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Thor

Member Since: 17 Dec 2011
Location: Didcot
Posts: 446

GKN Overdive

I have done a search and read a few threads but...

I have a GKN overdrive fitted to my 2003 G4 Defender 110 which has operated faultlessly since I bought the vehicle five years ago

Yesterday, whilst towing it developed a problem. I engaged as as normal, the red light came on and I felt it engage. As I approached a hill I disengaged it. I felt the over drive "slip in and out" and could smell the clutch, it done this in both 4th and 5th gear.

The problem is sorted short term by stoping, switching off the ignition and starting a gain, no problems rough the gears including 4th and 5th. Once I engage the overdrive again, I can't disengage it with out stoping and switching off the ignition.

I've also emailed Devon 4x4 whom seem to hold GKN items in stock.
Any advice/ideas much appreciated. Strong people are harder to kill and generally more useful!

28th Mar 2016 1:27pm

Mjibex

Member Since: 21 Mar 2013
Location: Reading
Posts: 283

2013 Defender 110 Puma 2.2 XS CSW Loire Blue

I am not a fan of GKN overdrives.
I quickly swapped it out for 1.22 transfer ratio on my tweaked Td5.

But if your happy my suggestions would be:-

Stop using overdrive until it issorted.

To start with change the overdrive oil (has this been done whilst you owened it)? - get a gasket from D4x4. (From memory 6 or eight bolts holding a square plate on - make sure you can get the filler plug out 1st).

I wouldn't be using the overdrive whilst towing any weight.

Mark.

28th Mar 2016 1:38pm

Romadog

Member Since: 07 Jul 2011
Location: Powys
Posts: 1749

Have to disagree

Had a GKN in a 90 and spent 90% of the time towing an 18' trailer loaded 5 days a week. It was the best thing for towing as there was no loss in driveline momentum when changing down that half a gear.

Otherwise speak with Devon 4x4 as they are the ones with the expertise on them.

28th Mar 2016 2:04pm

Thor

Member Since: 17 Dec 2011
Location: Didcot
Posts: 446

Thanks for the speedy replies gents!

Mjibex I have stopped using the overdrive. Today was the 24 hours after the event to see if it had fixed itself, wishful thinking I know. I've read a lot af folk aren't fans of the unit but it's given me a faultless 5 years until now so I'd like to look into a bit more before binning it. A service of the unit is now the top of my todo list.

Romadog, I agree it has performed brilliantly so am defo keen on getting it back up and running. My original post is a copy, paste a adjustment of an email I've sent to Devon 4x4 so hopefully they'll get back to me soon. I've asked if they're aware of a service manual as I'm keen on doing that first. Strong people are harder to kill and generally more useful!

28th Mar 2016 2:15pm

Mjibex

Member Since: 21 Mar 2013
Location: Reading
Posts: 283

Has the overdrive oil been changed in your ownership?

28th Mar 2016 3:50pm

Thor

Member Since: 17 Dec 2011
Location: Didcot
Posts: 446

Yes mate, once when I bought it, and once again 2 years ago when I paid a small fortune for a full service. I serviced it my self last year on Easter bank holiday, but for reasons unknown overlooked the overdrive. Fortunately I only do 5k a year in it so once I realised I didn't think it'd be the end of the world it missing a year, and nearly a year later

Like I say I've emailed Devon re service items and hopefully a manual of sorts and then I'll be getting underneath it. Strong people are harder to kill and generally more useful!

28th Mar 2016 7:45pm

PCA42

Member Since: 15 Jun 2014
Location: Church Stretton
Posts: 468

2008 Defender 110 Puma 2.4 DCPU Tonga Green

Can't offer any real help with this, but I had a GKN from new in my old Td5. After about 5 years of faultless use, it started to develop problem after problem and I spent an absolute fortune on replacing nearly everything on it until parts started drying up (until Devon solved this issue to a degree). I just gave up on it, sold it on and replaced it with 1.22 transfer ratios.
The ideal solution would be a Roamerdrive, very robust, reliable and no leccys to worry about. But only if you are willing to spend one and a half grand!! Pete

2010 Discovery 4 GS TDV6
1972 Series III 88" 2.25P

29th Mar 2016 10:36pm

jst

Member Since: 14 Jan 2008
Location: Taunton
Posts: 8099

2011 Defender 110 Puma 2.4 USW Stornoway Grey

i ran one for 80k miles on my td5 (remapped) including lots of 2-3T towing. loved it and was faultless.

Sounds like electrical contact issue with speedbox/switch unit not telling solenoid to disengage. replace the solenoid switching unit with a simple on off switch to energise/or not the solenoid to switch the unit and then use the switch within the parameters that the speed switch operates the unit.

failing that go for a manual engagement system. Cheers

James
110 2012 XS Utility
130 2011 M57 bespoke Camper
90 2010 Hardtop
90 M57 1988 Hardtop

30th Mar 2016 4:05pm

ashtrans
Site Sponsor

Member Since: 08 Nov 2008
Location: Harpenden
Posts: 259

I would agree with James, bin the speed sensor and ECU and wire the switch to a relay to control the solenoid manually

Dave Dave

30th Mar 2016 8:12pm

Thor

Member Since: 17 Dec 2011
Location: Didcot
Posts: 446

Finally got time to get under the Defender today.

Changed the oik on the GKN, gave all the electrical connections a good clean as well as give the mesh filter a proper scrub and it's now working a treat! Lovely little 100 mile round trip with at least 80 of them with the GKN engaged.

Really happy with the results. Thanks for all your help and advice!!! Strong people are harder to kill and generally more useful!

1st May 2016 7:13pm

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