[ROVERNET - UK] Bleeding brakes!

[Roger.Matheson]

Hi Steven,

When you refer to a mity vac, does this mean a vacume device sucking fluid 
through from one of the callipers?  I have found air pressure effective.  I 
made up a new cap for the resevoir and connected it to 5 lbs air pressure. 
Releasing a blead screw allows the compresed air to push the fluid through. 
Obviosly you need to watch the level of fluid but you can move a lot of 
fluid quickly with this technique.  The last time I bled a recon servo I 
connected a resevoir with a little fluid in it with a short pipe above the 
servo outlet.  Pumping the pedal through full strokes very quickly 
eliminated air which I could see as bubbles in my dummy resevoir.  From what 
you say it seems that there is still air in the second servo.

Use spare blead screws in the outlets of the master (same thread)  A solid 
pedal will confirm the master is OK.  With air out of the servos by the 
above technique, lack of pedal can only mean air in the lines and in the 
callipers.  Use the compressed air method, push fliud out of the rear 
bleader (90% of the contents of the resevoir should be enough to change the 
total volume in this circuit.  Do the same with the front (furthest from the 
servos then the front nearest).

If you still have no pedal then there must be a fault in the seals/bores of 
the master and or the servos, or there is excessive play betwen the pads and 
disks.  Are there any leaks or bulging in the flexible pipes at he 
callipers?  Have you been using fresh fluid each time (fluid used for 
bleading can contain small air bubbles).  I have not found it necessary to 
start the engine, or raise the rear.  In relation to previous discussions, 
the blead screw on the rear is of course lower than the inlet pipe Stand 
well and trully corrected.

Cheers Roger

----- Original Message ----- 
From: "Steven Dibdin" <sdibdin at hotmail.com>
To: <rovernet at lyris.ccdata.com>
Sent: Wednesday, May 02, 2007 4:14 AM
Subject: [ROVERNET - UK] Bleeding brakes!


> Intended pun!
>
> Hi All,
>
> I'm after the collective knowledge of the RoverNet community. Some of you 
> may know my friend Rowland Copeland and his 1969 2000TC. He lost his 
> brakes a while ago and after investigating we found that most of his brack 
> fulid had ended up in side the vacuum canisters of both brake servos. So, 
> they were distpatched to Ruth Burgess and came back looking and feeling 
> great.
>
> So i have been helping him bleed his brakes so that he can get the system 
> working again. I did similar work on my '68 TC the year before lats and 
> after a bit of work and guidence from eric and Ruth git everything working 
> fine.
>
> With Rowland's car we have tried all the normal tricks; cracking open the 
> unions on the the nose of each servo, jacking the rear of the car up to 
> give the rear line a good incline to help stop air locks etc. And still no 
> joy, last weekend we tried a mity vac and got through a quart and a half 
> of fluid.
>
> I'm beginning to think that it's not me but something else that is causing 
> the problem, maybe the master cylinder. Here's what we've got so far:
>
>>Two pumps of the brake pedal give a bit of pressure.
>
>>The reaction piston that actautes the air valve on the servos rises on the 
>>rear servo, but not the front always (Suggests that rear system is working 
>>somewhat).
>
>>Rowland reckons that the brakes went with no warning of failure 
>>(fortunatly he was just coming out of the car wash when this happed!).
>
>>Judging by th estate of the fulid in the servo's vac canisters they had 
>>been leaking for a while.
>
> With the exception of the clutch system on my car (turned out to be a bad 
> master cylinder re-sleeve at some point). I've never had this trouble 
> bleeding a hydrolic system before.
>
> Sorry for the extra long email, but I've run a bit dry on ideas with this 
> one.
>
> Thanks to any one with suggestions,
>
> Steven Dibdin
>
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