Craig Simister Posted January 25, 2022 Share Posted January 25, 2022 Hello 👋 I need an overdrive gearbox for my 72 mk3 GT6. Does anybody have one for sale at all? Or advice on what I need to fit into the car, confused by it all! Kind regards Craig Quote Link to comment Share on other sites More sharing options...
Pete Arnold Posted January 25, 2022 Share Posted January 25, 2022 Possibly this might be of use to you. Triumph GT6 Overdrive Gearbox Rebuild Kit RHP bearings. incomplete. overhaul mk3" currently on offer. See eBay #265284326122 Quote Link to comment Share on other sites More sharing options...
Callan Hyde Posted January 25, 2022 Share Posted January 25, 2022 Hi Craig, aside from the gearbox itself you will need the associated wiring and solenoid/relay, a shorter overdrive length propshaft and the engagement switch. These are mounted either on the top of the gearstick or on the column behind the RH stalk. A lot of folks find the latter position to be awkward to use and in the way so a gearstick mounted switch would be the one to look for. Youll have to see how it is re. the diff ratios. Ill send you a message now via whatsapp on a chap to try for a gearbox 1 Quote Link to comment Share on other sites More sharing options...
RobPearce Posted January 26, 2022 Share Posted January 26, 2022 8 hours ago, Callan Hyde said: A lot of folks find the latter position to be awkward to use and in the way so a gearstick mounted switch would be the one to look for. I have never understood this perspective. The column switch is much nicer to use and the gearstick one is a pain. However, the OP's car is a Mk3 and would originally have had the gearstick one. Quote Link to comment Share on other sites More sharing options...
Clive Posted January 26, 2022 Share Posted January 26, 2022 9 hours ago, Craig Simister said: Hello 👋 I need an overdrive gearbox for my 72 mk3 GT6. Does anybody have one for sale at all? Or advice on what I need to fit into the car, confused by it all! Kind regards Craig is this for an overdrive conversion, or to replace a worn overdrive gearbox? If the latter, it is better to get yours rebuilt over a secondhand one. Pete Cox near Birmingham would be a good bet, or Mike Papworth (though I think he is very busy? but worth a try) If a conversion, from memory: Overdrive gearbox/with overdrive Different remote/top cover with OD inhibitor switch Overdrive rubber mount AND mounting plate Shorter propshaft OD speedo cable and Angle drive Overdrive gearstick/wiring/relay (or as above the earlier column style switch) The other twist for you is that on teh otehr cars, the diff ratio stayed the same if OD was fitted or not. However, on GT6 the non-OD cars were fitted with a 3.27 diff (as opposed to the OD cars with 3.89) which means both OD and non-OD cars have the same "top gear". You would be adding an additional, longer "5th" gear. (and apols to those who have posted similar stuff, I tried to include everything) 1 Quote Link to comment Share on other sites More sharing options...
Callan Hyde Posted January 26, 2022 Share Posted January 26, 2022 5 hours ago, RobPearce said: I have never understood this perspective. The column switch is much nicer to use and the gearstick one is a pain. However, the OP's car is a Mk3 and would originally have had the gearstick one. I've driven cars both with the gearstick switch and column. I found myself that the overdrive switch on the column was easily switched by accident and inhibited access to the dash. Also felt like it was made of cheese and was going to fall apart 😂 Quote Link to comment Share on other sites More sharing options...
RobPearce Posted January 26, 2022 Share Posted January 26, 2022 Hmm... I currently own cars with both (Spitfire Mk3, Vitesse, GT6 Mk3) and have previously owned several others (another Vitesse, some Dolomites, two 2500s). I've almost never switched the column one by accident and never found it obscured or inhibited access to anything. It's no flimsier than the indicator or light stalks (I have managed to break an indicator stalk off once). It does feel a bit floppy if the fixing nut is loose but then the cap of the gearknob ones is prone to working loose and falling off in your hand, too. Quote Link to comment Share on other sites More sharing options...
Clive Posted January 26, 2022 Share Posted January 26, 2022 Could be down to the quality of the repro parts...I have fitted a new column switch to our mk3spit, and it doesn't feel great. The new gearknow stuff is a bit poxy too. I quite like these, got one in my Tolly (and will move over to the dolly) Quote Link to comment Share on other sites More sharing options...
richard w Posted January 26, 2022 Share Posted January 26, 2022 2 hours ago, Clive said: Could be down to the quality of the repro parts...I have fitted a new column switch to our mk3spit, and it doesn't feel great. The new gearknow stuff is a bit poxy too. I quite like these, got one in my Tolly (and will move over to the dolly) That's what I have in the 2000, better than the gear top switch that I had in the Stag. I've driven plenty of column switched cars and found that good too. Horses for courses like most things - find the system you prefer and go with that 1 Quote Link to comment Share on other sites More sharing options...
Nick Jones Posted January 26, 2022 Share Posted January 26, 2022 Potentially have an OD gearbox and all the ancillary parts going spare following my MX5 gearbox conversion. The gearbox itself was rebuilt using a large tip mainshaft with machining done to the input shaft to match. It worked fine and was reasonably quiet. The overdrive however is very slow to engage and sometimes sticks in after a few miles at speed, so needs further attention. Nick 1 Quote Link to comment Share on other sites More sharing options...
Craig Simister Posted January 26, 2022 Author Share Posted January 26, 2022 12 hours ago, Clive said: is this for an overdrive conversion, or to replace a worn overdrive gearbox? If the latter, it is better to get yours rebuilt over a secondhand one. Pete Cox near Birmingham would be a good bet, or Mike Papworth (though I think he is very busy? but worth a try) If a conversion, from memory: Overdrive gearbox/with overdrive Different remote/top cover with OD inhibitor switch Overdrive rubber mount AND mounting plate Shorter propshaft OD speedo cable and Angle drive Overdrive gearstick/wiring/relay (or as above the earlier column style switch) The other twist for you is that on teh otehr cars, the diff ratio stayed the same if OD was fitted or not. However, on GT6 the non-OD cars were fitted with a 3.27 diff (as opposed to the OD cars with 3.89) which means both OD and non-OD cars have the same "top gear". You would be adding an additional, longer "5th" gear. (and apols to those who have posted similar stuff, I tried to include everything) Thank you for the info it really does help! Quote Link to comment Share on other sites More sharing options...
Craig Simister Posted January 26, 2022 Author Share Posted January 26, 2022 59 minutes ago, Nick Jones said: Potentially have an OD gearbox and all the ancillary parts going spare following my MX5 gearbox conversion. The gearbox itself was rebuilt using a large tip mainshaft with machining done to the input shaft to match. It worked fine and was reasonably quiet. The overdrive however is very slow to engage and sometimes sticks in after a few miles at speed, so needs further attention. Nick Very interested in it all Nick, I will need to chat to you about it, Regards Craig Quote Link to comment Share on other sites More sharing options...
Craig Simister Posted January 26, 2022 Author Share Posted January 26, 2022 Thank you everyone for all the information and help, it is very much appreciated 👍 1 Quote Link to comment Share on other sites More sharing options...
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