dan-t Posted September 6, 2012 Report Share Posted September 6, 2012 Hi Im sure this must be an easy question for some but what are the differences between the two boxes meaning can you fit overdrive to a standard 4 speed box Thanks to all Dan Quote Link to post Share on other sites
Rob Salisbury Posted September 6, 2012 Report Share Posted September 6, 2012 Hi, ...yes you can, but you will need the shorter Overdrive mainshaft, which in turn means a gearbox rebuild. Cheers Rob Quote Link to post Share on other sites
Austin Branson Posted September 7, 2012 Report Share Posted September 7, 2012 Hi, Dan, Rob is right. I am no expert, but I suspect you may need a different cross-member (that supports the tail of the gearbox/overdrive). This is no easy mod. You will need to sort out the sensors on the gearbox lid (to enable overdrive to be selected only in 2nd, 3rd and 4th), as well as the wiring to the new overdrive switch on the column. I'm not sur, but you may need to modify/change the speedo cable. There are more than 1 overdrives - the A type (as used on the earlier TR's), and the J type used on the later cars, as well as different ratio's. I am pretty confident that you will get a response from someone who has done it, but if not you might want to talk to one of the TR specialists. Good luck, and let us know how you get on. Austin Quote Link to post Share on other sites
Mark V Posted September 7, 2012 Report Share Posted September 7, 2012 I converted my'69 TR6 to overdrive and as an early car it should have the A type overdrive( operates on 2, 3 & 4 gear), later cars had the J type (overdrive on 3 & 4th only). The rear gearbox mountings are the same for O/D and non O/D cars but if you swap between an A or J type then these mountings are not the same and you'll nee to convert them. As mentioned above, you'll also need the wiring loom 9easily made up), the correct gearbox remote with the appropriate sensors for either the J or A type. Also an O/D switch, I went with the standard TR6 and fitted the stalk switch, but some people use the gearbox knob switch. For the A type O/D stalk switch you will have to change the the RH cover so the stalk can be fitted next to the light switch stalk. I didn't need to change the speedo cable, but be aware of the differences you can get in A-type O/D I rebuilt mine using gearbox internals and an O/D from a Stag which was fine except the O/D Solenoid, which is vertical in a TR but almost horizontal in a Stag. It needed a very small & unnoticable piece of the floor plan to be cutout. Might be worth fitting a gearbox tunnel (is not got one already) so you can access the operating pin adjustment. Propshaft is the same - didn't need to swap that. Thats about all I can recall as it was quite a few years ago. Others will chip too I'm sure. Mark. Quote Link to post Share on other sites
PIAA Posted September 8, 2012 Report Share Posted September 8, 2012 Hi Found a 'Guide to adding a J-Type Overdrive to your TR6' in this link: http://home.comcast.net/~v.navarrette/TR6_tech/tr6_tech_index.htm PIAA Quote Link to post Share on other sites
Kiwifrog Posted September 9, 2012 Report Share Posted September 9, 2012 Here is another guide for fitting a J type http://www.tr-register.com.au/Files/technical/2500gearbox.htm Quote Link to post Share on other sites
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