Brake noise and grabbing

[Steve Hepfer]

I have started experiencing a loud noise and grabbing from what seems like the front right wheel. This only happens after it sits overnight and after driving a short distance it goes away and everything is fine. Anyone else with a similar issue?

[Gary M]

Same here!! Had my brakes checked but no issues. But usually happens over longer parked period of time.

[Dr4Film]

My only front end brake problem is that occasionally when going down a steep grade and I have to really trounce on the brakes, the front end will jump to the left telling me that my slack adjusters need attention.

Below is an excerpt from an article from Mark Quasius on slack adjusters.

Brake Chambers And Wheel Components

On a motorhome with drum brakes, the air brakes are equipped with brake shoes and drums similar to a hydraulic brake system, but the mechanism to operate them is vastly different. Instead of hydraulic wheel cylinders that expand the shoes, air brakes employ a shaft with cams on the end. The brake shoes expand when the shaft is twisted, and the cams act upon the rollers on the end of the brake shoes. The shaft extends inboard and away from the wheel and is connected to a brake diaphragm chamber via an arm called a slack adjuster.

Slack adjusters are adjustable so that the brake diaphragm need only move a certain amount to apply the brakes. Today’s motorhomes have automatic slack adjusters, so under normal operating conditions they should remain properly adjusted. If the coach sits for long periods, the cams may rust, and the brakes might stick and not apply smoothly. In that case, the cams and rollers should be serviced and cleaned.

Brake diaphragms are fairly large in diameter, maybe 6 to 10 inches. A pushrod exits the center of the brake chamber and connects to the slack adjuster, which operates the brake shaft. If the brakes are worn or the slack adjuster is not properly adjusted, the shaft will expose a red band that indicates excessive extension of the chamber’s shaft. When that happens, it’s time for brake service.

[bobdinsmore]

Richard, thanks for the good info but the link to the jpeg doesn't work.

Bob Dinsmore

[Dr4Film]

Bob, I didn't post a jpeg link but instead I embedded a photo from the article using copy/paste. Maybe I need to save the photo then upload it. I'll try that with this post.

[bobdinsmore]

Thanks, Richard. Photo now shows.

Bob Dinsmnore

 

[Highwayman]

One other thing besides the cam sticking or bad came bushings is setting the slack adjusters. This is done by a hard stab braking. We all try to brake easy and steady but every now and then the slack adjusters need a jolt to reset properly.

[Ivan K]

Do you really have drum brakes in the front? I suspect not. The picture above shows a type of spring brake that would be on your drive axle, not in the front. Assuming you have a disk brake up front, I would check the caliper sliders for easy movement. If stuck or slow to back off of the rotor after you release the brakes, that could be your problem.  For that you would have to back off the automatic slack adjuster and check the movement. In this situation, one of the pads would wear more than the other. I thought we all have automatic adjusters but don't know it for fact. They need to be greased too and should not cause a drag but a slow response, longer shaft travel, if not functional. There is a number of grease points on each brake to help them move in and out smoothly. I know you said that they were checked but was the caliper movement that inspected too? It takes some effort to do but jacking up the wheel and reproducing your issue should not be hard.

[Harvey Babb]

Drum brakes are famous for being grabby if the shoes get contaminated with something that attracts moisture. With high humidity the shoe will become sticky and cause it to grab or chatter with light brake application. They will quickly dry out when used and work normally until allowed to rest and again absorb moisture.

You can sometimes cure the problem by applying the brakes while driving and burning off the contamination, or by removing the drum and cleaning the shoes and drum.

[Scotty Hutto]

6 hours ago, Ivan K said:

Do you really have drum brakes in the front?

From the FWIW department, lower end Monaco’s do have drum brakes in front. I have no information concerning years, but my 2006 Diplomat definitely has drum brakes. I do *wish* it had disc brakes in front, but I think only Dynastys and above (Exec, Sig)had discs in the mid 2000s. 

If I’m off I’m sure someone can correct me...😁

[Bob Nodine]

5 hours ago, Scotty Hutto said:

From the FWIW department, lower end Monaco’s do have drum brakes in front. I have no information concerning years, but my 2006 Diplomat definitely has drum brakes. I do *wish* it had disc brakes in front, but I think only Dynastys and above (Exec, Sig)had discs in the mid 2000s. 

If I’m off I’m sure someone can correct me...😁

You are spot on Scotty, our 2006 Diplomats have drum brakes on both the front and the rear. I suspect the OP's problem is a sticking S-cam. We had that problem and rebuilt the brakes all around. Made a huge difference. Even through my truck mechanic neighbor said ours shoes did not need to be replaced I did anyway. Glad I did and my sphincter muscle does not tighten anymore when it is time to stop.😊 Here are a few photos.

[throgmartin]

Drum brakes on our coach are prone to sticking if the coach has been parked for a while. This is especially true if you drove in rain and then parked.

Moisture collects between the drum and brake shoes and rust forms quickly. Typically after driving a short distance the rust clears on the drums and shoes and the brakes return to normal. In regards to periodic maintenance the air brake system at each wheel should be lubed and the slack adjusters checked. And Scotty, mark it down on your calendar, you are correct. All Monaco coaches came with drum brakes except the higher end models. Hard to believe a Mississippi Bulldog could be right but it does happen now and then. 🙂

[Scotty Hutto]

1 minute ago, throgmartin said:

 Hard to believe a Mississippi STATE Bulldog could be right but it does happen now and then. 🙂

...as my older brother would say, “Even a blind HOG finds an acorn once in a while...”😂😂😂

[Ivan K]

On 10/12/2020 at 11:39 PM, Scotty Hutto said:

From the FWIW department, lower end Monaco’s do have drum brakes in front. 

I learned śomething, thought they were a thing of the past even in those years. Ours has drums only at the tag and because there is a single wheel, they are relatively easily inspected from behind.