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OK, I did the hard work (2 clicks) and dug up the source:<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>
They claim the housing is modified as well, maybe with bevels on the
pressure relief ports?<br>
<br>
<div class="moz-cite-prefix">On 3/26/2021 7:34 AM, Michael Salter
wrote:<br>
</div>
<blockquote type="cite"
cite="mid:CAB3i7L+uQF2sUaBVMdOAfW2s7gfiM55SippNqWfb7LVhUXkvow@mail.gmail.com">
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<div dir="ltr">
<div class="gmail_default" style="font-family:comic sans
ms,sans-serif;font-size:small"><span
style="font-family:arial,sans-serif">Bob, I looked into
installing "O" rings into an accumulator many years ago but
couldn't figure out how to get around the problem presented
by the fact that the accumulator relieves pressure by
allowing the cast iron rings to pass over radial holes in
the body.</span></div>
<div class="gmail_default" style="font-family:comic sans
ms,sans-serif;font-size:small"><span
style="font-family:arial,sans-serif">When I tried them the
"O" rings were forced into those pressure relief holes and
tiny pieces were sliced off at each hole location!!<br>
</span></div>
<div class="gmail_default" style="font-family:comic sans
ms,sans-serif;font-size:small"><span
style="font-family:arial,sans-serif">How do the accumulators
with "O" rings address that issue?</span></div>
<div class="gmail_default" style="font-family:comic sans
ms,sans-serif;font-size:small"><span
style="font-family:arial,sans-serif"><br>
</span></div>
<div class="gmail_default" style="font-family:comic sans
ms,sans-serif;font-size:small"><span
style="font-family:arial,sans-serif">M</span><br>
</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Fri, Mar 26, 2021 at 10:26
AM Bob Spidell <<a href="mailto:bspidell@comcast.net"
moz-do-not-send="true">bspidell@comcast.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> Maybe of interest to some: AFAIK, all O/D accumulators
came with metal rings, which likely cause or at least
contribute to scoring. One of the Brit suppliers--probably
AHS but I'm not sure--has an accumulator setup that uses an
O-ring(s) instead of metal rings, which should prevent
scoring. I rebuilt my O/D a couple years back, and if I'd
known of the O-ring type I would have installed it. Earlier
O/Ds used metal rings in the actuator pistons, but later
ones had O-rings, and it's logical to conclude LdeN went to
O-rings there because of excessive scoring of the cases (or,
possibly, because they were cheaper).<br>
<br>
<div>On 3/26/2021 6:03 AM, Michael Salter via Healeys wrote:<br>
</div>
<blockquote type="cite">
<div dir="auto">Time this question was put to bed.
<div dir="auto">1. The throttle switch is not supposed
to disengage the overdrive if the dash switch is in
the "OVERDRIVE" position. If it does the system is
wired incorrectly. (BN1s are a little different)</div>
<div dir="auto">2. Overdrives which slip out, slip, or
won't engage WHEN HOT but do work when cold are
invariably suffering from low oil pressure which is
almost always caused by accumulator issues. The "O"
rings on the outside of the accumulator sleeve can be
a problem but in my experience scoring of the
accumulator bore and damage to the rings and piston
are a more common cause.</div>
<div dir="auto">3. Overdrives and gearboxes in Healeys
are meant to be lubricated with engine oil. Decades
ago I wrote to Laycock DeNormanville, back when
letters went in envelopes with stamps, and received a
response from their engineering department indicating
clearly that the oil specified for their products was
specified by the gearbox manufacturer and whatever
they specified was acceptable for the overdrive.</div>
<div dir="auto">M</div>
</div>
<br>
<div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Fri., Mar. 26,
2021, 2:13 a.m. WILLIAM B LAWRENCE via Healeys, <<a
href="mailto:healeys@autox.team.net" target="_blank"
moz-do-not-send="true">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>
<div>The symptoms I’ve seen and experienced are that
the OD will engage and function until the oil temp
comes up and the viscosity drops off and will then
fail. I suppose it depends on the degree of
degradation of the o-rings.</div>
<hr style="display:inline-block;width:98%">
<div
id="gmail-m_-7260173366705078485m_2913893478454826311divRplyFwdMsg"
dir="ltr"><font style="font-size:11pt"
face="Calibri, sans-serif" color="#000000"><b>From:</b>
Healeys <<a
href="mailto:healeys-bounces@autox.team.net"
rel="noreferrer" target="_blank"
moz-do-not-send="true">healeys-bounces@autox.team.net</a>>
on behalf of Bob Spidell <<a
href="mailto:bspidell@comcast.net"
rel="noreferrer" target="_blank"
moz-do-not-send="true">bspidell@comcast.net</a>><br>
<b>Sent:</b> Thursday, March 25, 2021 11:14 PM<br>
<b>To:</b> <a
href="mailto:healeys@autox.team.net"
rel="noreferrer" target="_blank"
moz-do-not-send="true">healeys@autox.team.net</a>
<<a href="mailto:healeys@autox.team.net"
rel="noreferrer" target="_blank"
moz-do-not-send="true">healeys@autox.team.net</a>><br>
<b>Subject:</b> Re: [Healeys] overdrive problem</font>
<div> </div>
</div>
<div>Sure, but wouldn't faulty O-rings prevent the
OD from engaging in the first place? Just
guessing, but wouldn't a deficient pump cause same
symptoms?<br>
<br>
<br>
<div>On 3/25/2021 4:07 PM, WILLIAM B LAWRENCE via
Healeys wrote:<br>
</div>
<blockquote type="cite">
<div>Sorry, but the Laycock deNormanville
overdrive is not supposed to kick down
automatically. The most common fault that
causes the OD to drop out is faulty o-rings on
the accumulator sleeve. This won’t allow the
OD to build full operating pressure.</div>
<div><br>
</div>
<div>Bill Lawrence</div>
<div>BN1 #554</div>
<hr style="display:inline-block;width:98%">
<div
id="gmail-m_-7260173366705078485m_2913893478454826311x_divRplyFwdMsg"
dir="ltr"><font style="font-size:11pt"
face="Calibri, sans-serif" color="#000000"><b>From:</b>
Healeys <a
href="mailto:healeys-bounces@autox.team.net"
rel="noreferrer" target="_blank"
moz-do-not-send="true"><healeys-bounces@autox.team.net></a>
on behalf of Kees Oudesluijs via Healeys <a
href="mailto:healeys@autox.team.net"
rel="noreferrer" target="_blank"
moz-do-not-send="true"><healeys@autox.team.net></a><br>
<b>Sent:</b> Tuesday, March 23, 2021 7:37 AM<br>
<b>To:</b> <a
href="mailto:healeys@autox.team.net"
rel="noreferrer" target="_blank"
moz-do-not-send="true">
healeys@autox.team.net</a> <a
href="mailto:healeys@autox.team.net"
rel="noreferrer" target="_blank"
moz-do-not-send="true">
<healeys@autox.team.net></a><br>
<b>Subject:</b> Re: [Healeys] overdrive
problem</font>
<div> </div>
</div>
<div><font size="2"><span style="font-size:11pt">
<div>That is the way it should be when
accelerating hard, Kick down!!<br>
<br>
Kees Oudesluijs<br>
<br>
<br>
Op 23-3-2021 om 01:06 schreef
healeymanjim via Healeys:<br>
> friends BT7 had o/d quit. solenoid
was bad so replaced it. now it will go
into o/d but pop out when
accelerating. any<br>
> ideas what the cause is and the
fix?<br>
</div>
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