Rear disc brake chatter/squall

[Suburban_Tyler]

What causes the rear disc brakes to chatter/squall. It does it when there is light pressure on the brakes. I'm a pretty casual driver and don't stop within the last 10 feet of a stop sign. So when I apply the brakes the reach a certain pressure and it sounds like a wallraces getting it on. As I apply more pressure it goes away. If I apply the brakes for slowing down it does the chatter/squall when I apply and release the brakes. I've tried different pads and and I cleaned and cleaned the rotors. It seems to mainly do it at 30mph and below. Seems as if theres enough residual pressure after releasing the brake pedal that 5mph below I can hear a faint chatter squall. The setup I have is a 12 bolt in the rear of my Suburban with The Right Stuff rear disc conversion with Cadillac calipers. I don't have the parking brake cables hooked up yet. The rotors are new of course. I'm not sure what to do or where to start outside of new pads which I've already done. Should I turn the rotors for some reason? The machining marks are about worn off. I thought maybe it was from that. I've never had this issue before.

[reaper71]

One thing you can try..(I do this with all my pads front and rear) bevel the pads edges all the way around this will help with noise and chatter.
good luck..
Mark...

[Suburban_Tyler]

Originally Posted by reaper71

One thing you can try..(I do this with all my pads front and rear) bevel the pads edges all the way around this will help with noise and chatter.
good luck..
Mark...

Thanks for the advice. Seems simple enough. Worth a try.

[homemade87]

I think you have answered your own question. ( I do not have the emergency/park brake hooked up ) . Those calipers have to have the park brake hooked up and use it quite frequently for those calipers to work. That is what adjusts them to compensate for the wear . If not used the pads will wear down and not make firm contact which is what is most likely causing your chatter at light peddle apply. Also most likely your not getting the braking power to those rear disc like you should . Get the cable hooked up and I think your problem will be fixed.


The right stuff has install instruction but I think there is better instructions out there for these calipers in better detail .

Here a mp brake instruction on the emer/brake lever install. http://www.mpbrakes.com/docs/orig-gu...STRUCTIONS.pdf

[Suburban_Tyler]

I'm at a loss. I tried a couple different brands of pads again with no luck. Tried semi metallic and ceramic pads. Best luck is with Duralast ceramic pads. I beveled every set of pads. As I said the Duralast yielded the best results before parking brake cables I put parking brake cables on. Adjusted them as the instructions said. I set the parking brake everytime I got out. It's now worse then ever. I can sometimes hear it faintly at 40+mph. It's loud enough at slower speeds that people stop what they are doing to look to see where the noise is coming from.

[homemade87]

Originally Posted by Suburban_Tyler

I'm at a loss. I tried a couple different brands of pads again with no luck. Tried semi metallic and ceramic pads. Best luck is with Duralast ceramic pads. I beveled every set of pads. As I said the Duralast yielded the best results before parking brake cables I put parking brake cables on. Adjusted them as the instructions said. I set the parking brake everytime I got out. It's now worse then ever. I can sometimes hear it faintly at 40+mph. It's loud enough at slower speeds that people stop what they are doing to look to see where the noise is coming from.

You may still have air in the calipers . Most aftermarket caliper do not have the correct angle at the bleeder screw to get all the air out .( hows the brake peddle feel ) I had to remove the top pin and tilt it back to get all the air out . If air is still in it is not applying the pad all the way .

It also could be your rubber hose above the rear-end has collapsed and not letting enough fluid past to apply the brakes properly . This would also keep a decent peddle feel . Did you have trouble bleeding the rears .

I cant stress enough about the parking brake being properly adjusted . If you are confident that it is I would look into the things above .

Something else that comes to mind is if the mounting bracket is properly spaced so the caliper is center so the pads have an even travel to the disc .

[Suburban_Tyler]

All of the flexible hoses are new throughout the brake system. The pedal is tight as it should be. It stops great. It was at a point that it squalled with light pressure to now it does it as if there's always slight pressure because its squalling with my foot off the brake. I'm about 75% sure the pistons are adjusted correctly. It was good when I first adjusted them The more ive set and released the parking brake the worse it has gotten. The brackets was one of my initial thoughts. Since the caliper can only slide outward so far I thought maybe the outer (closest to the wheel) pad was causing the issue. There is a small gap between the caliper and bracket. Maybe 2mm at most. That should be plenty I would think so the caliper could float as needed with endplay of the axle shaft.

[cadillac_al]

I think you have a caliper sticking. You shouldn't be hearing any brake noise at 40 mph. How old are these calipers? I have rear discs on a couple of my Caddys and I never ever use the E brake. I have always had very good brakes with no noises. I have had to replace my calipers twice in 15 years because the E brake adjustment gets frozen up from non use and I'm too lazy (or in a hurry) to take them apart and fix them. If there were noises associated with not using the E brake I would have heard them by now. I think you just have a sticking/defective caliper.

I am trying to use the E brake more often now since that's the way they designed it. Thankfully Caddys have automatic E brake release so it isn't that much of a hassle.

[craig113]

Run to the shop and get the high temp silicone, put a bead on the caliper cup where the brake pad back meets it. The sound that you are hearing is the harmonics of the cup. Its like a wet finger on the crystal glass, makes a tone. The silicone will act as a vibration dampener.

[Suburban_Tyler]

Originally Posted by cadillac_al

I think you have a caliper sticking. You shouldn't be hearing any brake noise at 40 mph. How old are these calipers? I have rear discs on a couple of my Caddys and I never ever use the E brake. I have always had very good brakes with no noises. I have had to replace my calipers twice in 15 years because the E brake adjustment gets frozen up from non use and I'm too lazy (or in a hurry) to take them apart and fix them. If there were noises associated with not using the E brake I would have heard them by now. I think you just have a sticking/defective caliper.

I am trying to use the E brake more often now since that's the way they designed it. Thankfully Caddys have automatic E brake release so it isn't that much of a hassle.

The calipers were new rebuilt with the conversion kit. They don't seem like they are sticking when I've taken them off before, but I have removed them since I've hooked the cables up.

Originally Posted by craig113

Run to the shop and get the high temp silicone, put a bead on the caliper cup where the brake pad back meets it. The sound that you are hearing is the harmonics of the cup. Its like a wet finger on the crystal glass, makes a tone. The silicone will act as a vibration dampener.

I will give it a try The duralast cmax pads have a small rubber insulator on the back of the back. Trying this is worth a try though. Can't hurt to try.