ken foster Posted November 4, 2009 Report Share Posted November 4, 2009 Hello, anyone know whats involved with fitting a stag A type overdrive gearbox in a side screen car? Many thanks ken. Quote Link to post Share on other sites
Ian Vincent Posted November 4, 2009 Report Share Posted November 4, 2009 Hi Ken, I have a TR3a non overdrive which I am rebuilding. I wanted to convert it to overdrive and acquired a Triumph 2000 Type A gearbox plus overdrive for nominal cost. In due course I will be fitting it into the car. I started by doing search on the forum for 'gearbox' and 'overdrive' - there is a heap of information here. Following on from there, here's what I have found out although I must stress that that mine is a Type A box and I think a Stag had a Type J box. I have broken it down into two parts. Overdrive The Type A Saloon overdrive has four springs instead of 8 holding the clutch away from the brake ring, it also has a smaller accumulator spring / piston, a different mounting position for the solenoid and the speedo drive is in a different position. You can buy all the parts to uprate a saloon overdrive to a TR version from either Overdrive Repair Services in Sheffield or Overdrive Spares in Rugby. The rear mount for a saloon overdrive box is also different but you can but an adaptor bracket from Moss or Overdrive Spares. Alternatively you can do what I decided to do which is send it to ORS and for £500 they will convert it for you including a new TR type rear casing and checking it over at the same time. The new rear casing means that I don't need to change the mounting arrangements. The final issue is the output flange - the recommended fix for that is to redrill the saloon flange at 45 degrees to suit the PCD of the TR back axle flange. I will recalibrate the speedo when I have finished the car, that way I get over any issues with the wheel / tyre sizes that I am planning to use being different to the original. Gearbox & Clutch The gearbox ratios will be different but not massively so. The biggest issue is the diameter of the saloon input shaft at 1" instead of the TR version which has a dia of 1.25". The easiest way around this is to replace the TR clutch driven plate with a Saloon one (note the saloon has an 8.5" driven plate whereas the TR has a 9" diameter but I have been assured by various members of this forum that the smaller clutch is still able to handle the power). You can at the same time replace the TR clutch cover which has 9 coil springs with the diaphragm clutch cover (and release bearing) from a saloon but that will necessitate redrilling the flywheel to make it fit or sourcing a suitable flywheel with the correct drilling. I have decided to keep the original clutch cover and clutch release bearing which has necessitated changing the front cover / sleeve on the saloon gearbox to the TR version - the difference is the diameter of the sleeve but the oil seal is the same size because it is only the splined drive portion of the input shaft that is 1" dia, the part of the shaft where the oil seal bears is the same diameter on the saloon and TR. You also need to use teh TR clutch release fork instead of the saloon version. And that's it - pretty straightforward really - I can't imagine the Stage box will be massively different. And finally, if you get stuck just put a post on the forum and someone will come up with the answer - none of the above is my own work, it came from various contributors on the forum for which many thanks. Rgds Ian PS for Triumph saloon spares, I have used Chris Witor in Somerset and found the service to be excellent. Quote Link to post Share on other sites
NickKerfoot Posted November 5, 2009 Report Share Posted November 5, 2009 Hi Ken! All of Ian's info above is good but...I have a nasty feeling that the Stag input shaft is quite a bit longer than the TR/Saloon one. This nececitates changing the input shaft and possibly the gear it meshes with inside - possibly a world of hurt! Someone with more info will no doubt comment... Regards Nick Quote Link to post Share on other sites
Ian Vincent Posted November 5, 2009 Report Share Posted November 5, 2009 If the Stag input shaft is longer then there are people who will 'cut and shut' the front end of the TR shaft to the input gear from the Stag box and re heat treat the finished item. That way you don't have to mess around with the TR clutch. Alternatively ORS said they can remanufacture a TR output shaft to make it suitable for fitting an overdrive thus meaning that you can keep your existing gearbox and just use the Stage overdrive. Talk to Pete at ORS, I found him very helpful. Rgds Ian Quote Link to post Share on other sites
ken foster Posted November 6, 2009 Author Report Share Posted November 6, 2009 Hi Ken, I have a TR3a non overdrive which I am rebuilding. I wanted to convert it to overdrive and acquired a Triumph 2000 Type A gearbox plus overdrive for nominal cost. In due course I will be fitting it into the car. I started by doing search on the forum for 'gearbox' and 'overdrive' - there is a heap of information here. Following on from there, here's what I have found out although I must stress that that mine is a Type A box and I think a Stag had a Type J box. I have broken it down into two parts. Overdrive The Type A Saloon overdrive has four springs instead of 8 holding the clutch away from the brake ring, it also has a smaller accumulator spring / piston, a different mounting position for the solenoid and the speedo drive is in a different position. You can buy all the parts to uprate a saloon overdrive to a TR version from either Overdrive Repair Services in Sheffield or Overdrive Spares in Rugby. The rear mount for a saloon overdrive box is also different but you can but an adaptor bracket from Moss or Overdrive Spares. Alternatively you can do what I decided to do which is send it to ORS and for £500 they will convert it for you including a new TR type rear casing and checking it over at the same time. The new rear casing means that I don't need to change the mounting arrangements. The final issue is the output flange - the recommended fix for that is to redrill the saloon flange at 45 degrees to suit the PCD of the TR back axle flange. I will recalibrate the speedo when I have finished the car, that way I get over any issues with the wheel / tyre sizes that I am planning to use being different to the original. Gearbox & Clutch The gearbox ratios will be different but not massively so. The biggest issue is the diameter of the saloon input shaft at 1" instead of the TR version which has a dia of 1.25". The easiest way around this is to replace the TR clutch driven plate with a Saloon one (note the saloon has an 8.5" driven plate whereas the TR has a 9" diameter but I have been assured by various members of this forum that the smaller clutch is still able to handle the power). You can at the same time replace the TR clutch cover which has 9 coil springs with the diaphragm clutch cover (and release bearing) from a saloon but that will necessitate redrilling the flywheel to make it fit or sourcing a suitable flywheel with the correct drilling. I have decided to keep the original clutch cover and clutch release bearing which has necessitated changing the front cover / sleeve on the saloon gearbox to the TR version - the difference is the diameter of the sleeve but the oil seal is the same size because it is only the splined drive portion of the input shaft that is 1" dia, the part of the shaft where the oil seal bears is the same diameter on the saloon and TR. You also need to use teh TR clutch release fork instead of the saloon version. And that's it - pretty straightforward really - I can't imagine the Stage box will be massively different. And finally, if you get stuck just put a post on the forum and someone will come up with the answer - none of the above is my own work, it came from various contributors on the forum for which many thanks. Rgds Ian PS for Triumph saloon spares, I have used Chris Witor in Somerset and found the service to be excellent. Quote Link to post Share on other sites
ken foster Posted November 6, 2009 Author Report Share Posted November 6, 2009 Thanks for your help, the stag box i am offered has i'm told an A type overdrive although I havn't seen it. Regards Quote Link to post Share on other sites
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.