99 xj 5spd Gear swapp - JeepForum.com
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post #1 of 4 Old 11-21-2011, 10:26 PM Thread Starter
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1999 XJ Cherokee 
Join Date: Nov 2011
Location: Wilkesboro
Posts: 13
99 xj 5spd Gear swapp

I bought a 99 XJ, it had a 3.07 rear Diff (Stock) and the D30 in the front had been swapped to the more common 3.55 gear. I thought no big deal just swap the front to a stock 3.07 and I will be wheeling. Not so. The 3.07 is not so prevalent in the junk yards around here and the 3.07 starts around $290.00 and tops out at $400. A friend found me a 1990 D35 Rear Diff. with low miles (around 70k Mi). We did the swap, now the speedometer is off by 10 mph, running a 205/75r tire. I want to install a 3.5 lift and 31 10 50s. What is the best 3.5 to 4.5 lift for the money? Should I keep the 3.55 gears and upgrade my tires to make up the difference in the gear ratio? I figure you guys have been here and done more, so what do you recommend? Keeping in mind I have a low budget!

HalfHitch is offline  
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post #2 of 4 Old 11-22-2011, 08:03 AM
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1983 CJ7 
Join Date: Oct 2009
Location: Chattanooga,TN
Posts: 505
Well if you have a 5 speed you have 3.07 gears and auto its 3.55. Do not put your jeep in the 4wd with different gear ratios. If it was me and I knew I was going to be lifting it, I would look for the 4 cylinder because they came with 4.10 gears. 3.07 or 3.55 gears will be fine with 3.5 lift and 31s it wont a be sports car so don't expect that. 3.55 gears are a lot easier to find in the junk yard because the cherokee came with alot more autos than manuals. Also not trying to be rude but have you double checked your front and rear diffs to make sure they do not have the same gear ratios. It seems kind of foolish to me for someone to put two different gear ratios in a stock jeep. If you look the diff there should be a plate or that says what gears it has.
Brg0012 is offline  
post #3 of 4 Old 11-22-2011, 09:45 AM
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1998 XJ Cherokee 
Join Date: Dec 2010
Location: Cackalacky
Posts: 178
Sounds like he's already got them to the same ratio. If I'm reading this right,
Started with: 3.55 front 3.07 rear (D30 front from someone else's aborted swap)
Now has: 3.55 front 3.55 rear ( replaced rear w/ a D35 from JY)

Don't worry about the speedo until you get your lift & tires dialed in, just know that it's a little off and drive accordingly. Heck, in most lifted Xjs you can't break the speed limit by much anyway ;-).

You should decide about what gearing based on how you plan to use it. Crawling? You will want deeper gears. 4.10s at least, 4.56s if you think you will ever go larger on the tires. Daily driver and weekend dirt road wheeling? You will probably be fine for a while with the 3.55s, and save your money for skids, armor, etc.

There are as many opinions about lifts as there are people with lifts I think. Just read a lot on here and decide for yourself. People will tell you to go big right away but that can cause more hassle than it's worth, what with having to get a SYE and stuff.
katuah is offline  
post #4 of 4 Old 11-22-2011, 10:05 AM Thread Starter
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1999 XJ Cherokee 
Join Date: Nov 2011
Location: Wilkesboro
Posts: 13
Yeah, the diff swap is complete. 3:55 front and rear. Mostly I want to build this as a daily driver and a fishing vehicle. Crawling on the coast of N.C. Fishng the outerbanks and the occasional logging road. Im not much of a bogger.
HalfHitch is offline  

gears , help needed , tires too small

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