MJH2454 Posted July 5 Share Posted July 5 Can you fit a 1500 engine to a MKIV 3 rail gearbox? Do you need to change anything, ie clutch or gearbox drive shaft? Quote Link to comment Share on other sites More sharing options...
drofgum Posted July 5 Share Posted July 5 MJH2524, The three-rail gearbox has a 10 spline input shaft. The 1500 has a finer 20? spline shaft. So you will need to find a driven disk with 10 splines. Regards, Paul Quote Link to comment Share on other sites More sharing options...
Clive Posted July 5 Share Posted July 5 Canleys and others sell the appropriate clutch plate, I believe it is from a morris minor/midget but a bit of time with google will tell you. The other option is to use the 1300 flywheel and clutch, though depending on year you may need to get the black&decker drill out for the flywheel bolts. (it can be done with a hand held derill as it only requires opening up a little) Quote Link to comment Share on other sites More sharing options...
glang Posted July 5 Share Posted July 5 Sure we discussed all this before! Anyway luckily some 1500 were supplied with 3 rail boxes (to US?) so a plate is available that has the bigger diameter of the 1500 plus 10 spline drive... Quote Link to comment Share on other sites More sharing options...
glang Posted July 5 Share Posted July 5 Just for the record I dont think 3 rail was used in any other make while of course the single rail was, extensively. I think the latter is what youre thinking of clive so applies in the case of fitting a single rail to a 1300.... Quote Link to comment Share on other sites More sharing options...
Clive Posted July 5 Share Posted July 5 14 minutes ago, glang said: I think the latter is what youre thinking of clive so applies in the case of fitting a single rail to a 1300.... Nope, the 10/coarse spline plate has been touted around for years. GCP103. oe to Midgets/sprites. It seems it was borrowed for the US spec cars. https://jamespaddock.co.uk/clutch-plate-usa-spec-7-14-coarse-10-splinegcp103 https://rimmerbros.com/Item--i-GCP103 Quote Link to comment Share on other sites More sharing options...
MJH2454 Posted July 5 Author Share Posted July 5 Thank you Clive, very helpful with the links as well Quote Link to comment Share on other sites More sharing options...
glang Posted July 5 Share Posted July 5 3 hours ago, Clive said: Nope, the 10/coarse spline plate has been touted around for years. GCP103. oe to Midgets/sprites. It seems it was borrowed for the US spec cars. Youre right Clive, I see they didnt use our 3 rail box but the one they did must have had the same shaft spline dimensions! Quote Link to comment Share on other sites More sharing options...
Clive Posted July 5 Share Posted July 5 1 minute ago, glang said: Youre right Clive, I see they didnt use our 3 rail box but the one they did must have had the same shaft spline dimensions! Spline sizes seem to be common across all sorts. So a Ford T9 box can use a TR7 clutch plate, and there is a ford escort plate that fits the single rail Triumph boxes ( you can use the cover too if the flywheel is redrilled) But even more bizarre is that Rover driveshafts slot perfectly into Subaru CV joints (as used on my spitfire) but again Ford, mazda and others use the same pattern. Quote Link to comment Share on other sites More sharing options...
mpbarrett Posted July 7 Share Posted July 7 On 05/07/2024 at 11:09, MJH2454 said: Can you fit a 1500 engine to a MKIV 3 rail gearbox? Do you need to change anything, ie clutch or gearbox drive shaft? no. I have a 1500 engine in my Herald with a 3 rail OD gearbox. Last clutch was from James Paddock, so you can buy a 20 spline clutch plate for it. But then I have another GB by TLD that has the 10 spline clutch plate. All depends on the input shaft fitted to the gearbox. mike Quote Link to comment Share on other sites More sharing options...
glang Posted July 8 Share Posted July 8 Yes if non standard all bets are off but otherwise Im 99% certain 3 rail will be 10 spline and single rail 20👍 As Mike has found the internals of each type can be swopped over but must not be mixed as there are different tip bearings, gear angles and synchro ring sizes.... 1 Quote Link to comment Share on other sites More sharing options...
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