93 Grand Caravan rear brake problem?

I changed the brake shoes on my 93 Dodge Caravan (3.3L, 150K miles).
The remanufactured shoes I bought at Autozone were fairly cheap
(approx. $27 for both sides). I've run into a few things I'd like to
ask about.

First, I had enormous trouble installing the drum over the new shoes on
the left side - there just wasn't enough clearance by a hair. I finally
noticed that the new pads where not all the same thickness: there were
2 that were a few millimeters thicker than the other 2. By bad luck
(25% chance of this), I had managed to grab the 2 thick ones to install
on the left wheel.

I started over and used one thick and one thin on the left. This went
fine. When I went to the right side, I ran into a clearance problem. It
was hard to get the drum on, but I did get the right drum mounted.
There is now some drag on this side.

I've driven the car about 60 miles and the right rear is getting
warm/hot, and after jacking it up I can barely spin the wheel by hand.
I had hoped the initial drag would go away as the pad got worn in, but
apparently not.

Before I go further with this, I'd like to check the parking brake
adjustment, even though I'm quite confident that the parking brake is
not the problem here.

Question: where is the parking brake adjustment? The Chilton book
doesn't match the parking brake cabling in my car (underr the left side
to the left rear and continuing around the back to the right wheel.

Larger question: is it likely that I have a bad brake shoe, given that
the drag problem moved from left to right when I moved one of the new
shoes from left to right? Is this kind of problem common? What else?
I've very carefully checked all of the wheel and brake parts for
correct installation, and nothing else seems mishapen.

Thanks.

 

That's why I don't buy Chiltons books. But I don't know the answer. I
either buy Factory Shop Manuals or get an on-line subscription to
Alldata for all of my cars ($25 per year for first car, $15 for every
car after the first one) - they have vehicle specific info. (procedures,
pictures, schematics) right out of the FSMs.

I don't know your specific vehicle, but with most drum brakes, the rear
shoe has a different material (and possibly even a different design)
than the front one. This is because drum brakes work on a self
energizing principle, and with the wheel cylinder at the top, the front
shoe does 90% of the normal braking, and the rear shoe is only for the
parking brake.

It's been a long time since I did a drum brake, but usually there is a
piece of paper in the box with the shoes with some instructions pointing
out how to identify the front from the rear. My guess is that it makes
a difference which is the front and which is the rear shoe (problem
caused by thickness, material, and/or shoe construction differences).
You need to find out for sure which shoe goes where and start over. If
problem still there, then tackle it, but you need to get that sorted out
first. In lieu of any definitive info., I'd say the thicker shoe goes
to the front.

Dumb question, but I have to ask: You did not mention the adjusters.
You did back in your adjusters before installing the new shoes and
drums, and then properly re-adjusted them out when done?

Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")

 

Drum brakes have an adjuster. The adjuster is threaded and you can turn it
to adjust it in or our as required so the shoes fit just right into the
drums. Even Chilton's should illustrate this.

To adjust the emergency brake, you should be able to follow the emergency
brake cables from the rear drums forward to the emergency brake pedal at the
front of the van. As you do so, you'll see an adusting screw somewhere
embedded in the cabling.

 

[snip]

Did you retract the automatic adjusters?

Are the rear wheel cylinder (pistons) frozen?
(I'd be surprised if they weren't)

If the return springs weren't overheated previously, they
probably are now from driving with the brakes dragging as
your post described, better replace them also.

 

The Park brake is self adjusting type on this 93. But it depends on correct
adjustment and correct installation of the primary and secondary brake shoes
on both sides. Obviously something is wrong with either your parts, your
installation of them, or your adjustment of the installation. Also as
mentioned, when doing brake shoes, it is always a good idea, and investment
to spend the few extra dollars and get the shoe kit (new springs etc) and
put them in at the same time. Also checking out the automatic adjusters is
important, as they are often very dirty and stiff and often will not work at
all if reinstalled in this condition. Very often if the star wheel teeth are
in good condition, just a good clean and relubrication will fix them. It is
also common on this vehicle, at this age for the adjuster star wheel teeth
to be worn out and the adjuster lever unable to actually turn the wheel. I
replaced mine both (on my 93 GC) at my last shoe job for this very reason.

 

I have been using and changing the Auto Zone liftime warranty front
pads and rear shoes on our 93 Caravan for a long time. 160K. It has
always been a very routin job. I have never noticed one shoe thicker
than the other. It is possible but I just never noticed it. I did use
the premium pads on the front and had to switch back to the cheaper
shoes because the harder pads made the rotors warp. Switched back to
the cheaper pads, 2 new rotors and all is well. Hope the info. helps.

Warren

 

snip<<

<<snip>>

Actually it is the REAR shoe that applies the most braking force when the
vehicle is traveling forward on a dual servo brake system (that is with no
anchor at the bottom of the shoes, they only attach to each other via the
self adjuster and a spring.

That is why the rear shoe is longer than the front shoe. The front shoe
provides most of the braking force when the vehicle is traveling in
reverse.

When the brakes are applied during forward travel the wheel cylinder rod
pushes the top of both shoes outward. The forward shoe contacts the brake
drum and the rotational force tries to move the forward shoe downward which
transfers the force of the rotational movement of the front shoe to the
rear shoe via the self adjuster, thus forcing the rear shoe against the
drum. The opposite effect happens when traveling in reverse.

With a non-servo brake system the bottom of the brake shoes are anchored.
It is the front shoe in this system that applies the most braking force
when the vehicle is traveling forward. The rear shoe in this system
provides the most braking force when the vehicle is traveling in reverse.

(This description of the non-servo system assumes that the wheel cylinder
is at the top of the backing plate.)

 

Yes - I believe you are correct - good catch. Just reverse the words
"front" and "rear" in my previous post. Thanks.

Bill Putney
(to reply by e-mail, replace the last letter of the alphabet in my
address with "x")