Gearbox for TC21/100

Gearbox to fit TC21/100 Grey Lady saloon. I have been told that a gearbox from TA21 through to possibly TD21 would drop straight in. Also a BMC 5 speed gearbox (as used in Austin Healeys) can be adapted without too much difficulty though the Alvis box is thought to be the stronger. Please contact me on 07919373836 or e-mail <!-- e --><a href="mailto:nrg@aslancre.co.uk">nrg@aslancre.co.uk</a><!-- e --> Posted by Nigel Griffiths 20/06/2014 07:24:59

A TA box will drop straight in but you may need to swap over the speedo drive pinion on the back beforehand otherwise the speedo may read inaccurately. A TD box would fit (BMC 4 speed) but you would need to alter the transmission tunnel, carpets and seats I think, because it is wider. You would also need an adaptor plate between engine and box to fit it. To fit the overdrive unit on the back of the BMC box is possible, but it involves altering the chassis &amp; propshaft. It has been done by several owners though. Best solution in my view would be to rebuild the gearbox you already have and refit it, rather than fit a secondhand box which will invariably give you trouble. You could also consider the taller ratio back-axle from an automatic TD21 for more relaxed cruising, if that is what you are trying to achieve....although they don't grow on trees these days?  Most parts are available from Chris Prince &amp; RT to cover the options above. Enjoy! Posted by Angus D'Arcy-Drake 23/06/2014 09:58:52

You may also have issues with the clutch operation as the TD is hydraulic and the TA/TC is a fiendishly complicated  mechanical set up,the clutch plate assembly is the same.I agree with Angus, overhaul what you have rather than fit some modified BMC cast off that was not that good anyway.Definitely worth exploring an O/D on the back of the existing box and/or the auto axle.  Good Luck Posted by Peter Martin 24/06/2014 08:54:13