[Healeys] Fw: Gearbox and Overdrive finally separated

[Earl Kagna]

John:

I learned long ago to always instictively confirm that the overdrive has 
actually disengaged when switching out.  In overdrive, when slowing or 
preparing to come to a stop, I switch out of overdrive first, and note that 
the RPMs have indeed increased, before downshifting.  I have seen various 
techniques used by drivers who are sometimes not aware that if an electric 
fault develops, the overdrive may still be engaged when the car is fully 
stopped.  If the car is reversed, thats when the shrapnel happens as you 
describe.

Earl Kagna
Victoria, B.C.
BT7 tri-carb
BJ8


----- Original Message ----- 
From: "John Harper" <ah at jharper.demon.co.uk>
To: "Earl Kagna" <kags at shaw.ca>
Cc: "Healey List" <healeys at autox.team.net>
Sent: Saturday, May 24, 2008 1:36 AM
Subject: Re: [Healeys] Fw: Gearbox and Overdrive finally separated


Earl

I fully agree. Trying to reverse a big Healey fitted with an overdrive
that is stuck in an engaged state and in so doing destroys it is a
problem often encountered. One of my colleagues has had just that and
has had to fit a new unit in the last few weeks.

If one is compiling a list of driver's do's and don'ts I suggest that
every time one tries to reverse an overdrive car that does not respond
as expected then don't try again except at very low engine revs. You
might just save the overdrive by doing this.

What happens, in reverse, when the main cone clutch is not engaged is
that the 'inners' rotate at about 8 times the normal speed depending on
the O/D ratio. The one way clutch cannot help because this only works in
the forward direction. The various gears will not stand running so fast
for long and will 'burst'.

Regards
>
>
>Ken:
>
>Sounds like at some point, the car was reversed with the overdrive still
>engaged - one of the switches likely failed.  We are working on a BN4 box
>with the same mess - totally destroyed planet / sunwheel set, one-way
>clutch, annulus, and gearbox mainshaft.  So far, we've found all the needed
>parts except the mainshaft - the BN4 stuff is getting pretty rare.
>
-- 
John Harper