Subject: Re: [Mgs] Bleeding brakes question...

From: Robert's New iPad via Mgs <[email-masked]>
Date: Fri, 26 Apr 2019 09:33:16 -0400

The MGB workshop manual says to do longest first. MGBs initially had a single circuit, then two, and a shuttle-device that would indicate if one system were leaking.  
   I suppose, and this is just supposition, that the longer lines have the possibility of more air therein, the shorter ones to front disc brakes move more fluid, so our bleeding longest first would be least likely to cause that valve to indicate a leak fault.
   Mine does indicate such a fault, as it leaks right through the $55 plastic switch, the inside fender paint showing that. 

> On Apr 26, 2019, at 9:18 AM, Richard Lindsay via Mgs <[email-masked]> wrote:
> 
>     On vehicles with independent front and rear brake hydraulic circuits, is it still advisable to bleed the longest pipe run first? That is, does it matter if one bleeds the front brakes first?
> 
> Rick
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From: Richard Lindsay via Mgs <[email-masked]>
Date: Fri, 26 Apr 2019 10:59:38 -0500

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>    Mine does indicate such a fault, as it leaks right through the $55
> plastic switch, the inside fender paint showing that.

Mine too, Bob! Exactly the same.

On Fri, Apr 26, 2019, 8:33 AM Robert's New iPad <[email-masked]> wrote:

>    The MGB workshop manual says to do longest first. MGBs initially had a
> single circuit, then two, and a shuttle-device that would indicate if one
> system were leaking.
>    I suppose, and this is just supposition, that the longer lines have the
> possibility of more air therein, the shorter ones to front disc brakes move
> more fluid, so our bleeding longest first would be least likely to cause
> that valve to indicate a leak fault.
>    Mine does indicate such a fault, as it leaks right through the $55
> plastic switch, the inside fender paint showing that.
>
> >     On vehicles with independent front and rear brake hydraulic
> circuits, is it still advisable to bleed the longest pipe run first? That
> is, does it matter if one bleeds the front brakes first?
> >
> > Rick

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<div dir=3D"auto">&gt;=C2=A0=C2=A0 =C2=A0Mine does indicate such a fault, a=
s it leaks right through the <span class=3D"money">$55</span><div dir=3D"au=
to">&gt; plastic switch, the inside fender paint showing that.=C2=A0<div di=
r=3D"auto"><br></div><div dir=3D"auto">Mine too, Bob! Exactly the same.</di=
v></div></div><br><div class=3D"gmail_quote"><div dir=3D"ltr" class=3D"gmai=
l_attr">On Fri, Apr 26, 2019, 8:33 AM Robert&#39;s New iPad &lt;<a href=3D"=
mailto:[email-masked]">[email-masked]</a>&gt; wrote:<br></div><blockquo=
te class=3D"gmail_quote" style=3D"margin:0 0 0 .8ex;border-left:1px #ccc so=
lid;padding-left:1ex">=C2=A0 =C2=A0The MGB workshop manual says to do longe=
st first. MGBs initially had a single circuit, then two, and a shuttle-devi=
ce that would indicate if one system were leaking.=C2=A0 <br>
=C2=A0 =C2=A0I suppose, and this is just supposition, that the longer lines=
 have the possibility of more air therein, the shorter ones to front disc b=
rakes move more fluid, so our bleeding longest first would be least likely =
to cause that valve to indicate a leak fault.<br>
=C2=A0 =C2=A0Mine does indicate such a fault, as it leaks right through the=
 $55 plastic switch, the inside fender paint showing that. <br>
<br>
&gt; On Apr 26, 2019, at 9:18 AM, Richard Lindsay via Mgs &lt;<a href=3D"ma=
ilto:[email-masked]" target=3D"_blank" rel=3D"noreferrer">[email-masked]=
m.net</a>&gt; wrote:<br>
&gt; <br>
&gt;=C2=A0 =C2=A0 =C2=A0On vehicles with independent front and rear brake h=
ydraulic circuits, is it still advisable to bleed the longest pipe run firs=
t? That is, does it matter if one bleeds the front brakes first?<br>
&gt; <br>
&gt; Rick<br>
&gt; _______________________________________________<br>
&gt; <br>
&gt; <a href=3D"mailto:[email-masked]" target=3D"_blank" rel=3D"norefer=
rer">[email-masked]</a><br>
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noreferrer" target=3D"_blank">http://www.team.net/donate.html</a><br>
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</blockquote></div>

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From: PaulHunt73 via Mgs <[email-masked]>
Date: Fri, 26 Apr 2019 14:42:25 +0100 F49iv9dbPdMLITzkXdpYcZLmMxMTi+XpfqShjdPQGfdzDn5nWkHcG6Hd7ID3N99ooa3R6dkUvHnJKSIK31Nut1wCk5MH6Agp4kIwD8e+vE5XIWchhkUCXJAN S5Z7dQO7j5M36TYGcHhzKTZ+Y2ePsg1hViI0S0AkDGQ=

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I can't see that it does as by the time you get to the pistons they are =
completely separate circuits, however perhaps one should still bleed the =
longest front circuit first (the difference between the rears is =
probably only a few inches in several feet).  I can't really see why it =
has to be done anyway.  Some places talk about air bubbles passing the =
shortest circuit when bleeding the longest, so if the shortest has =
already been done it could leave bubbles in there.  But that can happen =
regardless of which you are doing, and once you have bled the first =
circuit (longest or shortest) there shouldn't be any bubbles in that =
circuit.  It's perhaps more relevant to stop-start bleeding with the =
pedal where fluid and hence bubbles could be moving back and fore, less =
so with continuous pressure such as EeziBleed.=20

I've never done it, but I'd imagine pedal bleeding is a bit of a pain on =
a dual circuit as a 'good' circuit i.e. no air should be limiting how =
far the pedal can move when bleeding the one with air in.

There is also the question of the balance switch. I understand that on =
the earlier unboosted system the switch will always be tripped, and =
careful re-bleeding of first one circuit then another may be needed to =
centralise it again.  With the boosted system the switch can be =
partially unscrewed to stop it latching.  But then again will =
low-pressure bleeding such as with an EeziBleed on just a few psi be =
enough to cause the shuttle to move anyway?

PaulH.
  ----- Original Message -----=20

      On vehicles with independent front and rear brake hydraulic =
circuits, is it still advisable to bleed the longest pipe run first? =
That is, does it matter if one bleeds the front brakes first?
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<DIV><FONT size=3D2>I can't see that it does as by the time you get to =
the pistons=20
they are completely separate circuits, however&nbsp;perhaps one should =
still=20
bleed the longest front circuit first (the difference&nbsp;between the =
rears is=20
probably only a few inches in several feet).&nbsp;&nbsp;I can't really =
see why=20
it has to be done anyway.&nbsp; Some places talk about air bubbles =
passing the=20
shortest circuit when bleeding the longest, so if the shortest has =
already been=20
done it could leave bubbles in there.&nbsp; But that can happen =
regardless of=20
which you are doing, and once you have bled the first circuit (longest =
or=20
shortest) there shouldn't be any bubbles in that circuit.&nbsp; It's =
perhaps=20
more relevant to stop-start bleeding with the pedal where fluid and =
hence=20
bubbles could be moving back and fore, less so with continuous pressure =
such as=20
EeziBleed.&nbsp;</FONT></DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2>I've never done it, but I'd imagine pedal bleeding =
is a bit of=20
a pain on a dual circuit as&nbsp;a 'good' circuit i.e. no =
air&nbsp;should=20
be&nbsp;limiting how far the pedal can move when bleeding the one with =
air=20
in.</FONT></DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2>There is also the question of the balance switch. I =
understand=20
that on the earlier unboosted system the switch will always be tripped, =
and=20
careful re-bleeding of first one circuit then another may be needed to=20
centralise it again.&nbsp; With the boosted system the switch can be =
partially=20
unscrewed to stop it latching.&nbsp; But then again will low-pressure =
bleeding=20
such as with an EeziBleed on just a few psi be enough to cause the =
shuttle to=20
move anyway?</FONT></DIV>
<DIV><FONT size=3D2></FONT>&nbsp;</DIV>
<DIV><FONT size=3D2>PaulH.</FONT></DIV>
<BLOCKQUOTE=20
style=3D"BORDER-LEFT: #000000 2px solid; PADDING-LEFT: 5px; =
PADDING-RIGHT: 0px; MARGIN-LEFT: 5px; MARGIN-RIGHT: 0px">
  <DIV style=3D"FONT: 10pt arial">----- Original Message ----- </DIV>
  <DIV><FONT size=3D2></FONT><BR></DIV>
  <DIV dir=3Dauto>&nbsp; &nbsp; On vehicles with independent front and =
rear brake=20
  hydraulic circuits, is it still advisable to bleed the longest pipe =
run first?=20
  That is, does it matter if one bleeds the front brakes=20
first?</DIV></BLOCKQUOTE></BODY></HTML>

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