As we all know, the ZF5HP24 tranny isn't exactly the best one out there.

Just out of curiosity are there any other "(more) reliable" transmissions out there that are compatible with this car/original v8?

 

ZF6hp out of the next generation has been done I believe.

 

Here's a thought: Drive the car until it breaks and then worry the problem.

 

Your car might have a early enough trans. that could benefit from a main pressure valve upgrade.

http://jagrepair.com/images/AutoRepa...%20ZF5HP24.pdf

 

You're probably right!

But, the service techs that I work with have both warned me of doing this... It's a high milage trans that has never been opened before. And I have read several stories of people doing such a simple fix, drive the car for 10,000 miles or what have you and complete trans failure.... Not sure if I am looking at the worst of the worst, but I am definitely worried about having trans issues, as I am not about to shell out $6-9k for a full rebuild/new tranny.

The way I am looking at it, either I don't replace the PRV and I have the A-clutch drum go out on me, or I do replace it, and then the plates don't grab or I have some other issue with it...

I am looking at about $50 for the part, $300 labor, and $250? fluid. So, $600 could save me, but it's one of those things... I need some convincing that everything will be okay if I do it.

 

Where have you read about failure after changing the pressure valve? I have not seen it on the XJ8/XK8 forums. There have been many warnings of not doing a complete flush by machine, but just drain and replace the fluid appears to be safe.

The ones that I have replaced are working without problems, but I don't think they have gone 10K mi. yet.

 

I changed out my main pressure valve, along with fluid and filter, probably almost 5,000 miles ago. If anything, it seems to be shifting better as time goes by. It has 102,000 miles on it so anything can happen at any time of course. But, that's the reality of owning a 14 year old car.

I would certainly go the new pressure valve route before doing a "preventative transmission replacement".

Let me qualify my remarks though by informing you I am still very new to the Jaguar game. I just wanted to share my opinion.

 

Could you either point me in the right direction or with a link for that? I searched and wasn't successful at all.