My xj40 4.0 is the first car I owned with automatic trasmission (I had only a smart with sequential) so I don’t know if my ZF work as it should. I have seen a video of a 3.2 xj40 driving and I saw that normally it changed gears about 2500rpm.
My car , if I push very gently the gas, always changes gear under 2000 rpm , generally about 1800 rpm. So if I accelerate with little gas, even in the city the car arrives quickly in the 4th gear . The passage from one gear to the other is fast and without any apparent slippery. The passage from one gear to another is not completely smooth like a scooter, I feel the insertion of the next gear clearly in up shifting , in downshifting is quite unnoticeable. When I stop and insert reverse the insertion is a little abrupt instead. I have tried kick down and it works , I have still to try sport mode. What is the best practice when driving is steep routes? Leave the gearbox in drive or use 2 o 3 gear instead?
First thing you should do is check that the transmission fluid is at the correct level and a clean red colour.
I’ve owned and covered thousands of miles in two XJ40’s, on both of them the change between gears on both the up and down changes have been so smooth that you can barely detect it. In winter when the car is very cold the change was a little more noticeable but still very smooth. How you use the gearbox is a personal thing, I’m not sure there is a correct or incorrect procedure. When descending very steep inclines I like to use the left hand side of the ‘J’ gate and hold the transmission in 1 or 2 but travelling up hill I’ve always left the lever in fully auto and let the car decide when to change.
I also notice my trans shifting sometimes.
My fluid level is good but the fluid is dark red.
In the future i will replace the filter and top it up with fresh trans oil. Maybe that improves shifting.
But in the end i got 230’000km on my cat and i think a somewhat noticable shift isnt too big of an issue at that age.
also my xj has 210.000 km… its certainly not perfect as new in many ways. fortunately my daily drivers its an Honda and even if its more that 23 years old i does not feel any decadence in mechanic or performance. Maybe i am asking too much from the jag which is a very complex car. I also have a 1968 Fiat 500. I use it in summer i change oil every 2 years and except that i never had any mechanic problems in the last 20 years… simplicity is a rule of success… modern cars expecially the ones with a lot of electronic wont arrive to the 20 years goal i suppose.
Hi Andrea,
It’s difficult to diagnose the working of the Auto transmission just with words.
I would as a matter of course change the filter and the oil (which is easy and messy in equal measure).
Make sure you order the right filter and pan seal.
What you describe seems the normal behaviour, but the extent of the jerk is impossible to derive from a text… the ZF HP24 is electronically controlled, so other than making sure all connections and sensors are fine, there is little to tune: just change the oil and filter.
Possibly you know this already, but when you are at it, renew the coolant for correct-spec antifreeze/water mixture in any new purchase, unless you have clear evidence of when this was done.
This cars are incredibly strong in the engine/trans side, but aluminium does corrode and services get neglected.
Best,
Ll.
Best,
Ll.
Thanks! i bought the car from a reseller / mechanic who used it as personal car for almost 2 years before putting on the market. It was driven for 7000 KM in the last year and was regularly serviced. As he told me it was changed the oil, air filter, trasmission fluid and filter in the last year and many rubber tubes (hydraulic and water). But not all the issues of the car where solved before selling (abs accumulator, fan working only at max speed, a metallic clunk from the rear suspension) so i am fixing all those items and i am on a little budget at the moment. Next year i plan to make a full service to start from a know service base record.
Speaking for a USA spec 1990 XJ6 4.0. These cars had a “SPORT” button at the back of the shift console. Engaging this changes the shifting program to higher speeds for each up shift. Leaving it off, the gearbox will upshift sooner at lower engine RPM to conserve fuel. Not sure where you are on the globe, and if all cars for different markets had this feature. Might be useful to update your profile with your location, car, and other details. On my car is usually leave sport mode off and only down shift from D to 3rd if descending a long grade. Maybe if really steep select 2nd.
I too never use the sport button, car is nimble enough and if needed, kickdown feature works smoothly. With the J-gate gearshift selector over on the left I tend to drive the car just like a manual, downshifting on approaching sharp bends or slowing down/descending hills.
IMO, the most flexible transmission I’ve ever driven and the idea that anyone would want a manual trans in one of these cars, I find very odd!
If driving in heavy slow bumper to bumper traffic like where I used to live, the sport mode can be useful as the brakes do not have to be used as often as holding the gears longer gives more engine braking. Some may not know but the J gate can be modified to permit the lever to move to the 1st gear position but I see no real need for that…