<div dir="ltr"><div>When my BN2 transmission was rebuilt, the mechanic installed a Triumph TR2/3 overdrive piston. I don't know if it was new old stock or he ordered it from Moss, but the BN2 and Triumph TR2/3 overdrive piston have the same part number in the catalog. <br></div><div>Mike MacLean<br></div></div><br><div class="gmail_quote"><div dir="ltr" class="gmail_attr">On Fri, Aug 5, 2022 at 9:31 PM ahbn6--- via Healeys <<a href="mailto:healeys@autox.team.net">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">Look at the Moss catalogue. They are listed there. I had them om my bn6 (which had a tranny out of a BJ8))<br>
<br>
John Sims<br>
<a href="http://www.healey6.com" rel="noreferrer" target="_blank">www.healey6.com</a><br>
Matawan, NJ<br>
<br>
-----Original Message-----<br>
From: Healeys <<a href="mailto:healeys-bounces@autox.team.net" target="_blank">healeys-bounces@autox.team.net</a>> On Behalf Of Bob Haskell<br>
Sent: Thursday, August 4, 2022 5:28 PM<br>
To: Bob Spidell <<a href="mailto:bspidell@comcast.net" target="_blank">bspidell@comcast.net</a>>; Michael Salter <<a href="mailto:michaelsalter@gmail.com" target="_blank">michaelsalter@gmail.com</a>>; Warren Dietz <<a href="mailto:flyhihealey@gmail.com" target="_blank">flyhihealey@gmail.com</a>><br>
Cc: <a href="mailto:healeys@autox.team.net" target="_blank">healeys@autox.team.net</a><br>
Subject: Re: [Healeys] DW overdrive piston<br>
<br>
Might be something here that would work: <br>
<a href="https://www.lislecorp.com/oem-products-division/magnetic-plugs/pipe-thread/" rel="noreferrer" target="_blank">https://www.lislecorp.com/oem-products-division/magnetic-plugs/pipe-thread/</a><br>
<br>
Cheers,<br>
<br>
Bob Haskell<br>
Austin Healey 3000 BN7/BT7 registrar<br>
<br>
On 8/4/22 1:12 PM, Bob Spidell wrote:<br>
> OK, who sells magnetic plugs for MOWOG gearboxes? I'd be willing to <br>
> order from Canada ;)<br>
><br>
> I don't remember exactly when I started using MT-90 in my gearbox, but <br>
> it was probably around 90-100K miles. I was hoping it would make the <br>
> O/D a bit more responsive, but was surprised that shifting seemed <br>
> smoother (I wasn't expecting it, so little-no confirmation bias).<br>
><br>
><br>
> On 8/4/2022 9:38 AM, Michael Salter wrote:<br>
>> Based upon my observations when the aluminium overdrive accumulator <br>
>> housings are scored you will invariably find that there are chips out <br>
>> of the non syncro 1st and reverse gears and usually badly damaged <br>
>> laygear rollers.<br>
>> Because these gearboxes were not fitted with chip gathering magnet <br>
>> originally the tiny hardened steel chips eventually find their way <br>
>> into the overdrive then through the overdrive pump gauze (because the <br>
>> magnets originally fitted in the overdrive have been lost by " the <br>
>> lube guy") and lodge in the accumulator.<br>
>> Those chips very quickly score the cylinder as the accumulator piston <br>
>> moves.<br>
>> If you are careful to never grind 1st or reverse no chips will be <br>
>> created, that will mean that they don't go through the laygear <br>
>> bearings or find their way into the overdrive.<br>
>> A magnetic plug in the gearbox is great insurance.<br>
>><br>
>> M<br>
>><br>
>> On Thu., Aug. 4, 2022, 12:13 p.m. Warren Dietz, <br>
>> <<a href="mailto:flyhihealey@gmail.com" target="_blank">flyhihealey@gmail.com</a>> wrote:<br>
>><br>
>> Bob,<br>
>><br>
>> Interesting observation.<br>
>><br>
>> Only 30/40 wt non detergent oil was used from new till 2013 at<br>
>> which time I switched<br>
>><br>
>> to Redline MT90 @ 181,000 miles.<br>
>><br>
>> Sent from Mail <<a href="https://go.microsoft.com/fwlink/?LinkId=550986" rel="noreferrer" target="_blank">https://go.microsoft.com/fwlink/?LinkId=550986</a>><br>
>> for Windows<br>
>><br>
>> *From: *Bob Spidell <mailto:<a href="mailto:bspidell@comcast.net" target="_blank">bspidell@comcast.net</a>><br>
>> *Sent: *Thursday, August 4, 2022 9:38 AM<br>
>> *To: *Warren Dietz <mailto:<a href="mailto:flyhihealey@gmail.com" target="_blank">flyhihealey@gmail.com</a>>;<br>
>> <a href="mailto:healeys@autox.team.net" target="_blank">healeys@autox.team.net</a><br>
>> *Subject: *Re: [Healeys] DW overdrive piston<br>
>><br>
>> Warren,<br>
>><br>
>> Your accumulator piston and housing look to have a bit worse<br>
>> scoring than mine; I used synthetic fluid for over half the life<br>
>> of mine, I wonder if that made a difference?<br>
>><br>
>><br>
>><br>
>> Sent from Mail<br>
>> <<a href="https://go.microsoft.com/fwlink/?LinkId=550986" rel="noreferrer" target="_blank">https://go.microsoft.com/fwlink/?LinkId=550986</a>> for Windows<br>
>><br>
>> This was the condition of my piston and housing with close to<br>
>> 200,000 miles. Tranny was well maintained.<br>
>><br>
>> The original metal rings lasted 53 years. So I guess with<br>
>> unknown quality of either of todays metal vs rubber<br>
>><br>
>> O rings, let the experiments begin.<br>
>><br>
>> *From: *Bob Spidell <mailto:<a href="mailto:bspidell@comcast.net" target="_blank">bspidell@comcast.net</a>><br>
>> *Sent: *Wednesday, August 3, 2022 10:12 PM<br>
>> *To: *<a href="mailto:healeys@autox.team.net" target="_blank">healeys@autox.team.net</a><br>
>> *Subject: *Re: [Healeys] DW overdrive piston<br>
>><br>
>> The rings will score the inside of the piston housing, though<br>
>> not badly (photo at 205K miles). Looks like there's a side<br>
>> load on the piston, probably from the spring.<br>
>><br>
>> I donated this accumulator to another owner; never heard how<br>
>> they worked. Moss shows the rings available (but who knows?).<br>
>><br>
>> On 8/3/2022 12:36 PM, Henry G Leach via Healeys wrote:<br>
>><br>
>> I assemble ODs using the original metal rings and have<br>
>> not had any issues with pressure or<br>
>> engagement/disengagement.<br>
>><br>
>> When Mr. DeNormanville stayed up in the middle of the<br>
>> night to engineer the operation of the unit, I think he<br>
>> decided that the use of softer rings (sacrificial metal)<br>
>> against a hardened casing was the best solution for<br>
>> control and wear. If a rubber o-ring was a better<br>
>> solution, he would have used one with the proper buna rating.<br>
>><br>
>> I think the bigger problem, now-a-days, is the<br>
>> availability of the metal piston rings. Rubber O rings<br>
>> are a dime-a-dozen. If you contact Overdrive Spares in<br>
>> the UK, they should be able to supply the proper rings. <br>
>> If they too, have decided to go with rubber, then plan on<br>
>> a breakdown/rebuild in a shorter period of time than<br>
>> units equipped with the original parts that last a long,<br>
>> long time. Hank<br>
>><br>
>> -----------------------------------------<br>
>><br>
>> From: "Michael Salter"<br>
>> To: "<a href="mailto:healeys@autox.team.net" target="_blank">healeys@autox.team.net</a>" <mailto:<a href="mailto:healeys@autox.team.net" target="_blank">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>
>> I have a question about the "O" ring type of accumulator.<br>
>><br>
>> The way the accumulator works is that when it is fully<br>
>> charged the piston moves against the spring until the<br>
>> rings reach the radial holes in the wall of the housing<br>
>> which acts to relieve any excess pressure.<br>
>><br>
>> My concern is that at 3 - 400 p.s.i. oil will obviously<br>
>> get behind the "O" ring and force the material of the "O"<br>
>> ring into those radial holes and then, as the piston<br>
>> moves back over them, a piece of the ring will shear off.<br>
>><br>
>> I'm guessing that Laycock-DeNormanville used the complex<br>
>> cast iron rings rather than "O" rings because they<br>
>> recognized the possibility of this happening.<br>
>><br>
>> I'm sure that tiny pieces of the "O" ring would be found<br>
>> in the filter if this was a problem. Anyone found them or<br>
>> noticed damage to their accumulator "O" ring upon<br>
>> disassembly?<br>
>><br>
>> M<br>
>><br>
>> On Wed, Aug 3, 2022 at 9:08 AM Bob Spidell<br>
>> <<a href="mailto:bspidell@comcast.net" target="_blank">bspidell@comcast.net</a>> <mailto:<a href="mailto:bspidell@comcast.net" target="_blank">bspidell@comcast.net</a>> wrote:<br>
>><br>
>> I put one in my BJ8's O/D. It's subjective*--O/Ds<br>
>> seem to work a little<br>
>> quicker with cold, thick oil than hot oil--but it<br>
>> cuts maybe a third off<br>
>> engagement time on average. I had the O/D on the<br>
>> bench and disassembled,<br>
>> and the current one had a scored barrel so, why not?<br>
>> Engagement isn't<br>
>> much, if any, harsher than before which, I believe is<br>
>> the reason DMH<br>
>> wanted the weaker, smaller spring. If I'd known about<br>
>> it, I might have<br>
>> bought AHSpares' with an O-ring instead.<br>
>><br>
>> * I've never really 'timed' O/D functioning, it would<br>
>> be a bit awkward;<br>
>> anyone done it? I usually tap the clutch pedal when<br>
>> engaging O/D, and<br>
>> give a little throttle when disengaging. I thought<br>
>> mine engaged a little<br>
>> quicker when I switched to synthetic fluid from<br>
>> 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<br>
>> piston? If so, is it<br>
>> > worth the trouble ?<br>
>> ><br>
>> > Joe<br>
>> > BN1 #923<br>
>> ><br>
>><br>
>><br>
><br>
><br>
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</blockquote></div>