[V8] Bleeding the brakes

[Coleman, David]

Interesting stuff re: MC seal failure caused by typically unused bore area. I'd buy that.  

And my apologies for the bum info re: dot 3 as sufficient brake fluid -- for a second there I put the cars on the same level as a bimmer of that time (though again I'm not checking my facts here)...

DaveC. 



--------------------------
David A. Coleman
BlackRock
Sent via BlackBerry Wireless


-----Original Message-----
From: v8-bounces at audifans.com <v8-bounces at audifans.com>
To: v8 at audifans.com <v8 at audifans.com>
Sent: Thu Sep 29 09:57:40 2005
Subject: Re: [V8] Bleeding the brakes

First off, I really liked the idea of the extra brake fluid resevoir cap with a
tire valve in it. That is a cheap and easy method for any car. Seems less messy
too.

And - let me add some urban mythology to the brake bleeding:

The reason (so I have been told - and it makes sense) that you can damage the
master cylinder by manually pumping the fluid through is that the seals are
forced to travel over parts of the bore that they normally don't reach. After
many years, this ares gets corroded and or gunk builds up there. When the piston
travels over it, the seals get damaged. So - either don't use the full pedal
travel, or make part of your annual brake bleed include depressing the pedal
fully to clean out the bore.
It seems like the second option is actually the best to me, but you may be
taking a risk on an old system in unknown condition.

FWIW, I have been doing the full pedal travel bleed to mine with no apparent
problems.

Dave


Quoting "Coleman, David" <David.Coleman at blackrock.com>:

> Absolutely you can bleed the brakes w/ a friend working the pedal. The only
> danger is if helper buddy is too brutal when pumping, which can damage the
> master cylinder seals.
>
> I'd set the car up on 4 jackstands and pull the wheels. WD-40 all bleeders.
> Fill the reservoir -- I use castrol LMA but frankly any house brand dot 3
> will probably suffice. Crack all the bleeders and let gravity work while you
> call a friend, neighbor, or mildly gifted orangutang.
>
> After the gravity bleed barely does anything after 40 hours of standing
> there, have buddy SLOWLY + GENTLY depress the pedal about 3/4 of the way down
> and hold. Crack the r/r caliper screw to purge, then snug back up. Buddy then
> gently releases. Repeat until the fresh stuff comes out. Move around the car
> to the left rear, r/f, then l/f.  No jumping up and down on the pedal -- just
> down once and hold. After all have been done, you can go back around, to the
> fronts at least, and do the pumping thing, albeit gently...
>
> DaveC.
>
>
>
> --------------------------
> David A. Coleman
> BlackRock
> Sent via BlackBerry Wireless
>
>
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THE INFORMATION CONTAINED IN THIS MESSAGE AND ANY ATTACHMENT MAY BE PRIVILEGED, CONFIDENTIAL, PROPRIETARY OR OTHERWISE PROTECTED FROM DISCLOSURE. If the reader of this message is not the intended recipient, you are hereby notified that any dissemination, distribution, copying or use of this message and any attachment is strictly prohibited. If you have received this message in error, please notify us immediately by replying to the message and permanently delete it from your computer and destroy any printout thereof.