Years ago I changed out my 1984 Ranger rear end from stock (3.50 ?)
to approx. 3.7 ? and did not notice much difference in gas mileage.

If I changed out my stock 2000 XJ rear end to 3.73, would I lose that much in
gas mileage ? --- since it is not exactly conservative on gas as it is .

Thanks folks, Randy from Oceanside

 

I don't think it would change anything. If you have bigger tires than stock though, it can definitely help (but going from 3.55 to 3.73 is useless, while you're at it go 4.10+)

 

No there wont be any noticable difference. Its getting harder to find a set of 3.73 gears in an axle.

 

Most 3.73 gear Cherokees were from the first 3 years(1984,85,86), when they really needed it because of lack of power(Carbed 2.5 and GM2.8V6), though there were 4.0s that came with 3.73 behind them, usually Tow Package vehicles.

 

I just picked up a 01 8.25 that supposedly has 3.73s in it

 

If you have 4wd your tcase will hate you when you put it into 4wd...

 

That is what I have in my 85 2.5L, 3.73s Had the same thing in my 88 Ranger too.

 

Why is that ?

 

He didn't mention anything about changing the front gears

 

A little quicker, but no difference overall. I went from 3.45 to 3.73 as well, but I went from a 2.9L to 5.0L.....

You definitely should go 4.10 while in there. I love it with my 31s (might go 32s,let you know how that goes)

 

Well I assumed he either knew that he would have to or he's 2wd. I never thought that the op might not know. That's what I get for thinking that's common knowledge

 

Regearing for that little of a difference in final drive is a waste of money. If you're going to regear go at oeast to 4.10 or 4. 56 depending on your application.

 

Go big or go home ! I'm going from 307-410

 

Xj's are undergeared from the factory anyway. I say if you are going to regear, match the factory final drive and fire size, then add .5 revolutions. So if you went to a 31-32, the oem equivalent gear should be 4.10, but 4.56 would be much better. So on a stock tire size, from 3.54 I would go 4.10. Etc.

 

thanks guys for all the info !!!

Randy