"HELP PLEASE"with removing gearbox bearings

[daver clasper]

Hi everybody.
I have researched this a lot and some people have done it, but i can't.
Any tips on removing imput/main shaft bearings from gearbox casing. I have heated the casing with hot air gun until water bubbles on it, and also tried putting it in gas oven on medium heat (door would not close quite also) and then given imput shaft end (front) of gear box a few whacks with dead blow hammer). Also made some soft metal drifts (15mm copper pipe hammered flat at end) and tried drifting out (alternating 3 o'clock/9 o'clock taps), though obviously these drift pipes are quite light. Have thought of melting some lead and filling these to give more weight. clutching at straws as no other soft metal drifts.
Is heating casing worth while, as not sure what metal casing is made of and if it will expand more than bearings?.
Any detailed tips and advice regarding tools and technique on this this much appreciated as can't afford to pay someone and also love sussing it out myself.
Thanks
Dave    

[mikew]

The bearings need removing from the inside to the outside. Tapping on the input shaft will not remove the bearing.

assuming you have removed the layshaft, so the layshaft cluster drops to the bottom of the box, out of mesh with the main shaft gears, the drifts then need to be used inside the gearbox - usually at the top and sides of the main shaft hearings ,

Another method is to affix a slide hammer to the tailshaft (easy via the output shaft using the drive flange and nut) and use this to pull the main cluster out, removing the bearing as it comes out - you then have room to get at the input shaft bearing

[daver clasper]

Thanks a lot for the advice about where on bearing to drift. The layshaft is out and the lay cluster has dropped to bottom of g/b. Not sure if can do the slide hammer, as is a an overdrive box and also o/d has been removed, though can refit.  
Cheers
Dave

[yorkshire_spam]

Not sure which box, but when I stripped a single rail for the spitfire I did the following:
drop the layshaft cluster into the bottom of the box
tap the input shaft forward out of the box.
Gently (do not damage!) drive the mainshaft through the rear bearing until you have about 1/2" gap between the 1st gear and the bearing.
Put a "spacer" between the bearing and the 1st gear and push back the other way (gentle taps with plastic/copper hammer!) until the bearing "pops" out of the back of the casing.
Wedge the bearing on the case and GENTLY tap the shaft through the bearing until the bearing is free.
Remove bearing
Lift mainshaft up through top of box with gears/selectors on it.

All of the above is probably 100% WRONG and is certainly NOT how it's described in the workshop manual. But then I don't have all the "required" special tools.