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Hi all,=20
I'm a long time Healey owner having had my BT7 for over 30 years.
Recently I had a complete failure of a brake front drum (photos below) on my=
1956 Jensen 541 (a 4ltr Austin powered contemporary of the Healey) resultin=
g in a total loss of my brakes. Not an experience I want to go through again=
. As a result I am looking to do a drum to disc conversion using predominant=
ly Healey parts=20
My car uses several components in common with the BN1, in particular it uses=
the same king pin/swivel axle set up. I have pretty much go the parts neede=
d for the conversion (Denis Welsh Heavy Duty swing axles, AH 3000 steel whee=
l BTC101 hubs, taper bearings, disks and hub adapters etc) but I have some c=
oncerns about what changes I might need to make to the rest of the hydraulic=
system, particularly what changes I will need to make (if any) to the maste=
r cylinder and rear wheel cylinders.=20
I was wondering what the list subscribers have done to the MC and rear wheel=
cylinders when you've converted the front drums to disks on your early cars=
. I believe that the front calipers need higher pressures (900psi) to operat=
e than compared to the rear drums (400 psi) and was wondering if I need to f=
it some for of brake balance valve to stop the rears locking up before the f=
ronts. Do you change the bore of the rear wheel cylinders when doing a conve=
rsion as an alternative? I have also read on the web that there may be a che=
ck valve in the MC which I might have to remove. Apparently with a drum brak=
e set up the check valve retains some residual pressure after braking to pre=
vent any air getting into the wheel cylinders, but with a disk brake set up t=
his could cause brake drag.=20
I would hate to do the conversion only to have worse brakes than my twin tra=
iling shoe front drums that I have now.=20
Currently I have two 5/8" wheel cylinders on the rear, four 1 1/4" wheel cyl=
inders on the front and a 3/4" master cylinder with a pretty small reservoir=
. The system also incorporates a Lockheed 3:1 brake servo.=20
Any advice would be appreciated.=20
Phil
https://joc.org.uk/jensen-models/541-series/=
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<html><head><meta http-equiv=3D"content-type" content=3D"text/html; charset=3D=
utf-8"></head><body dir=3D"auto"><div dir=3D"ltr"><meta http-equiv=3D"conten=
t-type" content=3D"text/html; charset=3Dutf-8"><span style=3D"font-family: A=
rial, Helvetica; font-size: 13px; -webkit-text-size-adjust: 100%; background=
-color: rgb(255, 255, 255);">Hi all, </span><br style=3D"font-family: A=
rial, Helvetica; font-size: 13px; -webkit-text-size-adjust: 100%;"><span sty=
le=3D"font-family: Arial, Helvetica; font-size: 13px; -webkit-text-size-adju=
st: 100%; background-color: rgb(255, 255, 255);">I'm a long time Healey owne=
r having had my BT7 for over 30 years.</span></div><div dir=3D"ltr"><br></di=
v><div dir=3D"ltr"><span style=3D"font-family: Arial, Helvetica; font-size: 1=
3px; -webkit-text-size-adjust: 100%; background-color: rgb(255, 255, 255);">=
Recently I had a complete failure of a brake front drum (photos below) on my=
1956 Jensen 541 (a 4ltr Austin powered contemporary of the Healey) </s=
pan><span style=3D"font-family: Arial, Helvetica; font-size: 13px; -webkit-t=
ext-size-adjust: 100%; background-color: rgb(255, 255, 255);">resulting in a=
total loss of my brakes. </span><span style=3D"font-family: Arial, Hel=
vetica; font-size: 13px; -webkit-text-size-adjust: 100%; background-color: r=
gb(255, 255, 255);">Not an experience I want to go through again. As a resul=
t I am looking to do a drum to disc conversion using predominantly Healey pa=
rts </span></div><div dir=3D"ltr"><br style=3D"font-family: Arial, Helv=
etica; font-size: 13px; -webkit-text-size-adjust: 100%;"><span style=3D"font=
-family: Arial, Helvetica; font-size: 13px; -webkit-text-size-adjust: 100%; b=
ackground-color: rgb(255, 255, 255);">My car uses several components in comm=
on with the BN1, in particular it uses the same king pin/swivel axle set up.=
I have pretty much go the parts needed for the conversion (Denis Welsh Heav=
y Duty swing axles, AH 3000 steel wheel BTC101 hubs, taper bearings, disks a=
nd hub adapters etc) but I have some concerns about what changes I might nee=
d to make to the rest of the hydraulic system, particularly what changes I w=
ill need to make (if any) to the master cylinder and rear wheel cylinders.&n=
bsp;</span><br style=3D"font-family: Arial, Helvetica; font-size: 13px; -web=
kit-text-size-adjust: 100%;"><br style=3D"font-family: Arial, Helvetica; fon=
t-size: 13px; -webkit-text-size-adjust: 100%;"><span style=3D"font-family: A=
rial, Helvetica; font-size: 13px; -webkit-text-size-adjust: 100%; background=
-color: rgb(255, 255, 255);">I was wondering what the list subscribers have d=
one to the MC and rear wheel cylinders when you've converted the front drums=
to disks on your early cars. I believe that the front calipers need higher p=
ressures (900psi) to operate than compared to the rear drums (400 psi) and w=
as wondering if I need to fit some for of brake balance valve to stop the re=
ars locking up before the fronts. Do you change the bore of the rear wheel c=
ylinders when doing a conversion as an alternative? I have also read on the w=
eb that there may be a check valve in the MC which I might have to remove. A=
pparently with a drum brake set up the check valve retains some residual pre=
ssure after braking to prevent any air getting into the wheel cylinders, but=
with a disk brake set up this could cause brake drag. </span><br style=
=3D"font-family: Arial, Helvetica; font-size: 13px; -webkit-text-size-adjust=
: 100%;"><br style=3D"font-family: Arial, Helvetica; font-size: 13px; -webki=
t-text-size-adjust: 100%;"><span style=3D"font-family: Arial, Helvetica; fon=
t-size: 13px; -webkit-text-size-adjust: 100%; background-color: rgb(255, 255=
, 255);">I would hate to do the conversion only to have worse brakes than my=
twin trailing shoe front drums that I have now. </span><br style=3D"fo=
nt-family: Arial, Helvetica; font-size: 13px; -webkit-text-size-adjust: 100%=
;"><br style=3D"font-family: Arial, Helvetica; font-size: 13px; -webkit-text=
-size-adjust: 100%;"><span style=3D"font-family: Arial, Helvetica; font-size=
: 13px; -webkit-text-size-adjust: 100%; background-color: rgb(255, 255, 255)=
;">Currently I have two 5/8" wheel cylinders on the rear, four 1 1/4" wheel c=
ylinders on the front and a 3/4" master cylinder with a pretty small reservo=
ir. The system also incorporates a Lockheed 3:1 brake servo. </span><br=
style=3D"font-family: Arial, Helvetica; font-size: 13px; -webkit-text-size-=
adjust: 100%;"><br style=3D"font-family: Arial, Helvetica; font-size: 13px; -=
webkit-text-size-adjust: 100%;"><span style=3D"font-family: Arial, Helvetica=
; font-size: 13px; -webkit-text-size-adjust: 100%; background-color: rgb(255=
, 255, 255);">Any advice would be appreciated. </span><br style=3D"font=
-family: Arial, Helvetica; font-size: 13px; -webkit-text-size-adjust: 100%;"=
><br style=3D"font-family: Arial, Helvetica; font-size: 13px; -webkit-text-s=
ize-adjust: 100%;"><span style=3D"font-family: Arial, Helvetica; font-size: 1=
3px; -webkit-text-size-adjust: 100%; background-color: rgb(255, 255, 255);">=
Phil</span><div dir=3D"ltr"></div></div><div dir=3D"ltr"><span style=3D"font=
-family: Arial, Helvetica; font-size: 13px; -webkit-text-size-adjust: 100%; b=
ackground-color: rgb(255, 255, 255);"><br></span></div><div dir=3D"ltr"><a h=
ref=3D"https://joc.org.uk/jensen-models/541-series/";>https://joc.org.uk/jens=
en-models/541-series/</a></div></body></html>=
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