I've owned a beautifully cared for 2004 S Type for about 6 months. Had the (ZF 6 speed) gearbox oil changed almost immediately (about 150,000 km) because it would thump when accelerating from 50 - 60 kmh, but no change. Once warmed up it is an absolute delight, and if I start out and run at higher speeds then no problems at all. I've read that it could be solved by re-flashing (limited reports of success), by replacing the valve body, or by replacing the torque converter. I've learned to "humour" the car by driving in third gear until warm. Even after a 5 minute short drive and parking, it seems that heat soak will then warm up the box sufficiently enough to behave itself perfectly. Question is, is it likely to get worse? I have an aftermarket warranty that is good for another 6 months which should (?!) cover the cost of repair, but since the diagnosis seems difficult is it worth it? I can live with the workaround as above if it will not deteriorate. Thanks for any help!

 

The first thing to check is when the fluid was changed - probably never so it needs doing - and then to make SURE the level is correct as it may well not be.

 

I mentioned in my post that the first thing I did on purchasing the car was have the gearbox oil changed, by a mechanic with plenty of experience with the ZF six speed. It had no effect, the problem being apparent both before and after the change.

 

Ah, yes, sorry.

You may have a worn valve or sticking solenoid - either change the part(s) or live with it I suppose.

 

I had a harsh 1st to 2nd shift when cold....I got my sdd system 2 weeks ago and cleared the trans adaptations and reflashed it and now it is smooth as silk....it took about 300 miles to fully adapt but it is like new....reflash would be worth a try

 

Thank you scottjh9, that's very encouraging & I'll definitely get a reflash, I suppose I'll get a main dealer to do it for me.

 

At least that would take care of any non mechanical or wiring issues...if you get it done there is a sticky or tsb on the trans adaptations procedure as you drive..stick to it as best you can...for sure no sport mode or hard acceleration...if you are not near a dealer ask an independent shop if they have jaguar sdd capability and they can do it....not sure if warranty will cover it unless they diagnose it as needing the reflash....on my sdd diagnosis , sdd recommended a reflash for a hard shift complaint after a fluid check and possible trans filter change...you have already done that so make sure they are aware of it...they still will probably do a fill check to stay within sdd protocol

 

Does TSB PS3 07 - 14 describe the problem? If so, the software upgrade might just do the job.

 

Thank you Mikey, that's really helpful. Describes the problem exactly, I'll present the pdf to the service center.
Very grateful for all the support here, thanks again!