my parking brake only works when its loaded with a heavy load 1200 what
need to be adjusted what where which way its a 85 4x4 shrtbd 5 speed 1/2
ton

In article
<3ab09a42fd915e19f0d0a05c7bbbba5f (AT) localhost (DOT) talkabouttrucks.com>,
"bja" <clubpsycho (AT) yahoo (DOT) com> wrote:

You need to adjust either the parking brake cable, underneath the cab,
or the proportioning valve, on the frame above the rear axle.

The parking brake cable tends to stretch a bit over time, so you have to
take up the slack by tightening it.
The proportioning valve increases the braking pressure to the rear axle,
the heavier the load you carry.

That is counter intuitive. The Parking Brake should work WORSE under heavy
loads. To say it ONLY works when loaded is backwards from the way it should
normally work. In a perfect world, it should work the same under all loading
conditions, but the laws of physics prevails over logic in this instance.




"bja" <clubpsycho (AT) yahoo (DOT) com> wrote

"Ernie Leimkuhler" <stagesmith (AT) mindspring (DOT) com> wrote


But Earnie, his report is that the brake works when the truck is heavily
loaded. This would tend to suggest the brake itself is adjusted okay.

I have to wonder if he is altering his use of the brake when the truck is
loaded -- it has a load so he yanks the handle harder. If so, then perhaps
he is not yanking the handle hard enough when the truck is not loaded.

"bja" <clubpsycho (AT) yahoo (DOT) com> wrote

The parking brake should work the same whether the vehicle is loaded or
not. If the parking brake does work only with a heavy load I would take a
good look at the frame to make sure it is not rusted out and flexing. If the
frame is sagging due to rust it would cause the parking brake cable to
tighten up and act as you described. If no problems are found, first make
sure the rear brake shoes are properly adjusted and the praking brake levers
and cables move freely. If the parking brake still doesn't hold then you can
adjust the cable.

"Mike" <mik (AT) localnet (DOT) com> wrote


But, his report is that the Parking Brake works BETTER on a heavy load than
a light one.

In article <7F1Gh.27$iD4.14@trnddc06>,
"Jeff Strickland" <crwlr (AT) verizon (DOT) net> wrote:

For a short while I had a 86 4WD axle on my 86 2WD truck.

It did give me more torque, but I never came up with a good solution to
the parking brake incompatibility between 4WD and 2WD.

2WD toyotas use a separate cable to each rear drum, while 4WD toyotas
use a single cable that links both drums.

It had the same problem in that the parking brake only really worked
when the truck was heavily loaded.

It has to do with the geometry of the rear axle and how loading the axle
shortens the brake cable.
The parking brake is supposed to grab harder under a heavier load.

I think if you tighten the parking brake cable at the tensioner under
the cab, it will solve your problem.