So my 2003 jaguar s type r has had a few problems.I put the car in passing gear and GEAR BOX FAULT light came on and it would kick in and out of gear.well i have been taking it easy for a bit and started to shift good,so i kicked it into passing gear again now it shifts good just cut out.I replaced a coil that was going out and cleaned oil off the other coils from the valve cover gaskets that are leaking went and ran it hard up to 120mph 3 times and is great.has anyone had this prob? I fixed the miss and it fixed the trans too.after i replace the vc gaskets do yall think i will be ok???or will the trans mess up again,thanks for all the help.... Dustin

 

These gearboxes (I guess a ZF 5HP25 or later 6HP26) can be troublesome. It seems the early ones were controlled by bad software, the later ones like mine, bad atf fluid. If your autobox has done more than about 50,000mile, it's certainly a candidate for new fluid, as far as you're able to change it, i.e. only about 2/3 of the fluid unless you have one of those machines that connects to the cooler lines. Mine had done 120,000mile, a 6HP26, but fresh fluid has made a huge difference in the way mine doesn't shudder/judder or keep grunting at a partic. speed. I also feel a fluid change will extend the service life of the autobox. I used "Forte" additive at the same time as the atf change.
There are plenty contributors here who can help with autobox control software, but I don't know if updates are restricted to Jaguar dealers still.
Cheers, Leedsman.

 

I have the zf6hp26 with about 75k...I want to do a service on the trans.Is there a aftermarket fluid that i can use,if so what...And do i need to change the pan i think its the filter,or just change fluid.i dont want to go to the dealer cause the fluid is about $40 a qt

 

I used full synthetic meeting Dexron VI or LT71141. It was a nondescript make, but is apparently Mobil. It took 7litre, but there is about 3litre left in the torque converter you can't get out unless you have the gizmo. I also used "Forte" additive (make no mistake, this stuff has an effect) but I don't know if it's available in US. That "Lubeguard" seems to be favored by many there. The sump-tray has the filter built in. Mine cost £18:50., say $24:00 or so. Let us know if the atf change makes any difference? The full synth. should make the box run cooler by abt. 20degree F according to the scientists. Handy if you give it some welly.
Leedsman.

 

I have used Mobil 1 Synthetic ATF in several 6HP26s, with 10s of thousands on miles on them (including my own 6HP26) with no complaints at all. I highly recommend changing the fluid at the 50K to 70K mark for extended life.

On the 6HP26, the filter and gasket are both part of the plastic pan and must all be replaced as one single part. A number of the 21 #27 torx screws that hold the pan in place typically freeze in place (steel screw against aluminum casing) and will need replacement - sometimes you get lucky, but I just order all 21 when I order the pan. Next, the 6 speed has a plastic connector sleeve (seal) that is a notorious leaker. The sleeve is only $14 and should be replaced at the same time, as the lock that releases it is only accessible from inside the pan. It would be a shame if you changed fluid and pan/filter and not the sleeve only to have it leak a short time later.