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Rear brakes not working at all

10K views 26 replies 6 participants last post by  ErickSaint 
#1 ·
2007 LT3 3.9L

So for a while now I've had a rubbing sound coming from my brakes. This past weekend I did rear struts, pads and rotors. I found out the passenger side parking brake was sticking. After not being able to find the parking brake rebuild kit in stock locally, and having a wedding to get to, I put that side back together without the adjusters or parking brake pad. Convinced this was the cause of the rubbing sound finished up the brake job and put it all back together. Took it for a drive and it's still rubbing someplace.

Fast forward to yesterday. I had new rear end links coming, so I pulled the wheels off to get them done. This is what the rotors look like on both sides, after about 100 miles, give or take a few. They don't even look used. The pistons compressed just fine when I went to fit them for the new pads, so I don't think they are seized, and definitely not sticking. Now before originally putting the wheels back on after getting everything back together, I spun the rotor, and there was a little bit of a rubbing sound on both sides, just chalked it up to new pads and rotors, and figured it would go away when the pads bed in a bit. When I took the wheels off yesterday and saw this, I did the same, same slight sound when I spin them by hand.

Now admittedly I do need to change the fluid, I sucked some out of the res today and it's dark like tea, and do a complete bleed/flush. But I'm not convinced that's the true problem. How do you perform a diagnosis on the master cylinder? I have a funny feeling that's where my problem lies. What are the odds of both calipers having the same exact problem, at the same time?

Thanks.

 
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#2 ·
I'd just drive a few thou and check again. changing the fluid is always a good idea. I don't think you can see a lot of wear in 100 miles and there probably hasn't been any detectable wear. there is some sort of proportioning valve in the brake system that regulates front to rear braking. I don't know where it is on the impala. On older cars it used to be part of the valving underneath the brake fluid resevoir. Usually the proportioning is way biased to the front and your rear brakes last 2-3 times as long as the front. maybe mark the rear rotor with a magic marker or something and see it it gets rubbed off, if you just want to make sure the pad is contacting the rotor.

back in the day, I used to change the proportioning to 50/50 but the rear brakes still lasted a lot longer than the front.

I like changing brake fluid by using speedbleeders and ATE brake fluid. Easy for one person for 90 percent of the work. then bring the wife/GF for the final pressure bleed.
 
#3 ·
I'm going to try changing fluid and bleeding this weekend when I change the rear sway bar bushings. In the meantime I'll try adding a sharpie line to the rotors. But I still hear that rubbing sound every time I drive. Guessing it has to be on the insides because there is still zero wear on the outside even after another 100 mile road trip this past weekend.
 
#6 ·
ok, missed that in your opening line....you heard rubbing before and after new brakes. assume then you have many miles on the car. seems to me the noise is more like wheel bearings. coasting fast downhill in neutral, do you still hear it? if so, apply brakes lightly-noise change? do you notice a whu-whu-whu character to the noise?

Its possible that with such old brake fluid the accumulation of water in the fluid turns quickly to steam (a gas) and it would not compress the brakes rear pistons enough to provide braking action. (little known fact: brake fluid attracts water vapor from the atmosphere and pulls it in through the molecules of the brake hose. Its why brake fluid has to be changed periodically.)

bottom line - you may have a couple of things going on that are not totally related.
 
#7 ·
Car has about 148k miles. Yes, I did hear the sound for that last month or so, before changing pads and rotors on the 18th, just wrote it off as needing to replace parts. The sound is there most of the time, but lately not every time. Hard to explain. Sometimes from a stop I'll hear nothing out of the ordinary. But only sometimes. More often than not I hear the rubbing. If it is rubbing, it's no matter if I'm coasting, in neutral or in gear, when I apply the brakes there is zero discernible change in sound other than no noise while stopped. Not a wobble sound or weird rotational sound, I've had hubs go bad, this is more rubbing than a bearing going out.

The thing that had me thinking braking system is this, when I lift the car and spin the back tire or rotor with the tire off, I hear a very similar sound just not as loud, probably because it's not under weight or as fast. If I pull the caliper off and spin the rotor there is zero rubbing sound, it just spins like you'd expect it to. When I did the pads and compressed the cylinder in the caliper for the new pads, it compressed just fine. But the sound is almost like the caliper cylinder is putting just enough pressure on the pad to make a noise, but not putting any pressure on when the pedal is pressed.

I'm going to try to get the fluid changed and the brakes bled this weekend if time allows. Hopefully that will shed a bit more light on things. My pedal is a bit spongy, but it's been like that since I got the car. never really had a very firm or hard pedal in the time I've owned it.
 
#9 ·
Thought so too, but it seems to be coming from both sides. So I was questioning the odds of both calipers tanking at the same time. That's what made me start wondering about the master cylinder being dodgy. I suppose if I took the calipers off and started pumping the pedal I should see them close after a while.

Bottom line is I just need to find the time and start trouble shooting more things.
 
#10 ·
You didn't happen to just push back the caliper piston (the old way) with a c-clamp etc. to make room to install the new pads did you?

You may have damaged the caliper thus no rear brakes.

Remember the rear caliper pistons on these newer GMs require you to use the "tool" to TURN the pistons back into the caliper body for new pad install clearance.
 
#11 ·
Sure did just push it in with a clamp and an old pad. I'm almost 100% certain that these are not the turn in/out calipers in this car (2007). I've done the rear brakes before this way.

Pretty sure that the turn in kind will not let you even press in the cylinder with a clamp, unless you are way over cranking on it. I barely had to use any pressure to push it in.
 
#12 ·
Yeah, I don't think ALL of the 8th gens have the turn-in kind in the rear. If they were the turn-in type, I think it would be pretty obvious (they look different than the push-in type) and like mentioned, I don't think you can just push them in so easily like you did.

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#14 ·
Yeah, that's not the turn-in type then. The turn-in type are no hollow like a normal caliper piston. They have notches in them that the cube tool uses to get a grip on them.

I think you did it correctly. The turn-in type probably appeared after your car was made.

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#17 ·
Actually, some 8th gens *do* have the turn-in type - mainly the newer ones (not sure what year it started though). My 2012 rears are the turn-in type.
FWIW, my 07 Pontiac G6 has the turn-in type while my 07 Impala SS does not.

Fortunately, when I put rears on my G6 a few years ago, I managed to sort it out without destroying the caliper with my C-clamp :) IIRC, I bought the cube at Pep Boys for about 10 bucks.

Doug

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#19 ·
I could be wrong, but I *believe* that cars without dedicated e-brake shoes in the rear have the turn-in style. I *think* that when you press the e-brake, it "manually" tuns the caliper piston to make it apply the e-brake (via the regular brake pads).

So, if you have e-brake shoes in the rear, my guess is that you have the push-in style caliper pistons and if not, you have the turn-in style caliper pistons.

At least that's my theory and I'm sticking to it! :)

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#24 ·
I could be wrong, but I *believe* that cars without dedicated e-brake shoes in the rear have the turn-in style. I *think* that when you press the e-brake, it "manually" tuns the caliper piston to make it apply the e-brake (via the regular brake pads).

So, if you have e-brake shoes in the rear, my guess is that you have the push-in style caliper pistons and if not, you have the turn-in style caliper pistons.

At least that's my theory and I'm sticking to it! :)
Correct. The turn-in type use the regular pads for the parking brake function. So there's no extra shoe needed.

Doug

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#21 ·
Not me - I'll take disc brakes over drums any day! :) Disc brakes are *so* much easier to deal with... And I think that they generally perform better as well, which is why every car nowadays has disc brakes in the rear!

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#23 ·
Either which way, when you do a brake job, brake cleaner is your friend. Use brake cleaner, never blow off anything with compressed air as brake dust can be toxic and bad for you! Brake cleaner has so many other uses than just brakes also, good stuff to keep around. Just don't use it to clean anything in your induction system.
 
#25 ·
Brake fluid change done. Everything bled. I don't think there is anything wrong with the rear system. A few days ago I wrote the date on the rear rotors with a sharpie, it was barely noticeable when I pulled the tires off today. So it must be compressing. Rear calipers bled fine, but I'm not sure if they still bleed right even if the caliper is shot. There was a ton of air that came out with the junk fluid when I bled the first caliper.

Found the cause of the rubbing. Not the rear brakes at all. Both dust shields behind the front rotors were rubbing on the back side of rotors. They must have gotten bent to hell when I did the front struts a couple months ago.

The parking brake is still disabled on one side because I wasn't smart enough to get to rebuild kits before I took them all back apart this weekend.

Now I need to to find out my rear sway bar size. They gave me the complete wrong set so I couldn't replace them today while I had everything apart. They originally gave me a front set. And the ones they gave me in replacement are for a 16mm bar. They said there was also an 18mm bar, but I have no idea what mine is. There is zero info about suspension on the door sticker and I have no idea how to figure it out based on VIN.

Any chance somebody has some tips on the bushing size? It's likely the last thing that needs to be done back there. Unless maybe the trailing arm bushings are shot too.
 
#26 · (Edited)
measure the bar so you know what to look for. 16mm is .6 or just over a half inch. 18mm is .7 or just under a 3/4 inch.

find your spid label in the trunk - its a list of codes for the composition of the car. you are looking for codes fe1, fe2 or fe3. tell me which one you have in the list and the year of your car and I can look it up on my parts list document. I'm assuming you are looking for the part number of the rear sway bar bushings.
 
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