B&WBeast

Hey guy i have a 98' XJ and just had a 4" skyjacker lift put on with some 31" tires. i was wondering if this changes my speed guages a lot? Will they be off a bit? If so how can i adjust them to work properly with the new size lift and tires?

BLKXJ 96

31's off set the speedo by about 5mph faster. so when the speedo says 40mph your doing 35mph. You can change the small plastic gear on the speed sensor in the t-case to a different size or tooth count to correct this.

B&WBeast

oh okay so im actually going slower then it says i am? gotcha!

and is this a simple little fix? I'm not really familiar with it

BLKXJ 96

Yep you just need to know what gear you need for your application.

warthog

i just lifted mine 4.5 with 32's and when i am showing 60 on the speedo i am actually doing around 66-67.

i think you have your numbers swapped

winston427

Warthog is correct. With larger tires you cover more distance with each revolution of the tire causing the speedo to read slower than you are actually going. The larger the tire the more the speedo calibration is off.

B&WBeast

Ah alright i gotcha. Well i just needed to know that for sure before i go out and get a ticket.

BLKXJ 96

Your probably right, my jeeps been torn apart so long........

Best way to be sure is with a GPS so you can tell exactly how much your off by.

winston427

At least your speedo works. I had to have my wife drive at different speeds on the interstate while I followed her so I could memorize RPM ranges for each speed.

warthog

Yea that would be the easy way, but i dont have one of those high dollar tech gadgets. i used a buddy on the way to work. i just pulled up next to him and rolled down the window and shouted out "how fast are you going?"
i do need a gps though. it could have saved me a lot of hours in my life.

B&WBeast

hahaha wow that would be ridiculous. I would hate that

fafafofi

I got 31's and there isn't much change until I hit 60 on the speedo, the Garmin says 62-63. At 75 its 78-79.