So, for the past few months (especially when below 40 degrees outside) every time I start my jag, and put it in reverse it gives a slight jerk, nothing too bad, and it gives a slight jerk when shifting from first to second, it only happens once a day (is usually fine after I drive the car to work, and leave 12hrs later)... That is until today, when I started it and put it in reverse it was fine, had a slight jerk shifting from first to second when I put it in drive. And it seemed fine until I was on the highway and went to pass someone, put it in sport mode, and gave it the beans, well I got up to about 70, and the car stopped accelerating and gave a huge jerk (as if you very quickly press the brake firmly and let go) then it seemed fine again, and continued to accelerate without an issue. I have no idea what it did, but it was fine the rest of the way home, I've been putting off replacing the valve body, but is this a sign of possible trans failure or A-clutch failure?

The vehicle currently has roughly 118400 miles.

 

When was the last time you changed your fluid ....could be a simple clogged filter? Other than that it could be a number of things, but initially to me it sounds like either a torque converter or pump. But in any case, it will cause you to burn your bands.
Its almost at the end and there's not a lot on it, but check this... http://www.jagrepair.com/images/Auto...ansmission.pdf ...and you can search more on this...JagRepair.com - Jaguar Repair Information Resource

 

I got the vehicle for a steal, being that there were few service records available. To the best of my knowledge the transmission has never been opened. And I've been afraid to open it due to the difficulty of refilling and cost of ZF fluid. I haven't had the extra money, since that's been spent on other areas of the car! haha. I want to get an idea of what's going on before I have the shop take a look at it.

Elaborate on what you mean by "bands"?

Thank you for your reply.

 

Bands are the friction faced metal bands used to stop or release the outside of a drum that has a planetary gear arrangement - used to change gears. I am pretty sure (unless my memory is playing tricks on me) the ZF box in an XJ8 is a bandless design, using face clutches instead.

 

So perhaps I will start with a torque converter and filer + new fluid before messing about with the valve body. I do not know much when it comes to the transmission! Haha

 

Your transmission may not have the updated main pressure valve. This is an easy and cheap fix, not requiring removal of the transmission.

http://www.jagrepair.com/images/Auto...%20ZF5HP24.pdf

I have been using Castrol Transmax import multi-vehicle for almost four years. It's available almost everywhere and not expensive.

 

That is pretty inexpensive! $68.00 for a 3 pack of 1 gallon jugs on Amazon!

I know the PRV has never been replaced, I have someone willing to lend me a lift, but the fill procedure is what worries me the most.