reb78 Posted July 30, 2017 Share Posted July 30, 2017 2 hours ago, Oakmaster said: You are correct - there was a thread somewhere (i thought on here but I cant find it) - I also looked at the RS components sensor, but it was not a like for like replacement - in fact it was quite different. Im slightly surprised that one of the smarter people on here, haven't made some sort of adaptor for it. I'll try to track down the Sheffield place thanks B Looking at the link Ralph has posted, it would only be a case of splicing wires? Cut off the original connector and splice the ends of the new one to the existing wiring? 1 Quote Link to comment Share on other sites More sharing options...
sighnbox Posted July 31, 2017 Share Posted July 31, 2017 (edited) See you got it sorted Ralph but just in case others read with the same prob ......... I also had this problem after a new clutch went in (replaced every thing uprated fork, metal bearing, slave cylinder, master etc etc) wasn't slipping bad but noticed it when put your foot down......No idea what it was but after a week or so it sorted its self out and been fine ever since (that was 2 - 3 year ago)......and I had to fit the new one due to a melted thrust bearing (I went LUK clutch) Edited July 31, 2017 by sighnbox Quote Link to comment Share on other sites More sharing options...
reb78 Posted July 31, 2017 Share Posted July 31, 2017 2 hours ago, sighnbox said: See you got it sorted Ralph but just in case others read with the same prob ......... I also had this problem after a new clutch went in (replaced every thing uprated fork, metal bearing, slave cylinder, master etc etc) wasn't slipping bad but noticed it when put your foot down......No idea what it was but after a week or so it sorted its self out and been fine ever since (that was 2 - 3 year ago)......and I had to fit the new one due to a melted thrust bearing (I went LUK clutch) Sounds like it was bedding in in your case. Its the same process as bedding in new brakes. Quote Link to comment Share on other sites More sharing options...
Oakmaster Posted July 31, 2017 Share Posted July 31, 2017 20 hours ago, reb78 said: Looking at the link Ralph has posted, it would only be a case of splicing wires? Cut off the original connector and splice the ends of the new one to the existing wiring? Im not so sure - I thought that they were different threads and so-on - not sure if they electronically compatible? thats the great thing about Forums like this, eventually you will find somebody who does know? Thanks Quote Link to comment Share on other sites More sharing options...
reb78 Posted July 31, 2017 Share Posted July 31, 2017 58 minutes ago, Oakmaster said: Im not so sure - I thought that they were different threads and so-on - not sure if they electronically compatible? thats the great thing about Forums like this, eventually you will find somebody who does know? Thanks I don't know about the thread. If I ever need one though, I will risk the RS part in the hope it will fit. Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 31, 2017 Share Posted July 31, 2017 In this thread, it says the threads are different: Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 31, 2017 Share Posted July 31, 2017 And the specs on here is 3/8-24 UNF(!) http://uk.rs-online.com/web/p/magnetic-pickups/0285756/?searchTerm=285-756&relevancy-data=636F3D3126696E3D4931384E525353746F636B4E756D6265724D504E266C753D656E266D6D3D6D61746368616C6C26706D3D5E5C647B337D5B5C732D2F255C2E2C5D5C647B332C347D2426706F3D313426736E3D592673743D52535F53544F434B5F4E554D4245522677633D4E4F4E45267573743D3238352D37353626 Quote Link to comment Share on other sites More sharing options...
Oakmaster Posted July 31, 2017 Share Posted July 31, 2017 17 minutes ago, Bowie69 said: In this thread, it says the threads are different: Yes - the problem is its ME saying it in that thread Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 31, 2017 Share Posted July 31, 2017 Doh On another note, the old dolomite set up for this OD was to have a switch on top of the gearbox selector, which only enabled the OD in third and fourth. I'm sure a creative chap could rig up a microswitch with a flexible wand on it to only allow it in 3,4,5 easily enough? That way you don't even need a speed sensor, only a £1 switch and a bit of fab! Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 31, 2017 Share Posted July 31, 2017 Or, if it was only reverse you were worried about, then hook it up to the reverse light switch via relay. Quote Link to comment Share on other sites More sharing options...
reb78 Posted July 31, 2017 Share Posted July 31, 2017 1 hour ago, Bowie69 said: Or, if it was only reverse you were worried about, then hook it up to the reverse light switch via relay. This is the easiest solution. Apparently the GKN doesn't like the likely high torque in 1st and 2nd and will break if you engage in reverse hence 30mph is thought to avoid all of those conditions (which is what the speed sensor is roughly set to). I guess that doesn't work in low range though. Quote Link to comment Share on other sites More sharing options...
Peaklander Posted July 31, 2017 Share Posted July 31, 2017 2 hours ago, Bowie69 said: On another note, the old dolomite set up for this OD was to have a switch on top of the gearbox selector, which only enabled the OD in third and fourth. Oh that takes me back! I'd only just passed my test and got to drive my future in-laws' Triumph 2500 with the OD switch on the gearstick knob. It was a great way to drive. They later had a Dolomite Sprint but I don't remember if it had OD. Most of the time I was simply trying to keep it under control! Quote Link to comment Share on other sites More sharing options...
Bowie69 Posted July 31, 2017 Share Posted July 31, 2017 2 hours ago, reb78 said: This is the easiest solution. Apparently the GKN doesn't like the likely high torque in 1st and 2nd and will break if you engage in reverse hence 30mph is thought to avoid all of those conditions (which is what the speed sensor is roughly set to). I guess that doesn't work in low range though. Then, with another relay, use the hi low switch on the lt230 as well. Still, you could easily make something to work against the selector. Quote Link to comment Share on other sites More sharing options...
reb78 Posted July 31, 2017 Share Posted July 31, 2017 Hmmm. Yep. That'd work too (plus give a use for the hi lo switch on my transfer box!) Quote Link to comment Share on other sites More sharing options...
western Posted May 14, 2018 Author Share Posted May 14, 2018 (edited) On 5/14/2018 at 10:40 PM, reb78 said: Being sure whats wrong is the hardest part. Get it apart and check the clutch but it could be as simple as weak springs in the clutch unit legs. it was giving me a intermittent drive, posted about it here back in Aug '17 once the OD was off & standard gear was refitted the intermittent drive disappeared, so I & others on here suspect a slipping or poor grip of the OD clutch. Edited November 18, 2019 by V8 Freak Removed defunct reference - Threads merged for continuity of discussion Quote Link to comment Share on other sites More sharing options...
reb78 Posted May 15, 2018 Share Posted May 15, 2018 Mo had that when he was using Neils old OD. We changed the clutch but it still did it. Since then the springs were changed and it seemed to make a big difference. Looking at the clutch material should give you the answer though i think. 1 Quote Link to comment Share on other sites More sharing options...
V8 Freak Posted May 15, 2018 Share Posted May 15, 2018 I think there are potentially two main reasons why a GKN drive could slip when not engaged... - The spring pressure is reduced over time through heating and cooling and therefore the "clutch" or brake mechanism doesn't clamp well and loses direct drive - The cone brake material wears so there is little or no friction. Of course there can be a combination of the two as well.... There is probably a need for the ATF to be in good order and in sufficient quality as I think it helps to condition the brake material and has some grip qualities.... (I recall reading somewhere that certain oils that are used for power steering don't have these grip characteristics... AQF versus ATF??) 1 Quote Link to comment Share on other sites More sharing options...
reb78 Posted May 15, 2018 Share Posted May 15, 2018 (edited) Agree. I tried MTF94 in mine and also that fancy difflock evo stuff. None have performed as well as ATF and even that suffers over longer oil change intervals. The difflock evo which is specced for gearboxes using ATF came out as black and burnt as can be after 6,000 miles so I was very disappointed with that. Edited May 15, 2018 by reb78 Quote Link to comment Share on other sites More sharing options...
Snagger Posted May 15, 2018 Share Posted May 15, 2018 Is there any way you could fit an oil cooler? Quote Link to comment Share on other sites More sharing options...
reb78 Posted May 15, 2018 Share Posted May 15, 2018 Possibly, but I guess an additional pump would also be needed then. David and I have been talking about a finned sump like the roverdrive sump for the LT230. A similar design would increase capacity and provide some extra cooling. We are thinking of doing some tests with temp probes built in to the back plate so we can get a before and after. Visual inspection of the oil would be interesting too - you can see it has worked hard after 6000 miles at the moment as it is no longer the nice red that it went in as (unlike my gearbox oil as an example). Quote Link to comment Share on other sites More sharing options...
vulcan bomber Posted May 16, 2018 Share Posted May 16, 2018 Certainly looks better than the one I have here. Chaps, the bluing you see is done at the manufacturing stage, it appears there is a join there so they obviously heat and sweat the parts together. While this thread is current, does anyone have any GKN parts they want to get rid of? Quote Link to comment Share on other sites More sharing options...
monkie Posted May 17, 2018 Share Posted May 17, 2018 Realy interesting thread, good write up on how you took it apart. I've often been tempted to look at getting an overdrive and this has rekindled that thought, although as said above the roamerdrive at £1,600 quickly puts cold water on that idea. I can't find any new GKN units for sale, so I presume they are no longer made. When were these in production? Quote Link to comment Share on other sites More sharing options...
western Posted May 17, 2018 Author Share Posted May 17, 2018 went out of production a few years ago, GKN sold all the spares to Devon4x4, they can rebuild a used unit but not sure if they can supply a brand new unit. bought mine 2nd hand back on 2005 IIRC. 1 Quote Link to comment Share on other sites More sharing options...
reb78 Posted May 17, 2018 Share Posted May 17, 2018 If I was spending the money on a brand new overdrive it would be a Roamerdrive now. My GKN has been pretty good, but i have heard of others (on here) who have had nightmares with theirs. Quote Link to comment Share on other sites More sharing options...
V8 Freak Posted May 17, 2018 Share Posted May 17, 2018 I still have a Roamerdrive if you want one Rich... (And a GKN....) Quote Link to comment Share on other sites More sharing options...
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