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--></style></head><body lang=EN-US link=blue vlink="#954F72" style='word-wrap:break-word'><div class=WordSection1><p class=MsoNormal>Bob,</p><p class=MsoNormal>Interesting observation.</p><p class=MsoNormal>Only 30/40 wt non detergent oil was used from new till 2013 at which time I switched</p><p class=MsoNormal>to Redline MT90 @ 181,000 miles.</p><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Sent from <a href="https://go.microsoft.com/fwlink/?LinkId=550986">Mail</a> for Windows</p><p class=MsoNormal><o:p> </o:p></p><div style='mso-element:para-border-div;border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal style='border:none;padding:0in'><b>From: </b><a href="mailto:bspidell@comcast.net">Bob Spidell</a><br><b>Sent: </b>Thursday, August 4, 2022 9:38 AM<br><b>To: </b><a href="mailto:flyhihealey@gmail.com">Warren Dietz</a>; <a href="mailto:healeys@autox.team.net">healeys@autox.team.net</a><br><b>Subject: </b>Re: [Healeys] DW overdrive piston</p></div><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal>Warren,<br><br>Your accumulator piston and housing look to have a bit worse scoring than mine; I used synthetic fluid for over half the life of mine, I wonder if that made a difference?<br><br><br><br><o:p></o:p></p><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal>Sent from <a href="https://go.microsoft.com/fwlink/?LinkId=550986">Mail</a> for Windows<o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal>This was the condition of my piston and housing with close to 200,000 miles. Tranny was well maintained.<o:p></o:p></p><p class=MsoNormal>The original metal rings lasted 53 years. So I guess with unknown quality of either of todays metal vs rubber<o:p></o:p></p><p class=MsoNormal>O rings, let the experiments begin. <o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p><div style='border:none;border-top:solid #E1E1E1 1.0pt;padding:3.0pt 0in 0in 0in'><p class=MsoNormal><b>From: </b><a href="mailto:bspidell@comcast.net">Bob Spidell</a><br><b>Sent: </b>Wednesday, August 3, 2022 10:12 PM<br><b>To: </b><a href="mailto:healeys@autox.team.net">healeys@autox.team.net</a><br><b>Subject: </b>Re: [Healeys] DW overdrive piston<o:p></o:p></p></div><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal style='margin-bottom:12.0pt'>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?).<o:p></o:p></p><div><p class=MsoNormal>On 8/3/2022 12:36 PM, Henry G Leach via Healeys wrote:<o:p></o:p></p></div><blockquote style='margin-top:5.0pt;margin-bottom:5.0pt'><p class=MsoNormal>I assemble ODs using the original metal rings and have not had any issues with pressure or engagement/disengagement. <o:p></o:p></p><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal>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.<o:p></o:p></p></div><div><p class=MsoNormal> <o:p></o:p></p></div><div><p class=MsoNormal style='margin-bottom:12.0pt'>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<o:p></o:p></p><p>-----------------------------------------</p><p class=MsoNormal style='margin-bottom:12.0pt'>From: "Michael Salter" <br>To: <a href="mailto:healeys@autox.team.net">"healeys@autox.team.net"</a><br>Cc: <br>Sent: Wednesday August 3 2022 9:38:15AM<br>Subject: Re: [Healeys] DW overdrive piston<o:p></o:p></p><div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif'>I have a question about the "O" ring type of accumulator.</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif'>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.</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif'>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.</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif'>I'm guessing that Laycock-DeNormanville used the complex cast iron rings rather than "O" rings because they recognized the possibility of this happening.</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif'>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?</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif'> </span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif'>M</span><o:p></o:p></p></div><div><p class=MsoNormal><span style='font-size:12.0pt;font-family:"Arial",sans-serif'> </span><o:p></o:p></p></div></div><p class=MsoNormal> <o:p></o:p></p><div><div><p class=MsoNormal>On Wed, Aug 3, 2022 at 9:08 AM Bob Spidell <a href="mailto:bspidell@comcast.net"><bspidell@comcast.net></a> wrote:<o:p></o:p></p></div><blockquote style='border:none;border-left:solid #CCCCCC 1.0pt;padding:0in 0in 0in 6.0pt;margin-left:4.8pt;margin-top:5.0pt;margin-right:0in;margin-bottom:5.0pt'><p class=MsoNormal style='mso-margin-top-alt:0in;margin-right:0in;margin-bottom:12.0pt;margin-left:153.6pt'>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>><o:p></o:p></p></blockquote></div></div></blockquote><p class=MsoNormal> <o:p></o:p></p><p class=MsoNormal> <o:p></o:p></p></blockquote><p class=MsoNormal><o:p> </o:p></p><p class=MsoNormal><o:p> </o:p></p></div></body></html>