Jump to content

GKN overdrive


GBMUD
 Share

Recommended Posts

Can one still buy them new? A quick Google failed to find one - in fact it just showed forum results with people having problems, which is why I am thinking new rather than used and buying someone else's problems!

I did find a 'Roamerdrive', any thoughts/feelings about them? I guess they work differently.

Cheers

Chris

Link to comment
Share on other sites

Roamerdrives are much more reliable, being epicyclic and using EP90. I have had one on my 109. I had to rebuild it because I damaged the bearings when the transfer box lost a lot of its oil, but the rest of it stood up very well indeed, which is testament to its strength. It's a shame they don't have the option of solenoid control, like the GKN, rather than just the extra lever, but you can buy one with confidence.

Link to comment
Share on other sites

I'd buy the Roamerdrive!

I talked to the guy who designed it at Peterborough one year - and he gave me a lot of confidence! Lever operation is preferable to a solenoid - at least you can feel whether it's in and there's less to go wrong long term!

Si

Link to comment
Share on other sites

Roamerdrives are much more reliable, being epicyclic and using EP90. I have had one on my 109. I had to rebuild it because I damaged the bearings when the transfer box lost a lot of its oil, but the rest of it stood up very well indeed, which is testament to its strength. It's a shame they don't have the option of solenoid control, like the GKN, rather than just the extra lever, but you can buy one with confidence.

Yet I've had two GKN's, one on a 200 TDi Defender which did over 250k without a problem (still on the vehicle, but vehicle being rebuilt) and another which put up with a hell of a lot of abuse use on a V8 110 - sitting quietly in the garage till I decide which vehicle to put it in....

Link to comment
Share on other sites

I've fitted and still look after a few GKN overdrives. The unit itself seems strong enough,but the oil in it works hard so don't neglect it if you find one. The electrical side of things gives more trouble,I've had a couple of speed sensors fail and if you mount the switch in the gear lever then the wires can fail from constant flexing,like the HDC switch wires on a Freelander 1.

They also benefit from using the clutch for a smooth shift,although they are capable of full power shifting.

Link to comment
Share on other sites

Ally, What do you think would make one slip when not engaged?

I've got one that used to be found under my 110 V8 but it had a sabbatical and lived in a box in the garage for a while.

We've replaced the clutch material and replaced the filters..... Still slips under power. Do you think the pressure springs pushing the cone clutch in can soften with age?

Neil

Link to comment
Share on other sites

Roamerdrives are much more reliable, being epicyclic and using EP90. I have had one on my 109. I had to rebuild it because I damaged the bearings when the transfer box lost a lot of its oil, but the rest of it stood up very well indeed, which is testament to its strength. It's a shame they don't have the option of solenoid control, like the GKN, rather than just the extra lever, but you can buy one with confidence.

The GKN unit is epicyclic......

Link to comment
Share on other sites

Thanks everyone for your thoughts and ideas.

The Roamerdrive certainly sounds like a good solution, though I am not a fan of extra cabin levers. I might see if it is possible to adapt something less intrusive. Anyone got one and have a picture of the lever setup? I wondered if something more like a PTO control - just a knob that pulls/pushes in the front of the seatbox to the left of the handbrake - might work?

Thanks again

Chris

Link to comment
Share on other sites

Ally, What do you think would make one slip when not engaged?

I've got one that used to be found under my 110 V8 but it had a sabbatical and lived in a box in the garage for a while.

We've replaced the clutch material and replaced the filters..... Still slips under power. Do you think the pressure springs pushing the cone clutch in can soften with age?

Neil

Sorry,can't really help much with this,the last time I took a GKN / Laycock overdrive apart was about 30 years ago on my Dolomite Sprint... The recent LR ones have only had external faults,so I've had no need to remember how they work or come apart.The old ones would slip with O/D engaged if there was insufficient hydraulic pressure to force the cone clutch fully into its engaged state.I seem to remember mine did this because the O rings on the solenoid went hard and leaked. I can't think of any reason why they would slip in direct drive...

Link to comment
Share on other sites

Them springs were already on top of my list....

Will call some experts today and see what they say !

Edit:

The helpful chap at Overdrive Repair Services was talking about a Uni-directional clutch which has a plastic carrier that he suspects may have broken up and therefore not be applying the pressure required. Apparently the cone clutch is only engaged when reversing or in Overdrive ! (Hard to figure that one out but he's the one who knows his stuff...)

He doesn't like working on them as he has no way to test them and suggested Devon 4X4 as the only other company he knew working on them.

Last time I called them they were talking at least half of a new Overdrive to "potentially" provide a fix.. They assumed cone clutch, which has been replaced..

So... we are no further forward... Might be time to get it apart on the bench again !

Rich....... You wanna play some more?

Neil

Link to comment
Share on other sites

I had a Roverdrive, (before they were called Roamerdrives), and back in 2006 it burnt all its synthetic gear oil on very hot day at 100kmh here in Western Australia. I was offered a replacement finned housing, but it never materialised, despite a few reminders on my part, some on a public forum.

Apart from the complete failure to handle extreme heat, it was very good otherwise, but after this I didn't use it much. No doubt they will probably be fine in a British climate, but for me that was a big slab of cash gone for good.

Link to comment
Share on other sites

Thanks everyone for your thoughts and ideas.

The Roamerdrive certainly sounds like a good solution, though I am not a fan of extra cabin levers. I might see if it is possible to adapt something less intrusive. Anyone got one and have a picture of the lever setup? I wondered if something more like a PTO control - just a knob that pulls/pushes in the front of the seatbox to the left of the handbrake - might work?

Thanks again

Chris

Picture of the OD lever location, new gearlever gaiter with extra hole for OD lever. http://www.roamerdrive.com/ds_overdrive.html

post-20-0-66856200-1460482930_thumb.jpg

Link to comment
Share on other sites

Them springs were already on top of my list....

Will call some experts today and see what they say !

Edit:

The helpful chap at Overdrive Repair Services was talking about a Uni-directional clutch which has a plastic carrier that he suspects may have broken up and therefore not be applying the pressure required. Apparently the cone clutch is only engaged when reversing or in Overdrive ! (Hard to figure that one out but he's the one who knows his stuff...)

He doesn't like working on them as he has no way to test them and suggested Devon 4X4 as the only other company he knew working on them.

Last time I called them they were talking at least half of a new Overdrive to "potentially" provide a fix.. They assumed cone clutch, which has been replaced..

So... we are no further forward... Might be time to get it apart on the bench again !

Rich....... You wanna play some more?

Neil

Happy to take it apart again Neil! I'm struggling to think of any plastic components in there though. I cant recall any in yours, or in my working one when i took that apart either. There don't seem to be any parts matching that description on the ORS site either. Those for springs are quite cheap to replace - i think they were only a few quid each on the d44 site, but they didnt look broken when we took yours apart?

I have another theory to add to the mix. I wonder if there is wear in the cylinder where the solenoid sits that is allowing pressure to pass through? We have replaced the seals on that solenoid, (in fact, i think you have tried a new one), but perhaps there is enough wear in there to prevent them working properly. (just a theory, but came to me whilst having a discussion about the reasons for the RR TD6 gearbox failures).

Link to comment
Share on other sites

Maybe he was an expert on other Overdrives :)

I think taking it apart again without buying any new spares is worthwhile...

Getting those last few areas opened up will help us to decide if it could be springs losing their strength over time... Could add spacers temporarily under the retaining plates to increase pressure I guess and replace springs if proven correct?

I don't have a convenient test bed now as mine is 1.2 T/box.... (Mo... Where are you when I need you.. Well your truck !!!)

Link to comment
Share on other sites

Maybe he was an expert on other Overdrives :)

I think taking it apart again without buying any new spares is worthwhile...

Getting those last few areas opened up will help us to decide if it could be springs losing their strength over time... Could add spacers temporarily under the retaining plates to increase pressure I guess and replace springs if proven correct?

I don't have a convenient test bed now as mine is 1.2 T/box.... (Mo... Where are you when I need you.. Well your truck !!!)

Yep, I agree. There are only a couple of other areas of it that we haven't opened up.

The springs are so cheap, i don't think i would mess with spacers - i have a feeling that adding spacers may make it impossible to get the retaining bars back on as there isnt much thread available as it is from memory.

I guess we could test it on mine - afterall, the electrics are there and we wouldn't even have to take the adapter plate off. Only thing would be that we would need to make a decision that day on whether to leave it on there for a prolonged trial as i use it daily, so cant have it slipping!

Link to comment
Share on other sites

Maybe he was an expert on other Overdrives :)

I think taking it apart again without buying any new spares is worthwhile...

Getting those last few areas opened up will help us to decide if it could be springs losing their strength over time... Could add spacers temporarily under the retaining plates to increase pressure I guess and replace springs if proven correct?

I don't have a convenient test bed now as mine is 1.2 T/box.... (Mo... Where are you when I need you.. Well your truck !!!)

Fear not uncle, I'm never far away ?

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...

Important Information

We use cookies to ensure you get the best experience. By using our website you agree to our Cookie Policy