[Healeys] another overdrive problem

Ross Osborne ross.osborne at xtra.co.nz
Fri Nov 9 00:13:50 MST 2012

Following a recent rebuild I have 470-490 psi but it drops to 110-120 when 
O/D selected and does not engage until the pressure builds back up to about 
130. The pressure then slowly climbs back to 470-490.

I am experiencing a similar problem to Gary's where the O/D  'slips' when 
the vehicle slows down with no throttle applied. In my case at about 30 mph. 
This did not happen until the gauge was removed but I assume the pressure 
leaks off when travelling slowly and the oil is hot.

Any ideas why there is such a large drop in pressure, I understand it should 
drop only 100-150 as O/D engages.

Ross Osborne NZ

----- Original Message ----- 
From: "Michael Salter" <michaelsalter at gmail.com>
To: <warthodson at aol.com>
Cc: <healeys at autox.team.net>
Sent: Friday, November 09, 2012 4:54 AM
Subject: Re: [Healeys] another overdrive problem

> Hi Gary,
> I believe that this is also caused by low hydraulic pressure in the
> overdrive.
> The pressure has to overcome spring pressure when "overdrive" is selected.
> If the pressure is too low the cone clutch lifts off its "normal" position
> but does not move all the way to the "overdrive" position and stays in
> no-mans-land. When you apply throttle the unidirectional clutch provides
> the drive but that only works when the engine is pushing the car, not the
> car pushing the engine.
> You should start by checking the overdrive oil pressure, it should be 
> 470 -
> 490 p.s.i.....the seldom are that high.
> Michael S
> On Thu, Nov 8, 2012 at 9:05 AM, <warthodson at aol.com> wrote:
>> Recently, I mentioned that my overdrive has begun to shift into OD more
>> slowly. The shifts can take up to 3-5 seconds. This problem has 
>> progressed
>> to
>> the point that now about 50% of the time it does not shift into OD at 
>> all.
>> When this happens I noticed an unusual phenomena. If I shift into OD, but
>> the
>> OD does not engage, and I take my foot off the gas, the engine RPM drops
>> immediately to idle, even though the clutch is still engaged & I may be
>> going
>> 60 MPH. The RPM does not drop to idle if I am in direct drive & I take my
>> foot
>> off the gas at 60 MPH. So, apparently the OD has partially engaged but 
>> not
>> completely. Does anyone know what is happening in this example? 
>> Obviously,
>> the
>> electrical part of the OD is engaging or it would act just like direct
>> drive.
>> I have not had an opportunity to check the OD operating pressure, but 
>> will
>> soon. The transmission is full of the correct oil.
>> Gary Hodson
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> -- 
> Michael Salter
>                         *I have BJ8 water pump kits!!*

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