Graze Posted June 29, 2016 Report Share Posted June 29, 2016 Gents I have sent my gearbox and newly acquired JType off to a guy to check ovr the overdrive and then mate them together to go back in the car with the new engine He tells me I'm missing the correct shaft (input? Output? Not sure) to mate them together I am going out the Friday - what should I be looking for or photgraphing, measuring to identify the needed parts Graeme Quote Link to post Share on other sites
TR 2100 Posted June 29, 2016 Report Share Posted June 29, 2016 If the gearbox was previously non-overdrive, then you will need a new mainshaft. The overdrive mainshaft is shorter. AlanR Quote Link to post Share on other sites
Rob Salisbury Posted June 30, 2016 Report Share Posted June 30, 2016 And it needs to be a J type mainshaft which has a metric front spigot, this then has to be mated with the (probably) imperial input shaft. Rob Quote Link to post Share on other sites
AlanG Posted June 30, 2016 Report Share Posted June 30, 2016 And it needs to be a J type mainshaft which has a metric front spigot, this then has to be mated with the (probably) imperial input shaft. Rob Hi Rob, As I'm going through he same exercise could you expand on the "probably" please. Alan. Quote Link to post Share on other sites
Graze Posted June 30, 2016 Author Report Share Posted June 30, 2016 And it needs to be a J type mainshaft which has a metric front spigot, this then has to be mated with the (probably) imperial input shaft. Rob Rob thanks as Alan G said any more detail would be appreciated Graeme Quote Link to post Share on other sites
Rob Salisbury Posted June 30, 2016 Report Share Posted June 30, 2016 Hi, the "probably" is taking into account any internal changes that may have happened to the TR4 gearbox over the last 50 or so years, assuming none, then the constant pinion (input) shaft and mainshaft will have an imperial spigot bearing, this is up to gearbox CD20281, the J type Overdrive requires the metric spigot mainshaft TKC832, therefor the imperial input shaft will either have to be replaced along with the constant pinion gear, or it will have to be adapted with a special, made up spigot bearing. Reference to the TR5/6 gearbox/overdrive section of the MossEurope website gives quite a few clues as to which combination of parts may be required. Good luck, Cheers Rob Quote Link to post Share on other sites
TR 2100 Posted June 30, 2016 Report Share Posted June 30, 2016 Graeme, Don't know how clued up your guy is. There are a few essential upgrades of underdesigned components that would be folly to overlook. AlanR Quote Link to post Share on other sites
Graze Posted June 30, 2016 Author Report Share Posted June 30, 2016 Graeme, Don't know how clued up your guy is. There are a few essential upgrades of underdesigned components that would be folly to overlook. AlanR Alan I don't know how clued up he is either - just that he has rebuilt overdrives in the past Guess I'll find out more today when I go have a chat to him Any hints on the recommended upgrades? Graze Quote Link to post Share on other sites
TriumphV8 Posted July 1, 2016 Report Share Posted July 1, 2016 Rob explained where the problem is located. To add is that the the bearing connecting input and output shaft is called open or closed bearing. Open bearing is the metric bearing, imperial the old one. Mike Papworth does a hybrid main shaft that has the old front for the old gearboxes and a new rear for the new (J-type) overdrive. Might be worth a call to avoid all that fiddeling with the adaptor bearing. What I can say its not easy to put the input shaft in a lathe and modify the hole to take the open bearing. Its pretty hard. One of the modifications that make sense is again the open and closed bearing that is now located down at the layshaft. The old ones are the open bearings that can be swapped to closed ones that are fitted with a slight press fit. To ad a third bearing at the layshaft is not necessary for a TR4 but I would look for proper condition of the shaft itself and if necessary take a good new one that is tuftrided. Quote Link to post Share on other sites
TR 2100 Posted July 1, 2016 Report Share Posted July 1, 2016 Graeme, It was the gearbox itself I was referring to, not the overdrive. There are upgrades that can be made on overdrives, but really not necessary unless you are seriously thrashing the car. The gearbox itself - there are a few upgrades but I'm not an expert. I'll just give you the layshaft as one example. The original design layshaft had a roller bearing - this is not man enough for the job - it needs a proper bearing. Reading your post again, it seems your 'man' is doing an overdrive conversion only, not a gearbox rebuild. AlanR Quote Link to post Share on other sites
The_Doc Posted July 1, 2016 Report Share Posted July 1, 2016 Hi Graeme I have recently done what you're doing now. I took my TR4A gearbox and put on a J-Type OD. I bought the J-Type OD as a complete unit on a Dolomite Sprint gearbox since I needed to change the main shafts over. So I took the main shaft from the Dolomite Sprint gear box and put that into my old TR4A gear box. The real problem I had was that where the main shaft mates with the input shaft, the sizes were different as the Dolly gear box was later when they decided to swap to metric gauges. I had a sleeve made to fit onto of the end of the main shaft to increase it's diameter slightly and then had it pressed on. It worked a charm and now everything fits together well. Other then that, there was no real challenge, except for the usual dismantling of parts and then remembering where it all went when you come back to it a week later. If you want to know more just message me. Adam Quote Link to post Share on other sites
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