Alex Lowe Posted July 19, 2020 Report Share Posted July 19, 2020 Hi all I’m looking at purchasing a over drive gearbox for my late GT6 MK3. Iv found a unit which I believe is for a 1850 dolomite with J type overdrive fitted. My question is will this fit into my Gt6 by swapping the bell housing from my current Non O/D box? Or are there other things to consider. I’ll place a link to the add below. https://www.ebay.co.uk/itm/174346821436 Link to comment Share on other sites More sharing options...
Colin Lindsay Posted July 19, 2020 Report Share Posted July 19, 2020 With the usual mods - chopped tunnel, different rear mount and shortened propshaft it's a straight fit; but the clutch plate will need to be Dolomite to fit the input shaft. Bellhousing requires no mods. I have one in my Mk1, almost twenty years now and no problems. EDIT! This was a rough draft that somehow self-posted when I tried to cancel after realising it was a single rail... blame the software!! (Hides....) Link to comment Share on other sites More sharing options...
GT6M Posted July 19, 2020 Report Share Posted July 19, 2020 Err yes, but alot of work needed, see other thread on single rail into a GT Ye really need a 3 rail, as the adaptor bit is shorter too the GL will be a better fit too. M Link to comment Share on other sites More sharing options...
Nick Jones Posted July 19, 2020 Report Share Posted July 19, 2020 Ok...... so there are other things to consider. That is the later 1850 gearbox. The single rail - so named because it has a single selector rod - it has the flat top. The good news is that it is stronger than the earlier three rail (three selector rods, bubble top) typre used on earlier Dolomites and Vitesse/GT6. The less good news is that unlike the earlier 3 rail Dolly box (also with J-type) which is a direct swap after a bellhousing change: - It's 1" longer than the earlier box (adapter plate between gearbox and OD is longer as is the mainshaft) so you'll need a special propshaft 1" shorter than the GT6 OD one and the space is very tight at the back, especially around the speedo drive. Some "relief" may be needed -The single rail selector sticks through the front of the main casing without any oil seal. The 1850 bell housing has extra material with a hole in it here to act as a closing plate for it. The GT6/Vitesse one does not. People have got around this in various ways - it's fixable. - You'll need to modify the gearstick to resemble a GT6 one. - Fine spline clutch plate needed (as observed above). Late Dolly 1850, TR7 4 speed, certain Sierras and Saabs all can be used. It is possible to overcome the bell housing problem by building the internals into your original 3 rail casing but the length problem remains. That's a fair price at present. Though there is no guarantee it's not knackered - they quite often are, but not as often as the early ones which almost always are! Nick Link to comment Share on other sites More sharing options...
Graham C Posted July 19, 2020 Report Share Posted July 19, 2020 (edited) Hello Alex I wrote a detailed account on the forum covering this. It is located under the gearbox section. It is possible I enjoyed the challenge of doing this. The bell housing needs altering, prop shaft reducing, a small section of chassis cutting out for the angle driver, a speedo counter cable from a 2000, approx 5 feet long and a support plate for the OD making up The gear box tunnel needs making longer . I quite like the new position of the gear lever . Yes it is a harder route but can be enjoyable than a standard switch. Graham Edited July 19, 2020 by Graham C Correction Link to comment Share on other sites More sharing options...
Graham C Posted July 19, 2020 Report Share Posted July 19, 2020 Interesting price £400, 7 years ago I paid £250 for mine on eBay. Graham Link to comment Share on other sites More sharing options...
Colin Lindsay Posted July 20, 2020 Report Share Posted July 20, 2020 Nya nya, £180 for mine back in 2001 and they threw an engine in too.... but it was seized solid. It was a 3-rail with J-type and I can very definitely recommend it. Link to comment Share on other sites More sharing options...
Graham C Posted July 20, 2020 Report Share Posted July 20, 2020 Colin, good deal. What happened to the engine? Graham Link to comment Share on other sites More sharing options...
thescrapman Posted July 21, 2020 Report Share Posted July 21, 2020 I paid £250 for a reconditioned single rail one. That's was this year. I also paid £100 for 2 3-rail 1850 boxes, but that was 30 years ago. Link to comment Share on other sites More sharing options...
Colin Lindsay Posted July 22, 2020 Report Share Posted July 22, 2020 On 20/07/2020 at 09:22, Graham C said: Colin, good deal. What happened to the engine? Graham Seized solid - completely! I think the seller wanted rid of it. It was well beyond economic repair. It still yielded a lot of good parts, though, being a MK2 GT6 engine, so repaid some of the outlay. Link to comment Share on other sites More sharing options...
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