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GKN Overdrive


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Thoughts are turning to lower engine revs when on motorways.

Just found out that GKN stopped making their overdrive a few months ago due to excessive warranty claims. Bit of a sod. Devon 4x4 don't have any left.

The question is does anyone know if GKN are planning to re-introduce it or do I simply chat with Ashcrofts about a Disco transfer box and Q gears?

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Are you sure you want to buy something that suffers from excessive waranty claims?

Anywho, there's also the Rocky Mountain "Roverdrive". The website ( http://roverdrives.com/ ) seems to be offline at the moment, but their other site http://www.parabolicsprings.com/ seems to be running.

Edited to add:

http://www.rockymountainspares.co.uk/?p=21

(since Berkshire sounds like one of those UK places ;) )

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I was considering an overdrive for my 90 TD5 but a certain gearbox specialist told me that of all the GKN one's he's sold, 50% came back, but mainly with electrical problems due to the driver not disengaging them in the lower gears.. The 'Overdrive' guy is currently developing a Land Rover specific overdrive but there won't be any available just yet. Says he wants it to be THE LR overdrive and isn't selling until it's right. He told me there won't be any before spring '08 anyway, and the Rocky Mountain importer says there's a problem in Vancouver with production.. So, I'm reverting to Ashcrofts and the Disco transfer box gears, as usual, and next week! Hope this helps.. EdF

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Does anybody know if GKN are still doing spares?!?!??! I need a new speed sensor & an adapter for an R380 gearbox.

What specific problems do the units suffer from so that 50% fail, I have to admit to never having heard they were so bad!

it bolts onto the back of the transferbox NOT the main gearbox, for spares just ring GKN use the number in the overdrive booklets that were supplied with it.

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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.

There will be no replacement model.

Chaps, do you still recommend this as a sound purchase? I could use your honest responses quickly.

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had my gkn fitted for 72k now and still all original parts no problems less a small electrical issue activating the solenoid, l han't heard of any mech problems with them though
Mine will be staying fitted, just use it correctly & remember to disengage when dropping below 30mph & change the oil regularly as per the handbook that comes with it.

Well i am keeping mine and will transfer it when i change the vehicle as well. (if i change it)

ralph - correct oil change is only every 60k K or similar isin't it, so you dont really need to do alot with them once fitted. Even if the electrical side of it causes problems then you could always hardwire the solenoid to switch it straight in to a relay.

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Well i am keeping mine and will transfer it when i change the vehicle as well. (if i change it)

ralph - correct oil change is only every 60k K or similar isin't it, so you dont really need to do alot with them once fitted. Even if the electrical side of it causes problems then you could always hardwire the solenoid to switch it straight in to a relay.

oil change is 1st after fitting 1500km's then at 55,000km intrevals.

it's a newer version of the old laycock overdrive used in the old Triumph 2000 IIRC & they only had a in/out switch & no speed sensors to auto disengage it, connecting as you suggest would make it work, with the speed sensor disconnected or a blank fitted in it's place.

I think BigSi would be best to go for the transfer gears.

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  • 1 month later...

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.

Will take it apart when I get time and see if the design can be improved.

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Guest wunntenn

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.

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oil change is 1st after fitting 1500km's then at 55,000km intrevals.

it's a newer version of the old laycock overdrive used in the old Triumph 2000 IIRC & they only had a in/out switch & no speed sensors to auto disengage it, connecting as you suggest would make it work, with the speed sensor disconnected or a blank fitted in it's place.

I think BigSi would be best to go for the transfer gears.

For my GKN overdrive the manual says oilchange every 20000 km and the use of automatic gearoil. Personally I change after 10000km and I believe it has done well over 120000 km in a 110stw 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.

Lars

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Guest wunntenn

I hear what your saying Simon. Mine is still going ok, although I do have a problem, but that only started after a recent clutch renewal, and I think its a clutch release mech/bearing problem rather than the o/drive (says he with crossed fingers!).

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For my GKN overdrive the manual says oilchange every 20000 km and the use of automatic gearoil. Personally I change after 10000km and I believe it has done well over 120000 km in a 110stw 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.

Lars

the owners/service book that came with my OD states the subsequent oil changes are 55,000Kms copy below

post-20-1201548174_thumb.jpg

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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.

Best bet is Q gears, much cheaper, 100% reliable - much better solution.

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  • 3 months later...

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