my brakes SUCK

[iangoround]

For a while now I've had a pretty crappy pedal. Making a panic stop is pretty much impossible because the pedal will travel to the floor and the idiot light will come on before the brakes lock up, unless I pump the pedal a few times.

I just got finished replacing all the E brake cables, adjusting the rear drums, and I installed a fresh set of rotors and pads on the front. The front rotors looked a little pitted and glazed, looked kind of like grease had gotten on them.

Absolutely no change in the pedal. What gives? The calipers aren't frozen or leaking. The wheel cylinders didn't look like they were leaking. My next step is to replace the front two flex lines as one of them has a nick in the rubber showing the stainless underneath. I'll flush the brake system when I do that tomorrow.

Aside from those rubber lines and crappy contaminated brake fluid (I've never had brake fluid get THAT bad before), what else could be causing this?

Oh, its an 85 laser. Front brakes are off my 88 shelby z, rears are the stock drums. The MC in the car has a big 1 stamped on it, and the MC in my shelby z has a 7/8 stamped on it, so the MC shouldn't be too small, right?

[iangoround]

Does that 1 mean 21mm and the 7/8 mean 7/8"?

Are the shelby z calipers really big enough to need to swap to the larger MC?

[Capt'n Dave]

sounds like you need to bleed or replace the Master cyclinder,let us know if that takes care of it!

[AllYourBase2101]

Sounds like a problem I had in my 86 firebird a while ago. Brakes were weak, and didn't lock up. You may want to check your brake booster, that was the problem with mine.

[ShelbyZD]

The front rotors looked a little pitted and glazed, looked kind of like grease had gotten on them

That sounds to me like they are glazed aka ruined. Don't know about the pits especially.. but glazed rotors definately have a greasy color to em. Granted.. brand new rotors could have that look too.. heh As long as your sure they aren't glazed that's all that matters.

From my experience a problem at 1 brake could definately make your brake pedal feel soft.

Also you didn't say anything about bleeding your brakes... ... although Im sure you did.

[iangoround]

The MC shouldn't have air in it, but just for the heck of it I'll replace/upgrade to a 24mm MC to provide for future upgrades. Might pull the booster off my shelbyz too.

If I had the money to rebuild the rear calipers from the shelby i'd just go to 4-wheel disc tomorrow. ah well...

[iangoround]

Brakes were bled last time the system was opened up. I replaced the rotors because they were so glazed. New rotors were given a health bath of brakleen and a wipedown before they were installed.

Like I said, tomorrow I'm going to replace more stuff just because/make room for upgrades later and flush the system completely with some spiffy synthetic brake fluid. I'll recheck the rear wheel cylinders and replace if needed also.

[tryingbe]

If I had the money to rebuild the rear calipers from the shelby i'd just go to 4-wheel disc tomorrow. ah well...

Costed me $14 to rebuild my rear calipers, but I have the internal drum rear disc, not the stupid 87/88 rear calipers with the e-brake built into the calilpers.

[butchsuppe]

Anytime the red brk light comes on means a LOST OF HYD. PRESURE in the brk. sys. check out this site to learn how to diag. the sys. http://www.aicautosite.com/garage/garmenu.asp

[turbovanman²]

Sounds like a bad MC.

[iangoround]

I replaced the cracked flex line up front and re-bled that side, it seems a little better. I checked the rear brakes more closely when I replaced the uber out-of-round drums. Wheel cylinders look like they are leaking a little bit so I got a new set and brake shoes. Also splurged the $40 on a new 24mm master cylinder with the reservoir and everything all attached. That might go in if doing a full rear brake job doesn't help. I realize that its probably a bit large, but I do plan on going with rear discs when spring really decides that it is here.

[iangoround]

All better. Redid the back brakes and replaced the MC. Old one was leaking. So thats two wheel cylinders and a master leaking. boy...

Pedal is super firm with the 24mm mc. Did a fluid flush too. Stops on a dime now. yee haw.

[turbovanman²]

I am so glad you bought a new MC.

Its common on older vehicles, with old fluid etc, you change one item and then a snowball effect happens.

[iangoround]

Yep, everything is brand new except for the drum adjusters (cleaned em up nice and good, just like new) and some of the brake lines.

I forgot who, but someone once posted something on some forum somewhere about spinning the wheel cylinders off the line instead of breaking the line. BEST IDEA EVER. After some convincing with the propane torch they spun off and then I was able to make the nuts on the ends an offer they couldn't refuse.

All in all, it was a fairly enjoyable job. It was 60 here today and I was outside working in a t shirt. Now that the brakes work, I can fix the wastegate and go fast again!

[turbovanman²]

^^That idea could have been mine,

[slasky]

I am so glad you bought a new MC.

Its common on older vehicles, with old fluid etc, you change one item and then a snowball effect happens.

+1

What usually happens is the MC piston only travels a short distance instead of its full travel. Over time crap builds up in the area where the MC piston has not moved past. Now when you bleed the brakes, your foot goes to the floor which causes the piston to travel where it has not been in quite some time. The seals on the piston get torn up from all of the crap that has built up in that area. So soon after you end up replacing the MC because now it leaks.

[Tony Hanna]

+1

What usually happens is the MC piston only travels a short distance instead of its full travel. Over time crap builds up in the area where the MC piston has not moved past. Now when you bleed the brakes, your foot goes to the floor which causes the piston to travel where it has not been in quite some time. The seals on the piston get torn up from all of the crap that has built up in that area. So soon after you end up replacing the MC because now it leaks.

That's why I always throw a board or something under the brake pedal when bleeding the brakes. It limits the travel so the seals don't get pushed through that crap.

[butchsuppe]

Now that your brks are good do yourself a favor and flush the sys. once a year and they,ll work right for many, many years.

[iangoround]

^^That idea could have been mine,

If it was, thanks!

Now that your brks are good do yourself a favor and flush the sys. once a year and they,ll work right for many, many years.

System was completely flushed out with some fancy Valvolene synthetic brake fluid that claims to be better that dot4. It was on sale. This was my first major brake job with this car. I figure every time I do the drums (if they stay on that long) I'll flush the system out. The back brakes on my old acclaim were similar and lasted about a year and a half before they needed new shoes.

[slasky]

I really need to do the brakes on my charger. My daytona, which I just got last november, has not moved out of the driveway and it has new brake hoses, pads, calipers, rotors, and new fluid. I am embarrassed to say I have never touched the brakes on my charger and it is in the 11 second range in the 1/4 mile. In my defense, our track has a very long shutdown lane. I learned to appreciate that when I went to LVD and almost hit the dirt pile at the end of the track.