This is in response to Dir de Boers signature.
I believe, with certainty, that I know what your MGB's problem is with
regard to the gearbox. The layshaft in the box has "cracked" and
prevented proper meshing of the cluster gear with the main gears and/or
your reverse gear has stripped. As I recall, the '66 has no syncros in
first gear or reverse (not a bad thing in my opinion but. . . ) and
occasionally these non-syncro gears can cause problems. At first, some
balky reverse activity will occur and then. . . no reverse.
You can fix the gearbox yourself if you are a good weekend mechanic,
but make sure you give yourself some time. Pull out the engine/gearbox
as a unit. (Yes, you can just remove the gearbox but you risk a good
chance of damaging the pilot bearing or the input shaft of the box and
then you've got more trouble and expense. Once out of the car remove
engine from trans and put the trans in a BIG parts washer. (If you
need to, get a 50 gallon drum, split it down the side, make a "grate"
of expanded metal). Then open up the inspection plate on the side of
the transmission. (I would get a "impact driver" the kind often used
on motorcycles for this task.) Now you should have a good view of
what's gone wrong.
You can remove the layshaft without total transmission disassembly by
carefully sliding out the front (via access plate near input shaft)
while making sure everything else stays put! (i.e. main gears, forks,
bearings, etc.) and then fish out the cluster and reverse gears.
Insert everything in reverse order.
Your problem, unfortunately, is not unique but apparently harmless
(that is it won't crater the box or cause other problems). The
layshaft on these earlier gearboxes apparently has a smaller diameter
layshaft which is prone to break.
P.S. Make sure that you CLEAN the box liberally with a solvent (diesel
works in a pinch) and refill with fresh engine grade/viscosity oil.
Also, make sure that you then change the oil as you would during a
break-in period after new parts replacements.
P.S.S. Check all the bearings if you can by rotating the shafts that
ride on them. If you notice ANY roughness or binding (ANY!) that's a
bad bearing and it needs to be replaced! Fortunately, you can get
these bearings from any good industrial bearing supplier (out here in
Sacramento it would be King Bearing or Orange Bearing) and this saves
considerable $$ and the quality is much improved.
Good luck.
Matt "what do you mean its my layshaft, sir?" Silveira
mws1@osi.com
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