BAC Forum

General Boards => Technical Support => Topic started by: CECIL SALMON on February 22, 2012, 10:36:43 PM

Title: Brakes
Post by: CECIL SALMON on February 22, 2012, 10:36:43 PM

I am having trouble with stopping our 2001 Beaver Patriot C12 455hp, when backing up and coming to red stop lights at an idle.  It seems the torque is so great that it continues to creep, even thought I am almost standing on the brake pedal.  I am frustrated with the air over hydraulics, and am tempted to try lowering the idle down to about 500 rpm instead of the current 700rpm. Any thoughts would be appreciated.

CECIL SALMON 2001 BEAVER PATRIOT 455HP- 4000 ALLISON.

Title: Re: Brakes
Post by: Steve Jewell on February 22, 2012, 11:24:06 PM

Cecil,
  When was the last time your brakes were serviced. There are quite a few pieces that need to be lubed and adjusted on that system. Here is the link to the maintenance manual                                                              ( http://www.meritorhvs.com/MeritorHVS_Documents/mm4m.pdf ).

Steve

Title: Re: Brakes
Post by: Dick Simonis on February 22, 2012, 11:30:41 PM

I've noticed that also...just chalked it up to a heck of a lot of torque even at idle.

Title: Re: Brakes
Post by: Tom and Pam Brown on February 23, 2012, 12:40:44 AM

One of the things that will help is to hold and release several times quickly. It works for me.......

Title: Re: Brakes
Post by: Jeremy Parrett on February 23, 2012, 02:00:16 AM

Cecil,  
You are advised to slip the transmission into neutral when you are at a stop light, or stopped for more than a minute. If you don't do this, the transmission will overheat.......switching to Transcynd will help enormously.
 Your brakes need to be serviced.  It may be that the rotors are glazed.......from light use, or little use.  Glazing can be removed by resurfacing the rotors.......or by a light application of emery paper in circular motions, if glazing is not too bad.
Either way, you must be safely able to hold the coach on the service brakes even on steep hill.  

Title: Re: Brakes
Post by: Gerald Farris on February 23, 2012, 03:30:41 AM

There is some confusion here in brake systems between the ADB (air disc brake) brakes that are used on the Marquis, and the air over hydraulic brakes that are used on the Thunder up through 2002 . The maintenance link that Steve posted pertains to the ADB brakes that are used on the Magnum chassis equipped Marquis coaches that were built up through 2002. It has no relation to the brakes that are used on the 2001 Thunder in the original question

Gerald

Title: Re: Brakes
Post by: Gerald Farris on February 23, 2012, 03:41:20 AM

Steve,
If the brakes on your coach are functioning properly when driving and your only complaint is that you have to press hard on the brake pedal to hold the coach at stop lights, you may not have a problem. However I would check the brake lining and caliper hardware to be certain that everything is in good condition.

I am not sure what will be involved in lowering the coach idle speed, or if it is possible since it is computer controlled and I have never looked into changing it. I will have to defer that question to someone else.

Gerald  

Title: Re: Brakes
Post by: Joel Weiss on February 23, 2012, 03:45:08 AM

Quote from: Gerald Farris

There is some confusion here in brake systems between the ADB (air disc brake) brakes that are used on the Marquis, and the air over hydraulic brakes that are used on the Thunder up through 2002 . The maintenance link that Steve posted pertains to the ADB brakes that are used on the Magnum chassis equipped Marquis coaches that were built up through 2002. It has no relation to the brakes that are used on the 2001 Thunder in the original question

Gerald

Is there an equivalent maintenance manual you know of for the air over hydraulic brakes on the Thunder?

Title: Re: Brakes
Post by: Gerald Farris on February 23, 2012, 04:05:05 AM

Joel,
I am sure that there must be such a manual, however I have never looked for one so I can not say where to find it. The only times that I have worked on the brakes on a 2002 or earlier Thunder, a manual was not needed since they are very similar to the hydraulic brakes on medium duty trucks which I was familiar with.

Gerald

Title: Re: Brakes
Post by: Joel Weiss on February 23, 2012, 04:52:27 AM

Gerald--

I wasn't sure how common they were; if they're fairly standard truck brakes I won't worry about them.  Last fall we had to replace the parking brake pads and rotor and there were no problems obtaining parts, which was reassuring, but I've been trying to make sure I had as much information as possible about all of the major subsystems.  It's not that I'm such a do-it-yourself guy, but I figure it never hurts to have documentation you can share with someone who's doing a repair.

Joel

Title: Re: Brakes
Post by: CECIL SALMON on February 25, 2012, 04:27:51 AM

 Thanks everyone for your suggestions,Iam having  a mechanic look at the pads and rotors also checking with Cat to see if the rpms can be changed Cecil