2011 Silverado braking vibrates during downhill

Campfire Time wrote:
It is not warped rotors. True rotor warp is very rare. If it was warped rotors you'd get the pulsation all the time at all speeds.

It's hardened pad material stuck to the rotors. And yes it's caused from heat. Moreover it's caused from improper bedding of the pads, or lack of, after installation. Especially with ceramic pads. After it happens pull over and look at the rotors. You'll see little comet like deposits. It's more prevalent with ceramic pads but can happen with any type of pad. Thickness of pads is not an indicator that this will or will not happen.

I'd put new pads on before doing anything else. And readjusting the BC would not hurt either.

This is what's happening, exactly!

Sounds like high spots from stopping while the friction material is hot and still
out-gassing...to bake a high spot on the rotor surface(s)

Take it out on the freeway up to 65MPH...NAIL the brakes several times and DO NOT STOP

Keep rolling so that the out-gassing will NOT bake a high spot, but leave an
even coating on the rotor surfacce

Or, change friction material to higher performance. The point at which it will
out-gas will be higher and most likely not bake on a high spot...though they will
too...if you get them hot enough

whosgreg wrote:
Hi fellow RVers,

For the 3rd time, going downhill in the mountains, the brakes vibrate. I had to manually use the BC instead of the truck brakes. Tires are brand new. Brake pads are good.

Yep, brakes have been too hot and caused glazing on the pads and/or rotors.

Is the truck diesel or gas? If diesel, do you have an exhaust break or does your transmission have and engine braking feature? If gas, are you leaving the transmission in 'D' or are you shifting to lower gears?

When descending a hill, you really need to let the driveline work for you to scrub off speed. A general rule of thumb is to descend in the same gear you ascended the hill. We have a long steep climb in eastern KY that was always 2nd gear @ 40MPH. I would leave it in 2nd gear on the downhill side and let the engine backpessure scrub speed so I only needed to tap the brakes occasionally to maintain control. If I don't, I'd be on the brakes the entire descent and they would cook in a hurry.

Sounds like you're overworking the truck brakes. Check the adjustment of the brakes on your trailer. Trailer brakes need to be adjusted often as they are not self adjusting. Dexter says every 3,000 miles, as I recall.

Do you manually downshift your transmission? Most all hills I go down are done in 4th gear and sometimes 3rd if it's really steep. It helps keep the speed down. I also have the exhaust brake which works well.

Also, could you be towing too much trailer or not have enough truck?

I have this exact same issue with my 2012 Chevy. Just had the oil changed and tires rotated after a 2500 mile trip and while the wheels were off I personally inspected the front rotors pads & calipers. They were perfect in all regards. I did not use a dial indicator to check for warp but I did spin them and saw no visible warp. I have come to suspect that this issue is caused by the ABS system. Anyone agree?
RichH

It is not warped rotors. True rotor warp is very rare. If it was warped rotors you'd get the pulsation all the time at all speeds.

It's hardened pad material stuck to the rotors. And yes it's caused from heat. Moreover it's caused from improper bedding of the pads, or lack of, after installation. Especially with ceramic pads. After it happens pull over and look at the rotors. You'll see little comet like deposits. It's more prevalent with ceramic pads but can happen with any type of pad. Thickness of pads is not an indicator that this will or will not happen.

I'd put new pads on before doing anything else. And readjusting the BC would not hurt either.

Yes, no one makes decent rotors anymore. Even the GM parts are made in China. They warp from heat almost immediately. The new-ish rotors on my Avalanche are okay until they get hot - like slowing down from highway speeds. Yours are vibrating because they're getting hot slowing the trailer down. I hate to say it's normal, but it sort of is these days. At least on GM products.

Warped rotor(s) cause(s) brakes to vibrate.

Overheated and now warped brake caliper. Sort of common on GM products. I suspect your riding the brakes? Instead, brake hard to get below your desired speed and get off the brakes. Riding the brakes overheats everything.