Bigger Tires/ Cruise Control

I put bigger tires on my 1992 xj 31's and now my crusie control runs a muck! Do I need to do the speedo gear? any input would be good!

Gearing probably. It is vac controlled, so probaby having a hard time with the extra mass.

Gearing plus the speed signal is now slow...

What is it doing?

Jeep a Knocking said:

I put bigger tires on my 1992 xj 31's and now my crusie control runs a muck! Do I need to do the speedo gear? any input would be good!

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When I changed from 225-70-15 to 30X9.5X15 my XJ AW4 went all hay-wire when using cruise and asending even the slightest hill. It is termed gear hunting. The AW4 will shift to 3rd then back to OD for a few seconds then back to 3rd until I get annoyed enough to put my foot down or manually shift to 3rd and leave it there until the XJ is over the hill. Speedo gear change will not help you. You need a differential gear change or manually change the gear to 3rd when going up hills.

You could turn off the cruise and work the pedal with your foot.

techno1154 said:

When I changed from 225-70-15 to 30X9.5X15 my XJ AW4 went all hay-wire when using cruise and ascending even the slightest hill. It is termed gear hunting. The AW4 will shift to 3rd then back to OD for a few seconds then back to 3rd until I get annoyed enough to put my foot down or manually shift to 3rd and leave it there until the XJ is over the hill.

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'Made the same change about 4 years ago, had the same problem.(Actually, it's OD, locked converter - unlock - downshift, speed up, up-shift --re-lock converter - slow down - repeat) The easy work-around is to just drop it in 3rd when it starts to hunt.
Had to re-do the rear axle 2 years ago(pinion bearing), had a spare 3.73-up front carrier laying around, and re-geared both axles to 3.73. Problem went away, and the speedo is accurate again. If you go this route and have/are planning tires bigger the 30", go to 4.10 gears.

Thanks for the help guy's! Now I know which way to go!