Question about transmissions...
 

My '98 XK8 coupe has an issue with the transmission; the warning light stating transmission failure is on and it creeps in first gear - I just about have to floor it to barely move it forward - it goes in reverse just fine...

I was speaking to a guy who I purchased some 18" Milan wheels from (more on that in another post...) last week who knows a lot about Jags and works on them for dealerships - he told me to drop the pan and change the filter before dropping and replacing the entire transmission - the car has 90,000 miles on it - he said with that mileage it's quite uncommon - from his experience - that the transmission needs replacing. Thoughts?

Also, I have my eye on a 2001 XK8 vert that I could purchase for cheap and use as a parts car (windshield, interior, etc.). The car has 86,000 miles on it and according to the seller it runs and drives - are there any differences between a '98 and an '01 transmission? Does the '01 have the upgraded A drum in it or would I be better off having mine rebuilt with the upgraded A drum - assuming the filter isn't the issue?

Thanks in advance for your thoughts mates!

It's unlikely the filter is at fault. If the other gears are OK it's probably drum failure. The 2001 has the same drum. ZF has stated that installing an updated pressure regulator valve could prevent drum failure, so an alternate transmission with the cheap and easily installed valve may be a good answer.

Can anyone point me in a direction to get this modification done? My car has 75000 on it and all good at the moment so if I can avoid the A drum failure it has to be worthwhile.
Thanks

This link will take you to specific info on the valve body part numbers but the entire thread contains much more info on the subject.

https://www.jaguarforums.com/forum/x...69/#post659105

This is great information! Thanks so much - this is the first I've heard of the pressure regulator valve being the cause for the A drum failure. I'm going to look into getting the vert, pulling the transmission and replacing the pressure regulator before changing it out.


Is swapping the transmissions a direct swap? Is replacing the pressure regulator valve something I can do myself or is this best left to a transmission shop?

Direct swap. Pressure valve not difficult. After removing the filter you just have to pull the two dozen or so long bolts that hold the forward valve body in. Not the short ones that hold the valve body together. Disconnect plug on the front and link on left side and wiggle the valve body off the locating stud. On the bench, use a bar clamp to hold the cover plate while removing screws and release carefully to kepp springs from becoming airborne. Inspect the bore for wear, reassemble. It is handy to have an assistant and two clamps when replacing the cover plate. No gaskets involved except on the pan. Your ZF dealer will have larger head screws for the pan, a good idea. It will take about 8 qts. fluid to refill. I used Castrol, but many others available that meet the spec.

Again, great information! A few questions: How do you differentiate between the long and the short bolts in the valve body - does anyone have any photos or diagrams? In regard to a ZF dealer, is there any one in particular that you would recommend via online or does anyone know of one in the Southern California area to get the new pressure regulator, filter (might as well change it), pan gasket and bolts? Castrol is ok to use in the ZF? I've read that only certain specific fluid should be used. What about mixing a different fluid with the current fluid - any issues? Should the torque converter be drained as well? Are there any aftermarket performance torque converters with a different stall speed to increase performance? And lastly, since the valve body will be off are there any aftermarket shift kits available? I've taken apart engines before but have never worked on an auto transmission - I might try this on the current transmission in the 8 to get a feel for the procedure since it's already jacked up before attempting to do this on the good transmission - or is it better left to a transmission shop?

For the valve, I used thectsc.com, bolts also. Gasket and filter good price from rockauto.com.

The long valve body screws have a larger dia, head, I think. Don't worry, pull a few and you will see the difference.

The castrol fluid I used was the European or multi-national, I forget what the label says, but any fluid that meets the spec. will work. If you have the transmission itself apart you can drain the torque converter, but not if it's in the car. I changed the fluid several times, instead.

i have not been in the transmission, but there are several t5hreads on the forum by people who have rebuilt them.

No opinion on your other questions.

Thank you for the information, it is greatly appreciated! Well the price on the auction for the parts car I had my eye on has gone over and above what I feel is feasable. That being said, I've found a used transmission on eBay from a dismantler - it has 103k miles on it for $650 including shipping and comes with a 6- month warranty. They state it fits 99-02 8's and said it may fit the 98 - the part number on the bell housing they supplied is MNE4400AA - will it fit? Thoughts on buying it?

you'll be better off just having a transmission shop disassemble and put the upgraded A drum and valve into your unit. Otherwise, you're just on borrowed time with the 'replacement' tranny. Consider it carefully.