<html><body>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><div class="reply-new-signature"></div><p>-----------------------------------------</p>From: "Michael Salter" <michaelsalter@gmail.com><br>To: "healeys@autox.team.net"<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;"></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>
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