Howling brake pad fix?

DanEC · #1 (**permalink**) 12-13-2014, 01:53 PM

My left front brake pad (Chevy calipers) has a bit of howl when I turn a corner to the left. I know, not the best brakes. Pretty certain of the source as when I pulled the front wheel off and spun the disc I got a touch of the same howl at the same, apparently slightly high spot on the disc as it rotated. Bearnings are tight, brake brackets and bolts are tight, KO pins are properly torqued. Braking action is fine.

What's the easiest fix for this - sand the pads, apply some anti-rattle compound to the back of the pad, replace the pads?

cycleguy55 · #2 (**permalink**) 12-13-2014, 02:04 PM

If there's a 'high spot' on the rotor, the only way I know to fix that is to replace the rotor or have it turned down on a lathe. OTOH, I would think you'd feel a bit of a pulse in the pedal, but you say everything is fine. Interesting...

DanEC · #3 (**permalink**) 12-13-2014, 03:17 PM

It's apparently very slight runout - just enough to activate the howl. Obviously though, when I go around a corner there is just enough deflection in the brackets, disc, etc, to create some slight drag and the howl. As soon as the wheel straightens up I don't hear it. If I hadn't recreated it by spinning the rotor I would have suspected a wheel bearing.

RICK LAKE · #4 (**permalink**) 12-14-2014, 04:54 AM

DanEc Dan howling is normally a disc pad problem, a crack or a hard spot in the pad or the smoothless of the surface of the rotor ir too rough. You said there was a high spot. Max out of round for checking a flat surface for GM is .0015" any thing more will cause a pulsation of the pedal when applied. If you drive normal, resurface the rotors and replace the pads. Rotors will take 3 cuts and still be above min thickness. there is a spec on the rotors for min. Unless you are hard driving, standard brake pads are fine. When I ran 11" rotors the DR 52 pads from GM worked great. I little brake dust on the wheels but it washes off easy. I when to the 12" from ERA and have used the pads that come with the kit. Still have about 4/32 left of pad life. This is 98% autocross and roadracing. These pads don't like a ton of heat. Make sure the pads release from the rotor surface. I use CRC anti squeak that goes on the back of the pads and acts like glue to pull the pads off the rotors with the brakes are not on. If you are worried, replace pads and rotors. make sure you are not too loose or too tight on wheel bearings. I use channel locks and tighten nut to snug and back off to hole for pin. When done check for any play in wheel assembly by grabbing top and bottom of wheel and rock top to bottom Should have a VERY small movement. These bearing should be repacked with either a pressurized bearing packer or a hand job the pushes the grese through the bearing. Hand pack takes 10 minutes and is a mess and pain. This should correct any problem with front brakes. good luck.

DanEC · #5 (**permalink**) 12-14-2014, 05:04 AM

Thanks Rick - car only has a few hundred miles on it so I think I will try changing the brake pads. I think the rotors are fine and there is absolutely no pulsating through the brakes when applied. Wheel bearings were all all pressure lubed, torqued to seat, backed off and re-torqued to 15 inch-lbs so should be good. I'll try the CRC stuff to as I think I just used some high-temp RTV when I assembled it.

Bobcat · #6 (**permalink**) 12-14-2014, 07:14 AM

Dan ...as others have said , try turning both rotors ... just enough to clean them up . Best to use the method that turns them on the car ( remove the pads first and clean rotors thoroughly ) as that compensates for any suspension irregularities .
Just curious as I don`t know what pads ERA is currently using , but did you bed the pads and rotors in ? I know some just drive the car and assume that beds them in correctly , but each pad manufacturer has a bed in procedure that needs to be followed . If you didn`t , try deglazing the pads/rotors with 60 grit sandpaper on a FLAT surface and then go through the bed in procedure . Easier than turning the rotors ... and you can still try that if they still squeal .
FWIW , I had the Wilwood pads and they would always squeal at low speed and if I used the brakes easy . Using the brakes hard , no problems .
However , I have gone to the CarboTech pads as I can change from street to track pads with minimal rotor prep and aggravation . Great street pad and very rotor friendly .

DanEC · #7 (**permalink**) 12-14-2014, 03:09 PM

To be honest I probably fell in the latter group - just drove the car. I didn't have a good road nearby to bed them in as described without creating traffic havoc. When I got a clear stretch I made an effort but it probably was less than required. I'm working on a few things over the winter so scuffing the rotors and pads will be added to the list.

Thanks