Front Brake Issue - 2007 XC Chassis

[Mnichols4]

Hi everyone. I 2007 Winnebago Journey on the XC chassis. I am getting a clunking noise when the front brakes are hit fairly hard. It almost feels like the pads grab and then rotate. I had it serviced and inspected and they said the brakes are like new (only 9Kmiles on the coach). It seems to go away after 4 or 5 times of braking, then reappears after the coach has sat between trips. I am also looking for instructions on how to properly remove the front hubs.

Mark N.
2007 Winnebago Journey 39K
2007 Lincoln MKX

[J Walker]

From my experience with my XCS chassis over 11 years your experience is normal and not harmful. I don't know which part if causing the clunking but it is not harmful.

[Pusherman]

Have a good brake chassis mechanic check your s-cam rollers. They are most likely binding from rust. The mechanic will pull the wheel, remove and clean the parts, and lubricate the ends of the cams and mechanisms (not the rolllers themselves).

The binding s-cams is what causes the famous 'clunking' upon braking.

[powerboatr]

Quote:

Originally Posted by Pusherman Have a good brake chassis mechanic check your s-cam rollers. They are most likely binding from rust. The mechanic will pull the wheel, remove and clean the parts, and lubricate the ends of the cams and mechanisms (not the rolllers themselves). The binding s-cams is what causes the famous 'clunking' upon braking.

what he said

to me its the chassis way of telling us we are not driving it enough
mine does it after we sit for a bit

[Fred Cooper]

Assuming that your front wheels are similar to those on my 2000 era freightliner chassis, here's how to fix the problem. Below is a write-up I posted on another forum that I've copied & pasted below....Fred

Ok...I'm a happy camper. I got the repair done today. It really was not a bad job. About 1.5 hours start to finish. I used 3/4 inch drive bar with 6 ft pipe extension to loosen the lug nuts. Then I used the motorhome jacks to raise the front slightly, leaving about 1/2 inch of space below the tire. Installed jack stands, and used a 1/2 inch electric impact wrench to remove the lug nuts. When wheel removed, I just laid it over and slid it back under the brake drum as something to hold the drum in case it was too heavy to lift (It was lighter than I expected). Tapped the brake drum several times with a medium hammer, and it slid off easily. I didn't weigh the drum, but I'd estimate weight about 45 pounds. After moving the tire/wheel and drum out of the work area, it was easy to see and work on the S cam and rollers. I had to pry up each brake shoe to get the roller unclipped and the roller removed. The S cam and both rollers were very dry and slightly rusty. It's easy to see what happens when it's disassembled. During braking, air pressure is applied trying to turn the S cam. Since everything is dry and rusty, it does not turn. As air pressure builds, it finally overcomes the friction and suddenly turns the S cam. This slams the brake shoes into the drum, making the sharp clunk sound. I cleaned and lubed the roller seats, the rollers, and the S cam surfaces using some Hi Temp brake grease from NAPA that I had in the tool box. I examined brake shoes and they were good with no oil/grease on them. Reassembly was easy. I used a carpenter's pry bar under the tire to lift it slightly to align holes to studs. Took the motorhome on a test drive, and no more "clunk". I hope this description helps someone with this same problem.

[Hooligan]

That clunk may be from the automatic slack adjusters.
Automatic slack adjusters should NEVER be manually adjusted (with a wrench) however there is a application procedure to get them to fully adjust themselves and give a firmer pedal. Apparently light brake applications do not always activate the adjusters.

The procedure is to keep air pressure above 90 psi during the test. Engine running,wheels chocked and be sure the parking brake is off. (Some brake systems can be damaged by heavy brake application with the parking brake engaged)

Apply full pressure to the brake pedal and release, repeat 6 times and the automatic adjusters should adjust themselves. Mine clunk the first few applications as they adjust...

procedure discussed on page 72...of:
http://www.mpi.mb.ca/PDFs/AirBrakeMa...M_Section8.pdf

hope this helps - it's alot easier than taking the hubs off....

[Mnichols4]

I did followed your suggestion and applied the brakes firmly six times and my pedal was much better and I did not feel or hear the clunk !!! Thanks For the tip Hooligan

[Mnichols4]

Here's an update to my post on the clunking front brakes. I pulled all the wheels off the DP this last weekend to clean and polish the rims and inspected the brakes while I had the fronts off. I did find the s-cam rollers very rusted and lube them beofre reassembling.

Here are some pictures for those wondering what was being discussed here.

[Sammie]

Quote:

Originally Posted by Mnichols4 Here's an update to my post on the clunking front brakes. I pulled all the wheels off the DP this last weekend to clean and polish the rims and inspected the brakes while I had the fronts off. I did find the s-cam rollers very rusted and lube them beofre reassembling. Here are some pictures for those wondering what was being discussed here. http://i610.photobucket.com/albums/t...rs6-26-111.jpg http://i610.photobucket.com/albums/t...rs6-26-112.jpg http://i610.photobucket.com/albums/t...rs6-26-113.jpg

Just wondering, when you pull the front wheels, what do you have to do to remove the front brake drums?

Thanks, Sammie

[Martind4]

On ours all I had to do was remove retaining clips on the lug bolts, the brake drum slipped right off.

I think the retaining clips are used to keep the drums on the axles when they are shipped from the axle manufacturer to Freightliner for final assembly.

When I did our "S" cams a couple of years ago, the Freightliner Help Desk walked me through the process and recommended I completely remove the brake pads and remove/lubricate the anchor rollers at the bottom of the pads. Mine were seized so tightly that I had to pound them out before I could clean and lubricate them. No problems since then.

I thought I was the only person silly enough to remove the wheels for polishing.

[sandcar361]

I am wanting to do this very thing but I don't think I can break the lug nuts loose. What did you all use?

[Martind4]

I have a piece of black pipe about 6' long that is large enough to slip over the handle of my 3/4" drive socket. Never had a problem getting any of them loose but sometimes I have to grunt a little. Be sure to remove the decorative chrome lug nut caps first.

Going a step further, I was too cheap to buy a 600 ft# torque wrench or a torque multiplier so I made my own torque extension. Here is a website that explains the calculations and technique. I use the same cheater pipe as my extension so I can torque nuts to 450# with a setting of 85# on my torque wrench. I confirmed my setup by taking the rig to a tire shop that had a big enough torque wrench, everything checked out so I'm confident that I'm close enough to spec probably closer than a guy using a cranked up air impact wrench.

Torque Wrench extensions

[sandcar361]

Nice info. Anyone know what size socket I need for a 2006 xc chassis.

[Fred Cooper]

Quote:

Originally Posted by sandcar361 I am wanting to do this very thing but I don't think I can break the lug nuts loose. What did you all use?

3/4 inch breaker bar with 6 ft piece of pipe added to it. An 8 ft piece would be better. I barely got mine off with the 6 ft piece of pipe. Once I had them loose, I used an electric impact to finish removing the nuts.
Fred