knucklebust

1999 Silverado, 4X4, Z71, 5.3litre (323 c.i.),automatic, new style:

I started to change the rotors, found the backing plates all rusted to hell, got sage advise from this forum for how to do that, but not gonna take the axles out just yet to change backing plates, gonna wait until spring, sooo...
I changed the rotors, got it all back together, then drove her down the road. Left the windows open in case of squealing or scraping. No noise. Yay! But when I take my foot off the gas, it feels like it's dragging, like it's sluggish. I'm wondering what's causing it to bog down like that. I didn't change the pads because there's probably 60-75% left. Any ideas? Thanks in advance.

myotherchevyisablazer

did you bleed the system when you were done?

mudmaniac

Did you readjust the rear interior drums too much when you were removing and reinstalling them? If you only changed the rotors, bleeding shouldn't be an issues.

knucklebust

no need to bleed; didn't touch the hydraulic system. I changed the rotors. I decided to go with a quick fix instead of taking the axles out to get at the backing plates. I also decided to leaver the shoes out for now until I do it up right in the spring. So, no shoes to adjust inside of the "hat-rotor" which means they aren't causing any drag. I'm thinking one of the calipers isn't releasing all the way back. Any additional ideas are welcome and appreciated. Thanks for your input up to now.

racerx55

did you check that the slider pins arent froze on the calipers? Those always need cleaned up and regreased.
if you drive it dragging you will warp the new rotors really quick.

cam3439

When you let go of the gas, does it pull to one side or the other? When you brake, does it pull to one side or the other? One of the brake lines could be kinked or clogged and isn't releasing the fluid and thus is staying stuck closed. You might also be able to check this by having the wheels off and turning the rotor yourself while someone else periodically applies the brakes. If one side feels more sluggish than the other then the defective line might be the case. If this is the case, you will need to replace the line, and I would suggest changing them both to keep the brakes working evenly. Remember that if you brake and it pulls to one side then the defective line is usually on the opposite side.

knucklebust

To answer the last few posts: I checked the slider pins. They were still lubricated, but I cleaned and greased them. The lines are all in good shape; no kinks, corrosion or other obvious defects. No, it doesn't brake unevenly. It just drags. I left the emergency shoes off for now, so it's not them dragging. I have it up on jack stands now, and can turn the hub assemblies with the calipers pivoted up. When I put the calipers back over the pads, it's pretty tight and, consequently, hard to turn the hub assembly. I'm thinking that the piston is out too much, and maybe stays out too much when driving. Not sure if that makes sense, or if it does, how to remedy it. Ideas, thoughts, conjectures, all welcome and appreciated. Thanks for all the help thus far.

mudmaniac

2 thoughts, are you sure the rotors are the correct ones and if so then try depressing the piston all the way into the cylinder and then try it.

cam3439

I'd then follow Mudmaniac's post. Just an FYI, the lines don't have to look corroded for them to be defective. They tend to collapse inside with no signs on the outside, but USUALLY only happens to one side or the other and after a brake job. This happens due to the rubber brake lines being older and easily collapse due to being twisted, bent, etc.

knucklebust

Yes, they're the correct rotors. "Try depressing the piston all the way into the cylinder" with the bleeder valve open or closed? I'm guessing "open."
BTW: what will depressing the piston show me? How does doing this show me what the problem actually is? I'm looking for a causal chain to follow. For instance: 1)the piston is or may be gummed up from sludge in the line; 2)opening the bleeder valve and depressing the piston will force said sludge out of the line through the bleeder valve (leaving the bleeder valve closed and forcing the piston closed would send said sludge back into the hydraulic system); 3) the piston should now operate freely rather than getting gummed up and stuck. Is that about the size of it, or am I off base?
Thanks