Stuart Wilson Posted March 10, 2015 Share Posted March 10, 2015 Some of you may have seen my various posts about upgrading/repairing the Moss.I'm thinking of fitting an overdrive, the question is do I get an overdrive and fit it to my current gearbox or do I get a 2nd hand complete gearbox with overdrive?Is there any advantage over one gearbox type to the other, single rail vs three rail?The current gerabox is a single rail from a spitfire 1500.Next, obviously there will be wiring to sort out, I'm guessing it is not overly difficult to do.This is not something I'm planning on doing straight away, just looking at the options so I can have an idea of budget.Thanks in advance Quote Link to comment Share on other sites More sharing options...
Clive Posted March 10, 2015 Share Posted March 10, 2015 You can't just bolt an overdrive on your box. Requires a new mainshaft, adapter plate, and in your case a different gearbox top (hensteeth).best bet is a complete unit.Use a 3 rail od box and it is a straight swap in terms of length and current propshaft. just clutch plate to swap. Quote Link to comment Share on other sites More sharing options...
yorkshire_spam Posted March 10, 2015 Share Posted March 10, 2015 The main issue is the single rail selector assembly. Made of unobtainium.Look at between 200 and 300 quid for a box+OD, mount, prop etc may or may not be included at that sort of money.New mainshaft to swap a non-od single rail to OD will be about 120ukp, then you have the "adapter" about 40ukp used.... add in the cost of the OD, prop etc and it's gonna be cheaper just to buy a complete set together if you can. Quote Link to comment Share on other sites More sharing options...
Stuart Wilson Posted March 10, 2015 Author Share Posted March 10, 2015 Thanks so far......so if I was looking for 2nd hand complete would I be better off looking for single rail or three rail? or just get what is available I realise the prop may need altering depending on which box Quote Link to comment Share on other sites More sharing options...
Tim Bancroft Posted March 10, 2015 Share Posted March 10, 2015 I have always rathered the 3 rail box, seems a better box to me??? Quote Link to comment Share on other sites More sharing options...
Spider Posted March 11, 2015 Share Posted March 11, 2015 I have a single rail gearbox which I removed from a 1500 engine in a Spitfire, I believe it was originally fitted to a Dolomite. If you are really stugling to source one I might be persuaded to part with it. I do have plans to build a Sammio Spider special one day and I was going to use it in that. However I do also have a lot of other projects to complete before I even contemplate starting that one and as I am setting up a small business as a sideline buying and selling classic parts and doing restoration work etc I really should think of passing it on. :-/ Condition is unknown but the guy I bought it off said he tested it up and down his 3/4 mile driveway and it worked okay, not sure if It would need a rebuild or refurb but best to assume it might, also I do not have the gear lever for it. So if you are finding it difficult to source a known good box it may be available.Best of luck in your search.Spider. Quote Link to comment Share on other sites More sharing options...
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