NEED HELP Inconsistent brake pedal travel

[BaconBandage]

Hey everyone- first post here. Recently bought a '05 trailblazer LT, short wheelbase, just turned over 130k miles. Brake pedal travel would sometimes be "normal" (comparable to my '09 G8 GT), or right at the top and rock hard. Long story short, It now has EXT front brakes made up of new (not reman) raybestos calipers, and a powerstop plain rotor/pad kit. Also changed the booster check valve and grommet, because it was cheap enough. Now when I start off driving, it has a fair amount of pedal travel, but not enough to hit the floor. But if I drive long enough, it firms up a bit and travel is less- but still not as high and hard as before the calipers were replaced. I have also noticed light pulsation when coming to a stop after driving a bit, and the FL feels/smells hotter than the other 3 wheels. The hoses look fairly new, there is no rust on the metal parts of them, and the fluid in the reservoir looks clean- but I have no idea if the lines have actually been flushed. I only bled the fronts after the caliper change, and only enough to get rid of any air. I suppose I ought to order the correct reservoir cap adapter for my power bleeder and do a complete flush, but any other thoughts in the mean time?

 

[Mooseman]

We were just having a discussion on New vs reman brake calipers .

Maybe it just needs more bleeding and maybe do the rears at the same time to refresh the fluid everywhere. It's possible that the one that is hotter is just working better rather than being seized.

Was there a particular reason you replaced the calipers?

 

[BaconBandage]

I replaced them, as I felt the FL was shot. The outboard side of the FL rotor wasn't being hit by the pads much, or at all- there was a definite rust ring in the middle, while all the other rotors were clean on both sides. At times, especially after hwy speeds, the pedal had almost no travel, and was rock hard- like when you pump the brakes with the engine off. I tried new guide pins and brackets when I did the EXT upgrade, without much change. After that, I did the calipers- wish I had done them the first time instead I did the bedding procedure last night, and it seemed a little better today after a ~30 mile trip, mostly highway- but it still was hot(ter) and smelly at the FL. Guess I'll get the correct adapter for my power bleeder and start with fresh fluid.

 

[Mounce]

Don't forget to bleed the abs as well. It can catch air and hold it sometimes. Will need a high end scanner or a dirt road to lock the brakes up on to activate the module.

 

[Chickenhawk]

I second the suggestion to work the ABS with a Tech 2 or a gravel road.

I am however somewhat concerned that maybe one of the new caliper pistons is not releasing properly. Please keep us informed.

I am especially concerned because I am looking at those new Raybestos calipers for my truck, even though there is no indication my calipers are bad. I just get uneven pad wear on the inside pad, which is pretty normal for our trucks. I hate to take out good factory calipers and replace them with cheap Chinese-made Raybestos calipers, and then have them worse than before!

 

[BaconBandage]

… Thought about this late last night, and didn't think it was possible- but the inboard pad was wedged in the caliper, along the short side- like this "/" if looking from the end. The caliper appears to be fine, had to compress one piston at a time due to the size of the clamps I had, but they both went in easily. After a hwy driving loop, things appear to be better! Still going to do a proper bleed once the proper adapter shows up, weather permitting.

 

[BaconBandage]

Well, things didn't stay better for long... had to checkbook it, getting too cold here to wrench outside. Culprit ended up being the booster! And it was definitely affecting the fuel economy- did a short 10 mile highway drive at 70mph and gained 6mpg! And now it appears the exhaust manifold or gasket gave up.

 

[mrrsm]

Avoid trying to "Tighten Down the Exhaust Manifold Bolts ...just a little bit..." It won't work... those EM Bolts have been exposed to way too much Cold Weather, Road Salt and Electrolytic Corrosion...and they will Snap Off like #2 Pencils. The Flange line of your EM has also had the chance to Warp as well... and aligning the Flange to the Aluminum Head can be problematic. It will be very likely that more than one of the EM Bolts... have broken off.

If you wind up replacing the Stock GM OEM Exhaust Manifold with the usual available one produced by DORMAN.... Please know that the Flanges on the New One will be approximately (5) MM THICKER. As such... The Stock M10 EM Bolts will NOT hold the DORMAN EM onto the Head very well. DORMAN does make some M10 X 1.25MM X 35 MM Replacement Bolts that are better suited for this purpose.

But... if you want some Larger Head Surface Flanged Bolts ...you can also view the Link below of my Photo-Bucket to get the Specs and Part Number for these necessary fasteners and look at the DORMAN Exhaust Manifold Kit and Google for suppliers:

http://s557.photobucket.com/user/60...INEREPAIR/DORMANEXHAUSTMANIFOLD?sort=3&page=1

..and just in case Photo-Bucket is Non-Responsive, here are some images of the data on these 10.9 Fasteners:

 

[BaconBandage]

Yeah, I'm well aware of the bolts being a problem- I'm waiting until spring to do it for that reason alone. Well, that and warmer temps. Luckily I have another vehicle to drive at that point, it's just not that good for snow.