[Healeys] DW overdrive piston

Michael Salter michaelsalter at gmail.com
Wed Aug 3 10:20:03 MDT 2022


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> 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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