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Guys-my thought on that is agreeing with both of you and additionally=0A=
I think the procedure for replacing the steel rings is very delicate=0Aa=
nd wasteful; if not careful, the rings will shatter. Slipping on an=0Ao-=
ring is much easier and less abrasive to the soft alloy body.=0ATo me, t=
he biggest "cost cutting measure" was by making the alloy=0Asleeve for t=
he smaller accumulator piston, they salvaged many=0Aon-the-shelf early c=
astings and did not have to modify the future=0Amolding of them to make=
the piston area smaller. Only the Laycock=0Aengineers could explain it=
now...from the grave. =0AA couple of reasons to replace the 8 springs:=
they do not measure up,=0Aor if installed improperly, when previously r=
ebuilt, coil bound (bent)=0AHank=0A=0A=09-------------------------------=
----------From: "Michael Salter" =0ATo: "Bob Spidell"=0ACc: "Hank Leach"=
, "healeys@autox.team.net"=0ASent: Sunday August 13 2023 9:45:48AM=0ASub=
ject: Re: [Healeys] Laycock overdrive=0A=0A Re: I think the fact Laycoc=
k went from steel rings on the operating=0Apistons to O-rings is telling=
I would think that that was a cost=0Acutting measure. =0A=0A On Sat.,=
Aug. 12, 2023, 7:34 p.m. Bob Spidell via Healeys, wrote:=0A I think t=
he fact Laycock went from steel rings on the operating=0Apistons to O-ri=
ngs is telling. Both will wear, but the steel rings=0Awill score the cyl=
inder.=0A=0AOn 8/12/2023 9:40 AM, Hank Leach wrote:=0A Bob-good point. I=
just got a set of springs from Moss (from OD Spares=0Ain UK, I imagine)=
The cost was $99 or about $12/spring which in the=0Ascope of things is=
really not relevant. Holding that clutch in tight=0Acontact to the brak=
e ring is paramount and just imagine the number of=0Amiles in direct dri=
ve that the car has experienced...many at high RPM.=0AThe other side of=
the brake for overdrive position is the "lazy side"=0Aas the operating=
pistons under hydraulic pressure have plenty of clout=0Adriving mostly=
steady RPMs. Yes, springs wear out. =0A I place them on the bench and l=
ine up the lengths. They should=0Ameasure 4-1/2" for the long springs an=
d 4-1/4" for the short ones but=0Ainvariably there is differences in the=
resting length. After 50+ years=0Aof pushing you would tend to get tire=
d. When in overdrive, the springs=0Aare greatly depressed. That is askin=
g a lot for spiral metal to=0Aaccomplish. So, yes they may look good, bu=
t have poor stamina-oops, I=0Ajust describe all of us. Hank=0A=0A=09----=
------------------------------------- From: "Bob Spidell"=0A To: healeys=
@autox.team.net=0A Cc:=0A Sent: Friday August 11 2023 9:19:34PM=0A Subje=
ct: Re: [Healeys] Laycock overdrive=0A=0A re: "... The health of the 8 s=
prings that keep the unit in direct=0Adrive=0A is important to keep the=
clutch from slipping...."=0A=0A I believe the shop manual admonishes ow=
ners to replace these when=0A overhauling the unit, even if the old ones=
look and feel fine (some=0Asay=0A not so). I think my old ones are in a=
box on a shelf somewhere if=0A anybody wants them.=0A=0A Note the O/D p=
ump is a positive displacement pump that will continue=0Ato=0A produce p=
ressure--driven by the full power of the engine--unless=0Athere=0A is a=
pressure relief mechanism.=0A=0A On 8/11/2023 10:34 AM, Hank Leach via=
Healeys wrote:=0A > Guys-this is a very lively topic and one of sometim=
es great mystery=0A > and confusion. The unit is complex but the end res=
ult is working=0Awell=0A > or not functioning at all.=0A >=0A > On the s=
ubject of pressure required to operate the shift into=0A > overdrive the=
re are many schools of thought. Some people replace or=0A > stretch spri=
ngs or add washers to increase the pressure needed. The=0A > health of t=
he 8 springs that keep the unit in direct drive is=0A > important to kee=
p the clutch from slipping. The pressure supplied=0Ato=0A > overcome the=
strength of these 8 spring , and effect overdrive,=0Arelies=0A > on ade=
quate hydraulic pressure. The change from direct to overdrive=0A > needs=
to be smooth, not harsh, and if pressures are high the unit=0Awill=0A >=
snap into and out of OD rather than the smooth interchange we are=0Ause=
d=0A > to while driving.=0A >=0A > When applied to the Austin Healey 100=
, the Laycock overdrive was=0A > initially a 32% reduction unit. It was=
soon found out in these=0Aearly=0A > Warwick cars that 32% was too much=
reduction. DHMC swapped units=0A > three times in the original DMH tour=
car until they finally found a=0A > combination that produced the smoot=
h shift and complimentary=0Agearing=0A > desired.=0A >=0A > It is diffic=
ult, today, to find any information on this original=0A32%=0A > gearbox,=
however if you examine the booklet (attached) supplied by=0A > Laycock=
for the early cars, you will notice that the casting=0Aallowed=0A > for=
a large accumulator piston (seen on p6 in brochure). After some=0A > re=
search and modified engineering, the company came up with this=0Aalloy=
=0A > "sleeve" called the piston housing (photo) which partially filled=
=0Athe=0A > chamber of the original large accumulator casting and allowe=
d for a=0A > smaller accumulator piston that we see in all the later 28%=
=0Areduction=0A > units. That size piston, in proper condition, produced=
from 350-450=0A > lbs of needed hydraulic pressure to overcome the spri=
ngs influence.=0A >=0A > I'm confident that the remark made by Geoff Hea=
ley in his writings=0A > about the early transmissions "harsh shifting"=
revolved around this=0A > huge accumulator piston producing too much pr=
essure. Additionally,=0A > there were three various accumulator springs=
supplied which=0Aadjusted=0A > the pressure. The early boxes produced a=
bout 350lbs and the later=0A > about 450.=0A >=0A > Today, Overdrive Spa=
res supplies that sleeve housing with only one=0A > rubber O-ring as it=
is basically a filler part and not under=0Aextreme=0A > pressure. The a=
ccumulator piston within is under that pressure.=0AThey=0A > supply a mo=
dified piston using O-ring technology. So, it is not=0A > unusual to get=
good pressures over the normal 450 lbs required. If=0Ait=0A > works wel=
l don't fix it. The only concern is if the pressure does=0Anot=0A > rele=
ase when overdrive is not called for. A clean unit, with proper=0A > 30W=
oil, will allow that to happen. All this some old theory and=0A > histo=
ry to ponder. Hank=0A=0A _______________________________________________=
=0A Support Team.Net [1]http://www.team.net/donate.html [2]=0A Suggeste=
d annual donation $12.75=0A=0A Archive: [3]http://www.team.net/pipermai=
l/healeys [4] =0A[5]http://autox.team.net/archive/healeys [6]=0A=0AHeale=
ys@autox.team.net=0A [7]http://autox.team.net/mailman/listinfo/healeys [=
8]=0A=0A Unsubscribe/Manage: =0A[9]http://autox.team.net/mailman/options=
/healeys/michaelsalter@gmail.com=0A[10]=0A=0A =0A=0ALinks:=0A------=
=0A[1] http://www.team.net/donate.html=0A[2] http://www.team.net/donate.=
html=0A[3] http://www.team.net/pipermail/healeys=0A[4] http://www.team.n=
et/pipermail/healeys=0A[5] http://autox.team.net/archive/healeys=0A[6] h=
ttp://autox.team.net/archive/healeys=0A[7] http://autox.team.net/mailman=
/listinfo/healeys=0A[8] http://autox.team.net/mailman/listinfo/healeys=
=0A[9]=0Ahttp://autox.team.net/mailman/options/healeys/michaelsalter@gma=
il.com=0A[10]=0Ahttp://autox.team.net/mailman/options/healeys/michaelsal=
ter@gmail.com=0A
--=_58c0d00b408840181ad5a6fc891707d6
Content-Transfer-Encoding: quoted-printable
<html><body>Guys-my thought on that is agreeing with both of you and add=
itionally I think the procedure for replacing the steel rings is very de=
licate and wasteful; if not careful, the rings will shatter. Slipp=
ing on an o-ring is much easier and less abrasive to the soft alloy body=
<div><br></div><div>To me, the biggest "cost cutting measure" was by ma=
king the alloy sleeve for the smaller accumulator piston, they salvaged=
many on-the-shelf early castings and did not have to modify the future=
molding of them to make the piston area smaller. Only the Laycock engin=
eers could explain it now...from the grave. </div><div><br></div><d=
iv>A couple of reasons to replace the 8 springs: they do not measure up,=
or if installed improperly, when previously rebuilt, coil bound (bent)=
Hank<br><br><div class=3D"reply-new-signature"></div><p>---------------=
--------------------------</p>From: "Michael Salter" <michaelsalter@gmai=
l.com><br>To: "Bob Spidell"<br>Cc: "Hank Leach", "healeys@autox.team.net=
"<br>Sent: Sunday August 13 2023 9:45:48AM<br>Subject: Re: [Healeys] Lay=
cock overdrive<br><br>=0A<div>=0A<div>Re: <span style=3D"font-size:12.8p=
x;">I think the fact Laycock=0Awent from steel rings on the operating pi=
stons to O-rings is=0Atelling. </span></div>=0A<div>I would think t=
hat that was a cost cutting=0Ameasure. <span style=3D"font-size:12.=
8px;"><br></span></div>=0A<div><span style=3D"font-size:12.8px;"><br></s=
pan></div>=0A<div><span style=3D"font-size:12.8px;"><br></span><br><div=
class=3D"gmail_quote">=0A<div dir=3D"ltr" class=3D"gmail_attr">On Sat.,=
Aug. 12, 2023, 7:34 p.m.=0ABob Spidell via Healeys, <<a>healeys@auto=
x.team.net</a>> wrote:<br></div>=0A<blockquote class=3D"gmail_quote"=
style=3D"margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex;=
">=0A<div>I think the fact Laycock went from steel rings on the=0Aoperat=
ing pistons to O-rings is telling. Both will wear, but the=0Asteel rings=
will score the cylinder.<br><br><br><div>On 8/12/2023 9:40 AM, Hank Lea=
ch wrote:<br></div>=0A<blockquote>Bob-good point. I just got a set=
of=0Asprings from Moss (from OD Spares in UK, I imagine). The cost was=
=0A$99 or about $12/spring which in the scope of things is really not=0A=
relevant. Holding that clutch in tight contact to the brake ring is=0Apa=
ramount and just imagine the number of miles in direct drive that=0Athe=
car has experienced...many at high RPM. The other side of the=0Abrake f=
or overdrive position is the "lazy side" as the operating=0Apistons unde=
r hydraulic pressure have plenty of clout driving=0Amostly steady RPMs.=
Yes, springs wear out.=0A<div><br></div>=0A<div>I place them on the ben=
ch and line up the lengths. They should=0Ameasure 4-1/2" for the long sp=
rings and 4-1/4" for the short ones=0Abut invariably there is difference=
s in the resting length. After=0A50+ years of pushing you would tend to=
get tired. When in=0Aoverdrive, the springs are greatly depressed. =
; That is asking=0Aa lot for spiral metal to accomplish. So, yes they ma=
y look good,=0Abut have poor stamina-oops, I just describe all of us. Ha=
nk<br><br><p>-----------------------------------------</p>=0AFrom: "Bob=
Spidell"<br>=0ATo: <a>healeys@autox.team.net</a><br>=0ACc:<br>=0ASent:=
Friday August 11 2023 9:19:34PM<br>=0ASubject: Re: [Healeys] Laycock ov=
erdrive<br><br>=0Are: "... The health of the 8 springs that keep the uni=
t in direct=0Adrive<br>=0Ais important to keep the clutch from slipping.=
.."<br><br>=0AI believe the shop manual admonishes owners to replace th=
ese=0Awhen<br>=0Aoverhauling the unit, even if the old ones look and fee=
l fine (some=0Asay<br>=0Anot so). I think my old ones are in a box on a=
shelf somewhere=0Aif<br>=0Aanybody wants them.<br><br>=0ANote the O/D p=
ump is a positive displacement pump that will=0Acontinue to<br>=0Aproduc=
e pressure--driven by the full power of the engine--unless=0Athere<br>=
=0Ais a pressure relief mechanism.<br><br><br>=0AOn 8/11/2023 10:34 AM,=
Hank Leach via Healeys wrote:<br>=0A> Guys-this is a very lively top=
ic and one of sometimes great=0Amystery<br>=0A> and confusion. =
The unit is complex but the end result is=0Aworking well<br>=0A> or=
not functioning at all.<br>=0A><br>=0A> On the subject of pressur=
e required to operate the shift=0Ainto<br>=0A> overdrive there are ma=
ny schools of thought. Some people=0Areplace or<br>=0A> stretch sprin=
gs or add washers to increase the pressure=0Aneeded. The<br>=0A> heal=
th of the 8 springs that keep the unit in direct drive=0Ais<br>=0A> i=
mportant to keep the clutch from slipping. The pressure=0Asupplied=
to<br>=0A> overcome the strength of these 8 spring , and effect=0Aov=
erdrive, relies<br>=0A> on adequate hydraulic pressure. The change fr=
om direct to=0Aoverdrive<br>=0A> needs to be smooth, not harsh, and i=
f pressures are high the=0Aunit will<br>=0A> snap into and out of OD=
rather than the smooth interchange we=0Aare used<br>=0A> to while dr=
iving.<br>=0A><br>=0A> When applied to the Austin Healey 100, the=
Laycock overdrive=0Awas<br>=0A> initially a 32% reduction unit. It w=
as soon found out in these=0Aearly<br>=0A> Warwick cars that 32% was=
too much reduction. DHMC=0Aswapped units<br>=0A> three times i=
n the original DMH tour car until they finally=0Afound a<br>=0A> comb=
ination that produced the smooth shift and complimentary=0Agearing<br>=
=0A> desired.<br>=0A><br>=0A> It is difficult, today, to find a=
ny information on this=0Aoriginal 32%<br>=0A> gearbox, however if you=
examine the booklet (attached)=0Asupplied by<br>=0A> Laycock for the=
early cars, you will notice that the casting=0Aallowed<br>=0A> for a=
large accumulator piston (seen on p6 in brochure). After=0Asome<br>=0A&=
gt; research and modified engineering, the company came up with=0Athis a=
lloy<br>=0A> "sleeve" called the piston housing (photo) which partial=
ly=0Afilled the<br>=0A> chamber of the original large accumulator cas=
ting and allowed=0Afor a<br>=0A> smaller accumulator piston that we s=
ee in all the later 28%=0Areduction<br>=0A> units. That size piston,=
in proper condition, produced from=0A350-450<br>=0A> lbs of needed h=
ydraulic pressure to overcome the springs=0Ainfluence.<br>=0A><br>=0A=
> I'm confident that the remark made by Geoff Healey in his=0Awriting=
s<br>=0A> about the early transmissions "harsh shifting" revolved aro=
und=0Athis<br>=0A> huge accumulator piston producing too much pressur=
e.=0AAdditionally,<br>=0A> there were three various accumulator sprin=
gs supplied which=0Aadjusted<br>=0A> the pressure. The early boxes pr=
oduced about 350lbs and the=0Alater<br>=0A> about 450.<br>=0A><br>=
=0A> Today, Overdrive Spares supplies that sleeve housing with only=
=0Aone<br>=0A> rubber O-ring as it is basically a filler part and not=
under=0Aextreme<br>=0A> pressure. The accumulator piston within is u=
nder that=0Apressure. They<br>=0A> supply a modified piston using O-r=
ing technology. So, it is=0Anot<br>=0A> unusual to get good pressures=
over the normal 450 lbs=0Arequired. If it<br>=0A> works well don't f=
ix it. The only concern is if the=0Apressure does not<br>=0A> r=
elease when overdrive is not called for. A clean unit, with=0Aproper<br>=
=0A> 30W oil, will allow that to happen. All this some old theory=0Aa=
nd<br>=0A> history to ponder. Hank<br></div>=0A</blockquote>=0A<br></=
div>=0A_______________________________________________<br>=0ASupport Tea=
m.Net <a href=3D"http://www.team.net/donate.html";></a><a href=3D"http://=
www.team.net/donate.html">http://www.team.net/donate.html</a><br>=0ASugg=
ested annual donation $12.75<br><br>=0AArchive: <a href=3D"http://=
www.team.net/pipermail/healeys"></a><a href=3D"http://www.team.net/piper=
mail/healeys">http://www.team.net/pipermail/healeys</a> <a href=3D"http:=
//autox.team.net/archive/healeys"></a><a href=3D"http://autox.team.net/a=
rchive/healeys">http://autox.team.net/archive/healeys</a><br><br><a>Heal=
eys@autox.team.net</a><br><a href=3D"http://autox.team.net/mailman/listi=
nfo/healeys"></a><a href=3D"http://autox.team.net/mailman/listinfo/heale=
ys">http://autox.team.net/mailman/listinfo/healeys</a><br><br>=0AUnsubsc=
ribe/Manage: <a href=3D"http://autox.team.net/mailman/options/healeys/mi=
chaelsalter@gmail.com"></a><a href=3D"http://autox.team.net/mailman/opti=
ons/healeys/michaelsalter@gmail.com">http://autox.team.net/mailman/optio=
ns/healeys/michaelsalter@gmail.com</a><br><br></blockquote>=0A</div>=0A<=
/div>=0A</div>=0A</michaelsalter@gmail.com></div></body></html>
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Archive: http://www.team.net/pipermail/healeys
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