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Weak brakes

1588 Views 7 Replies 5 Participants Last post by  Schurkey
Lately my brakes have felt really weak. At first it just seemed that way when they were cold and got better after a couple hard stops, but now they are weak all the time.

From low speeds even considerate force applied results in the car slowly creeping to a stop...put it this way if I were following someone through a parking lot at a reasonable distance and they stopped suddenly, I'd prolly end up rolling into them.

Fluid levels are normal. Pads are about half gone, still a lot of pad left.

Other than bleeding them, what should I start looking at?

The brakes do have enough force to hold the car for a power brake, but actual stopping is what seems off.

Thanks for any advice!

PS: pedal feel is normal and doesn't go excessively far to the floor or anything
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thanks guys, I'll check the pads and scuff them up

for what its worth, the right front was making noise but I couldn't find any reason, that has went away now

its possible they might have glazed recently...I had a pretty bad day and went for a very spirited drive on some winding backroads and I was hard on them once or twice
Well it turns out the brake booster has had issues since I first installed it 8 years ago.

It was new in the box and the pedal had assist and everything, but the brakes never seemed as good as they should (e.g. would not lock on dry pavement no matter what) but worked well enough I could write it off.

I had also been searching for a vacuum leak most of this whole time which was always messing with my carb jetting and efi tunes.

Well after doing a head cam swap on the ls1 recently, there was a squeal coming from under the hood. I feared alternator or pulley damage during the dis-assembly process or something like that. But then noticed it would squeal for a couple seconds after killing the car.

The pedal would still have some power assist in the mornings. But the closer I listened to more it seemed like it was coming from the booster. So I reluctantly ordered one for $95 shipped on ebay. Put it on yesterday and it's a whole new more idle hunts even on a cold start. I put it in gear and was amazed I had to completely lift off the pedal before the car tried to roll.

First couple times I tried to brake I nearly through myself into the steering wheel. Pedal feel is now a little firmer but consistent all the way instead of almost weightless for the first half then applying firm. The old booster was installed during a disc swap so I just assumed that's how it was supposed to be. Since it was new I never pointed my fingers back to the booster. I have literally replaced or swapped every other component: calipers, pads (tried 3 different brands), dot 4 racing fluid, checked lines, replaced blocks/valves, rear disc swap, and about 5 different master cylinders.

Lesson learned...out of the box brand new (not even rebuilt) should not be of much comfort when troubleshooting.

Now that the 1 thing I've never been happy with about the car is working superb I feel like a million bucks.
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That was the intention, I assumed falsely it was the type of thing that worked or didn't.

Drove the car some more today and it feels entirely different. Brakes come on a lot sooner in the travel and pedal feel is much firmer and constant. Idle hunt is back but I'm guessing that is the EFI which was tuned with the leak trying to regain it's qualities caused by the leak.

I will report back after a retune of the VE tables and idle tables. A simple battery disconnect and idle relearn could even cure it.
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