<html><body>I checked with David at OD Spares as to availability. Here is his response:<div><br></div><div><span style="font-family: Arial, Helvetica, sans-serif; font-size: 16px;">Hi Hank we use both styles the steel piston rings are all still available as are new pistons and the aluminium housing they both work equally well</span><div style="font-family: Arial, Helvetica, sans-serif; font-size: 16px;">We can supply any of your overdrive requirements</div><div style="font-family: Arial, Helvetica, sans-serif; font-size: 16px;"><br></div><div style="font-family: Arial, Helvetica, sans-serif; font-size: 16px;">best regards Dave<br><br><div style="clear: both;"><div style="font-variant-numeric: normal; font-variant-east-asian: normal; font-stretch: normal; font-size: 12pt; line-height: normal;"><div style="font-variant-numeric: normal; font-variant-east-asian: normal; font-stretch: normal; font-size: 12pt; line-height: normal;"><br><div><b><i><br></i></b></div><div><b><i>Overdrive Spares</i></b><div><b><i>10 Arches Business Centre</i></b></div><div><b><i>Mill Road</i></b></div><div><b><i>Rugby</i></b></div><div><b><i>Warwickshire</i></b></div><div><b><i>CV21 1QW</i></b></div><div><b><i>England</i></b></div><div><b><i><br></i></b></div><div><b><i>Email: odspares@aol.com</i></b></div><div><b><i>Telephone Number: 01788 540666</i></b></div><div><b><i>Fax Number: 01788 570777</i></b></div><div><b><i>Web: <u><span style="color: rgb(0, 0, 255);">www.odspares.com</span></u></i></b></div></div></div></div></div></div><br><div class="reply-new-signature"></div><p>-----------------------------------------</p>From: "Bob Spidell" <bspidell@comcast.net><br>To: healeys@autox.team.net<br>Cc: <br>Sent: Wednesday August 3 2022 7:15:22PM<br>Subject: Re: [Healeys] DW overdrive piston<br><br>
The rings will score the inside of the piston housing, though not
badly (photo at 205K miles). Looks like there's a side load on the
piston, probably from the spring.<br><br>
I donated this accumulator to another owner; never heard how they
worked. Moss shows the rings available (but who knows?).<br><br><br><div class="moz-cite-prefix">On 8/3/2022 12:36 PM, Henry G Leach
via Healeys wrote:<br></div>
<blockquote>
I assemble ODs using the original metal rings and have not had any
issues with pressure or engagement/disengagement.
<div><br></div>
<div>When Mr. DeNormanville stayed up in the middle of the night to
engineer the operation of the unit, I think he decided that
the use of softer rings (sacrificial metal) against a hardened
casing was the best solution for control and wear. If a
rubber o-ring was a better solution, he would have used one with
the proper buna rating.</div>
<div><br></div>
<div>I think the bigger problem, now-a-days, is the availability of
the metal piston rings. Rubber O rings are a
dime-a-dozen. If you contact Overdrive Spares in the UK, they
should be able to supply the proper rings. If they too, have
decided to go with rubber, then plan on a breakdown/rebuild in a
shorter period of time than units equipped with the original parts
that last a long, long time. Hank<br><br><p>-----------------------------------------</p>
From: "Michael Salter"<br>
To: <a class="moz-txt-link-rfc2396E">"healeys@autox.team.net"</a><br>
Cc:<br>
Sent: Wednesday August 3 2022 9:38:15AM<br>
Subject: Re: [Healeys] DW overdrive piston<br><br><div dir="ltr">
<div class="gmail_default" style="font-family:arial, sans-serif;font-size:small;">I have a question
about the "O" ring type of accumulator.</div>
<div class="gmail_default" style="font-family:arial, sans-serif;font-size:small;">The way the
accumulator works is that when it is fully charged the piston moves
against the spring until the rings reach the radial holes in the
wall of the housing which acts to relieve any excess
pressure.</div>
<div class="gmail_default" style="font-family:arial, sans-serif;font-size:small;">My concern is that
at 3 - 400 p.s.i. oil will obviously get behind the "O" ring and
force the material of the "O" ring into those radial holes and
then, as the piston moves back over them, a piece of the ring will
shear off.</div>
<div class="gmail_default" style="font-family:arial, sans-serif;font-size:small;">I'm guessing that
Laycock-DeNormanville used the complex cast iron rings rather than
"O" rings because they recognized the possibility of this
happening.<br></div>
<div class="gmail_default" style="font-family:arial, sans-serif;font-size:small;">I'm sure that tiny
pieces of the "O" ring would be found in the filter if this was a
problem. Anyone found them or noticed damage to their accumulator
"O" ring upon disassembly?<br></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 class="gmail_default" style="font-family:arial, sans-serif;font-size:small;"><br></div>
</div>
<br><div class="gmail_quote">
<div dir="ltr" class="gmail_attr">On Wed, Aug 3, 2022 at 9:08 AM
Bob Spidell <<a>bspidell@comcast.net</a>> wrote:<br></div>
<blockquote class="gmail_quote" style="margin:0px 0px 0px .8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex;">
I put one in my BJ8's O/D. It's subjective*--O/Ds seem to work a
little<br>
quicker with cold, thick oil than hot oil--but it cuts maybe a
third off<br>
engagement time on average. I had the O/D on the bench and
disassembled,<br>
and the current one had a scored barrel so, why not? Engagement
isn't<br>
much, if any, harsher than before which, I believe is the reason
DMH<br>
wanted the weaker, smaller spring. If I'd known about it, I might
have<br>
bought AHSpares' with an O-ring instead.<br><br>
* I've never really 'timed' O/D functioning, it would be a bit
awkward;<br>
anyone done it? I usually tap the clutch pedal when engaging O/D,
and<br>
give a little throttle when disengaging. I thought mine engaged a
little<br>
quicker when I switched to synthetic fluid from engine oil, but in
all<br>
cases confirmation bias may be involved.<br><br><br><br>
On 8/2/2022 8:09 PM, Joseph Costa wrote:<br>
> Has anyone installed their upgraded overdrive piston? If
so, is it<br>
> worth the trouble ?<br>
><br>
> Joe<br>
> BN1 #923<br>
><br><br></blockquote>
</div>
</div>
</blockquote>
<br></bspidell@comcast.net></div></body></html>