brake problems

[Daniellane]

alright so my brakes were a little sluggish. me and my dad swapped the master cylinder cause we thought that would fix it. it helped none. after the swap the brakes on the front would barely bleed. so we got new calipers and shoes too. They bled with new calipers. but now the pedal is hardly sitff at all. when you press it it goes down then hits like a hard spot in the pedal and the brakes work but barely. i have to slam it with both feet to the floor to get it to stop. any ideas as to what the problem could be? please help before i go broke fixing this truck

[Restrorob]

You can gander at this thread until someone else that can help chimes in;

http://67-72chevytrucks.com/vboard/s...d.php?t=389290

Sounds like you may have the same issue.....

[Daniellane]

ive looked through that thread but he had no brakes. i have some when i push hard on the pedal. seems like im not getting enough pressure brakes to stop the truck

[JWall]

I know the rubber brake lines on the trucks collapse on the inside overtime & cause problems.
But generally this issue will cause the truck to pull badly to one side or the other.

[Daniellane]

yeah i doubt its that. my brakes seem like they dont have enough pressure on the calipers or whatever to make it stop faster.

[packers05]

I often find the metal hose support clamps have rusted so much that they squeeze the hoses on the front so tight that it causes reduced fluid flow to and from the calipers. To diagnose it try spreading the clamp so the hose is loose in the clamp and rebleed see if any change if so replace and replace if you nick the hose when spreading the clamps!!

[boogie67]

It could be your power booster is bad.I had a 97 like that and it was the power booster.

[Daniellane]

yeah. it seems like once you hit the stiff part in the pedal the brakes work but slighty. idk im not really a mechanic. im just trying to get good brakes.

[TennesseeZ]

Does your MC have the loops in the lines coming off of it?
If so, I've seen air get trapped in the loops when the MC was changed.

[Tinker1980]

I had this same problem. Brakes barely worked, pedal was squishy. I plumbed the brake line around the accumulator, and now the truck stops great. Nice solid pedal. If you want to keep your abs, and not redneck-up your truck, I think NAPA has rebuild kits for the Isolation/Dump Valve.

I'll try to post a pic of the part that was giving me problems:

[Daniellane]

mine is different from the picture. sorry i couldnt get a better view. this came off the internet because i cant find a camera to take a picture of my actual truck but this is identical.

[ChevyTech]

Once again we have a thread with NO VEHICLE INFORMATION which makes it hard to give accurate advice.

I did look at the other thread, referred to in the second post, which does show it is a 1998, which looks right for the photo of a vortec engine compartment posted above.

Nothing in the other thread will apply to this truck which should have 4 wheel anti lock and not RWAL.

First see if it has any trouble codes stored.
Information on reading codes can be found here:
http://www.aa1car.com/library/abs_kelseyhayes.htm


Next thing to consider:
Service Bulletin #02-05-25-006B: Antilock Brake (ABS) Activation at Low Speeds (Clean Wheel Speed Sensor Mounting Surface) - (Jan 5, 2006)

Subject: Antilock Brake (ABS) Activation At Low Speeds (Clean Wheel Speed Sensor Mounting Surface)
Models: 1999-2000 Cadillac Escalade
1995-1999 Chevrolet Silverado (Old Style)
1995-2000 Chevrolet Suburban, Tahoe (Old Style)
1995-2003 Chevrolet Astro Van, Blazer, S10
1995-1999 GMC Sierra (Old Style)
1995-2000 GMC Yukon, Yukon XL (Old Style)
1995-2001 GMC Envoy, Jimmy
1995-2003 GMC Safari Van, Sonoma
1995-2001 Oldsmobile Bravada

[Daniellane]

i dont get what your trying to say about my abs? mine doesnt lock down unless i slam on the brakes on mud or ice or somthing of that form. so my abs works.

[ChevyTech]

Originally Posted by Daniellane

i dont get what your trying to say about my abs? mine doesnt lock down unless i slam on the brakes on mud or ice or somthing of that form. so my abs works.

On several models of GM trucks, the front wheel sensor issues can cause the system to detect that a wheel has stopped turning (is skidding), when it is not, which can cause the antilock system to release brake pressure to at least some wheel/wheels.

Longer braking distance can be cause by wheel sensor issues. This does not mean your truck locks up a wheel.

Do a search.

Find the bulletin.

Read it.

See if it seems like it could be the problem.