Both Jaguar and Land Rover have used the ZF 6hp/26/27/28 automatic gearbox extensively in their more modern model ranges. In the Jaguar they are are present in the S type and XF model ranges and in Land Rover they are present in the Discovery 3/4 and Range Rover models. I have found that the ZF is an extremely reliable and smooth transmission, if they are serviced properly. The problem is, that is a BIG IF. The issue is the car manufacturers suggested service schedule of the transmissions, with statements such as sealed for life and 240,000km thrown around. The transmission is essentially a mechanical and electronic part that operates solely, with a single hydraulic fluid supply. Personally I don't see it as a part that should have a limited lifetime considering the fact that, second only to the engine, it is definitely the next most expensive part to repair, replace, or overhaul.
So generally what I have found is around that at the 150,000km to 180,000km range, the transmissions generally start to show a few gremlins, whether it's slight judders taking off or lazy gear selection.
So how to fix it???
SERVICING THE TRANSMISSION which isn't a large job!!!
On the Jaguars it is simple, but the Land Rover is slightly more complex. The good thing is transmission serving kits are readily available for both marque.
On Jaguars, it involves draining the transmission fluid and removing the transmission pan. The pan has a built in filter so replacing it is very simple. At this point the transmission must be refilled with ZF Automatic specification lubricant and have the level set following the appropriate procedures.
On the Land Rover models, it is the same as the above, however due to a cross member going straight across under the transmission pan it's not quite so easy. It can be overcome by either undoing an engine mount and lifting up the engine to create the clearance needed or by changing to a two piece transmission pan. These two piece pans are an aftermarket part. They use a separate filter and pan to allow the technician to replace the pan without lifting the engine. The only hard part is that in removing the old pan, you must brake the "pan pick up neck" in order to get it out. This method is well worth the time saved.
So, when should the transmission service be undertaken on your Jaguar or Land Rover???
Well, on a Jaguar we have found the 80,000km mark works well and seems to prevent those faults which can occur later in your cars life.
On the Land Rovers it does depend on what the vehicle is being used for. For general use the 80,000km mark is fine, however if you tow a lot or do extensive offroading then the best option is around the 70,000km mark.
I am a big fan of the ZF transmissions and with the right care, they will serve you well for a long time. A couple of transmission services will be far cheaper than a full transmission overhaul.
If you have a Jaguar or Land Rover feel free to contact us with any questions regarding your transmission service. You can contact Pickards Automotive at www.pickardsautomotive.com.au or at (03) 9428 9655.