XK8 GEARBOX RELATED CLONK

[jag5014]

Hi

I have recently bought a 2005 XK8 (74000 miles) and wondered if anyone could help with the following. On the downshift there is a light knock when the gearbox changes from 2nd to 1st on coming to a braked stand. However if you release the brake on coming to a stand this change from 2nd to 1st becomes a clonk which you can feel throughout the car. This is more obvious when the engine is at normal temperature.I can't positively identify where the clonk is coming from but appears to come from the gearbox/transmission and definitely coincides with the change from 2nd to 1st and vice versa in stop/start traffic.
I took it into a main dealer and they diagnosed it as an internal gearbox fault needing a replacement box but i'm not convinced as the car drives well and changes on the upshift are smooth and clean without noise.
I am a new member to the JEC and this is my first post so any help or info would be most welcome.

Clive R.

[mike020150]

Hi Clive,

Early in the life of the 6 speed gearbox, there was a fault in some gearboxes which gave the symptoms you describe. In that case, the first line of attack was a gearbox re-flash with what was then the latest software. Consequently, I would be tempted to take the car to a Jaguar specialist (rather than your dealer) who could try re-flashing the software before assuming there is a mechanical fault with the gearbox. If you live within reach of David Marks Garages Ltd (Nottingham) or XJK Ltd at Newcastle under Lyme, I expect either would recall the problem and its solution. Mike.

[jag5014]

Hi Mike

Thanks for the info.
i am in Wantage ,Oxfordshire so Nottingham is a bit far. Would you know of a recommended Jag specialist in the Oxford Swindon area ?

Thanks
Clive R.

[mike020150]

Hi Clive,

It's along time since I inhabited your area so I'm out of touch with your local specialists. If no-one else reads this thread and makes a recommendation, I'd suggest going along to your local meeting to quiz members on their views of local specialists and then make up your mind on the basis of the evidence you uncover. Mike.

[J44EAG]

I know it is a bit further to travel than is ideal for you, but many of us have used Bristol Transmissions near Fishponds in Bristol.

They have been in business for years and are well versed with the repair of the gearboxes found in our cars. I have used them and can recommend them. The S-type V8 Ford 5R55N gearbox they re-built for me has now covered over 60k miles and continues to be totally faultless. That is more than can be said for the original build!

Hope that helps.

Mike K

[Rictus]

Hi Clive,

I have a similar issue with my XK8. I had the gearbox oil changed a couple of years ago which appeared to help for a while but have been considering a reflash as the best option. Your post has prompted me to give XJK a call!
As for who you can use, I believe Tom Lenthall near Reading is a good Independent and a bit nearer than the other suggestions.

[J44EAG]

Tom is "Mister Magic"! I use his services. Highly recommended and will get results.

Mike K

[Rictus]

I have my XK8 booked in for a gearbox reflash at XJK next week an will report back with the results

[Rictus]

I am pleased to report much improvement following a gearbox reflash at XJK (cost £95.40 inc VAT). The change up from 1st to 2nd is now seemless although there is still occasionally a small clunk when coming to a halt and the box changing down to 1st. I'd say a 75% improvement

[mike020150]

That's good news for you and anyone wondering whether to try this solution for similar gearbox issues. Thanks for reporting back. Mike.

[wombat]

Hi, sounds a little like my problem.

I have a 1999 xk8 with 120k on the clock, I had the oil flushed and filter change as soon as I bought at around 110k.

The main problem I have is after a fast run and slowing quickly to a stop, when I then go to pull away again it seems to be in too high a gear followed by a loud "clunk" as it drops down to 1st.

Maybe connected to my other problem - when I push down on the throttle to drop a gear while driving - it seems to hesitate, select a few gears before it settles on one. First few times was a bit hairy as overtaking at the time.

So needs flashing? If so, who could do this around Devon/Cornwall for me?

Thanks for your responses in advance.

[mike020150]

The original thread referenced a not uncommon problem with the 6 speed ZF gearbox. Without wishing to sound too pessimistic, your car has the earlier 5 speed unit with less sophisticated programming so the issue may well be due to a different cause. A visit to a ZF gearbox specialist (not necessarily a Jaguar specialist) might be worth considering. Mike.

[Truggy]

Can anyone a garage in Northern England (Lancashire if possible) to work on my gearbox?

It's an XKR 2003 - 90k - and it's in need of a flush/flash/both.