Re: [MV] M35A2 brake woes

From: Ron (rojoha@attbi.com)
Date: Tue May 07 2002 - 06:31:31 PDT


 Hi all:
    In the -10 manual it states not to use the engine for compression
braking. There's no Jake brake here, so over revving is definite
possibility.
    Silicone brake fluid has to be poured very slowly to avoid entrapping
miniscule air bubbles which expand when subjected to heat, causing a spongy
pedal. He has silicone in his truck, and this may be the cause. Only way to
prove it would be a drain and flush the system and refill with conventional
brake fluid.
    Silicone fluid will also entrain water and hold it in suspension, which
is why the military uses it in the first place for vehicles in storage.
Regular fluid will absorb water from the atmosphere, destroying a brake
system that is in storage. Silicone does not 'suck' moisture out of the air
(hydroscopic) like conventional fluid, and does not distribute it through
the system like conventional fluid. However, if you get water into the
system (which an M35A2 is prone to when you check the fluid level) it will
stay in the system in tiny bubble form and when it is put under heavy
continuous breaking, it will flash into steam and expand in the lines. This
forces brake fluid back to the master cylinder, causing a lower pedal since
steam, and for that mater heated air, is very compressible, while the fluid
is not.

    Hope this helps,
    Ronzo

----- Original Message -----
From: <MVTrucker@aol.com>
To: "Military Vehicles Mailing List" <mil-veh@mil-veh.org>
Sent: Monday, May 06, 2002 10:35 PM
Subject: [MV] M35A2 brake woes

> Had a fellow call me for answers to his brake problem. He hauls
> 10,000 lbs. on steep grades. He uses engine compression to assist
> the brakes on long down hills, but the brake pedal eventually gets
> lower and lower so that it's only a couple of inches from the floor.
> At the same time the brakes get spongy. He said the brakes do
> get hot and after being on level ground a while, they return to normal.
> I try to answer the many questions people pose, but this is a new
> one on me. Could it be the DOT 5 Silicone fluid?
> Joe Young
>
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