new rear brakes and brakes unevenly

[kikkegek]

hi there,

I recently replaced the rear brakepads and cilinders, because I thought they were worn.

I went to the yearly inspection and the test shows I have 83% difference in brake power in the rear. (DAMN!) thats like one side is almost not braking at all.

any advise?

we bleeded the rakes, longest line first...and brakes seems to be incely installed...what can couse this?

[motornut]

gee what all do they test if no etest?
jack up the rear wheels and see if there is a noticable difference
is one dragging and the other not
use the ebrake a click at a time
may need to take the drums off and make sure the shoes are wearing even
not tapering the pad edge

[kikkegek]

thanks, I wanted to check that 2nite, but my repairbuddy didnt have time and my wife is 36wks pregnant...fridaynight will be next opportinity, I'll keep ya posted!

[Gyawo]

How did they find out that your rear brakes were stopping "83%" on one side? I don't think I have ever heard of a test that could determine your stopping %'s from left to right. When the rear brakes were replaced were they adjusted properly?

[caddyhack]

I also agree that the brake drums arent adjusted properly.. jack it up take the drum off and adjust the adjuster on the bottom one- two clicks at a time untill you can hear the drums dragging slightly and have little resistance when spinning them ( its kindof a feeeling/hearing thing dont under adjust abd dont over adjust them) Good luck .... some drums have a slot so you can adjust them with the drums on the axle
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[kikkegek]

Originally Posted by caddyhack

I also agree that the brake drums arent adjusted properly.. jack it up take the drum off and adjust the adjuster on the bottom one- two clicks at a time untill you can hear the drums dragging slightly and have little resistance when spinning them ( its kindof a feeeling/hearing thing dont under adjust abd dont over adjust them) Good luck .... some drums have a slot so you can adjust them with the drums on the axle
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thanks for the help.
when I mounted them, I did just that. I tightened the adjusters till the drum started dragging on both sides...

I am taking the wheels and drums of 2nite to see if they are wearing evenly and to check if the cilinders come out evenly and equally far...
hope I find something, I'll report back here.

thanks sofar!

[kikkegek]

okay, here are some pics from 2nite.

we tested the cilinders and they come out just fine on both sides and evenely far also.

but the brake pads seem to wear only on the inside and no were else...as can be seen by the dark marks on the pads.

and the other strange thing is that the rear thickers and longer pads seem to have this strange pattern on them (is staggered the right word?)...

We have put the old shoes back on, just to be sure and hopefully now the difference is gone. I do notice that with the old pads the car brakes better...but can realy feel if the difference between left and right is gone.

any ideads whats going on?

We compared the old and new ones and the geometry seems 100% the same, just the thick long pads on the new ones are about a quarter inch longer.

[Gyawo]

Did you have the drums machined?

[kikkegek]

Originally Posted by Gyawo

Did you have the drums machined?

thats the only thing we havent done yet.

I now have the old pads back on, so we can make it past the yearly checkup. After that I"ll probaly habe the drums measured to see of they are indeed in need of some machining...I think so, because I dont know, why the new pads wont work!

[99-LS1-SS]

I wonder if your drums aren't worn out?

[kikkegek]

somebody told me there is a brake pressure divider in the back which could be dirty?

is there such a divider in the lines that could be dirty?

[motornut]

the proportioning valve? thats on a front cross member
after that it's like a 1/4 line to the back
with a flex to the rear axle then both wheels
all ive seen for back there
follow the brake failure wire, brown i think
strsight down on the drivers side frame rail at the front

[Gyawo]

There should be a proportioning valve, that changes the braking pressure so the rear brakes dont lock up under heavy braking. Could possibly have an older weight proportioning valve, not sure if these trucks were equipped with such a thing. The outside may be dirty, what is the condition of the fluid?

[motornut]

Originally Posted by Gyawo

There should be a proportioning valve, that changes the braking pressure so the rear brakes dont lock up under heavy braking. Could possibly have an older weight proportioning valve, not sure if these trucks were equipped with such a thing. The outside may be dirty, what is the condition of the fluid?

I've seen those on lowered vans a piece attached to the rear suspension,it read how much the van's rear axle is traveling away from the body.the piece kinda looked like a gas tank sending unit?
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[kikkegek]

car passed inspection yesterday. So happy.

put the old brake pads back on and brought the car to the shop. They spent 2,5 hours adjusting the brakes and then the difference was back to 8% and 0% on the second test.

imagine that! adjusting the brakes makes a big difference. I just dont understand why I didnt get it right!

[motornut]

weird
is that a yearly "saftey " inspection?
how would they or what do they hook that up too
did you see where they had probs
do you have that other braking valve on the suspension?

[kikkegek]

yes, its a yearly inspection you HAVE to take.

they check lots of stuff.
CO exhaust
lights on the car
suspension
tires
etc...

the brakes can be tested two ways:
- a roller bank
or
- plates on the ground. They drive on to them and then slam the brakes. the plates are connected to sensors and measure the slow down

[Keith Seymore]

Originally Posted by kikkegek

or
- plates on the ground. They drive on to them and then slam the brakes. the plates are connected to sensors and measure the slow down

We have a system like that at the Proving Ground.

After reading through, a couple thoughts:

1) Some folks asked about a rear brake proportioning valve (height sensing valve), the device above the rear axle: that would affect front to rear brake balance, but not side to side.

2) Looking at your new material after you pulled the drums: that pattern (most wear in the center) is intended. The pads are "overcrowned" both along the length and also across the width, in the manufacturing process which tends to keep them from being noisy while they are getting broken in.

As a result - I'd say your new material was not "burnished in". I'd put that new material back on and get it "broken in" and see if the side to side balance was better.

K

[motornut]

Originally Posted by kikkegek

yes, its a yearly inspection you HAVE to take.

they check lots of stuff.
CO exhaust
lights on the car
suspension
tires
etc...

the brakes can be tested two ways:
- a roller bank
or
- plates on the ground. They drive on to them and then slam the brakes. the plates are connected to sensors and measure the slow down

Cept for an (2year)etest ,none of that stuff done here.
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