Gearbox

[amalgamated users from prior forum]

Message originally posted by: Tony Wylde
Can a Triumph Spitfire 1500 Overdrive box be fitted to a B series engine if I swap the bellhousing. I have been offered one at a fair price and although it has been indicated that a Dolomite 1850 box can be used I wondered whether this is the same type.

[amalgamated users from prior forum]

Re: Gearbox

Message originally posted by: Matthew Sykes
I think it's the same box as the 1300 marina but not the 1800 so I don't think it'll fit. I have an 1800 MGB OD box at work and could get you a price if interested.

[paulhyder]

Re: Gearbox

Tony,
The following info is based on a dolomite 1850 box and MAY apply to 1500 spitfire as ther was a high degree of standardisation between marina and triumph boxes.
A 1850 box will fit on the marina bellhousing but the 1st motion shaft has a different no of splines so a triumph clutch plate is required,however this has a potential snag in that the splines on the triumph box don't extend as far as the marina so may cause 'clutch drag'.This is the main reason why the majority of conversions to triumph overdrive involve building the triumph internals into the marina box.This keeps the original marina 1st motion shaft but has the triumph mainshaft neccessary for the overdrive takeoff.It also utilises the triumph gearchange extension that is needed to clear the overdrive unit.A new mounting would be reqd for the gearbox,and the propshaft may require shortening.The gearshift position remains the same.

[lil_red_roadster]

Re: Gearbox

The Spitfire box, whilst very similar to the 1850 box, has a different input shaft - I believe it has 20 splines rather than 24 on the Marina/Dolly 1850. 1500 Spitfire and 1500 Dolly have identical input shafts...makes sense as it was the same engine.

So you can use the OD but you'll need to have this built into the Marina geartrain along the lines above. Any reputable "classic friendly" gearbox workshop should be able to do this. There is a chap local to me who quoted me c?200 to do just this, having done something similar for another local owner...if you want a contact name/number let me know - jezcox<at>tesco.net