[Healeys] DW overdrive piston
Michael MacLean
springer.mike51 at gmail.com
Sat Aug 6 02:03:23 MDT 2022
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.
Mike MacLean
On Fri, Aug 5, 2022 at 9:31 PM ahbn6--- via Healeys <healeys at autox.team.net>
wrote:
> Look at the Moss catalogue. They are listed there. I had them om my bn6
> (which had a tranny out of a BJ8))
>
> John Sims
> www.healey6.com
> Matawan, NJ
>
> -----Original Message-----
> From: Healeys <healeys-bounces at autox.team.net> On Behalf Of Bob Haskell
> Sent: Thursday, August 4, 2022 5:28 PM
> To: Bob Spidell <bspidell at comcast.net>; Michael Salter <
> michaelsalter at gmail.com>; Warren Dietz <flyhihealey at gmail.com>
> Cc: healeys at autox.team.net
> Subject: Re: [Healeys] DW overdrive piston
>
> Might be something here that would work:
> https://www.lislecorp.com/oem-products-division/magnetic-plugs/pipe-thread/
>
> Cheers,
>
> Bob Haskell
> Austin Healey 3000 BN7/BT7 registrar
>
> On 8/4/22 1:12 PM, Bob Spidell wrote:
> > OK, who sells magnetic plugs for MOWOG gearboxes? I'd be willing to
> > order from Canada ;)
> >
> > I don't remember exactly when I started using MT-90 in my gearbox, but
> > it was probably around 90-100K miles. I was hoping it would make the
> > O/D a bit more responsive, but was surprised that shifting seemed
> > smoother (I wasn't expecting it, so little-no confirmation bias).
> >
> >
> > On 8/4/2022 9:38 AM, Michael Salter wrote:
> >> Based upon my observations when the aluminium overdrive accumulator
> >> housings are scored you will invariably find that there are chips out
> >> of the non syncro 1st and reverse gears and usually badly damaged
> >> laygear rollers.
> >> Because these gearboxes were not fitted with chip gathering magnet
> >> originally the tiny hardened steel chips eventually find their way
> >> into the overdrive then through the overdrive pump gauze (because the
> >> magnets originally fitted in the overdrive have been lost by " the
> >> lube guy") and lodge in the accumulator.
> >> Those chips very quickly score the cylinder as the accumulator piston
> >> moves.
> >> If you are careful to never grind 1st or reverse no chips will be
> >> created, that will mean that they don't go through the laygear
> >> bearings or find their way into the overdrive.
> >> A magnetic plug in the gearbox is great insurance.
> >>
> >> M
> >>
> >> On Thu., Aug. 4, 2022, 12:13 p.m. Warren Dietz,
> >> <flyhihealey at gmail.com> wrote:
> >>
> >> Bob,
> >>
> >> Interesting observation.
> >>
> >> Only 30/40 wt non detergent oil was used from new till 2013 at
> >> which time I switched
> >>
> >> to Redline MT90 @ 181,000 miles.
> >>
> >> Sent from Mail <https://go.microsoft.com/fwlink/?LinkId=550986>
> >> for Windows
> >>
> >> *From: *Bob Spidell <mailto:bspidell at comcast.net>
> >> *Sent: *Thursday, August 4, 2022 9:38 AM
> >> *To: *Warren Dietz <mailto:flyhihealey at gmail.com>;
> >> healeys at autox.team.net
> >> *Subject: *Re: [Healeys] DW overdrive piston
> >>
> >> Warren,
> >>
> >> 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?
> >>
> >>
> >>
> >> Sent from Mail
> >> <https://go.microsoft.com/fwlink/?LinkId=550986> for Windows
> >>
> >> This was the condition of my piston and housing with close to
> >> 200,000 miles. Tranny was well maintained.
> >>
> >> The original metal rings lasted 53 years. So I guess with
> >> unknown quality of either of todays metal vs rubber
> >>
> >> O rings, let the experiments begin.
> >>
> >> *From: *Bob Spidell <mailto:bspidell at comcast.net>
> >> *Sent: *Wednesday, August 3, 2022 10:12 PM
> >> *To: *healeys at autox.team.net
> >> *Subject: *Re: [Healeys] DW overdrive piston
> >>
> >> 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.
> >>
> >> I donated this accumulator to another owner; never heard how
> >> they worked. Moss shows the rings available (but who knows?).
> >>
> >> On 8/3/2022 12:36 PM, Henry G Leach via Healeys wrote:
> >>
> >> I assemble ODs using the original metal rings and have
> >> not had any issues with pressure or
> >> engagement/disengagement.
> >>
> >> 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.
> >>
> >> 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
> >>
> >> -----------------------------------------
> >>
> >> From: "Michael Salter"
> >> To: "healeys at autox.team.net" <mailto:healeys at autox.team.net
> >
> >> Cc:
> >> Sent: Wednesday August 3 2022 9:38:15AM
> >> Subject: Re: [Healeys] DW overdrive piston
> >>
> >> I have a question about the "O" ring type of accumulator.
> >>
> >> 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.
> >>
> >> 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.
> >>
> >> I'm guessing that Laycock-DeNormanville used the complex
> >> cast iron rings rather than "O" rings because they
> >> recognized the possibility of this happening.
> >>
> >> 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?
> >>
> >> M
> >>
> >> On Wed, Aug 3, 2022 at 9:08 AM Bob Spidell
> >> <bspidell at comcast.net> <mailto:bspidell at comcast.net> wrote:
> >>
> >> I put one in my BJ8's O/D. It's subjective*--O/Ds
> >> seem to work a little
> >> quicker with cold, thick oil than hot oil--but it
> >> cuts maybe a third off
> >> engagement time on average. I had the O/D on the
> >> bench and disassembled,
> >> and the current one had a scored barrel so, why not?
> >> Engagement isn't
> >> much, if any, harsher than before which, I believe is
> >> the reason DMH
> >> wanted the weaker, smaller spring. If I'd known about
> >> it, I might have
> >> bought AHSpares' with an O-ring instead.
> >>
> >> * I've never really 'timed' O/D functioning, it would
> >> be a bit awkward;
> >> anyone done it? I usually tap the clutch pedal when
> >> engaging O/D, and
> >> give a little throttle when disengaging. I thought
> >> mine engaged a little
> >> quicker when I switched to synthetic fluid from
> >> engine oil, but in all
> >> cases confirmation bias may be involved.
> >>
> >>
> >>
> >> On 8/2/2022 8:09 PM, Joseph Costa wrote:
> >> > Has anyone installed their upgraded overdrive
> >> piston? If so, is it
> >> > worth the trouble ?
> >> >
> >> > Joe
> >> > BN1 #923
> >> >
> >>
> >>
> >
> >
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