thunder85

iTrader: (1)

here's what i got.. brakes felt weird, so i went with steel braided lines, completely bled the whole system till i had all clear fluid with no bubbles. master cylinder appears to be in decent shape. vacuum assist seems to hold vacuum.

i cannot lock up my brakes. i have to press really hard to stop quickly. i mean hard... i'm a big dude so when i'm straining, its not a small thing. its like my vacuum assist isn't working.... when i am going fast, its easy to slow down to around 20-30 quickly.. but after that i have to strain to stop quickly. and no matter what speed i am going, i cannot lock up the wheels. all the calipers move, i have checked them with the wheels off. what is the probability that my vacuum assist is shot, and how would i test it?


thanks all... i'm trying to get ready for a trip to florida, and its one thing after another. you have been a great help, and i really appreciate it.

thunder

ps.. on a side note the more research i do on the boards, the more i find people with the EXACT same problem. all of the posts i find talk about it, but none offer the solution. any of you who had this issue, and did end up solving it, please post.

thunder85

iTrader: (1)

update: per some old posts, i have checked my booster and it holds at close to 15, but only works for about 1 pedal after the engine is off... well, about 1 and a half.

i have read where people refer to something called "glazing" but i don't know what that means... can someone help me out here?

di11avou

iTrader: (1)

I know what you're talking about. My car is the same way and I'm starting to think that's just how these cars are. I've also read many posts from people with the same problem with no real solution.

I've replaced every brake component except the brake booster, master cylinder, combo valve, and a couple hard lines. I'm going to try a new master cylinder as soon as I get my car out of storage. If that doesn't work, I'm going to start looking into the LS1 brake kits. I'm sick of dumping money into the crappy factory brakes.

Glazing is caused from overheating the friction surfaces creating a very smooth coating on the pads. If your brakes look like they have a cloudy/glassy finish, they are glazed. Hit the pads and rotors with some sandpaper to get rid of it. 150 grit should do.

thunder85

iTrader: (1)

yeah... i have read numerous posts... no answers. i have been told that the LS1 master cylinder is a direct fit, so if you upgrade be sure to snag one of those. if nothing else, having a screw cap instead of that goofy rubber thing and metal cover will be a beautiful thing.

on a side note check out the post on the brake board called "prop valve question" the one guy has pictures of his excellent setup using an ls1 booster, no factory prop valve, an adjustable for the rear and a line lock selenoid. i'm probably going to do that next month.... screw this old outdated crap.

Cadillac

In this case, a picture may say a thousand words (see attached). The rotor on the right is the stock size I had on my car originally and the other is, well... better.



Before I swapped to the LS1 brake kit I couldn't get my car to lock down. It was kinda scary. In contrast, my wife's Volvo had the best brakes ever on it and I was sick of being jealous. I swapped to the LS1 kit and then eventually changed my rear axle upgrading the drums to disks on all four corners. With a new prop valve and MC, the car stops on a dime now.

In short, the price on all that was roughly 2.5K but that also got me a posi and better rear end gears along with the better braking.

Priceless.

thunder85

iTrader: (1)

thats what I figured. the thing that startles me is why nobody can get our factory brake systems to work right. it makes no sense to me that my POS rusty beat to death winter rat truck has better stopping power than my sports car. thats just messed up.

on a side note, i already have 4 wheel disk, a posi and 3.23 gears. is there a brake hardware upgrade that is cheaper but offers better technology than i have now? i can't afford 2.5k right now... but am willing to pull some things off in order to be safe.

Cadillac

I'm by no means an expert here (Ed is) and I was just explaining my situation which seemed similar and how I fixed it. Seems to me that with the disks you already have you could be looking at a failing MC. They fail in strange ways in my experience...

Have that checked lately?

thunder85

iTrader: (1)

huh. the only way i have experienced a failing mc is when you push on it, and it slowly starts to sink to the floor. u think maybe its just not generating the pressure its supposed to be? with the installation of my new brake lines and such i bled the mc again (cleaned out all the gunk in the resevoir) and purged it till i had all clear fluid... i did this to the rest of the lines so i was operating on new lines, and fresh clean fluid.

i guess i am lookin at a new ls1 master cylinder. when i get back from florida, i am going to throw one in and see how it goes.

ps. those new rotors look freakin AWESOME

383GTABoy

Im in the same boat as you thunder. I have had weak brakes for about 3 years now. It helped a little bit to add a vacuum reservoir but when I want to lock them up I have to realy slam on the brakes hard. I have already had 2 post going trying to solve this problem. If ya find the answer please please please post back.

I wish I cold get brakes that big. Stupid GTA rims

cooter26

iTrader: (1)

There is definatly somithing amis with your system. An easy check on the brake booster is to disconnect it and plug the engine side. I know you said you pelaced the lines with steel braided, was that all the lines or just at the calipers? They make a tool to check the rubber lines that pinches them off 1 at a time untill u find the culprit. I am not sure how you would do this with steel braided. I am curious how you blead the brakes, If you did the guy in the car pumping method you could have easily missed some air. If you dont have a vacume pump, the best way is to gravity bleed starting from the farthest from the MC and working to the closest. I am not sure how ould your calipers are but the seals can start to deteriorate and cause air to get in, just because they move and you dont see fluid dosent mean they dont leak.
Good luck at troubleshooting.

vortec350s10

I have the same problem with my brakes, and I have just swapped over to LS1 rears and also swapped over to an LS1 master cylinder. I had my stock MC off the car and drained and never bench bled it, so I though that was the problem. So I bench bled my LS1 MC before putting it on and I still can not lock them up, but I am closer. I can do it on sandy tar now at least. You may just have some more air somewhere. I might too because when the engine is off with no vacuum left the pedal gets firm, but you can still push it down another half inch. In my sonoma with awesome stock brakes the pedal is firm and doesn't budge any further. More air somewhere???