October 24, 2010Hello everyone. I have read many posts on these trucks and their soft pedal problems and now I have to add to the list.
My grandfather has a 95 C1500 Silverado (great shape,120,000kms,original owner)that I cannot get a firm brake pedal anymore. It started in the spring when I used the truck and noticed the soft pedal and that the pedal would slowly drop to the floor which usually means that the master cylinder is bypassing. We have since tried 2 new master cylinders(rebuilt units have not worked well for me),and a known good master cylinder off my 96 Z71. Each time the master cylinder was bench bleed,bled at the ports and at each wheel till all air bubbles where gone.
The truck has new rubber flex lines,calipers,pads,steel brake lines,wheel cylinders,shoes and the shoes are adjusted good.
Then we tried plugging ports from the master cylinder(with the engine running);plug both ports=firm pedal,plug the front brake port=firm pedal,plug the rear brake port=really soft pedal. That test means that the problem is in the front brakes.
After reading some more posts and talking to a buddy mechanic, the only thing left is the ABS unit(and the truck does have its ABS dashlight on).So I removed the whole ABS unit, ran some new lines,rebled the master cylinder, all the rest of the system and guess what,still a soft pedal!
Last night was when we changed the calipers and saw no improvement. So we once again bench bled the master cylinder.This time one guy pushed on the piston while the other guy tapped on the cylinder to try and remove any trapped air bubbles.It took us 10-15 minutes but I was amazed at how much air was still in the cylinder after I thought it was bled good. Now I`m thinking that this must be my trouble all along. Put the master cylinder back on,rebled the brakes and STILL a soft pedal!
We decide to rebleed the brakes again only to find that now we are unable to get rid of the air bubbles to the calipers! It never did that before.
I HAD TO WALK AWAY!!!!
To add to this problem,last week I tried to replace my old stainless flex lines on my 96 Z71 with new ones only to find that both front flex lines leak.So much for being a quick job.I then put the old flex lines back on and spend TWO days trying to get my firm pedal back.I take the truck to a garage of my buddy to see if I missed something.They bleed the brakes and find no problems.They look it up on their computer and see that the ABS unit caused the same problem,This is where I got the idea to bypass the ABS unit on the 95 truck.Anyway the brakes on my truck are alot better but still not as good as they were before I started to change my flex lines.
To add to the rest,my 97 Honda Accord has the same exact problem,soft pedal!!! New MC,no leaks,no ABS.
So, 3 vehicles with the same problem,am I that lucky?
Sorry I wrote so much, I did not plan to.If anyone has any ideas please post them before I lose my mind, and thanks in advance to anyone who does.