AW4 Harsh Engagement

[1998XJltd]

Hi all -

I have a 1998 XJ that is lightly modified (OME suspension, some engine bolt ons, etc). For years - both before and after the mods - on occasion when shifting from Park to Drive or Neutral to Drive, the engagement to Drive is harsh. I would not refer to it as a 'clunk' because there is no metal on metal bang sound, but it is noticeable, more like a light tap in the rear. Otherwise the vehicle shifts just fine during normal driving. All shift points are smooth and exactly at the factory RPM intervals.

The vehicle has been sitting for the last few years and driven maybe 1x per month just to keep everything circulating. I couldn't tell you the last time the transmission fluid was changed but I do recall this issue occurring intermittently long before it entered its current resting status.

Hoping more experienced techs can help me narrow down a short list of things to check in order to fix.

TIA!

 

[Tim_MN]

The behaviors you describe are somewhat common and normal. The AW-4 is known to shift firmly, and wear in the driveline from road mileage and/or off-road use increases the backlash in the differentials. Worn motor or transmission mounts may contribute to the harshness. A worn driveshaft slip yoke may also contribute. Adjusting the Throttle Valve Cable/kick-down cable may or may not improve the shifts.

Other than regular routine maintenance, nothing really needs to be done. You may be able to reduce the felt engagement by replacing any worn mounts, and/or by pausing momentarily in Neutral when shifting from Park to Drive or Reverse to Drive.

 

[RCP Phx]

A complete transmission flush is always the best starting point when trying to diagnose automatic transmission issues! A draining only gets a small portion of the entire system.

 

[lawsoncl]

Agree with what Tim said. I would inspect the driveshaft ujoints in case they are worn out and sloppy. Also look at motor and trans mounts.

 

[acruz95]

These symptoms sound like what I dealt with at first. It developed to vibrations at 60mph. It ended up being a worn centering yoke on my front driveshaft. I removed it, went for a test drive...no more vibrations. I could have rebuilt it but chose to buy a new one.

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