GKN overdrive - gremlins in the machine!!!!

[ebygum110]

I'm hoping someone can help me navigate through some problems that may or may not be related.

I have a late 03 110 CSW with a GKN r type overdrive fitted - which has performed well for the past 6 months and 6,000 miles since I acquired the vehicle (only 42k on the clock).

for the past couple of weeks in the hot weather the vehicle has been parked up most of the time except for a trip to a show and some mild off roading.

I took it out for the first time last week and all was fine until I returned to the car having left it parked at the supermarket - it almost stalled reversing out of the parking space as if the handbrake was still on. I had used the OD on the way there but disengaged using the clutch as always before dropping speed down to 30.

Driving forwards again seemed to be fine - drove a few miles and stopped again to check reverse - same 'binding' problem. A few forwards and backwards actions and it seemed to free up. However the OD then didn't seem to operate (although the LED seemed to be ok and warned at low speed).

Changed the oil in the OD and cleaned the filter - hasn't seemed to cure the problem (no debris apart from the grey gunk on the magnetic plate) no leaks.

Took out for a longer run a couple of days ago and experienced jolting at low speed second (suspected the TPS but I think it was down to the low range lever not all the way back to the right after reconnecting the diff lock light and checking operation)

(told you this was complicated!)

I also experienced some 'surging' at around 50 mph - but that happened only once before filling up with fuel (so that may have been pressure in the tank!?!)

So today I checked the breather on the OD - all fine and clear. Checked the leads to the solenoid - a bit grubby but terminals appear clean.

Tested the OD switch with ignition off - 10 flashes and then constant on until switch off - which is odd because it does NOT do this when selecting at speed.

Leave the switch off, turn on ignition, there's no indication - but then I don't remember there ever having mean one (some forum posts say it should flash once at start up)

Still binding in reverse - so now I suspect the OD is not fully disengaged and may be winding itself up - again, forward motion is fine - but then that is also odd because I would expect acceleration to be very sluggish if the OD is constantly engaged.

Crawled under the vehicle this evening after a 10 mile road test and the OD is hot to the touch - not sure if that's normal.

Any advice gratefully received.

T

[reb78]

I'm not sure this is all your OD. I thought these went bang and broke if engaged in reverse - i.e. you will break it. If it hasn't, then I'm not sure this is your reversing problem. With the failure to engage, I would usually say change the oil first, but you have done that. Has it failed to engage again after changing the oil?

Are you sure your handbrake isn't binding? Might be worth servicing that to be sure.

I think the flashing when ignition off is normal - pretty sure mine does that. The temperature is normal too. They only take ~700ml of oil and mine gets roasting hot after a run at 80 on the motorway. It really would benefit from a larger oil sump to increase capacity and also cooling ability - I wonder if I can get someone to manufacture one....

BTW - I change my OD oil every 6000 miles any more and it gets really burnt and doesn't do the unit any good.

[TSD]

The surging suggests you are correct, it's not fully engaged or disengaged. If it were fully engaged, then as Reb78 says, it would have properly gone bang when you reversed.

Mine was immediately noticeable when coasting down off the motorway, as soon as I touched the throttle, it was obvious all was not well.

Oil change and filter clean was a good first step, but I would drop the high pressure filter out too and clean the swarf out of it. It's under one of the round caps behind the screen filter.

There are complete service manuals online for either the Volvo or Triumph versions. Both are pretty much identical except for the added electronics pack and coaxial drive arrangement.

I rebuilt mine completely with new seals, but I think the cone clutch is slipping and causing it to overheat. It sits on the workshop floor as an object of hate now. Hope you have better luck with yours.

[reb78]

For some reason i forgot about my own thread. There is some useful info here:

http://forums.lr4x4.com/index.php?showtopic=84641

if by surging, you mean the same thing i was experiencing, then the next step would be the HP filter as TSD suggests. There are some useful links and advice in the thread above.

[ebygum110]

thanks guys

as a first step, is it possible to bench test the solenoid with just a simple 12v supply just to check it is actually doing what its supposed to and not sticking.

I had a brief run today - didn't bother selecting the OD at all - no problems with reversing - so its either residual pressure from a sticky solenoid (me thinks) I'm inclined to think its not the handbrake because it didn't do it today.

As for the handbrake adjuster - on my old 90 its easy to spot at 9 o-clock on the rear plate - on the 110 there appears to be a large weight in the way ( presumably a damper of some sort) have they moved the adjuster - is it the bolt head at the 6 o-clock position now?

[western]

the transmission brake adjuster on your 110 is at the 6 o'clock position -- item 3 in http://lrcat.com/#31/4/53764

no idea what the weight is

appears to be a large weight in the way ( presumably a damper of some sort)

can't see anything in the parts info like that

[ebygum110]

thanks for the link, very useful

will take a photo of the 'weight' tomorrow - just out of interest

[101sean]

The weight is a vibration damper. You need a cranked spanner or a shallow 17mm socket to get to the adjuster. No need to take the weight off.

[western]

thanks for the link, very useful

will take a photo of the 'weight' tomorrow - just out of interest

found a diagram of it in http://lrcat.com/#31/4/53755 item 47 on Td5 on models only.

[TSD]

thanks guys

as a first step, is it possible to bench test the solenoid with just a simple 12v supply just to check it is actually doing what its supposed to and not sticking.

I had a brief run today - didn't bother selecting the OD at all - no problems with reversing - so its either residual pressure from a sticky solenoid (me thinks) I'm inclined to think its not the handbrake because it didn't do it today.

You can just hit the solenoid with 12V and Ground, and see if it throws the shuttle in and out against the spring. However, I suspect that's not where the problem lies - if the oilways in the main unit become partially blocked, then even with the solenoid in the released position enough oil pressure is built by the pump to prevent the clutch seating back in the rest position - or at least that the impression I got from spending a few tedious days messing around with mine.

Another theory is that if the clutch slips at all, the heat generated causes it to jam when released, and it takes a while to sort itself out. The TGV engine gave enough grunt to climb steep motorway grades at 80+ with the OD engaged, and in a few places there was a definite 'clutch' smell by the time I reached the top . That would tend to support my second theory, but either would fit the symptoms I had.

[ebygum110]

found a diagram of it in http://lrcat.com/#31/4/53755 item 47 on Td5 on models only.

that's the puppy :-)

[ebygum110]

Thanks TSD.

I've got some business trips coming up and this truck is my main mode of transport.

Fortunately I have all the gears and cover plate that the previous owner kept - so for now I might just take it off.

If I disconnect the solenoid wiring for now - on the basis that its not engaged will it just 'sit there' i'e not pressurize itself - or is it just best to remove it for now.

and finally, I found a thread on how to fit a GKN - are there any guidelines / tips on how to remove it and refit the original drive gears?

[ebygum110]

The weight is a vibration damper. You need a cranked spanner or a shallow 17mm socket to get to the adjuster. No need to take the weight off.

thanks Sean

[TSD]

When mine was playing up, I found that once it was properly disengaged it seemed quite happy - so in the short term you can probably just leave it switched off.

Taking it out is easy enough, the only tip I can offer is don't try to do it after a 100hour+ working week and only 4 hours sleep....

If you try really hard it is possible to install the input gear back to front, and if you do, things get very bad, very quickly, when you (try to) drive off

[ebygum110]

oh dear, well I'm currently on about 80 hours sitting in front of a flippin PC or on the phone, so best I get my head straight first!

[reb78]

If you try really hard it is possible to install the input gear back to front, and if you do, things get very bad, very quickly, when you (try to) drive off

Yeah - then it really will go bang......

[western]

Yeah - then it really will go bang......

& it's a pain in the ass job changing the other gear if the teeth get damaged, been there.

[m0bcg]

i can tell you exactly whats wrong .

i have rebuilt my 2 overdrives 3 times since i had it , i have sussed it now .

youre problem is in the cone clutch , the lining has either had some or all of it come off the outside of the cone clutch .

pretty much all the gkn cone clutches fitted to their landrover overdrives were all fitted with silly little thin [to save money] linings , they are bonded on but are very thin, something like 1mm thick , and they come off .

usually they start breaking little bits off which you might find in the "sump" of ovderdrive when you take the filter plate off , and then possibly you might lose say 1/4 of the clutch lining but not all of it so it kind of works to a fashion for a short time , but it wont be long before the lot comes off .

the speed sensor only works IF the clutch is rotating below it , and if youve lost the lining and its trapped when the cone tries to move when the solenoid is engaged , then the speed sensor thinks its not moving and so wont switch the solenoid on .

the tightness you get in reverse is what happens when the lining comes off and wedges in and things go tight .

put it this way , on mine one day , on a 10 mile trip , the overdrive gearbox got that ot it melted the handbrake cable outer and inner plastic and rendered it inoperable .

i am now a dab hand at repairing these overdrives and i know where to get the cone clutches from which are superior to the gkn ones , ie they have thick well bonded linings .

if you are desperate to drive youre landy and dont mind doing this without the overdrive being used , then you can fix this easily to allow you "drive " and also to keep the overdrive gearbox still installed, but you will not use the overdrive function [ disconnect the power to the solenoid] , but it will still work as a "normal " 5 speed gearbox , ie you dont need to put all the original landrover gears back in place , you can simply render the o/d in a state as if the gearbox is working as a standard 5 speed but with the o/d box still fitted but with the lining material removed , until you can get it fully repaired .

remember though that once youve removed the lining you can physically still switch the overdrive in but it will slip all the time because it will be metal to metal contact on the cone clutch minus the lining , so hence you dont want the overdrive facility to be funtioning at all in this state , it will however have the clearances reqd to work in its OFF state and wont bind up with loose lining lodged in between the cone and the clutch . ..

in order to sort it what you have to do is to take the overdrive box off , and remove the broken lining , then the overdrive will work in its OFF state , but you CANNOT run it in overdrive mode until its been repaired .

i think you could get the broken lining out bit by bit if you just remove the backplate and the filter/sump plate , but it would be better to remove the overdrive unit and take apart , remove the broken bits and then blow it out with air and clean it and then put it back in place .

you wont get any spare cone clutches from gkn , theyve ceased selling or fixing any units , and devon 4x4 wont have any spare cone clutches ..

one thing you could do is find a laycock J type overdrive and remove the cone clutch from it , this will fit youre landy overdrive because the landy overdrive IS a j type overdrive [ but runs in reverse to the "normal" types of laycock overdrives .

i can tell you where you can buy a reconditioned cone clutch but im not saying on here because the guy might throw a wobbler if he gets inundated with requests for them for landrovers , he rebuilds the cone clutches on an exchange basis normally but you can buy outright if you pay the £50 surcharge , they arent cheap but i have 3 new spare cone clutches here .

you do need to know how to dismantle and rebuild the gkn overdrive, i know how to so its easy for me but if you pull one apart for first time you may not work out how it comes apart and will damage something .

do not hammer it to try and get it apart, it comes apart a particular way easily if you know how , its full of circlips etc , and you MUST NOT break the bronze thrust washer , as you cant buy them , unless like me you can make one or get one copied then youd be stuffed otherwise .

the epicyclic gearbox in the overdrive is not the same as the ones in the other laycock overdrives because they run in a different direction , so you cant swap those over and must keep the landy gkn epicyclic gears in it .

i have been running my "own repaired" overdrive for a few months now all fine , i cant guarantee how long it will last but to be honest i doubt the clutch lining will fail now i have a superior type in there .

i have my own ramp to work on so it isnt too hard for me to get under the landy and take things off but i guess for someone working on the ground it may take longer and give a bit more hassle .

when i repaired mine i put the vehicle on 4 heavy duty axle stands afterwards to test and check the overdrive was working .

on another note , if you were to have 285/75x16 tyres on a standard landy transfer box you wouldnt really need the overdrive , i hardly get to use mine now and i have these size tyres .

put it this way im showing 2600rpm at 70mph with 285 tyres and the overdrive on, its a bit too highly geared to pull the vehicle in overdrive other than on the flat ..

sorry i did a long reply to youre original message , but i hope it isnt too late for you to salvage the overdrive you have .

its a fairly simple repair to put it right again , so long as you know what and how to do it , and no doubt i would guess that every gkn overdrive thats failed on a landrover has had the same problem and no other .

even if you had an overdrive that was working , but had the original gkn "thin" clutch lining , i can guarantee it WILL FAIL at some point in time , no question about that .

i had 2 brand new gkn overdrives and both failed , and one failed within a day of fitting it ..

took me a while to suss out what the gkn engineers did to mees them up but i worked it out in the end .

i mean they might just have worked if the bonding solution actually stayed stuck on !!!.

they probably knew only too well what theyd done , but having sold perhaps thousands of gkn overdrives for landrovers , it would have been mighty expensive to repair every one of them under warranty , so what did they do , they went quietly .

funny thing is that these drives have been made for decades , and if you had a ford transit overdrive or a scimitar or mgb gt or triumph or vauxhall ventora etc then chances are it has the same type of unit , except for the fact those had decent clutch linings on the cone clutches .

dont try fitting one of those to a landrover though, first it wont fit anyway and secondly they run opposite direction and dont have many parts the same except for the cone clutch and a few other odd parts , solenoid is same though !! .

[reb78]

Tanuki gave the details of a company that sell the cone clutches in my link above.