OUCH!! HOT BRAKES on TAG

[Larry Dedrick]

To All:
               Took the coach for a weigh and came back, parked the coach and could smell my brakes. The trip was 20 miles there and back with some braking at a few stop lights. The investigation showed the Tag axle brakes to be the culprit. Used heat gun and the Wheels were 225 degrees, inside at the caliper was 290 degrees.
 
                My troubleshooting involved:
                    Releasing Park brake to see if coach would roll on a very slight incline and it did.
                    Set the park brake and engaged D "drive" and the brakes held the coach. Released Park brake and back to Neutral and the coach would roll.
                    Selected D "drive" brake off and accelerated slightly and went to neutral and the coach continued to roll.
                    This leads me to believe the pads are not dragging hard at the moment, However the pads appear to be up against the rotor but not                     applying enough pressure to stop the coach from rolling.
                    Parking brake was set, had the wife release Park brake while I observed the outside pad and did not see any retraction from the rotor, However once again with Park brake released the coach was able to roll.

                   I remember Roy Bueller and Gerald discussing the Meritter Brake Lube procedure, and if they were over lubed it is strange that both brakes on the tag axle are affected although I realize this could happen. I did have the chassis lubed along with the brakes and had the mechanic show me the grease and I did not care for his high temp general purpose grease. So there is my story.
                 Advice is greatly Appreciated.

                      Thanks:     Larry D.
                    
                    

[Larry Dedrick]

Gerald or Roy:
         I am sure the brakes are Air and not Air Over Hydraulics, Can you confirm this please. 2001 Marquis Amethyst
          The reason I ask, the Cat rep never heard of Disc with just Air. ??

           Thanks:   Larry D

[Larry Dedrick]

To All:
         Just one more item for thought:
            The extra air line to the back of the coach for our toad was tested by us and this is what we did:
                Uncapped air line and Laura applied brakes and air did discharge as we were told. We did this three times. Also set the parking brake, I was curious if we would still have any air discharge. Could this procedure of checking this air line contribute to my tag brakes?

               Thanks Again:       Larry D

[Gerald Farris]

Larry,
Yes, your 2001 Marquis has air disc brakes. They are not air over hydraulic.

I cannot diagnose your brake system problem without being there to look at it, but I just sent you an email with the complete repair manual for your coach's air disc brake system.

Gerald

[Larry Dedrick]

Gerald:
             Thanks much just the same, I will look over the manual. I will be headed to Cat tomorrow with the manual.

                             Larry D.

[Steve Jewell]

Larry, Your parking brake is only on your drive axle and not on the tag axle. Caliper pin problems were common on those calipers. Rust would form under chrome on pin causing caliper to not move properly.Your calipers more than likely do not have helper spring to help release the caliper. They were added a few years later and there was a service bulletin on them. All 6 of your calipers should have these springs. They should be in manual Gerald sent you. If not let me know and I will find a copy of the service bulletin with part numbers.

Steve J

[Larry Dedrick]

Steve:
      Thanks for the info. I passed this on to the techs at cat and they are going to look and make sure operation is as it should be. Drove the coach this morning and no heat build up whatsoever  so as a precaution mechs are looking at it. If these coaches were not so big I would do it myself. I'm sure it is very similar to auto calipers which I'm familiar with, but it is a weight and size issue for me.
     Once again Steve, Thanks for the info.