Sounds like your air pack is working fine. With it disabled, though, your
brakes should work just as well, but be much harder to apply. The airpack
is simply "power brakes". It does not increase the braking power of the
system. It works exactly like a vacuum booster but uses positive pressure.
The next stop should be to adjust all the brakes at the wheels. Each wheel
has two bolts on the back of the backing plate. They are cams that adjust
the brakeshoe. Jack up each wheel until it turns freely. Start turning the
wheel and turn the adjusting cam nut until the wheel stops turning. Back it
off until the wheel turns without dragging. Do this on both cam nuts. as
each one only controls half the brakes on that wheel. Once you have
adjusted all six wheels, you may have to adjust the brake pedal itself, as
it may be set too tight. Symptoms will be brakes lights that take a long
time to go off, or brakes that stay applied after you release them.
The next stop is to flush the system. If it was my truck, I would
completely flush the system with DOT 3 brake fluid. From your description,
changing the brake fluid is most likely what is needed. (The changing to
DOT 3 is a separate issue based on opinion).
When workign properly, the brakes on an M35 are just as effective as
anythign you will find on a modern pickup truck. You should not be feeling
uncertain of their stopping power. Just because you asked the question, I
would say there is defintiely something wrong.
Let us know how you make out. We don't get a lot of feedback from these 911
calls.
Joe Garrett
cell 425-344-1402
-----Original Message-----
From: Military Vehicles Mailing List [mailto:mil-veh@mil-veh.org]On
Behalf Of Jim Newton
Sent: Friday, September 21, 2001 1:14 AM
To: Military Vehicles Mailing List
Subject: [MV] M35A2 Weak Brakes -- Need Suggestions...
Hi List...
A friend (thanks, G!) drove my M35A2 last week and told me the brakes
are very weak.
This being the first M35A2 I've ever even SEEN, let alone drive, I
thought the brakes were normal.
So I emailed to another lister (thanks, J) and he gave me some good
suggestions, and indicated it might be the air pack.
So I tested the air pack by opening the air tank bleed valves and
draining the air tanks to no pressure, then driving (carefully) the
truck to see if the brakes were the same or worse. They were WAY
worse, with almost no braking. This means the air pack is working at
least a little bit.
So I'm not sure what to try next.
Could the air pack be only working partially?
Could the brake shoes be worn or glazed?
Could the hydraulics be going bad?
Should deuces stop easily if the brakes are working properly, or are
they always scary at stoplights?
Here are some facts:
o Brake fluid full (silicone as specified on sticker)
o Brake pedal is firm (not spongy as if bleeding were required)
o Air pressure charges up to a full 120 PSI
o Trailer air brake line shoots air when brake is pressed
o Small air puff hiss sound is heard when brake is released
o Tremendous leg strength is required to stop
o No leaking brake fluid around master cylinder or wheel cyls
o I have not inspected brake shoes or drum inner surfaces yet
Thanks!
--Jim "Ike" Newton
o 1984 M1007 CUCV Military Suburban 6.2 Liter Turbo-Diesel Engine 5/4 Ton Cargo Capacity, 4WD
o 1971 M35A2 Military Troop/Cargo Truck "Deuce and a Half" 478 Cubic Inch Turbo-Diesel Multi-Fuel Engine Air Shift Front Axle 2 1/2 Ton Cargo Capacity, 6WD
See them at: http://www.CUCV.net
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This archive was generated by hypermail 2b29 : Mon Oct 08 2001 - 10:59:00 PDT