My car has 54,000 miles. The gearbox, I assume, has never been serviced.

It does do the classic ZF slammed downshifts. When pulling to a stop, 1/50
times it will slam a downshift, which is jarring.

It shifts smoothly in normal situations (save for above). It does hold gears awkwardly in "S" sometimes. meaning, after a bout of acceleration on the throttle, you let off and slow slightly. 1/20 times it would downshift for no reason, putting you over 3500 even though you are barely on the gas at all (just maintaining speed at that point), which is odd. (it wouldv'e already been in 4th, knowing that I've slowed down, and then jamming into 3rd)

It takes a couple seconds between going from Park into gear (R or D).

To me, these are signs of a gearbox in need of servicing. In your experience, is this a gearbox that still has the opportunity for long life?

I'd like to avoid the common "death at 80,000", because as a 'dependent', my parents are not going to approve of me owning a car which has impending gearbox failure. I.e., being forced to sell the car.

I am calling my independent to see what he recommends, and whether he thinks that my unit has the ability to live a long and prosperous life.

My current idea is that my independent replace the fluid 2l at a time, and replace the pan gasket.

Any advice?

Much appreciated,

Ian

 

A fluid change would do no damage but I would include the filter which you did not mention.

I certainly have no credentials to remotely diagnose transmission issues but the random nature would seem to fit an electrical problem more than an internal parts failure.

All the shifting is managed by the TCM electrically operating valves in the valve body. The valve body has been clearly implicated in the all too often failure of the 'A' drum. I had a TCM that would fail to disengage the torque converter lockup when down shifting from 5 to 4th. That caused a dramatic 'jarring' as the transmission shifted gears under engine torque.

I was able to find an used TCM for a $100 from a wreaking yard that instantly fixed the problem. You might want to pull and replace the TCM and the connector on the back of the transmission to clean the contacts a bit.

That creates my fix parade as change fluid/filter, swap TCM, replace valve body. Rebuilt valve bodies are available fairly reasonable.

 

^^what TP said^^

 

agree with the above, with slightly different ordering. I'd do the fluid n filter change first...I no longer have the harsh downshifts after doing the fluid drain/fil myself, found the previous change by the dealer left it 1/2 qt shy...no delay in shifting from P-> R, but yours could be enough to do both the downshift and engagement to P-> D/R. Don't forget to re-check the level after a few days of driving, making sure nothing is leaking, all bolts are still torqued (I had one back out, or missed it the first time?!). I ended up with a little more needed fluid-wise.

Because the a-drum is going to fail at some point, i'd plan on budgeting that as a preventative maintenance item, making sure to get the re-built version that has a reinforced ring that the original did not.

I think worse case, and less problematic in a statistical world, would be the TCM.

 

Did you ever have the fluid level checked?

Both of the boxes the ZF and the MB box has to have the correct fluid at the proper level -- they will act up if low and you will damage them if they are run with low fluid.

You should not have any delay going into gear.

The pressure problem resulting in the drum failure is not fluid related.



You need to have the fluid level checked and if low -- fill it to the proper level and see of this fixes the problem.

Then you can move on to the next step ........ have the level checked.

 

I hate the idea of this transmission failing on me soon. Whenever it does,
I will essentially have no car. I'm thinking an XJR may be a nice way around
this, since the 2002-2003 XJR is super reliable (the 722.6 is way better than
my ZF unit!). I'm having the fluid level checked next week on my trans.

An '03 R1 XJR would be great, but this XJ Sport has sentimental value, it's my
first ever car. From what the trans shop said, leave it until 100,000 unless you're
having serious issues. And the likely fault you'll have is the A-Drum, not something
related to the fluid. (their words)

My interest with changing the fluid was elongating this transmission's life, but
now I feel very paranoid.

I am taking your advice and getting the fluid checked.

Thanks
Ian

 

I have had the fluid & filter changed on my tranny and it is as strong as ever. When I'm towing, even with the car trailer with a car on board, the car will still crawl in D without any feet on pedals. It is a good bit of kit, just needs looking after like every other part of a Jag.

 

i am having similar issues on a replacement trans. i had a couple of trans guys look at it and drive the car, both say it points to valve body. i found the link to this valve body kit on ebay im thinking of pulling the trigger on.

eBay - New & used electronics, cars, apparel, collectibles, sporting goods & more at low prices

 

Does anyone know if these transmissions were upgraded at any time during the X308 run from 98 to 03? Are transmissions from later cars just like the earlier ones?

 

I can't comment on what has been changed or upgraded -- I'm sure changes being made throughout the production -- some of the numbers change.

The ZF box is used in all kinds of cars and equipment and was one of the first of the newer generation of sealed transmission with specialized fluid. When you compare it to what came just before it -- they are very robust.

With every transmission - at the first sign of any problems you must have it looked at to check for leaks and make sure the fluid level is correct. Driving will damage the transmission if it is low.

Must use the correct fluid

 

Hi ianclements

Checkout this valve body information thread (it gives reasons & a how to guide on the valve body issues) by another forum member:

https://www.jaguarforums.com/forum/x...d-again-61537/

Although he mentions XJR transmission in some of the posts, he is really working on the ZF5hp24 that is in a 1999 XJ Vanden Plas.
Lots of photos and posts on valve body worn parts that might cause transmission failure.

Jim Lombardi

 

In my limited knowledge on the transmission failure, other than my own transmission failure, you aren't suffering from the symptoms of the dreaded transmission drum failure. The transmission fails rapidly after any symptoms, so I would probably assume it would have failed by now if the drum was the culprit.

I would have the fluid level check though.