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2002 chevy trailblazer_lt
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15 Posts
Discussion Starter #1
So I just did a bunch of work but the only stuff relating to the brakes was installing a new master cylinder (the pedal was sinking to the floor when stopping and the pedal was also spongy). Sure enough, the master cylinder had a slight leak on the back of the cylinder. We did a complete brake job in September of 2012. I had a problem with sticking calipers on the front brakes, so we had been replacing those last year in March and April. We replaced the front brake lines, too, as we heard flappers can develop in old lines as well as the lines losing the strength, too. Everything looked fine last week when we did the work. I know that one of my rotors is warped as before we replaced the master last week, I had to slam on my brakes at one point. And it was that time I noticed the warped rotor.

So my apparent problem is this...the pressure feels great. The pedal is not really that spongy anymore. However, coming up to stoplights/stop signs braking still (intermittently)requires more effort; it doesn't happen every time I stop. When it does it's not like I still have to press down hard on the brake pedal to come to a complete stop. I just notice it still takes longer to come to a complete stop and still feel like somethings up. We never replaced the rear brake calipers, so that could be the problem. And we never did the rear brake line(s), as the rear has a "t" on the axle and two brake lines going left and right. Could the brake booster be to blame? My dad pulled the vacuum hose off of the booster and air came out, so it's holding a vacuum fine. I do notice the pressure can almost fluctuate...it's like sometimes stopping the pressure can be really good and then it will be somewhat weaker, but better than before putting in the master cylinder...
 

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2003 chevy trailblazer_ls
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1,236 Posts
A spongy feel to the brake system is normal on the TB platform. Many have complained and many tried to make it go away with no real success. But, the brakes work.

Most now feel that this is a design issue with the anti-lock brake pump system, which is very difficult to bleed.

I generally recommend taking the vehicle someplace "slippery" like grass, gravel, snow or ice, etc., and just ramming down the brake pedal to lock up the brakes until the vehicle stops. This will, if everything is working correctly, energize the anti-lock pump (just keep holding the pedal down while it does crazy stuff under your foot -- this is normal) and will help to bleed out the system. It may take a couple of tries. After this procedure many people report better brake feel and more consistent stopping.

Also, I have notice on my own 03 model, after several brake changes, that the parts I use for the brake job have a distinct relationship to stopping feel. I've used several varieties of parts from Autozone to NAPA to GM to whatever, and I am getting the best brake feel ever from the parts I am currently running.

http://www.amazon.com/gp/product/B0037R8I8E/ref=oh_details_o07_s00_i00?ie=UTF8&psc=1
http://www.amazon.com/gp/product/B001O0VNJ2/ref=oh_details_o07_s00_i01?ie=UTF8&psc=1
http://www.rockauto.com/catalog/moreinfo.php?pk=371763&cc=1412277
http://www.rockauto.com/catalog/moreinfo.php?pk=452073&cc=1412277
 

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Registered
2002 chevy trailblazer_lt
Joined
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15 Posts
Discussion Starter #3
A spongy feel to the brake system is normal on the TB platform. Many have complained and many tried to make it go away with no real success. But, the brakes work.

Most now feel that this is a design issue with the anti-lock brake pump system, which is very difficult to bleed.

I generally recommend taking the vehicle someplace "slippery" like grass, gravel, snow or ice, etc., and just ramming down the brake pedal to lock up the brakes until the vehicle stops. This will, if everything is working correctly, energize the anti-lock pump (just keep holding the pedal down while it does crazy stuff under your foot -- this is normal) and will help to bleed out the system. It may take a couple of tries. After this procedure many people report better brake feel and more consistent stopping.

Also, I have notice on my own 03 model, after several brake changes, that the parts I use for the brake job have a distinct relationship to stopping feel. I've used several varieties of parts from Autozone to NAPA to GM to whatever, and I am getting the best brake feel ever from the parts I am currently running.

http://www.amazon.com/gp/product/B0037R8I8E/ref=oh_details_o07_s00_i00?ie=UTF8&psc=1
http://www.amazon.com/gp/product/B001O0VNJ2/ref=oh_details_o07_s00_i01?ie=UTF8&psc=1
http://www.rockauto.com/catalog/moreinfo.php?pk=371763&cc=1412277
http://www.rockauto.com/catalog/moreinfo.php?pk=452073&cc=1412277
That's why my dad thought, originally, too. He thought there are differences between brake components from the different companies...we use Napa products for brakes.

You know, now I noticed last night that my dad forgot to hook the crankcase ventilation hose back up to the valve cover port (that goes back to the air intake resonator)...this may be affecting my vacuum? I mean it seems like my car is holding a vacuum but this may affect vacuum while I'm driving since at idle the whole PCV system is totally different compared to when you're driving...that's why I may be having intermittent trouble currently?

:thx
 
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