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With these mods does 12 mpg sound right to you?

P

Plays For Jeeps

NAXJA Forum User
Location
Allentown PA
NP-231 transfercase with Advance Adapters SYE modification'
Non vacuum disconnect HP30 front from 89 XJ
33" BFG's

Recently with 17 gallons of fuel my odo read out 220 miles to the tank. ABOUT 12 MPG. That cant be right can it?

Thanks guys!
 
first you need new speedo gear to correct for tire size, next your gonna wanta regear for 33's
 
Assuming your odometer was correct for 29" tires, and that you haven't changed the speedo gear, you are getting around 14.5 mpg.

Fred
 
norcalchris said:
hey dude/..im running 31's and it says 220-250 a tank.....


i cam eout with 12.5 mpg...but my speedo is off too so our mileage is gonna be wrong for sure
Click to expand...

your speedo should be about 10% off or soo, anyway mine is with 31's and 3.55. i get 15 in town. and on highway the best i have gotten was 19.


another question, since you guys were talkin bout the speedo gear, is it worth replacing it? i know that my speedo is off about 10% so im not speeding or anything and i can figure my mpg. so is it worth changing gears? but i did hear it was easy? :dunno: sorry for the threadjack!
 
Changing the speedo gear is simple.
1. Order the correct gear for about $25 bucks.
2. Lay on the ground under the transfer case.
3. Remove the screw that holds in the odometer cable.
4. Pull out the housing, pull off the old gear and install the new one.
5. Put it back together.

Takes maybe 5 minutes including cleaning your hands and drinking a beer.
 
Don't expect too much more though.
 
Speedo gear is one of the easiest things to change on the Jeep!

I'm running an RE 3.5" kit, 4.10's and 31" mud terrains. I corrected my speedo and per my calculations are pulling 15mpg. I don't drive it easy, this was at 70-75 on the freeway and over alot of hills.

I'd probably get 18 if I was easier on it.
 
I have 33in BFG's and 4.56 gears. I always get around 300 miles per tank of gas and am sure I could do much better if I tried. 1987 XJ, 5 Speed AX-15, 4.0, 6.5 inch lift. Gears make a very big difference, as well as frequent oil changes and regular maint!
 
jeepboy381 said:
I have 33in BFG's and 4.56 gears. I always get around 300 miles per tank of gas and am sure I could do much better if I tried. 1987 XJ, 5 Speed AX-15, 4.0, 6.5 inch lift. Gears make a very big difference, as well as frequent oil changes and regular maint!
Click to expand...

WOW. Must be the 5 speed.

I get about 13.5 to 14mgp but it's mosty around town because even my typical "freeway" driving is slow and go. If I'm doing purely freeway driving (if for some reason I can go near the speed limit) I get about 17-19mpg.

Changing your speedo gear is very easy. But if you regear, you will have to change it again. If during the regear, it all works out just right, you may get to put your old speedo gear back in (maybe).
 
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