Subject: Re: [Healeys] Laycock overdrive

From: Bob Spidell via Healeys <[email-masked]>
Date: Sat, 12 Aug 2023 12:18:02 -0700

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I think the fact Laycock went from steel rings on the operating pistons 
to O-rings is telling. Both will wear, but the steel rings will score 
the cylinder.

On 8/12/2023 9:40 AM, Hank Leach wrote:
> Bob-good point.  I just got a set of springs from Moss (from OD Spares 
> in UK, I imagine). The cost was $99 or about $12/spring which in the 
> scope of things is really not relevant. Holding that clutch in tight 
> contact to the brake ring is paramount and just imagine the number of 
> miles in direct drive that the car has experienced...many at high RPM. 
> The other side of the brake for overdrive position is the "lazy side" 
> as the operating pistons under hydraulic pressure have plenty of clout 
> driving mostly steady RPMs. Yes, springs wear out.
>
> I place them on the bench and line up the lengths. They should measure 
> 4-1/2" for the long springs and 4-1/4" for the short ones but 
> invariably there is differences in the resting length. After 50+ years 
> of pushing you would tend to get tired. When in overdrive, the springs 
> are greatly depressed.  That is asking a lot for spiral metal to 
> accomplish. So, yes they may look good, but have poor stamina-oops, I 
> just describe all of us. Hank
>
> -----------------------------------------
>
> From: "Bob Spidell"
> To: [email-masked]
> Cc:
> Sent: Friday August 11 2023 9:19:34PM
> Subject: Re: [Healeys] Laycock overdrive
>
> re: "... The health of the 8 springs that keep the unit in direct drive
> is important to keep the clutch from slipping...."
>
> I believe the shop manual admonishes owners to replace these when
> overhauling the unit, even if the old ones look and feel fine (some say
> not so). I think my old ones are in a box on a shelf somewhere if
> anybody wants them.
>
> Note the O/D pump is a positive displacement pump that will continue to
> produce pressure--driven by the full power of the engine--unless there
> is a pressure relief mechanism.
>
>
> On 8/11/2023 10:34 AM, Hank Leach via Healeys wrote:
> > Guys-this is a very lively topic and one of sometimes great mystery
> > and confusion.  The unit is complex but the end result is working well
> > or not functioning at all.
> >
> > On the subject of pressure required to operate the shift into
> > overdrive there are many schools of thought. Some people replace or
> > stretch springs or add washers to increase the pressure needed. The
> > health of the 8 springs that keep the unit in direct drive is
> > important to keep the clutch from slipping.  The pressure supplied to
> > overcome the strength of these 8 spring , and effect overdrive, relies
> > on adequate hydraulic pressure. The change from direct to overdrive
> > needs to be smooth, not harsh, and if pressures are high the unit will
> > snap into and out of OD rather than the smooth interchange we are used
> > to while driving.
> >
> > When applied to the Austin Healey 100, the Laycock overdrive was
> > initially a 32% reduction unit. It was soon found out in these early
> > Warwick cars that 32% was too much reduction.  DHMC swapped units
> > three times in the original DMH tour car until they finally found a
> > combination that produced the smooth shift and complimentary gearing
> > desired.
> >
> > It is difficult, today, to find any information on this original 32%
> > gearbox, however if you examine the booklet (attached) supplied by
> > Laycock for the early cars, you will notice that the casting allowed
> > for a large accumulator piston (seen on p6 in brochure). After some
> > research and modified engineering, the company came up with this alloy
> > "sleeve" called the piston housing (photo) which partially filled the
> > chamber of the original large accumulator casting and allowed for a
> > smaller accumulator piston that we see in all the later 28% reduction
> > units. That size piston, in proper condition, produced from 350-450
> > lbs of needed hydraulic pressure to overcome the springs influence.
> >
> > I'm confident that the remark made by Geoff Healey in his writings
> > about the early transmissions "harsh shifting" revolved around this
> > huge accumulator piston producing too much pressure. Additionally,
> > there were three various accumulator springs supplied which adjusted
> > the pressure. The early boxes produced about 350lbs and the later
> > about 450.
> >
> > Today, Overdrive Spares supplies that sleeve housing with only one
> > rubber O-ring as it is basically a filler part and not under extreme
> > pressure. The accumulator piston within is under that pressure. They
> > supply a modified piston using O-ring technology. So, it is not
> > unusual to get good pressures over the normal 450 lbs required. If it
> > works well don't fix it.  The only concern is if the pressure does not
> > release when overdrive is not called for. A clean unit, with proper
> > 30W oil, will allow that to happen. All this some old theory and
> > history to ponder. Hank

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    I think the fact Laycock went from steel rings on the operating
    pistons to O-rings is telling. Both will wear, but the steel rings
    will score the cylinder.<br>
    <br>
    <br>
    <div class="moz-cite-prefix">On 8/12/2023 9:40 AM, Hank Leach wrote:<br>
    </div>
    <blockquote type="cite"
      cite="mid:c02183110a608b1b7fa676318c90572c41f2fd02@webmail">
      <meta http-equiv="content-type" content="text/html; charset=UTF-8">
      Bob-good point.  I just got a set of springs from Moss (from OD
      Spares in UK, I imagine). The cost was $99 or about $12/spring
      which in the scope of things is really not relevant. Holding that
      clutch in tight contact to the brake ring is paramount and just
      imagine the number of miles in direct drive that the car has
      experienced...many at high RPM. The other side of the brake for
      overdrive position is the "lazy side" as the operating pistons
      under hydraulic pressure have plenty of clout driving mostly
      steady RPMs. Yes, springs wear out.
      <div><br>
      </div>
      <div>I place them on the bench and line up the lengths. They
        should measure 4-1/2" for the long springs and 4-1/4" for the
        short ones but invariably there is differences in the resting
        length. After 50+ years of pushing you would tend to get tired.
        When in overdrive, the springs are greatly depressed.  That is
        asking a lot for spiral metal to accomplish. So, yes they may
        look good, but have poor stamina-oops, I just describe all of
        us. Hank<br>
        <br>
        <p>-----------------------------------------</p>
        From: "Bob Spidell" <[email-masked]><br>
          To: <a class="moz-txt-link-abbreviated" href="mailto:[email-masked]">[email-masked]</a><br>
          Cc: <br>
          Sent: Friday August 11 2023 9:19:34PM<br>
          Subject: Re: [Healeys] Laycock overdrive<br>
          <br>
          re: "... The health of the 8 springs that keep the unit in
          direct
          drive<br>
          is important to keep the clutch from slipping...."<br>
          <br>
          I believe the shop manual admonishes owners to replace these
          when<br>
          overhauling the unit, even if the old ones look and feel fine
          (some
          say<br>
          not so). I think my old ones are in a box on a shelf somewhere
          if<br>
          anybody wants them.<br>
          <br>
          Note the O/D pump is a positive displacement pump that will
          continue to<br>
          produce pressure--driven by the full power of the
          engine--unless
          there<br>
          is a pressure relief mechanism.<br>
          <br>
          <br>
          On 8/11/2023 10:34 AM, Hank Leach via Healeys wrote:<br>
          &gt; Guys-this is a very lively topic and one of sometimes
          great
          mystery<br>
          &gt; and confusion.  The unit is complex but the end result is
          working well<br>
          &gt; or not functioning at all.<br>
          &gt;<br>
          &gt; On the subject of pressure required to operate the shift
          into<br>
          &gt; overdrive there are many schools of thought. Some people
          replace or<br>
          &gt; stretch springs or add washers to increase the pressure
          needed. The<br>
          &gt; health of the 8 springs that keep the unit in direct
          drive
          is<br>
          &gt; important to keep the clutch from slipping.  The pressure
          supplied to<br>
          &gt; overcome the strength of these 8 spring , and effect
          overdrive, relies<br>
          &gt; on adequate hydraulic pressure. The change from direct to
          overdrive<br>
          &gt; needs to be smooth, not harsh, and if pressures are high
          the
          unit will<br>
          &gt; snap into and out of OD rather than the smooth
          interchange we
          are used<br>
          &gt; to while driving.<br>
          &gt;<br>
          &gt; When applied to the Austin Healey 100, the Laycock
          overdrive
          was<br>
          &gt; initially a 32% reduction unit. It was soon found out in
          these
          early<br>
          &gt; Warwick cars that 32% was too much reduction.  DHMC
          swapped units<br>
          &gt; three times in the original DMH tour car until they
          finally
          found a<br>
          &gt; combination that produced the smooth shift and
          complimentary
          gearing<br>
          &gt; desired.<br>
          &gt;<br>
          &gt; It is difficult, today, to find any information on this
          original 32%<br>
          &gt; gearbox, however if you examine the booklet (attached)
          supplied by<br>
          &gt; Laycock for the early cars, you will notice that the
          casting
          allowed<br>
          &gt; for a large accumulator piston (seen on p6 in brochure).
          After
          some<br>
          &gt; research and modified engineering, the company came up
          with
          this alloy<br>
          &gt; "sleeve" called the piston housing (photo) which
          partially
          filled the<br>
          &gt; chamber of the original large accumulator casting and
          allowed
          for a<br>
          &gt; smaller accumulator piston that we see in all the later
          28%
          reduction<br>
          &gt; units. That size piston, in proper condition, produced
          from
          350-450<br>
          &gt; lbs of needed hydraulic pressure to overcome the springs
          influence.<br>
          &gt;<br>
          &gt; I'm confident that the remark made by Geoff Healey in his
          writings<br>
          &gt; about the early transmissions "harsh shifting" revolved
          around
          this<br>
          &gt; huge accumulator piston producing too much pressure.
          Additionally,<br>
          &gt; there were three various accumulator springs supplied
          which
          adjusted<br>
          &gt; the pressure. The early boxes produced about 350lbs and
          the
          later<br>
          &gt; about 450.<br>
          &gt;<br>
          &gt; Today, Overdrive Spares supplies that sleeve housing with
          only
          one<br>
          &gt; rubber O-ring as it is basically a filler part and not
          under
          extreme<br>
          &gt; pressure. The accumulator piston within is under that
          pressure. They<br>
          &gt; supply a modified piston using O-ring technology. So, it
          is
          not<br>
          &gt; unusual to get good pressures over the normal 450 lbs
          required. If it<br>
          &gt; works well don't fix it.  The only concern is if the
          pressure does not<br>
          &gt; release when overdrive is not called for. A clean unit,
          with
          proper<br>
          &gt; 30W oil, will allow that to happen. All this some old
          theory
          and<br>
          &gt; history to ponder. Hank</[email-masked]><br>
      </div>
    </blockquote>
    <br>
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_______________________________________________

Archive: http://www.team.net/pipermail/healeys http://autox.team.net/archive/healeys

[email-masked]
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From: Michael Salter <[email-masked]>
Date: Sun, 13 Aug 2023 11:52:04 -0400

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Re: "Yes, springs wear out."
Correctly designed, manufactured and installed springs don't wear out.
Very occasionally they will suffer from fatigue cracking but that is rare
and a function of poor design.
Think valve springs or distributor point springs; millions and millions of
cycles and still as good as the day they were installed.

M

On Sat., Aug. 12, 2023, 2:25 p.m. Hank Leach via Healeys, <
[email-masked]> wrote:

> Bob-good point.  I just got a set of springs from Moss (from OD Spares in
> UK, I imagine). The cost was $99 or about $12/spring which in the scope of
> things is really not relevant. Holding that clutch in tight contact to the
> brake ring is paramount and just imagine the number of miles in direct
> drive that the car has experienced...many at high RPM. The other side of
> the brake for overdrive position is the "lazy side" as the operating
> pistons under hydraulic pressure have plenty of clout driving mostly steady
> RPMs. Yes, springs wear out.
>
> 4-1/2" for the long springs and 4-1/4" for the short ones but invariably
> there is differences in the resting length. After 50+ years of pushing you
> would tend to get tired. When in overdrive, the springs are greatly
> depressed.  That is asking a lot for spiral metal to accomplish. So, yes
> they may look good, but have poor stamina-oops, I just describe all of us.
> Hank
>
> Support Team.Net http://www.team.net/donate.html
> /> Suggested annual donation $12.75
>
> Archive: <http://www.team.net/donate.html%3Cbr>
> http://www.team.net/pipermail/healeys
> http://autox.team.net/archive/healeys
> />
> [email-masked]
> <http://autox.team.net/archive/healeys%3Cbr>
> />
> Unsubscribe/Manage: <http://autox.team.net/mailman/listinfo/healeys%3Cbr>
> http://autox.team.net/mailman/options/healeys/[email-masked]
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> Support Team.Net http://www.team.net/donate.html
> Suggested annual donation  $12.75
>
> Unsubscribe/Manage:
> http://autox.team.net/mailman/options/healeys/[email-masked]
>
>

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<div dir=3D"auto">Re: &quot;Yes, springs wear out.&quot;<div dir=3D"auto">C=
orrectly designed, manufactured and installed springs don&#39;t wear out.</=
div><div dir=3D"auto">Very occasionally they will suffer from fatigue crack=
ing but that is rare and a function of poor design.</div><div dir=3D"auto">=
Think valve springs or distributor point springs; millions and millions of =
cycles and still as good as the day they were installed.</div><div dir=3D"a=
uto"><br></div><div dir=3D"auto">M<br><div dir=3D"auto"><br style=3D"font-s=
ize:12.8px"></div></div></div><br><div class=3D"gmail_quote"><div dir=3D"lt=
r" class=3D"gmail_attr">On Sat., Aug. 12, 2023, 2:25 p.m. Hank Leach via He=
aleys, &lt;<a href=3D"mailto:[email-masked]">[email-masked]=
</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:=
0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex"><div>Bob-good point=
.=C2=A0 I just got a set of springs from Moss (from OD Spares in UK, I imag=
ine). The cost was $99 or about $12/spring which in the scope of things is =
really not relevant. Holding that clutch in tight contact to the brake ring=
 is paramount and just imagine the number of miles in direct drive that the=
 car has experienced...many at high RPM. The other side of the brake for ov=
erdrive position is the &quot;lazy side&quot; as the operating pistons unde=
r hydraulic pressure have plenty of clout driving mostly steady RPMs. Yes, =
springs wear out.<div><br></div><div>I place them on the bench and line up =
the lengths. They should measure 4-1/2&quot; for the long springs and 4-1/4=
&quot; for the short ones but invariably there is differences in the restin=
g length. After 50+ years of pushing you would tend to get tired. When in o=
verdrive, the springs are greatly depressed.=C2=A0 That is asking a lot for=
 spiral metal to accomplish. So, yes they may look good, but have poor stam=
ina-oops, I just describe all of us. Hank<br><br><div></div><p>------------=
-----------------------------</p>From: &quot;Bob Spidell&quot; <u></u><br>T=
o: <a href=3D"mailto:[email-masked]" target=3D"_blank" rel=3D"noref=
errer">[email-masked]</a><br>Cc: <br>Sent: Friday August 11 2023 9:=
19:34PM<br>Subject: Re: [Healeys] Laycock overdrive<br><br>
re: &quot;... The health of the 8 springs that keep the unit in direct
drive<br>
is important to keep the clutch from slipping....&quot;<br><br>
I believe the shop manual admonishes owners to replace these
when<br>
overhauling the unit, even if the old ones look and feel fine (some
say<br>
not so). I think my old ones are in a box on a shelf somewhere
if<br>
anybody wants them.<br><br>
Note the O/D pump is a positive displacement pump that will
continue to<br>
produce pressure--driven by the full power of the engine--unless
there<br>
is a pressure relief mechanism.<br><br><br>
On 8/11/2023 10:34 AM, Hank Leach via Healeys wrote:<br>
&gt; Guys-this is a very lively topic and one of sometimes great
mystery<br>
&gt; and confusion.=C2=A0 The unit is complex but the end result is
working well<br>
&gt; or not functioning at all.<br>
&gt;<br>
&gt; On the subject of pressure required to operate the shift
into<br>
&gt; overdrive there are many schools of thought. Some people
replace or<br>
&gt; stretch springs or add washers to increase the pressure
needed. The<br>
&gt; health of the 8 springs that keep the unit in direct drive
is<br>
&gt; important to keep the clutch from slipping.=C2=A0 The pressure
supplied to<br>
&gt; overcome the strength of these 8 spring , and effect
overdrive, relies<br>
&gt; on adequate hydraulic pressure. The change from direct to
overdrive<br>
&gt; needs to be smooth, not harsh, and if pressures are high the
unit will<br>
&gt; snap into and out of OD rather than the smooth interchange we
are used<br>
&gt; to while driving.<br>
&gt;<br>
&gt; When applied to the Austin Healey 100, the Laycock overdrive
was<br>
&gt; initially a 32% reduction unit. It was soon found out in these
early<br>
&gt; Warwick cars that 32% was too much reduction.=C2=A0 DHMC
swapped units<br>
&gt; three times in the original DMH tour car until they finally
found a<br>
&gt; combination that produced the smooth shift and complimentary
gearing<br>
&gt; desired.<br>
&gt;<br>
&gt; It is difficult, today, to find any information on this
original 32%<br>
&gt; gearbox, however if you examine the booklet (attached)
supplied by<br>
&gt; Laycock for the early cars, you will notice that the casting
allowed<br>
&gt; for a large accumulator piston (seen on p6 in brochure). After
some<br>
&gt; research and modified engineering, the company came up with
this alloy<br>
&gt; &quot;sleeve&quot; called the piston housing (photo) which partially
filled the<br>
&gt; chamber of the original large accumulator casting and allowed
for a<br>
&gt; smaller accumulator piston that we see in all the later 28%
reduction<br>
&gt; units. That size piston, in proper condition, produced from
350-450<br>
&gt; lbs of needed hydraulic pressure to overcome the springs
influence.<br>
&gt;<br>
&gt; I&#39;m confident that the remark made by Geoff Healey in his
writings<br>
&gt; about the early transmissions &quot;harsh shifting&quot; revolved arou=
nd
this<br>
&gt; huge accumulator piston producing too much pressure.
Additionally,<br>
&gt; there were three various accumulator springs supplied which
adjusted<br>
&gt; the pressure. The early boxes produced about 350lbs and the
later<br>
&gt; about 450.<br>
&gt;<br>
&gt; Today, Overdrive Spares supplies that sleeve housing with only
one<br>
&gt; rubber O-ring as it is basically a filler part and not under
extreme<br>
&gt; pressure. The accumulator piston within is under that
pressure. They<br>
&gt; supply a modified piston using O-ring technology. So, it is
not<br>
&gt; unusual to get good pressures over the normal 450 lbs
required. If it<br>
&gt; works well don&#39;t fix it.=C2=A0 The only concern is if the
pressure does not<br>
&gt; release when overdrive is not called for. A clean unit, with
proper<br>
&gt; 30W oil, will allow that to happen. All this some old theory
and<br>
&gt; history to ponder. Hank<br>
&gt;<br><br>
_______________________________________________<br>
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[email-masked]

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From: Michael Salter <[email-masked]>
Date: Sun, 13 Aug 2023 12:45:35 -0400

--===============5683149501904393221==

--0000000000007bfe920602d0ada6

Re: I think the fact Laycock went from steel rings on the operating pistons
to O-rings is telling.
I would think that that was a cost cutting measure.

On Sat., Aug. 12, 2023, 7:34 p.m. Bob Spidell via Healeys, <
[email-masked]> wrote:

> I think the fact Laycock went from steel rings on the operating pistons to
> O-rings is telling. Both will wear, but the steel rings will score the
> cylinder.
>
>

--0000000000007bfe920602d0ada6
Content-Transfer-Encoding: quoted-printable

<div dir=3D"auto"><div>Re: <span style=3D"font-size:12.8px">I think the fac=
t Laycock went from steel rings on the operating pistons to O-rings is tell=
ing.=C2=A0</span></div><div dir=3D"auto">I would think that that was a cost=
 cutting measure.=C2=A0<span style=3D"font-size:12.8px"><br></span></div><d=
iv dir=3D"auto"><span style=3D"font-size:12.8px"><br></span></div><div dir=
=3D"auto"><span style=3D"font-size:12.8px"><br></span><br><div class=3D"gma=
il_quote" dir=3D"auto"><div dir=3D"ltr" class=3D"gmail_attr">On Sat., Aug. =
12, 2023, 7:34 p.m. Bob Spidell via Healeys, &lt;<a href=3D"mailto:healeys@=
autox.team.net" target=3D"_blank" rel=3D"noreferrer">[email-masked]=
</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"margin:=
0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
 =20
   =20
 =20
  <div>
    I think the fact Laycock went from steel rings on the operating
    pistons to O-rings is telling. Both will wear, but the steel rings
    will score the cylinder.<br>
    <br>
    <br>
    <div>On 8/12/2023 9:40 AM, Hank Leach wrote:<br>
    </div>
    <blockquote type=3D"cite">
     =20
      Bob-good point.=C2=A0 I just got a set of springs from Moss (from OD
      Spares in UK, I imagine). The cost was $99 or about $12/spring
      which in the scope of things is really not relevant. Holding that
      clutch in tight contact to the brake ring is paramount and just
      imagine the number of miles in direct drive that the car has
      experienced...many at high RPM. The other side of the brake for
      overdrive position is the &quot;lazy side&quot; as the operating pist=
ons
      under hydraulic pressure have plenty of clout driving mostly
      steady RPMs. Yes, springs wear out.
      <div><br>
      </div>
      <div>I place them on the bench and line up the lengths. They
        should measure 4-1/2&quot; for the long springs and 4-1/4&quot; for=
 the
        short ones but invariably there is differences in the resting
        length. After 50+ years of pushing you would tend to get tired.
        When in overdrive, the springs are greatly depressed.=C2=A0 That is
        asking a lot for spiral metal to accomplish. So, yes they may
        look good, but have poor stamina-oops, I just describe all of
        us. Hank<br>
        <br>
        <p>-----------------------------------------</p>
        From: &quot;Bob Spidell&quot; <u></u><br>
          To: <a href=3D"mailto:[email-masked]" rel=3D"noreferrer n=
oreferrer" target=3D"_blank">[email-masked]</a><br>
          Cc: <br>
          Sent: Friday August 11 2023 9:19:34PM<br>
          Subject: Re: [Healeys] Laycock overdrive<br>
          <br>
          re: &quot;... The health of the 8 springs that keep the unit in
          direct
          drive<br>
          is important to keep the clutch from slipping....&quot;<br>
          <br>
          I believe the shop manual admonishes owners to replace these
          when<br>
          overhauling the unit, even if the old ones look and feel fine
          (some
          say<br>
          not so). I think my old ones are in a box on a shelf somewhere
          if<br>
          anybody wants them.<br>
          <br>
          Note the O/D pump is a positive displacement pump that will
          continue to<br>
          produce pressure--driven by the full power of the
          engine--unless
          there<br>
          is a pressure relief mechanism.<br>
          <br>
          <br>
          On 8/11/2023 10:34 AM, Hank Leach via Healeys wrote:<br>
          &gt; Guys-this is a very lively topic and one of sometimes
          great
          mystery<br>
          &gt; and confusion.=C2=A0 The unit is complex but the end result =
is
          working well<br>
          &gt; or not functioning at all.<br>
          &gt;<br>
          &gt; On the subject of pressure required to operate the shift
          into<br>
          &gt; overdrive there are many schools of thought. Some people
          replace or<br>
          &gt; stretch springs or add washers to increase the pressure
          needed. The<br>
          &gt; health of the 8 springs that keep the unit in direct
          drive
          is<br>
          &gt; important to keep the clutch from slipping.=C2=A0 The pressu=
re
          supplied to<br>
          &gt; overcome the strength of these 8 spring , and effect
          overdrive, relies<br>
          &gt; on adequate hydraulic pressure. The change from direct to
          overdrive<br>
          &gt; needs to be smooth, not harsh, and if pressures are high
          the
          unit will<br>
          &gt; snap into and out of OD rather than the smooth
          interchange we
          are used<br>
          &gt; to while driving.<br>
          &gt;<br>
          &gt; When applied to the Austin Healey 100, the Laycock
          overdrive
          was<br>
          &gt; initially a 32% reduction unit. It was soon found out in
          these
          early<br>
          &gt; Warwick cars that 32% was too much reduction.=C2=A0 DHMC
          swapped units<br>
          &gt; three times in the original DMH tour car until they
          finally
          found a<br>
          &gt; combination that produced the smooth shift and
          complimentary
          gearing<br>
          &gt; desired.<br>
          &gt;<br>
          &gt; It is difficult, today, to find any information on this
          original 32%<br>
          &gt; gearbox, however if you examine the booklet (attached)
          supplied by<br>
          &gt; Laycock for the early cars, you will notice that the
          casting
          allowed<br>
          &gt; for a large accumulator piston (seen on p6 in brochure).
          After
          some<br>
          &gt; research and modified engineering, the company came up
          with
          this alloy<br>
          &gt; &quot;sleeve&quot; called the piston housing (photo) which
          partially
          filled the<br>
          &gt; chamber of the original large accumulator casting and
          allowed
          for a<br>
          &gt; smaller accumulator piston that we see in all the later
          28%
          reduction<br>
          &gt; units. That size piston, in proper condition, produced
          from
          350-450<br>
          &gt; lbs of needed hydraulic pressure to overcome the springs
          influence.<br>
          &gt;<br>
          &gt; I&#39;m confident that the remark made by Geoff Healey in hi=
s
          writings<br>
          &gt; about the early transmissions &quot;harsh shifting&quot; rev=
olved
          around
          this<br>
          &gt; huge accumulator piston producing too much pressure.
          Additionally,<br>
          &gt; there were three various accumulator springs supplied
          which
          adjusted<br>
          &gt; the pressure. The early boxes produced about 350lbs and
          the
          later<br>
          &gt; about 450.<br>
          &gt;<br>
          &gt; Today, Overdrive Spares supplies that sleeve housing with
          only
          one<br>
          &gt; rubber O-ring as it is basically a filler part and not
          under
          extreme<br>
          &gt; pressure. The accumulator piston within is under that
          pressure. They<br>
          &gt; supply a modified piston using O-ring technology. So, it
          is
          not<br>
          &gt; unusual to get good pressures over the normal 450 lbs
          required. If it<br>
          &gt; works well don&#39;t fix it.=C2=A0 The only concern is if th=
e
          pressure does not<br>
          &gt; release when overdrive is not called for. A clean unit,
          with
          proper<br>
          &gt; 30W oil, will allow that to happen. All this some old
          theory
          and<br>
          &gt; history to ponder. Hank<u></u><br>
      </div>
    </blockquote>
    <br>
  </div>

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<br>
</blockquote></div></div></div>

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[email-masked]

--===============5683149501904393221==--

---

From: Roger Grace <[email-masked]>
Date: Sun, 13 Aug 2023 10:03:21 -0700

--===============8336024655306788587==

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Yes totally agree that hi carbon spring steel does not age if not abused.
Having said that, it would be good practice to compare free lenghts against
a known good quality one

Found this on a spring manufacturers site.

*The first question is =E2=80=98could a spring last forever?=E2=80=99 and t=
he answer is
yes, it could do if*

   - *The operating stresses are not too high*
   - *The working temperature does not cause the spring to lose too much
   load*
   - *The environment does not cause corrosion*
   - *The spring is not abused*
   - *The spring is well-made and free from imperfections.*

*If a spring meets the above requirements, yes it could potentially last
forever!*

rg

<http://www.avg.com/email-signature?utm_medium=3Demail&utm_source=3Dlink&ut=
m_campaign=3Dsig-email&utm_content=3Dwebmail>
Virus-free.www.avg.com
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On Sun, Aug 13, 2023 at 9:40=E2=80=AFAM Michael Salter <michaelsalter@gmail=
.com>
wrote:

> Think valve springs or distributor point springs; millions and millions o=
f
>> Bob-good point.  I just got a set of springs from Moss (from OD Spares i=
n
>> UK, I imagine). The cost was $99 or about $12/spring which in the scope =
of
>> things is really not relevant. Holding that clutch in tight contact to t=
he
>> pistons under hydraulic pressure have plenty of clout driving mostly ste=
ady
>> there is differences in the resting length. After 50+ years of pushing y=
ou
>> they may look good, but have poor stamina-oops, I just describe all of u=
s.
>> Unsubscribe/Manage: <http://autox.team.net/mailman/listinfo/healeys%3Cbr=
>
> http://autox.team.net/mailman/options/healeys/[email-masked]
>
>

--0000000000002053350602d0ed7c
Content-Transfer-Encoding: quoted-printable

<div dir=3D"ltr"><div>Yes totally agree that hi carbon spring steel does no=
t age if not abused. <br></div><div>Having said that, it would be good prac=
tice to compare free lenghts against a known good quality one<br></div><div=
><br></div><div>Found this on a spring manufacturers site.</div><div>
<p><i style=3D"font-family:comic sans ms,sans-serif">The first question is =
=E2=80=98could a spring last forever?=E2=80=99 and the answer is yes, it co=
uld do if</i></p><ul><li><i style=3D"font-family:comic sans ms,sans-serif">=
The operating stresses are not too high</i></li><li><i style=3D"font-family=
:comic sans ms,sans-serif">The working temperature does not cause the sprin=
g to lose too much load</i></li><li><i style=3D"font-family:comic sans ms,s=
ans-serif">The environment does not cause corrosion</i></li><li><i style=3D=
"font-family:comic sans ms,sans-serif">The spring is not abused</i></li><li=
><i style=3D"font-family:comic sans ms,sans-serif">The spring is well-made =
and free from imperfections.</i></li></ul><p><i style=3D"font-family:comic =
sans ms,sans-serif">If a spring meets the above requirements, yes it could =
potentially last forever!</i></p><p><font face=3D"arial,sans-serif">rg<br><=
/font></p>

</div></div><div id=3D"DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2"><br><table sty=
le=3D"border-top:1px solid #d3d4de"><tr><td style=3D"width:55px;padding-top=
:13px"><a href=3D"http://www.avg.com/email-signature?utm_medium=3Demail&amp=
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target=3D"_blank"><img src=3D"https://s-install.avcdn.net/ipm/preview/icons=
/icon-envelope-tick-green-avg-v1.png" alt=3D"" width=3D"46" height=3D"29" s=
tyle=3D"width: 46px; height: 29px;"></a></td><td style=3D"width:470px;paddi=
ng-top:12px;color:#41424e;font-size:13px;font-family:Arial,Helvetica,sans-s=
erif;line-height:18px">Virus-free.<a href=3D"http://www.avg.com/email-signa=
ture?utm_medium=3Demail&amp;utm_source=3Dlink&amp;utm_campaign=3Dsig-email&=
amp;utm_content=3Dwebmail" target=3D"_blank" style=3D"color:#4453ea">www.av=
g.com</a></td></tr></table><a href=3D"#DAB4FAD8-2DD7-40BB-A1B8-4E2AA1F9FDF2=
" width=3D"1" height=3D"1"></a></div><br><div class=3D"gmail_quote"><div di=
r=3D"ltr" class=3D"gmail_attr">On Sun, Aug 13, 2023 at 9:40=E2=80=AFAM Mich=
ael Salter &lt;<a href=3D"mailto:[email-masked]">michaelsalter@gma=
il.com</a>&gt; wrote:<br></div><blockquote class=3D"gmail_quote" style=3D"m=
argin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left=
:1ex"><div dir=3D"auto">Re: &quot;Yes, springs wear out.&quot;<div dir=3D"a=
uto">Correctly designed, manufactured and installed springs don&#39;t wear =
out.</div><div dir=3D"auto">Very occasionally they will suffer from fatigue=
 cracking but that is rare and a function of poor design.</div><div dir=3D"=
auto">Think valve springs or distributor point springs; millions and millio=
ns of cycles and still as good as the day they were installed.</div><div di=
r=3D"auto"><br></div><div dir=3D"auto">M<br><div dir=3D"auto"><br style=3D"=
font-size:12.8px"></div></div></div><br><div class=3D"gmail_quote"><div dir=
=3D"ltr" class=3D"gmail_attr">On Sat., Aug. 12, 2023, 2:25 p.m. Hank Leach =
via Healeys, &lt;<a href=3D"mailto:[email-masked]" target=3D"_blank=
">[email-masked]</a>&gt; wrote:<br></div><blockquote class=3D"gmail=
_quote" style=3D"margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204=
,204);padding-left:1ex"><div>Bob-good point.=C2=A0 I just got a set of spri=
ngs from Moss (from OD Spares in UK, I imagine). The cost was $99 or about =
$12/spring which in the scope of things is really not relevant. Holding tha=
t clutch in tight contact to the brake ring is paramount and just imagine t=
he number of miles in direct drive that the car has experienced...many at h=
igh RPM. The other side of the brake for overdrive position is the &quot;la=
zy side&quot; as the operating pistons under hydraulic pressure have plenty=
 of clout driving mostly steady RPMs. Yes, springs wear out.<div><br></div>=
<div>I place them on the bench and line up the lengths. They should measure=
 4-1/2&quot; for the long springs and 4-1/4&quot; for the short ones but in=
variably there is differences in the resting length. After 50+ years of pus=
hing you would tend to get tired. When in overdrive, the springs are greatl=
y depressed.=C2=A0 That is asking a lot for spiral metal to accomplish. So,=
 yes they may look good, but have poor stamina-oops, I just describe all of=
 us. Hank<br><br><div></div><p>-----------------------------------------</p=
>From: &quot;Bob Spidell&quot; <u></u><br>To: <a href=3D"mailto:healeys@aut=
ox.team.net" rel=3D"noreferrer" target=3D"_blank">[email-masked]</a=
><br>Cc: <br>Sent: Friday August 11 2023 9:19:34PM<br>Subject: Re: [Healeys=
] Laycock overdrive<br><br>
referrer" target=3D"_blank">http://www.team.net/donate.html<br>
Archive:</a> <a href=3D"http://www.team.net/pipermail/healeys" rel=3D"noref=
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=3D"_blank">http://autox.team.net/archive/healeys<br>
tinfo/healeys%3Cbr" rel=3D"noreferrer" target=3D"_blank">http://autox.team.=
aleys/[email-masked]%3Cbr" rel=3D"noreferrer" target=3D"_blank">http:/=

/&gt;<br></a>
<u></u></div></div>
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[email-masked]

--===============8336024655306788587==--

---

From: warthodson--- via Healeys <[email-masked]>
Date: Sun, 13 Aug 2023 18:01:15 +0000 (UTC)

--===============6211981028385350201==
	boundary="----=_Part_398731_796503292.1691949675383"

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 That was my thought, too.Gary
    On Sunday, August 13, 2023 at 12:32:36 PM CDT, Michael Salter <michaels=
[email-masked]> wrote: =20
=20
 Re: I think the fact Laycock went from steel rings on the operating piston=
s to O-rings is telling.=C2=A0I would think that that was a cost cutting me=
asure.=C2=A0

On Sat., Aug. 12, 2023, 7:34 p.m. Bob Spidell via Healeys, <[email-masked]=
eam.net> wrote:

  I think the fact Laycock went from steel rings on the operating pistons t=
o O-rings is telling. Both will wear, but the steel rings will score the cy=
linder.
=20
=20
 On 8/12/2023 9:40 AM, Hank Leach wrote:
 =20
 Bob-good point.=C2=A0 I just got a set of springs from Moss (from OD Spare=
s in UK, I imagine). The cost was $99 or about $12/spring which in the scop=
e of things is really not relevant. Holding that clutch in tight contact to=
 the brake ring is paramount and just imagine the number of miles in direct=
 drive that the car has experienced...many at high RPM. The other side of t=
he brake for overdrive position is the "lazy side" as the operating pistons=
 under hydraulic pressure have plenty of clout driving mostly steady RPMs. =
Yes, springs wear out.=20
  I place them on the bench and line up the lengths. They should measure 4-=
1/2" for the long springs and 4-1/4" for the short ones but invariably ther=
e is differences in the resting length. After 50+ years of pushing you woul=
d tend to get tired. When in overdrive, the springs are greatly depressed.=
=C2=A0 That is asking a lot for spiral metal to accomplish. So, yes they ma=
y look good, but have poor stamina-oops, I just describe all of us. Hank
=20
=20
-----------------------------------------
 From: "Bob Spidell"=20
 To: [email-masked]
 Cc:=20
 Sent: Friday August 11 2023 9:19:34PM
 Subject: Re: [Healeys] Laycock overdrive
=20
 re: "... The health of the 8 springs that keep the unit in direct drive
 is important to keep the clutch from slipping...."
=20
 I believe the shop manual admonishes owners to replace these when
 overhauling the unit, even if the old ones look and feel fine (some say
 not so). I think my old ones are in a box on a shelf somewhere if
 anybody wants them.
=20
 Note the O/D pump is a positive displacement pump that will continue to
 produce pressure--driven by the full power of the engine--unless there
 is a pressure relief mechanism.
=20
=20
 On 8/11/2023 10:34 AM, Hank Leach via Healeys wrote:
 > and confusion.=C2=A0 The unit is complex but the end result is working w=
ell
 > important to keep the clutch from slipping.=C2=A0 The pressure supplied =
to
 > Warwick cars that 32% was too much reduction.=C2=A0 DHMC swapped units
 > works well don't fix it.=C2=A0 The only concern is if the pressure does =
not
 =20
=20

Archive: http://www.team.net/pipermail/healeys http://autox.team.net/archiv=
e/healeys

[email-masked]

[email-masked]

Archive: http://www.team.net/pipermail/healeys http://autox.team.net/archiv=
e/healeys

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 =20
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Content-Transfer-Encoding: quoted-printable

<html><head></head><body><div class=3D"ydpe8a884a1yahoo-style-wrap" style=
=3D"font-family:Comic Sans MS, sans-serif;font-size:16px;"><div></div>
        <div dir=3D"ltr" data-setdir=3D"false">That was my thought, too.</d=
iv><div dir=3D"ltr" data-setdir=3D"false">Gary</div><div><br></div>
       =20
        </div><div id=3D"ydp6aa59758yahoo_quoted_2386916458" class=3D"ydp6a=
a59758yahoo_quoted">
            <div style=3D"font-family:'Helvetica Neue', Helvetica, Arial, s=
ans-serif;font-size:13px;color:#26282a;">
               =20
                <div>
                    On Sunday, August 13, 2023 at 12:32:36 PM CDT, Michael =
Salter &lt;[email-masked]&gt; wrote:
                </div>
                <div><br></div>
                <div><br></div>
                <div><div id=3D"ydp6aa59758yiv0041674271"><div><div><div>Re=
: <span style=3D"font-size:12.8px;">I think the fact Laycock went from stee=
l rings on the operating pistons to O-rings is telling.&nbsp;</span></div><=
div>I would think that that was a cost cutting measure.&nbsp;<span style=3D=
"font-size:12.8px;"><br clear=3D"none"></span></div><div><span style=3D"fon=
t-size:12.8px;"><br clear=3D"none"></span></div><div><span style=3D"font-si=
ze:12.8px;"><br clear=3D"none"></span><br clear=3D"none"><div class=3D"ydp6=
aa59758yiv0041674271gmail_quote"><div id=3D"ydp6aa59758yiv0041674271yqt0417=
3" class=3D"ydp6aa59758yiv0041674271yqt5338644676"><div dir=3D"ltr" class=
=3D"ydp6aa59758yiv0041674271gmail_attr">On Sat., Aug. 12, 2023, 7:34 p.m. B=
ob Spidell via Healeys, &lt;<a shape=3D"rect" href=3D"mailto:healeys@autox.=
team.net" rel=3D"nofollow" target=3D"_blank">[email-masked]</a>&gt;=
 wrote:<br clear=3D"none"></div><blockquote style=3D"margin:0 0 0 .8ex;bord=
er-left:1px #ccc solid;padding-left:1ex;" class=3D"ydp6aa59758yiv0041674271=
gmail_quote">
 =20
   =20
 =20
  <div>
    I think the fact Laycock went from steel rings on the operating
    pistons to O-rings is telling. Both will wear, but the steel rings
    will score the cylinder.<br clear=3D"none">
    <br clear=3D"none">
    <br clear=3D"none">
    <div>On 8/12/2023 9:40 AM, Hank Leach wrote:<br clear=3D"none">
    </div>
    <blockquote type=3D"cite">
     =20
      Bob-good point.&nbsp; I just got a set of springs from Moss (from OD
      Spares in UK, I imagine). The cost was $99 or about $12/spring
      which in the scope of things is really not relevant. Holding that
      clutch in tight contact to the brake ring is paramount and just
      imagine the number of miles in direct drive that the car has
      experienced...many at high RPM. The other side of the brake for
      overdrive position is the "lazy side" as the operating pistons
      under hydraulic pressure have plenty of clout driving mostly
      steady RPMs. Yes, springs wear out.
      <div><br clear=3D"none">
      </div>
      <div>I place them on the bench and line up the lengths. They
        should measure 4-1/2" for the long springs and 4-1/4" for the
        short ones but invariably there is differences in the resting
        length. After 50+ years of pushing you would tend to get tired.
        When in overdrive, the springs are greatly depressed.&nbsp; That is
        asking a lot for spiral metal to accomplish. So, yes they may
        look good, but have poor stamina-oops, I just describe all of
        us. Hank<br clear=3D"none">
        <br clear=3D"none">
        <p>-----------------------------------------</p>
        From: "Bob Spidell" <u></u><br clear=3D"none">
          To: <a shape=3D"rect" href=3D"mailto:[email-masked]" rel=
=3D"nofollow" target=3D"_blank">[email-masked]</a><br clear=3D"none=
">
          Cc: <br clear=3D"none">
          Sent: Friday August 11 2023 9:19:34PM<br clear=3D"none">
          Subject: Re: [Healeys] Laycock overdrive<br clear=3D"none">
          <br clear=3D"none">
          re: "... The health of the 8 springs that keep the unit in
          direct
          drive<br clear=3D"none">
          is important to keep the clutch from slipping...."<br clear=3D"no=
ne">
          <br clear=3D"none">
          I believe the shop manual admonishes owners to replace these
          when<br clear=3D"none">
          overhauling the unit, even if the old ones look and feel fine
          (some
          say<br clear=3D"none">
          not so). I think my old ones are in a box on a shelf somewhere
          if<br clear=3D"none">
          anybody wants them.<br clear=3D"none">
          <br clear=3D"none">
          Note the O/D pump is a positive displacement pump that will
          continue to<br clear=3D"none">
          produce pressure--driven by the full power of the
          engine--unless
          there<br clear=3D"none">
          is a pressure relief mechanism.<br clear=3D"none">
          <br clear=3D"none">
          <br clear=3D"none">
          On 8/11/2023 10:34 AM, Hank Leach via Healeys wrote:<br clear=3D"=
none">
          &gt; Guys-this is a very lively topic and one of sometimes
          great
          mystery<br clear=3D"none">
          &gt; and confusion.&nbsp; The unit is complex but the end result =
is
          working well<br clear=3D"none">
          &gt; or not functioning at all.<br clear=3D"none">
          &gt;<br clear=3D"none">
          &gt; On the subject of pressure required to operate the shift
          into<br clear=3D"none">
          &gt; overdrive there are many schools of thought. Some people
          replace or<br clear=3D"none">
          &gt; stretch springs or add washers to increase the pressure
          needed. The<br clear=3D"none">
          &gt; health of the 8 springs that keep the unit in direct
          drive
          is<br clear=3D"none">
          &gt; important to keep the clutch from slipping.&nbsp; The pressu=
re
          supplied to<br clear=3D"none">
          &gt; overcome the strength of these 8 spring , and effect
          overdrive, relies<br clear=3D"none">
          &gt; on adequate hydraulic pressure. The change from direct to
          overdrive<br clear=3D"none">
          &gt; needs to be smooth, not harsh, and if pressures are high
          the
          unit will<br clear=3D"none">
          &gt; snap into and out of OD rather than the smooth
          interchange we
          are used<br clear=3D"none">
          &gt; to while driving.<br clear=3D"none">
          &gt;<br clear=3D"none">
          &gt; When applied to the Austin Healey 100, the Laycock
          overdrive
          was<br clear=3D"none">
          &gt; initially a 32% reduction unit. It was soon found out in
          these
          early<br clear=3D"none">
          &gt; Warwick cars that 32% was too much reduction.&nbsp; DHMC
          swapped units<br clear=3D"none">
          &gt; three times in the original DMH tour car until they
          finally
          found a<br clear=3D"none">
          &gt; combination that produced the smooth shift and
          complimentary
          gearing<br clear=3D"none">
          &gt; desired.<br clear=3D"none">
          &gt;<br clear=3D"none">
          &gt; It is difficult, today, to find any information on this
          original 32%<br clear=3D"none">
          &gt; gearbox, however if you examine the booklet (attached)
          supplied by<br clear=3D"none">
          &gt; Laycock for the early cars, you will notice that the
          casting
          allowed<br clear=3D"none">
          &gt; for a large accumulator piston (seen on p6 in brochure).
          After
          some<br clear=3D"none">
          &gt; research and modified engineering, the company came up
          with
          this alloy<br clear=3D"none">
          &gt; "sleeve" called the piston housing (photo) which
          partially
          filled the<br clear=3D"none">
          &gt; chamber of the original large accumulator casting and
          allowed
          for a<br clear=3D"none">
          &gt; smaller accumulator piston that we see in all the later
          28%
          reduction<br clear=3D"none">
          &gt; units. That size piston, in proper condition, produced
          from
          350-450<br clear=3D"none">
          &gt; lbs of needed hydraulic pressure to overcome the springs
          influence.<br clear=3D"none">
          &gt;<br clear=3D"none">
          &gt; I'm confident that the remark made by Geoff Healey in his
          writings<br clear=3D"none">
          &gt; about the early transmissions "harsh shifting" revolved
          around
          this<br clear=3D"none">
          &gt; huge accumulator piston producing too much pressure.
          Additionally,<br clear=3D"none">
          &gt; there were three various accumulator springs supplied
          which
          adjusted<br clear=3D"none">
          &gt; the pressure. The early boxes produced about 350lbs and
          the
          later<br clear=3D"none">
          &gt; about 450.<br clear=3D"none">
          &gt;<br clear=3D"none">
          &gt; Today, Overdrive Spares supplies that sleeve housing with
          only
          one<br clear=3D"none">
          &gt; rubber O-ring as it is basically a filler part and not
          under
          extreme<br clear=3D"none">
          &gt; pressure. The accumulator piston within is under that
          pressure. They<br clear=3D"none">
          &gt; supply a modified piston using O-ring technology. So, it
          is
          not<br clear=3D"none">
          &gt; unusual to get good pressures over the normal 450 lbs
          required. If it<br clear=3D"none">
          &gt; works well don't fix it.&nbsp; The only concern is if the
          pressure does not<br clear=3D"none">
          &gt; release when overdrive is not called for. A clean unit,
          with
          proper<br clear=3D"none">
          &gt; 30W oil, will allow that to happen. All this some old
          theory
          and<br clear=3D"none">
          &gt; history to ponder. Hank<u></u><br clear=3D"none">
      </div>
    </blockquote>
    <br clear=3D"none">
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