[Mgs] Fw: Brake bleeding question

Paul Hunt paul.hunt1 at blueyonder.co.uk
Thu Sep 1 02:21:50 MDT 2011


Sent to the list as a direct reply was rejected.

----- Original Message ----- 
From: "Paul Hunt" <paul.hunt1 at blueyonder.co.uk>
To: "davewillner" <dwillner at ptd.net>
Sent: Thursday, September 01, 2011 8:49 AM
Subject: Re: [Mgs] Brake bleeding question


>I believe so.  But if the light comes on under hard braking, but then goes 
>off when you release the brakes, there is either some air in one of the 
>circuits or the shuttle is very near the switching point on one side.  Also 
>under normal conditions relatively little fluid will flow into the 
>callipers as the pads are kept pretty much in contact with the discs, 
>whereas the shoes are pulled back by springs which pushes the pistons back 
>into the cylinders when you release the brakes, so fluid has to flow back 
>into them to apply the rear brakes.  Normally this isn't an issue as the 
>rear slave piston surface area is much less then the front calliper area, 
>so much the same amount of fluid ends up flowing to the rears as to the 
>fronts.  However if the rear brakes (shoes and handbrake cable) are poorly 
>adjusted, giving a lot of travel, more fluid will flow.  Also if a flex 
>hose somewhere is expanding under heavy braking again more fluid will flow 
>into that circuit. Either of these will cause the shuttle to move, but it 
>shouldn't normally be enough to make the light come on, unless as I say 
>perhaps the shuttle is near the switching point on one side.
>
> PaulH.
>
> ----- Original Message ----- 
>> So Paul with a non-servo system then, even with the light off, I need to 
>> do a "regular" bleed rear to front with the nylon PDWA nut screwed in all 
>> the way, correct? As I mentioned extreme hard braking causes the light to 
>> come on momentarily near a complete stop...but its not always on, even 
>> with the key turned on, so does that mean the piston is centered now?


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