Brake Disc pad Possibly hanging up

[Gary Wolfer]

Has anyone had a brake pad hang up? I hear a sound like that may be happening to me when I take off from a dead stop and seems worse when I make a left turn from a stop.

[Keith Moffett]

Hi Gary.
Wow two coaches to do maintenance on.  That'll eep a guy busy.
Well, you might be in luck.  We used to own a 98 Pat. Monticello.
We also had the noise on left turn and found it to be the slightly larger tire size when Michelin went to the XA-2.  That was just enough to make the outer most tread bead rub on the wheel well liner bolt heads.  Since we have traded the coach, I have heard stories about insufficient pressure in air bags allowing more lean during a turn so I would verify that perhaps Gerald Ferris could add to that.  I also noted that there was slightly more room in front of the tires than behind and wondered about moving the axle forward a bit.

If you have a brake hanging up there is a critical question.  Have the 'caliper slide rails' ever been lubed?  Most truck shops have no idea what they are.  I actualy had to teach our local shop after observing the process at Coach Masters of Bend Or. and Beaver Coach Sales.  When they finaly pulled ours apart, it appeared that they had never been done and the calipers would only move very slightly.  They are supposed to slide in and apply perssure to the rotor and then release fully.  If this doesnt work right the rotor will wear to a dime thickness and suddenly shatter.  Usualy does it on the down hill side of a mountain.  These should be cleaned and lubed every two years according to my old manual.  I paid about $50 per wheel and gained power and mileage with no more drag.

Hope this helps
Keith

[Bill Sprague]

In addition to Keith's suggestion, you might call or email Marty Schenck.  As I recall, he had that issue, figured it out and fixed it.  

[Gary Wolfer]

The wierdest thing happened yesterday I pulled the front end over a speed bump and  went over it slow not to disrupt everything inside the coach when the rear axle reached the speed bump I gave it full throttle and it would not pull the rear wheels over the speed bump. I had to back up and try again. Never had anything like that happen before but seems like it is lacking in power when the noise occurs always when starting out. I have plenty of power climbing mountains like the brakes finally release or something at high speed. Nothing gets hot or smells like hot brakes. The right rear drivers are a little warmer than all the others though. But the squealing sounds like it is coming from the steering axle. It sounds exactly like a disc is rubbing on the rotor. I am not driving it much as I am home and parked for the summer now. I have a lot of issues this coach was not maintained very well but the paint and interior is premo.

[Gerald Farris]

Gary,
I believe that your coach uses a disc brake on the drive shaft for the parking brake, and if so it sounds like you have a problem with it not releasing fully. The caliper mounting bolts on this type of parking brake are bad about working loose, or you could have been low on air pressure or have an air leak in the actuator.

Gerald  

[Gary Wolfer]

Thanks Gerald I will look for old posts on that do you know if it has disc pads or brake linings? Where would I find information on adjustment?

[Joel Weiss]

Gary,
I believe that your coach uses a disc brake on the drive shaft for the parking brake, and if so it sounds like you have a problem with it not releasing fully. The caliper mounting bolts on this type of parking brake are bad about working loose, or you could have been low on air pressure or have an air leak in the actuator.

Gerald  

We had to replace the parking brake actuator last fall and in the process of doing so we became convinced that we've probably had a dragging parking brake pad for quite some time.  If the actuator releases but has a slow or intermittent leak it's quite possible for the brake caliper to close just enough to drag one or both pads.  Because the brake pad doesn't exert all that much force it's very difficult to know this is happening.  The symptom is a seriously worn brake pad even though you're confident you haven't driven with it on.  

[Gary Wolfer]

Thank you both that makes sense, If that is the problem it could cure two or 3 issues I am having like the step slide sticking because of low air pressure and my air pressure gage gaining and loosing 10# of pressure going down the road and the coach porpoising on rough road.

[Edward Buker]

Gary,

The needle gaining and losing 10 lbs down the road is pretty normal. As the coach leans or sways the suspension air valves are constantly moving air to keep the coach level. When I say moving air it is dumping some of the suspension air to lower pressure and adding air from the tanks to raise pressure depending on what is needed, it is very dynamic. My compressor comes on maybe every 30 seconds or so as the pressure drops and stays on until the cut off pressure is reached. If the road is interstate quality and level I may go up to a minute or two without the pressure dropping enough to get the compressor cut in. I'm not saying that you do not have a leak just that the needle moving up and down 10 lbs while driving is not an indicator that you have a leak. There are legitimate test methods for verifying the system if you suspect an air leak and I would go through that testing before getting under and spraying fittings.

Regarding the parking brake caliper, if it is hanging up and the pads are rubbing you should be able to see a significant temperature rise after driving the coach using an IR gun.

Later Ed

[Gary Wolfer]

Ed something sounds like it is definatly rubbing and it sounds like a brake lining. After driving a few miles I felt and smelled each wheel and all were relatively cool the right rear was the warmest and I could smell heat and possibly brakes but it was not smoking hot or anything. Not sure if you read the post about not being able to climb over a speed bump when stopped next to it or not. It climbs a hill good keeps up with loaded trucks with a 4 thousand pound trailer and a thousand pound car behind it.

[Joel Ashley]

Gary, out of curiosity, about where do your needles come up to on your pressure gauge, I mean top out before the air dryer purges?

Joel

[Edward Buker]

Gary,

In IR gun is an inexpensive tool that allows you to measure temperature using a beam of light to show the measurement spot and the thermal radiation is then measured by a detector on the gun. This can be done from a few feet away so you just need to get the beam of light on the metal rotor to see what is going on. I'm not promoting any unit, just read the ratings if you decide that you are going to get one. This is what you are after. It is easy to practice on a car to get the technique down.

http://www.amazon.com/Infrared-Thermometer-Contact-Temperature-Measurement/dp/B002OD0NCG

If you drive a ways and stop, the intent here is to not overuse the brakes, and then take a measurement on all the rotor faces. You should find that the two fronts and the two rears should have similar temperatures to each other in pairs and the front and rear may run a bit different from each other depending on how much proportional braking is being done but not all that far apart. The parking brake rotor if you have one should have much less heat emitted, literally no heat being emitted compared to the regular brakes. This test will definitively tell you if one brake is dragging including a rotor based parking brake. There is some remote chance that all four brakes have some issue and they may all get hot and then it would be hard to differentiate but that is unlikely. The other option is take the coach into a truck shop and have them check it over. You need to know that your brakes are working properly for safety and peace of mind. You should be able to climb over a speed bump, so maybe you do have some brake issue.

Later Ed

[Gary Wolfer]

Joel
     It has been sitting here in my space for a couple days. The orange needle is at 80# and the green needle is nearly out of air. I just fired it up and the green needle passed the orange needle at 80# then the both started climbing. The green needle went to top of 120# and orange needle is about 5# below that. The landing gear is down and I do not dump the air because the dump pipe would be lower than the dump in the park. When traveling the green needle travels from 110 to 120 and the orange needle does the same but 10# lower.

[Gary Wolfer]

EdI looked at the thermal temp meters and never saw anything like them before. Sounds like a good idea and the cheap ones would work for me as much as I used it. My question is do you have to be within a foot or two of the rotor to make it work? Would I have to do it from underneath and could I hit it from the opposite side of the coach shooting across from under the motorhome.  

[Edward Buker]

Gary,

It depends on the meter a bit and the exposed metal available as a target.....just have to try.  I have shot from 3 to 4 feet away with mine and I am guessing that you may be successful from the opposite side. You can play with it a bit and shoot your car front rotors through the holes in the rims and see how far away you get good readings. You do not have to get a perfect reading just determine if one or more is significantly hotter.

It is also sometimes good to map a few spots on things that may give you trouble in the future like the generator block temperature and generator radiator face in a few spots. You will know if you get an overheat shut down if it is just a bad sensor for example or a true overheat due to a slipping belt, or possibly a bad thermostat. As you map your brakes temperature you should record those for the future reference. You will find that you have a problem or not and know those values.

Later Ed