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@autox.team.net> On Behalf Of Bob Haskell
Sent: Thursday, August 4, 2022 5:28 PM
To: Bob Spidell <bspidell@comcast.net>; Michael Salter
<michaelsalter@gmail.com>; Warren Dietz <flyhihealey@gmail.com>
Cc: healeys@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@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
>>
>> *Sent: *Thursday, August 4, 2022 9:38 AM
>> healeys@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.
>>
>> *Sent: *Wednesday, August 3, 2022 10:12 PM
>> *To: *healeys@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"
>> 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
>>
>> 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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