So my brakes seem messed up. When I drive my car for the first time in the morning, the brake pressure is fairly firm, but by the end of the day I am basically putting my foot through the floor. Then this process will start over the next day. My break light and ABS light come on every once in a while. What do you think this could be?

2/3/2008 7:56:08 PM

old contaminated brake fluid and something in the brakes causing excess heat (and boiling the fluid) maybe?

YEAH MAKE MODAL?

2/3/2008 8:36:32 PM

tr00.

check fluid.

then bleed the brakes.

then set it on fire

2/3/2008 8:38:21 PM

it is a '95 tahoe Z71. i had the brake fluid changed and the brakes were also bled. should i take it back for a refund/for them to fix?

2/3/2008 8:46:25 PM

when was this?

2/3/2008 8:54:14 PM

i had the work done about 2 months ago

2/3/2008 8:58:37 PM

were you having a problem before then?

2/3/2008 9:11:01 PM

i bought the car about 3 months ago, then the brake light came on a month after and i noticed the brake pressure was getting very weak, i took it in and the brake pressure is better now then it was, but still is not great and it weakens throughout the day

2/3/2008 9:13:50 PM

well are you sure they bled the brakes when they changed the fluid?

2/3/2008 9:17:06 PM

yah. either take it back to them.

or bleed them yourself.

if that doesnt work you need to look at brake parts. its a 1995, if the brake system hasnt been checked out im sure it needs to be.

2/3/2008 9:47:06 PM

this is a common issue with 88-98 gm trucks. you will especially notice the stiffer pedal in colder weather when you first start driving. the problem is the seal in the master cylinder. you can get a new master cylinder and it will help this particular problem, but the brakes are still going to always inherently suck on those trucks.

they also have problems with the diaphragms going bad in the boosters, but yours sounds more like the mc from your description.

[Edited on February 4, 2008 at 12:03 AM. Reason : mc]

2/3/2008 11:59:23 PM

make sure the rear brake cylinders are not blown out.

2/4/2008 4:07:14 PM

^^what he said

2/4/2008 4:09:07 PM

^^surprisingly he's right. replace both wheel cylinders even if they aren't leaking. i'd put money that's the issue.

2/4/2008 5:32:12 PM

no, it's a retarded answer from him as usual. blown out wheel cylinders aren't going to give you a firm pedal sometimes and no pedal at others.

2/4/2008 5:43:53 PM

i beg to differ since i had this same exact problem on my old pos. i couldn't figure out for the life of me what the problem was (same situation as op). finally i said fuck it and replaced both wheel cylinders and the problem went away and brakes were like new. didn't make any sense to me especially since they weren't leaking but ill be damned if it didn't fix it.

2/4/2008 9:14:41 PM

durr what else did you have to do when you replaced the wheel cylinders???? bleed the brakes

im just sayin

2/4/2008 9:50:55 PM

trust me. i became a specialist on bleeding brakes. have fun trying to bleed brakes on a 88-93 w/ rear abs. the only way i found to efficiently do it is to gravity bleed it. i tried it all and that was the only way to do it effectively.

2/4/2008 9:54:26 PM

so what could have likely happened to the original poster when he took his truck in to have the fliud changed and the brakes bled is they actually changed the fluid in the res. and failed at sufficiently bleeding the brakes. hence the reason he still has the same problem.

2/4/2008 10:01:34 PM

ahhh, good possibility, but i doubt it since he has a '95 which has 4-wheel abs.

i know on the kelsey-hayes rear-wheel abs you actually have to cycle the abs in order to properly bleed it unless you can get it to gravity bleed. even then you risk leaving an air pocket in the solenoid.



[Edited on February 4, 2008 at 10:11 PM. Reason : -]

2/4/2008 10:09:01 PM

Quote :

"didn't make any sense to me especially since they weren't leaking"

then they weren't blown out, which is what drunkwrecker96 said. any wheel cylinder that's blown out (i.e. the seal is gone) is going to give you a soft pedal all the time because it's pissing fluid.

i can almost guarantee you what happened with yours. the wheel cylinders were sticking, causing a loss of fluid flow and thus a stiff pedal. when they would free up, you'd get the softer pedal. however, due to the cylinders sticking the shoes also weren't self adjusting properly (if at all) giving you the foot to the floor feeling.

Quote :

"have fun trying to bleed brakes on a 88-93 w/ rear abs. the only way i found to efficiently do it is to gravity bleed it. i tried it all and that was the only way to do it effectively."

yep, definitely a pain (as are a lot of early rwabs only trucks, not just gm). i've found that parking it on a hill or getting the back WAY up in the air helps along w/ a vacuum bleeder.



[Edited on February 4, 2008 at 10:20 PM. Reason : also, wheel cylinders are nearly as likely to trip the abs/brake light unless they're leaking bad]

2/4/2008 10:13:41 PM

Quote :

"i can almost guarantee you what happened with yours. the wheel cylinders were sticking, causing a loss of fluid flow and thus a stiff pedal. when they would free up, you'd get the softer pedal. however, due to the cylinders sticking the shoes also weren't self adjusting properly (if at all) giving you the foot to the floor feeling."

that does make sense. i had just got so fucking aggravated with it that i just started replacing shit since nothing made sense anymore.

haha, but no more! My God i love my new shit!

2/4/2008 10:23:11 PM

ivan is just making shit up to sound smart. i know because im smart.

2/4/2008 10:44:10 PM

yeah, i had to get creative. i was going to go with the whole fluid thing, but you already took it damn it.

2/4/2008 10:54:31 PM

poor brian, he had to pick up slowblacks sloppy seconds!

2/4/2008 10:55:31 PM

ill suspend every motherfuckin last one of you.

2/5/2008 9:17:48 AM

bitch be cool!

2/5/2008 10:01:41 PM

My new project: Replace brakes and Rotors

1997 Saab 900 SE Turbo 2.0

http://www.autopartswarehouse.com/details/QQSaabQQ900QQPBRQQBrake_Pad_SetQQ19971998QQW0133-1618546.html
+
http://www.autopartswarehouse.com/details/QQSaabQQ9-3QQBremboQQBrake_DiscQQ19992003QQBR25519.html

= 140 shipped.

Then take them to a shop to get the new rotors 'roughed up'. Pay my friend a sixpack of newcastle to show me how to make it all work.

Sounds good eh?

4/28/2008 3:43:43 PM

^^^ LOL

4/28/2008 4:46:53 PM