What is a gkn overdrive

I doubt you will have a problem. I've now got approval for this from Senior Management and have found a place with new stock. I've also spoken to GKN in Sutton Coldfield and they tell me that there will be no spares available once their current stock is gone. All produced spares have been allocated to warranty claims and after that there's no more. Chaps, do you still recommend this as a sound purchase?

I could use your honest responses quickly. Even if the electrical side of it causes problems then you could always hardwire the solenoid to switch it straight in to a relay. My GKN just failed after 40K miles. Never used as a splitter only as 6th gear on the motorway etc, hardly any towing, regular oil changes. I thought the clutch was slipping so fitted new clutch and hydraulics but it was the overdrive.

It appears that this is a very common fault and is why they are no longer available. Certainly wouldn't recommend one.

I just wonder if some of the cause of the failure rate is a consequence of laziness on the part of some owners. If you just flick the switch and let it hoof itself in, and then ignore it when slowing so it self-disengages the battering it gets is pretty hefty. Treating it like a proper gear and using the clutch seems far more kind. Anything that makes that much noise and vibration when it's doing it itself ie without clutch strikes me as being slightly less than healthy to one's drive mechanism, and to the unit itself.

For my GKN overdrive the manual says oilchange every km and the use of automatic gearoil. Personally I change after km and I believe it has done well over km in a stw TD5. It has start leaking a bit of oil and as I havn't checked where the leak are, I check oillevel more often now.

I hear what your saying Simon. Id not touch one with a bargepole, they are unrelaible and this is not compounded by the end of production, limited spares WILL become a problem fairly rapidly too.

The GKN overdrive has a poor reputation for reliability - mainly due to the electronics. Also, it only works on 4th and 5th gears. A brilliant bit of kit - it's more than paid for itself in saved fuel in a year 18, miles.

It also works on all the gears including reverse, just like the Fairey. Best upgrade I've ever done on the truck. John S likes this. John Barrett , Jun 10, Thanks diapson I didn't know that they only worked on 4th and 5th. Show 12 24 36 All per page. Page: 1 2 3 Next. Find out More. Shop By. Compare Products. I've not owned the unit for long enough to comment on the proffered fuel savings yet, but I will update this section when I feel competent to do so.

In the meantime, the two main advantages, a tall top gear and full power shifting, are real and worth having. Motorway cruising is now carried out at an indicated rpm at around 70mph, and feels much more relaxed. The moment a steep incline starts to knock off momentum, the flick of a switch results in a smooth downshift to hold the speed, or to aid in overtaking. The top gear feels very tall, but not ridiculously so, with the Tdi pulling well down to around rpm.

Update - I've been running with the overdrive now for approaching miles 3 weeks! There seems to be a trend to slightly better fuel economy, but only in the region of 1mpg improvement. This doesn't seem like a massive improvement but it is around a 3. It is fair to say that the purchase cost will never be recouped on that basis alone, but reduce engine wear and cabin noise will go a long way to closing the gap.

Several ways to improve the gearing suggested themselves :- Taller transfer box gears. The LT transfer box is fitted with It is possible to fit another of the other common Land Rover ratios. A