Firm

Drove my wife's 96 Firebird (3.8, AT) today after driving around for the last couple of days in my 97 SS and noticed a big difference in the amount of pedal travel in the Firebird, the brake pedal goes through about half (maybe more) of it's total travel range under normal braking, whereas the SS barely feels like it moves at all. The Firebird does stop pretty good...just takes a lot more pedal travel to do it.

I figure it's safe to say that the Firebird brakes need some attention, but I am not an expert and don't want to just start throwing parts at it so I figured I'd ask here and maybe get some help pinpointing the issue before I start in.

Firstly, the front brakes haven't been done in a number of years, but visually the pads have maybe 40% left, and the rotors look pretty good still. The rears (Drums!) were done (at a shop) last winter since a wheel cylinder started leaking in the middle of February and it was too cold for me to have any desire to work on it.

To help rule out the rears; my handbrake holds just fine, the lever doesn't need to travel much to "bite" and pushing the brake pedal with the handbrake engaged doesn't result in any difference in pedal feel.

I don't *think* it's a master cylinder issue since the pedal doesn't "sink" if I keep constant, even hard, pressure on it with my foot. Also, the fluid level is consistently on 'full', so no leaks.

So now I am thinking the issue is with the front discs. I recall looking at the pads when I last had the wheels off a month or so ago and noticed that one pad, inboard or outboard I can't recall, was worn more than the other. Some reading suggests that maybe the slider pins are seized and allowing the one side to drag? Would that cause the excess pedal travel I am getting?

As it stands my plan is to replace the front pads, rotors, slider pins and hardware and hope that does it.
Does my process of elimination here make sense? Anything else I can try to pinpoint the issue before I start? Any other tips?

HappySalesman

iTrader: (3)

While changing the hardware in the brakes never hurts, I don't think that's your pedal travel issue.

excessive pedal travel to me usually means there is air in the lines, or in the master cylinder. You can have a small amount of air in the master without having the pedal sink. I would bleed the master and then the brakes and see if that clears it up.

Firm

Thanks for the input man. I hate bleeding ABS equipped cars My working theory is that the seize sliders are allowing the caliper piston some extra travel before the pads make contact, hence the travel. Since the hardware is crap anyway, I am going to change it, and if that doesn't do it I'll start bleeding.

stp001

It could also be the front bearings are loosening up, causing the brake pads to be "knocked back". This extra movement back requires some "no resistance" pedal travel to bring the pads back tight prior to applying real braking force.

The old school rule of checking brakes for need of bleeding is that if you can double pump them up, they need bleeding. If pumping doesn't make a difference, look elsewhere. That's old school reasoning, so take it that way.

Firm

Thanks I'll check the front bearings as well.
For what it's worth, pumping makes no difference in this case.

TTur1996

Something people seem to overlook, is the rubber brake lines. They can be broken down and swelling. Which can cause a spongy brake pedal. When you bleed the brakes if the fluid looks dirty, its a sign your rubber brake lines are breaking down. But being the fact that you just had a wheel cylinder replaced I would lean towards air. Do not power bleed. Just crack, and only do one at a time, starting with the right rear, left rear, right front, then left front. Let them gravity bleed. (See what the fluid looks like.) If it looks dirty replace the rubber lines. ( all of them). Then Gravity bleed. Leave the lid off the master and make sure you keep it full. It takes a while but works perfect. Pumping the pedal never seems to get all the air out in most cases.

Firm

Thanks for the tip. When I put in my parts order for this I actually went ahead and ordered all new rubber lines, the stuff should all be here this week, so I'll tackle it in the next week or two.

What do you mean when you say "power bleed"

On the gravity bleed, are you only opening one at a time? How long do you typically need to let it gravity bleed for?

TTur1996

Power bleeding is pushing the pedal down pushing the air and fluid out. Problem is that sometimes the master will add more air. I'm not sure why, It just does. The best way to bleed them that I have found is gravity. The fluid moves very slow and drags the air with it instead of being pushed by, pushing the pedal down. Yes do one at a time. Sometimes it can take ten to fifteen minutes to start seeing fluid. But it will eventually get there. Usually only about five. I let each one drain the master down about 3/4's. Then refill and go after the next one. Has always worked perfect for me. I even have one of those mighty vac vacuum pumps. And this still works better. So don't waste your money.

TTur1996

Visually look at the fluid when it approaches the 3/4. Stare at it for a couple minutes. If you don't see any bubbles coming out you should be good to go.