I recently changed my rear pads and now my rear brakes are making a very strange noise when they are cold. It's like a howling hollow sounds. It's not screeching. Then after I brake a couple of times the sound goes away. It happens every time I start the car after it's been parked for a while. Any ideas ladies and gents?

 

What pads did you use?

 

Factory nissan pads. The rotors came with the car when I bought it used so I'm not sure about them.

 

Did you use any anti-squeal goop on the brake pads when you installed them and install the shims properly?

 

did you have the rotors turned?


And to ***** up this thread a bit, what is the point of the shims? Are they just an attempt to distribute the force of the caliper over the entire brake pad? My new pads didn't come with shims, and it would have been impossible to re-use my old shims (rusted, and wrong size), and I purchased a brake hardware kit from Napa, but it didn't come with shims either...

 

1. Do you use your parking brake?
2. When you replaced the pads, did you make sure you lined up the notches on the caliper pistons so that the nub on the pads seats in the notches?
3. Was the caliper piston hard to retract to make space for the new thicker pads?
4. After you reassembled the brakes with new pads and put the caliper pin back in, did you check to see if you could easily turn the rotor by hand (before putting the wheel back on). If you haven't tried that, you may want to do that. If the rotor doesn't turn easily with the wheel off, then your caliper is dragging.

 

I'm having brake problems. Is there a way to check if I have OEM Nissan pads on my front calipers without disassembling them? Do OEM pads give way better stopping power over others? Is it good I can push the brake pedal all the way to the floor at a stop light?

 

No. And even if you disassemble them I'm not sure if any markings will still be visible.

No. You probably have air in the brake lines. You should bleed the brakes (or have them bled if you don't feel comfortable doing it yourself).

 

From googling:

One big problem is that people tend not to retain the anti-squeal shims
(or don't replace them when they rust out) that are supposed to go on the
backs of the pads. The purpose of those shims is to change the vibration
frequency of the brakes so squeal is inaudible.

 

Wow a lot of responses so I'm going to go in order:
rmurdoch,

Yes I applied some b/w the shims and the pads and b/w the caliper and the shims. I used the red thick goop, like in the Chilton's manual.

Chickan,

No I didn't turn the rotors. What does this mean anyways? I did measure them and they are within specs.

njmodi,

1. Haven't tried it yet. I should test it out though...good point.
2. Yes. They would go in far enough without aligning the notch anyways. I learned the hard way...hehehe.
3. Yes. And the rubber boot would wrinkle a little before starting to rotate along with the piston. Then when I retracted the piston enough I turned it a little more (1/4 - 1/2 turn) so that I could then turn it in reverse to undo the rubber boot wrinkle (another 1/4 - 1/2 turn in the other direction).
4. Yes I tried and it was a little tight. Tighter than the front one's were when I changed them. But since the piston wouldn't retract anymore I thought that's the way it was suppose to be. I tried continuing to turn the piston to retract it but it appeared not to retract anymore. How can I fix this?

Black Maxima,

Your problem appears to be air in your brake lines or a leak. Is your brake oil level going down? The pedal should be soft at first and firm to a stop about half way down.

 

njmodi, thanks for the reply! I'll have to get some time to do it.

 

I have to push the pedal down pretty far, although it's very easy to push at first, it becomes firmer but never really feels like the pads grab solid.

I think my level is fine. I will check it out again.

 

Definitely sounds like you have air in the brake system. Bleed all 4 brakes and that should take care of the spongy pedal feel.

 

^bump...

 

Yup, my fluid level is fine. When I have some free time I will bleed the system with my dad.

 

Bump. Anyone...please.

 

Sorry for bumping again but I'm a little worried about my brakes since I'm driving on these suckers daily. I'm curious if anyone has any comments on my responses to njmodi below:

QUESTIONS:
ANSWERS:
thank you all.

 

^ Bump

 

1. Did you try the parking brake? Does it feel as though it is engaging and releasing without "dragging". It is a common problem for the parking brake cables to seize. The sounds you are describing are symptomatic of a binding caliper (either because the caliper is frozen or the parking brake cable is frozen).
2. You are sure you aligned the notch properly right? because if the notch is not seated in the piston groove the pad will not sit flat against the rotors and that will cause uneven wear of the pad and binding to some extent.
3. It is not uncommon for the boot to catch on the piston a little as you rotate the piston to retract it. Once you had the piston retracted far back enough to fit the pad, was the boot folded neatly? Did you have to really muscle the piston to get it to rotate?
4. It is hard to explain how hard the rotor should be to turn once the brakes are assembled, but the way you describe things, it sounds like you might have calipers that are binding. Try this, after going for a drive, come back and carefully touch the rear wheels. If they feel unusually hot, then the calipers are probably binding and you might want to replace both calipers.

Before you do anything, check to make sure the parking brake cable is extending/releasing when you operate the parking brake. If the cable looks ok, then the caliper is the problem.

If you get the groaning/sounds from the brakes every time you've let the car sit (without setting the parking brake), then I am inclined to lean towards seized calipers. If it only happens when you use the parking brake, then it could be either the cables or the caliper.

Since you just did the brake job, it would be wise to diagnose the problem quickly, so that you can use the same pads/rotors and just replace the parking brake cables or calipers.

Cheers. Sorry for the long winded post.

 

Thanks for the reply. Unfortunately I haven't tried the e-brake yet but I will this weekend and let you know. I'm pretty sure I aligned both notches properly but I'll check anyway. At first when I did the first side I could get the damn caliper on I pushed with all my might and couldn't get it one, finally I looked into the manual and read in Bold "Please make sure you align the notch"... dohhh!!! Once aligned the caliper slide down far enough to get the bolt through to the nut. But even still it felt tight. I remember when I did the front brakes the caliper slide in with a lot of room to spare. These rear brakes still required a lot of pushing the caliper down. Is this normal?

Now about the piston. Yes it took a lot of muscle to move even after it got turning it was still tough. I had to have my friend hold the caliper with both his hands while I turned the wrench with both my hands...one had to hold the tool in place in the notches and the other to turn the wrench and push into the caliper with. But it got to a point that it would keep turning but wouldn't go in further into the caliper. Is this normal? Are you suppose to push while turning or just turn? I tried both ways and it would not go in anymore...though it did turn. By the way, yes the boot was left neat but not by itself as I explained earlier. I had to give the piston a 1/4 turn in the opposite direction to straighten the boot out.

I'll test the e-brake and let you know...sorry also for the long post but I like to help people visualize what I'm experiencing.

 

Okay I've been testing my brakes extensively and now I'm sure the rears are braking before the fronts. I think they are dragging as njmodi pointed out. So my final question on this matter is the following.

Do you have to release the brake fluid from the rear calipers in order to lessen the pressure in the line in order to push back in the piston with the cheap $10 tool from autozone?


Explained here as such...

Reason I ask is b/c of how hard the piston was to retract and the fact that other more expensive piston retraction tools actually have a screw mechanism to force the piston in:


Please give me your thoughts guys...

 

No. You don't have to release the brake fluid from the caliper. You shuold open the master cylinder reservior cap - so that the fluid can be pushed back into the brake lines as you retract the piston. Another (possibly preferred) way, is to just loosen the bleeder screw on the caliper, then retract the piston (leave the master cylinder reservoir cap on). As you retract the piston the excess fluid will come out of the bleeder hole (use a rubber hose over the bleeder to catch the fluid). The only downside with this method is that you have to make sure you bleed the brakes after - as you can get air in the system this way. The reason I say its "possibly preferred" is because the dirty brake fluid is expelled from the brake system rather than pushed back into the lines.

The way you are supposed to use the tool you show first is to both twist and apply pressure (inwards) on the piston - thus rotating/retracting it at the same time.

Your best bet - assuming you are convinced the brakes are dragging, is to just replace both calipers. Out cars are getting old and given how much abuse brakes take over time, it probably is a good idea to spend the $150 and replace both calipers. Depending on how long ago the pads were changed, you might want to get new pads too.

Cheers.

 

njmodi,

I'm going to give it one last try today. When I did it last with the Master Cylinder cap off and the bleeder screw tight, I never saw the fluid rise as it did when I did the fronts with a C-clamp. It didn't rise even a millimeter. Which I found very strange. So I'm going to try loosening the bleeder screw and attaching the one-man bleeder system from autozone which stops air from getting in the system. This way I might not have to bleed the system afterwards. Thanks again.

 

njmodi and the rest of the .ORG members,

Good news I fixed the problem. I took apart the rear brakes and opened the bleeder screw while pushing the caliper piston further in. It did give enough to fit comfortably over the pads. No fighting to get the caliper back on like last time. I did it exactly like it states in the DIYNetwork link above...in one of my previous posts.

Thank you njmodi for all your help.

WOOOHHOOOOO!!!!!

 

You're welcome.