give you RPM's at speeds but dont take into account how it feels and acts with the extra weight that you have added and extra friction from bigger tires and so on..... don't rely on them fully.....

Kejtar