Date: Sat, 11 Oct 2008 10:12:39 -0400
Reply-To: Mike <mbucchino@CHARTER.NET>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Mike <mbucchino@CHARTER.NET>
Subject: Re: Brake hydraulic pressure
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reply-type=original
1500 psi is nominal automotive brake system applied pressure.
I tend to believe the statement regarding the 'low moisture absorption'
brake fluid keeping the water seperate from the fluid, and bringing on other
problems like severe corrosion. Moisture in the air does get into the brake
fluid reservoir and flows to and collects in the lowest points in the
system. The GM M/C reservoirs have a rubber 'accordion-type' diaphragm that
expands and contracts, automatically staying in contact with the top of the
fluid, and acting as a barrier between outside air and system fluid. I
wonder if there's any real, hard evidence that this is better than systems
that do not have this diaphragm, like VW's for example. The only
recommendation in either case is to flush and replace fluid every 2 years
(or less) per manufacturer's instructions.
(IIRC, ABS pressures can be much higher, as much as 3000 psi, even when the
vehicle is just sitting there, not running!)
BTW, this reminds me of an aviation-related fact. A pinhole-sized leak in
a 3000 psi line can create an 'invisible' stream of fluid that can slice
through skin like a laser, or even worse, inject you with a large amount of
toxic hydraulic fluid in very short amount of time (with possible amputation
required). I learned this as an aircraft mechanic. They taught us to never
run your hands along a line to check for leaks.
Also, this might be good time to remind us all that horseplay with a
compressed-air blowgun nozzle can painfully inject you (or your buddy) with
high pressure air, which, if it gets into the bloodstream, could travel to
the heart and kill a person. So, be careful 'dusting' yourself off, if you
use compressed air. I've seen many painters do this, and I know one that
lost an eye from this exact thing. I don't mean to be grim, but be careful
out there.
Mike B.
----- Original Message -----
From: "Jack R." <jack007@COMCAST.NET>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Saturday, October 11, 2008 8:52 AM
Subject: Re: Brake hydraulic pressure
>A mechanic friend told me that the new low moisture absorption and/or
> synthetic brake fluids can contribute to brake line rusting. He told me
> that the moisture that isn't absorbed into the fluid resides between the
> fluid and the lines, thus causing them to rust sooner.
>
> Is what he is telling me correct?
>
> I still feel that the best way to extend brake line life, is to bleed
> annually or bi-annually at least.
>
> Jack R.
>
> -----Original Message-----
> From: Vanagon Mailing List [mailto:vanagon@gerry.vanagon.com] On Behalf Of
> Larry Alofs
> Sent: Saturday, October 11, 2008 8:34 AM
> To: vanagon@GERRY.VANAGON.COM
> Subject: Re: Brake hydraulic pressure
>
> On a recent trip from Chicago to Texas, my brother and I replaced the
> rusted
> thru line leading to the rear brakes on his F*rd F-250 diesel. The first
> symptoms we noticed were the ABS light and lack of cruise control, Then we
> saw the fluid leaking; fixed it in an Aut*zone parking lot in central
> Illinois.
>
> Larry A.
>
>
> On Sat, Oct 11, 2008 at 6:02 AM, Mike Collum <collum@verizon.net> wrote:
>
>> Scott Daniel - Turbovans wrote:
>>
>>> my wild guess is up to 1,000 psi........and that's a very wild guess.
>>> why do you ask ?
>>>
>>
>>
>> Thanks. Lines nor hoses are bursting but Maine does put nasty stuff on
>> the roads and I was curious. A local mechanic says he has replaced more
>> brake lines in the past 3 years than in all the 15 years before. This
>> is mainly due to a change in what chemicals are put down.
>>
>> Mike
>>
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