Don2138 Posted January 19, 2009 Share Posted January 19, 2009 Hello. I have done a search and there are a number of descriptions but would anyone have a picture of where the overdrive inhibit switch is on a 1974 2.5 P.I. Gearbox. Reason for asking is the overdrive operates in all four gears and I am worried that I may leave the overdrive switched on when reversing. I have a Haynes manual and the big ( dark blue ) workshop manual for the 2.5 but I cannot find much information about the overdrive inhibit switch. This engine and gearbox is fitted to a Stag and I am assuming that gearbox is also from the 2.5 P.I as where the gearlever comes into the car through the transmission tunnel seems to have been modified in this area. I know I could put the car up on ramps etc but I am able to use a car lift in a garage and would like to know what a where I am looking as I can only use this lift for short periods of time. I am hoping that the switch is on the side of the gearbox as if it is on the top how could I get to it without removing the gearbox.Many thanks, Don Kennedy Link to comment Share on other sites More sharing options...
Glenn Posted January 19, 2009 Share Posted January 19, 2009 Hi Don,As you fear, the switch is on the top of the box, tucked into the transmission tunnel a bit forward of the gearstick. You might just manage to feel it from underneath the car.If you need to get to it, probably best to support the gearbox on a trolley jack, undo the four nuts holding the mounting to the floor of the car and lower the assembly as much as you can to get access. Careful - the rocker cover may push into the bulkhead so watch it doesn't cause damage.I'm not suggesting this will definitely give you enough room to do what you need to do now - but I reckon it's worth trying before dropping the 'box.All the best,Glenn Link to comment Share on other sites More sharing options...
Alex Posted January 19, 2009 Share Posted January 19, 2009 I think you'll find its on the top :-/Alex Link to comment Share on other sites More sharing options...
mikeyb Posted January 19, 2009 Share Posted January 19, 2009 Yes it's def on the top, if no-one else does, I'll post some pics over the next few days. If you drop the rear crossmember as above, I think you will be able to access it. But before going to those lengths, I suggest remove the centre console that fits around the gearstick (incl dash section). I just have a very vague recollection there may be a large access grommit somewhere around there?I would be definitely concerned about selecting reverse with o/d engaged - it could be terminal!Switch may be faulty or just maladjusted (ie. not screwed in far enough). Link to comment Share on other sites More sharing options...
Glenn Posted January 19, 2009 Share Posted January 19, 2009 mikeyb wrote:Switch may be faulty or just maladjusted (ie. not screwed in far enough).I'd agree with that, definitely. There should be a couple of fibre washers under the switch as standard. You might need to remove one or both to get the switch working again. If not I think a new switch is about £10. Link to comment Share on other sites More sharing options...
Alex Posted January 19, 2009 Share Posted January 19, 2009 If it used to be an auto stag the hole would be a type of tear drop,so with the back of the box dropped a small amount it may give clearence for you to get in from above...I think :-/Alex Link to comment Share on other sites More sharing options...
Mj17 Posted January 19, 2009 Share Posted January 19, 2009 As stated, it's on the top and a real...swine to get at.A '74 car should be running twin switches - one for reverse and one for 1st/2nd vs 3rd/4th, so you might not be in as much danger as you think...The wiring should be Reversing Light Switch (supplies the feed) - Inhibitor Switch - Gearstick Switch - O/D Solenoid - Earth (stolen from Richard B - http://club.triumph.org.uk/cgi-bin/forum10/Blah.pl/Blah.pl?m-1219792445/s-12/highlight-overdrive+wire/#num12), so...1) Switch the ignition on (but don't start the engine) out of gear and make sure your reversing lights aren't on all the time :)2) Pop it in to reverse and check they come one/go out when you slip out of reverse.Assuming all is well you SHOULD be safe but to check...3) Free the gear leaver gaiter and find the two bullet connectors linking the gearstick switch to the main loom.4) With ignition on as before, select 4th and overdrive 'In'.5) Try a multimeter between earth and each of the bullets in turn to find which is live (12V).6) Put the car in reverse and check the live bullet to earth again - you should get 0V.If that all works out the reverse inhibitor is working (like mine) but the 1st/2rd vs 3rd/4th is badgered.Using overdrive in 1st/2nd isn't good idea as it dumps more torque through than the overdrive really likes but it's unlikely to be terminal if it happens by accident a few times until you have the inhibitor fixed. Link to comment Share on other sites More sharing options...
Greeks Posted January 19, 2009 Share Posted January 19, 2009 I've been able to rewire my inhibitor switch using the slight lowering off the gearbox method and coming in from above. In my case all that happened is that a terminal had been damaged. There's not much room for fiddling though so it takes some time and perseverance and if you have a swear jar in your garage it could get expensive too ;) Link to comment Share on other sites More sharing options...
Don2138 Posted January 20, 2009 Author Share Posted January 20, 2009 Many thanks for your time replying. I will have a closer look and see if I can locate the switch. I have had a quick look from underneath and cannot see any switch on the side of the gearbox so must be the type that is at the top. I suspect that the previous owner has not connected the inhibit switch and has just connected the wires together. It sounds like the switch is a real bugger to get to and if there are any problems I will connect a normally closed contact relay in the overdrive feed and have it operated by the reverse light circuit. i.e. when reverse is selected it activates the relay and disconnects the feed to the overdrive solenoid. I know about it not being recommended using overdrive in first and second due to torque and if I did it would only be for example when in traffic and using little power.I think it could be easier to connect a relay than try to get to the inhibit switch. Once again, Many thanks, Don Kennedy Link to comment Share on other sites More sharing options...
shedmonkey Posted January 20, 2009 Share Posted January 20, 2009 I once developed a knack of getting at it-get the car up nice and high lay undeneath feet towards the front and loop your arm round as if you are cuddling the box you can just get enough access to get the crimps back onI have also managed to take the switch out from above - you need to take the gearlever off and centre consol -(its a long time since any of my 2000s have had a consul!) there is a grommet you can remove and along with the gearlever hole you can just about fiddle the bugger out with some long nose brake pliers etc once you have it out solder some leads onto it just long enough to let you screw it back in without twisting the wires up etc and to allow easy connection to the loom-I will try and get some pics up on my blog as its a usefull little tweak! they are such frustrating little buggers its worth doing a really good permanant robust solution when you have it in bits! Link to comment Share on other sites More sharing options...
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