Squeaky Brakes!

[Michaels]

More accurately, HOWLING brakes. Country Coach Allure, 22.5" tires, drum brakes. FRONT brakes have VERY LOUD howling sound when coming to a stop. Sounds just like the garbage truck! Sound is not for complete revolution of drum but about half of revolution. Took coach in to recommended brake shop, twice. Drums have been turned and brake pads have been arced to match drums (twice). Lasts for about as long as it takes to get home (about an hour), then howls as bad as before. Brake shop now says we can try replacing the drums but can't say it will solve the problem. Coach only has 17,000 miles. Any advice? Thank you.

[doc]

Hmmmm? We have had brakes squeal after the coach sits a while, but up to speed and a couple of braking episodes and they stopped. This sounds somewhat the same, yet with everything you have done I can't believe it is.
A crane operator we used to have years ago in my dad's company used to use carbon tetrachloride on the drums and liners inside the winch housing when they would squeal. The mechanical concept is the same, but with everything you've already done....??

[Michaels]

Thanks Doc. We are on the road at least every two weeks. Problem gets worse as the brakes heat up. Interested in hearing from you or others if changing out the drums provides a high likelyhood of resolving the problem.

[Cruzer]

It sounds to me like your drums are not the problem but your brake pads are. In the old days they used asbestos in brake linings to make them hold up under heat. Today's regs steer brake pad makers away from that because of lawsuits regarding asbestos and they've replaced asbestos with other compounds that quite frankly don't hold up as well.

Now, if you had metal brake pads and pressed them against the metal drums you can imagine what kind of squeeling that would cause. That's because the pads would be too hard and would vibrate and chatter when applied to the hard steel drum.

Brake pads are the same way. If they get overheated they become work hardened and the squeeling you here is the vibration - much like the metal on metal scenario but less severe.

Initially, when the howling begins it's just a glazed surface on the pad that is making the noise. There are techniques to deglaze these pads and the best way to describe that is a Freightliner owner's manual exerpt from the RV Tech Library at this page - http://www.rvtechlibrary.com/chassis/airbrakes.htm

Note that this removes the glazed crust. Once this progresses to the point where the lining has absorbed too much heat it's time to replace the linings.

[Michaels]

Thanks Mark. As always, you come through. You also helped me with my first coach, a 2003 Winnebago Adventurer. I'll pass this info on to my brake guy and see if we can solve the problem. Happy trails!

[Cruzer]

My first was a 2003 Itasca Suncruiser. Sister ship to the Adventurer (different decals ). It looks like we've both made some changes since then.

[Wayne M]

My 2008 Winnebago Destination has the squeal, mostly when first starting out. We are in a very humid climate and any moisture on the brake linings will cause this but as they get warmed up the moisture dissipates and the squeal goes away. Also, as stated in the article, there can be glazing. The process is identified in the article to try and remove the glaze.

I have also heard tell that when in moderate city driving to not use the exhaust brake, giving the brakes time to work and not glaze up. So far, this has worked for me. However, I only do it in light city driving.

[Cruzer]

Yep, I do get a few "cold start howls" if the coach has been sitting awhile. The moisture rusts up (lightly) the drums and they howl a bit but after a minute or two it's knocked off, the drums warm up, and that's the end of it. Just the opposite of what the original poster has happening.

You're correct on the exhaust brake. Many times the jake or exhaust brake gets used because it's easy. However, in the process your brakes get underused. Light applications tend to cause that glazing. If you read the link to Freightliner's deglazing procedure you'll see how heavier use of the brakes is the key to deglazing them. It's also the key to keeping them from glazing in the first place. Brakes are meant to be used fairly firmly, then back off. Light but steady pressure doesn't do them any favors and heats up the crust, glazing it. If you keep the jake brake off when in city traffic, or even easy highway traffic, you'll be able to apply the brakes more firmly rather than lightly, which will help prevent the glazing (and howling) in the first place.

[H. Miller]

We have air/drum brakes on an '04 Monaco product. When purchased 6 months ago we had a 60,000 mile check done - that's the big one and included wheel bearing pack. On pick-up we only made it around the block due to loud squeal and grinding noise. The maintenance facility said it was brake dust and blew the dust out with an air hose. Sounded better on the way home but still not zero noise like before. I hosed it with high pressure water then drove around the block drying the brakes. That's 6,000 miles ago with not a squeak since. I figured a little water couldn't hurt anything (otherwise we shouldn't drive in the rain)