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Spedometer question?

X

XJ Jeepin Girl

NAXJA Forum User
Location
Colorado Springs, CO
I was talking to my dad today about putting a 2" BB on my '96 sport. He is very opposed to me jackin' up my Jeep, but he'll get over it. Anyway, the subject of tires came up, of course, and he said that when you put tires bigger than the original stock tires on a car, the spedometer is no longer correct (as in, 60 mph would really be 75 mph or w/e). Anyway, is there a way you can get that adjusted, or would you just have to figure out what your "new" speeds would be if you changed the tires? Anyone experience problems with this?
 
It's not off to far about 5- 10 mph w' 33's. You could change the speedo gear in the t-case.
 
BingBing said:
It's not off to far about 5- 10 mph w' 33's. You could change the speedo gear in the t-case.
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Yeah, cuz my dad was freaking out about it... lol. He said his Mustang is like that... but he didn't put big tires on a Mustang, obviously, so I don't know what he's talking about.
 
IIRC, with my 31's and stock gearing, there is about a 5mph discrepancy between my speedometer and the GPS.
 
riverfever said:
IIRC, with my 31's and stock gearing, there is about a 5mph discrepancy between my speedometer and the GPS.
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Uhhhhh ......... yup.
Iam running a 2" BB and 31's.
Just not much room to flex it out. A little trimming and you should be fine.
Been that way for just over a year and NO speeding tickets.. yet ... knock on wood ... even with a heavy right foot.
I dont even really think its off by 5 mph, maybe just a little less?
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I say talk pop's into it. Show him the answers you get on this thread.
xyxthumbs.gif

If he's worried about the speedo being off... the gear for the tranny aint that much and its EASY to change.
Dont forget to extend your bumpstops if ya do it. ;)
100_2001.jpg

when i KNOW i need the room, i throw the 30's from my 91 on it.
Picturea64.jpg
 
Last edited:
You should be able to get a diffrent gear for the speedo sensor in the transfer case to compesate for the bigger tires. If it's that big of a deal.
 
See how far your's is off first, on my 98 which came with P215's it was dead on after I went to 30's...wonder if the factory puts the wrong gear in so you go thru the warranty faster :gonnablow
 
XJ Jeepin Girl said:
Yeah, that's a great looking Jeep. Pretty blue. But yeah... I really need to convince mi padre. Oh well, I have plenty of time considering I need the money first. lol. Wish me luck.
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Thanks, I like to call it blue also. (Its really amethyst
eek2.gif
according to the paint code)
Good luck.
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One gear may do a range on tire sizes, I run 31's with 4.10 gears and mine is only off by 5mph.
 
XJ Jeepin Girl said:
Yeah, I'll have to let him know that it can be changed. He should get it done to his Mustang, cuz he always gets pulled over in that car.. Then again it's red...
Click to expand...


Marcus has an excellent writeup on his website on changing the gear, dealer part numbers, etc. http://go.jeep-xj.info/HowtoSpeedoGears.htm . Lots of other good stuff on there as well. It's a 15-minute job if you know what you're doing. Maybe an hour for someone who isn't mechanically inclined. I doubt it's an issue if you're able to handle installing a budget boost. Last time I bought a speedo gear at the dealer is was $12 - much cheaper than a speeding ticket.

-Chris
 
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