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AH Spares has an accumulator and piston which uses an O-ring. It
appears the pressure relief hole is chamfered:<br>
<br>
<a class="moz-txt-link-freetext" href="https://www.ahspares.co.uk/austin-healey/performance-parts/gearbox-overdrive/o-ring-conversion-accumulator-piston.aspx">https://www.ahspares.co.uk/austin-healey/performance-parts/gearbox-overdrive/o-ring-conversion-accumulator-piston.aspx</a><br>
<br>
<br>
<div class="moz-cite-prefix">On 4/17/2022 12:03 PM, Michael Salter
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAB3i7LJxomfqn1w=1h5N9nbiXRVnY9babKt__E4FveBt+N0QYQ@mail.gmail.com">
<meta http-equiv="content-type" content="text/html; charset=UTF-8">
<div dir="auto">Actually Bob I've never used an "O" ringed
accumulator.
<div dir="auto">I spent a little time many years back looking
into using "O" rings on the accumulator but couldn't resolve
the issue of the ring being chaffed when passing over the
radial drillings in the accumulator body. </div>
<div dir="auto">Does anyone know how that has been solved?</div>
<div dir="auto"><br>
</div>
<div dir="auto">M</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Sun., Apr. 17, 2022, 2:49
p.m. Bob Spidell, <<a href="mailto:bspidell@comcast.net"
moz-do-not-send="true" class="moz-txt-link-freetext">bspidell@comcast.net</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0 0 0
.8ex;border-left:1px #ccc solid;padding-left:1ex">
<div> Michael, <br>
<br>
Sounds like you're implying the O-ringed accumulator is
superior to the metal ring (OEM) type? Wish I'd known about
it when I rebuilt my O/D (I bought the DWM 'uprated'
accumulator).<br>
<br>
I'll throw out another, very unlikely, potential cause: the
cone clutch could be stuck together. I've heard of this
happening, but have never experienced it my self--nor has
anyone I know--but it's theoretically possible (esp. if the
clutch is excessively worn). Could this be the reason the
manual is adamant about replacing the 8 strong springs, of
two lengths, that oppose the operating pistons on overhaul,
regardless if they still seem robust?<br>
<br>
<br>
<div>On 4/17/2022 9:31 AM, Michael Salter via Healeys wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div class="gmail_default"
style="font-family:arial,sans-serif;font-size:small">Simon,</div>
<div class="gmail_default"
style="font-family:arial,sans-serif;font-size:small">Based
upon your synopsis I conclude that the operating valve
is NOT opening when either the solenoid lever or the
setting lever is being moved to the position where the
operating valve ball would normally be lifted off its
seat.</div>
<div class="gmail_default"
style="font-family:arial,sans-serif;font-size:small">This
conclusion is based upon your discovery that the
pressure in the accumulator, as indicated on the
gauge, does not leak away overnight.</div>
<div class="gmail_default"
style="font-family:arial,sans-serif;font-size:small">There
is a small clearance between the operating valve push
rod and the overdrive housing. If the operating valve
ball was indeed lifted off its seat all the oil in the
accumulator would, over time, leak past the operating
rod thus discharge the accumulator. <br>
</div>
<div class="gmail_default"
style="font-family:arial,sans-serif;font-size:small">This
process would indeed take some time but would
certainly completely relieve most, if not all the
residual accumulator pressure overnight.</div>
<div class="gmail_default"
style="font-family:arial,sans-serif;font-size:small">If
however the operating valve ball is still in contact
with its seat (i.e. not being lifted) the oil pressure
would not reach the small clearance between the valve
push rod and the housing and, other than past the
accumulator rings there is nowhere for that pressure
to be relieved. <br>
</div>
<div class="gmail_default"
style="font-family:arial,sans-serif;font-size:small">I
would presume that Overdrive Spares installed an
accumulator with an "O" ring rather than the original
cast iron rings. If the original type accumulator
piston was still fitted, oil would seep past the cast
iron rings to relieve the pressure, albeit very
slowly, and again the accumulator pressure would be
discharged overnight..<br>
</div>
<div class="gmail_default"
style="font-family:arial,sans-serif;font-size:small">The
cam on the operating shaft, the one which lifts the
operating valve push rod and thus the operating valve
ball, is locked to the shaft with a small taper pin. I
would guess that the taper pin has either fallen out
or sheared. <br>
</div>
<div class="gmail_default"
style="font-family:arial,sans-serif;font-size:small">Bad
news is that this pin cannot be accessed without
removing and disassembling the overdrive.</div>
<div class="gmail_default"
style="font-family:arial,sans-serif;font-size:small"><br>
</div>
<div class="gmail_default"
style="font-family:arial,sans-serif;font-size:small">M<br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Sat, Apr 16, 2022
at 1:19 PM Simon Lachlan via Healeys <<a
href="mailto:healeys@autox.team.net" target="_blank"
rel="noreferrer" moz-do-not-send="true"
class="moz-txt-link-freetext">healeys@autox.team.net</a>>
wrote:<br>
</div>
<blockquote class="gmail_quote" style="margin:0px 0px
0px 0.8ex;border-left:1px solid
rgb(204,204,204);padding-left:1ex">
<div lang="EN-GB">
<div>
<p class="MsoNormal">My OD is driving me mad and I
definitely need some inspired advice. A bit of
background first. I’ll try to lay out all the
facts in a logical sequence. (I’m increasingly
reluctant to link ODs with logic!)</p>
<ol style="margin-top:0cm" type="1" start="1">
<li style="margin-left:0cm">I’d say that the OD
has done +/- 15k miles since a total rebuild
by Overdrive Spares here in UK.</li>
<li style="margin-left:0cm">The OD had issues
before Christmas (21) and was sorted out by OD
Spares. The accumulator was uprated and
pressure issues sorted.</li>
<li style="margin-left:0cm">OD functioned 100%
on the few times I’d been able to take it out
since then until..</li>
<li style="margin-left:0cm">One day, the OD
stopped functioning.</li>
<li style="margin-left:0cm">I checked the
electrics. All fine there so I delved a bit
deeper.</li>
<li style="margin-left:0cm">It had fried its
solenoid which I replaced. But…</li>
<li style="margin-left:0cm">That did not fix the
problem so…</li>
<li style="margin-left:0cm">I decided that the
operating valve’s adjustment might be off so..</li>
<li style="margin-left:0cm">I bought a dial
gauge and hoped to sort it out precisely
rather than by “feel”, which I lack in this
area.</li>
<li style="margin-left:0cm">Prior to using the
gauge I decided to see if the OD was
functioning at all so I raised the car on
stands and fitted my pressure gauge.</li>
<li style="margin-left:0cm">I get a reading of
500psi rising a bit when I rev the engine but
I’d suppose that would drop when the oil warms
up.</li>
<li style="margin-left:0cm">BUT, and this is
where things go pear-shaped…moving the little
lever on the RHS up and down does not
engage/disengage OD. There is no change on the
gauge to show OD engaging or disengaging.</li>
<li style="margin-left:0cm">AND, the gauge stays
at 500psi even when the engine is off. Moving
the lever 20 times has zero effect. Stayed at
500 overnight!</li>
<li style="margin-left:0cm">Of course, I checked
for dirt in the operating valve area. None.</li>
<li style="margin-left:0cm">Likewise, the tiny
hole in the “valve – operating” (the spindle
thing which the ball sits on)….that’s clear.
And surely, the pressure would diminish
overnight if something in that area was
partially obstructed?</li>
<li style="margin-left:0cm">When I remove the
pressure valve, there’s a small spillage – no
more than you’d expect – but repeating the
pressure gauge process only returns the same
results.</li>
<li style="margin-left:0cm">I see in the bible
according to Norman Nock that “Holding this
lever with your thumb and index finger, you
should be able to push the lever down lightly
about ⅜” until you feel a slight spring
pressure resistance. The lever should go down
another ¼” after encountering the
resistance……” ie there’s about ⅝” movement up
& down in that lever. Well, my lever does
move and does lift the ball, but there’s not
⅝” movement there. Could that be the problem
area???</li>
<li style="margin-left:0cm">Almost finished…keep
reading!</li>
</ol>
<p class="MsoNormal" style="margin-left:18pt">So,
I’m stumped. Every time I learn something new
about the OD, it has a new trick to baffle me.</p>
<p class="MsoNormal" style="margin-left:18pt">I’ve
no 100% sure way of telling whether it’s gone
into OD and stuck there or whether it’s simply
not going into OD at all.</p>
<p class="MsoNormal" style="margin-left:18pt">I’ve
done a lot of reading through my books and
collection of advice from the various gurus and
found reference to ODs being stuck but those
seemed to be to do with “weak springs” which,
particularly after a long lay-off, wouldn’t
disengage. The cure for this being a good smack
on the steel plate sandwiched in the OD from
below. Well, that seems to be a stuck mechanism
issue whereas I’m facing a hydraulic conundrum.
Or am I?</p>
<p class="MsoNormal" style="margin-left:18pt">There
is what is usually referred to as the “pressure
relief valve” adjacent to the accumulator. The
name suggested that pressure might be stuck in
that area….but surely not overnight?</p>
<p class="MsoNormal" style="margin-left:18pt"> </p>
<p class="MsoNormal" style="margin-left:18pt">Any
ideas? I am particularly reluctant to take the
gearbox and OD out. You’ll recall the ridiculous
business of the defective clutch kit? Well, I
forget whether we had the box in and out 3 times
or 4. I’d hoped not to do it again so soon or
ever for that matter.</p>
<p class="MsoNormal" style="margin-left:18pt"> </p>
<p class="MsoNormal" style="margin-left:18pt">I’m
hoping for a miracle of course but some sound
advice would be a godsend…………</p>
<p class="MsoNormal" style="margin-left:18pt"> </p>
<p class="MsoNormal" style="margin-left:18pt">Thanks,</p>
<p class="MsoNormal" style="margin-left:18pt">Simon</p>
<p class="MsoNormal" style="margin-left:18pt"> </p>
</div>
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