I have a 98 xk8 and it has started not shifting out of first gear when in drive. Shifting it manually does work when it is doing this. I also hear a clunking sound in the rear end when I stop but only when it is doing this. Sometimes it will correct itself after a few minutes. Any ideas? Thanks

 

Hi there,

Welcome to the forum. Sounds like you have signs of the classic problems with the ZF gearbox. Do you have any details on the car ie Mileage, any service history on the car esp. any work on the gearbox.

The ZF5HP24 gearbox, in my 1999 XK8 convertible 4.0L na, has known weaknesses and there are known DIY fixes to “TRY” and fix these. However if you have a bad solenoids, blown A Drum or cracked valve body, you’re into the realm of specialist garage overhaul or replacement. Costs will be expensive.

You haven’t mentioned if you’re handy with a wrench in the garage. If so I would go with changing the ATF fluid and filter. Plus there’s an upgraded PR valve you could try. Plenty of info of these DIY operations on this forum.

However, considering the low market value of the car, it’s a known fact that blown gearboxes will make professional garage repair costs prohibitive .... unless you can DIY.

 

I had a similar problem on my 2006 XKR. Turned out to be a badly adjusted brake light switch which intermittently had the brake lights on with my foot off the brake pedal. Evidently if the ECU thinks the brakes are on it will not change out of first gear. I was able to adjust (bend) the support for the switch so the brake lights were off and all was fine. Different gearbox on my car to yours but it may be the same issue,

 

Sorry, car has 181,000 miles on it. All work has Ben fine by local Jag dealership but no work ever on gearbox. It belongs to one of my clients and I was thinking about buying it. I can do a little work but time and a place to do it is sometimes difficult

 

I would second the inspection of the brake switch. With a helper, check if the brake lights are on with your foot off the brakes when this situation happens. As already pointed out, the car will not up-shift when it thinks you are braking.

If this is the problem, you can likely fix it for $0. The brake switch has a built-in ratchet adjustment in the "trigger". It is uncomfortable to work on due to the location up in the footwell, but it is adjustable without removing it.

Best of luck, keep us posted.

 

That is a gorgeous coupe Somebody needs to fix it!