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Topic: Intermittent Hot Brake (Read 1113 times) previous topic - next topic

Intermittent Hot Brake

Purchased Foretravel U320 40ft from MOT on April 13th, drove to California, then to Canada with no brake problems. Last week, drove 100 miles to attend the Coombs Blugrass Festival with no problems. When returning yesterday, after driving 50 miles, noticed a strong burning odor when running dash AC using fresh air. Stopped to investigate and discovered three brake rotors at 160-180 F, but driver  front was 450 F. Alcoa wheel was hot but not to hot to touch. I cooled with water spray before getting under coach to investigate. Slack adjuster moved as expected, inside disk puck moved easily with a screwdriver and I hit the caliper with a small hammer because I could not see the outside disk puck. I started engine and drove forward a couple feet before selecting neutral, coasted to a stop, and started rolling backward due to a very gentle slope which was not easily detectable. Started driving home and  checked rotor temperature at 5, 15, 25 miles, then when home. Temperature was normal.
Any ideas on what could have caused this extreme heating of one rotor, and what should I do now?

Wyatt, in Victoria, Canada
1996 U320 40 WTFE
1998 Suzuki X90 Towd
Wyatt
96 U320 40 WTFE, build 4943
84 Toyota Supra towd
2015 Jeep Wrangler towd
Victoria, BC, Canada

Re: Intermittent Hot Brake

Reply #1 –
Wyatt,
 
It would seem that you may have released a stuck caliper with your procedure.  But, next time (hopefully there won't be one) don't cool the assemblies with water.  This rapid cooling may warp the calipers/disk.  Pay close attention when braking to dertermine if there is any shimming, etc. to indicate warping.  Thankfully, the front brakes are not doing most of the braking as the rears along with the retarder (if you have one) do most of the work.
Peter & Beth Martin
No Forrest? What have you done?
MC# 15890 until Dec 2016; FMCA #F329677
Cincinnati, OH

Re: Intermittent Hot Brake

Reply #2 –
This is just a guess, but you may have had some binding of the caliper on the slide pins, that released after you noticed it.  These pins and the bushings are not supposed to be lubed as that would make them collect dirt leading to binding.  If there is binding just one pad could be pushing against the rotor.  I  found that condition on one rear brake and it took a good whack with a hammer to get it to release.  One end of a pad was worn down  almost to the metal backing plate.  Never noticed anything like a hot smell, or noise.  One pin was flush with a bushing the other not, was what got my attention.  Replaced pads, pins, and bushings on that brake.  If you can jack up that wheel and it rotates easily, it could have been a temporary problem.  If it happens again, you need to do something.  You could measure the pins with brakes applied, they should be about the same on each brake.  If flush with a bushing it's time for new pads.  Meritor has a manual posted on line.  Barry Beam at beamalarm.com may have it on his website or a link to it. 

Jerry Whiteaker
96 U270
Jerry Whiteaker former owner 96 U270  36' #4831 Austin,TX-Owner Mods LCD TV w/front cabinet rebuild - LCD TV bedroom - Dual Central AC, either can cool coach w 30 amp - Skylights at roof AC openings - Drop ceiling for ducting of AC - Shower skylight white gelcoat/wood/epoxy frame - Air Springs/Shocks replaced - 2014 CRV - 8K Home Solar - Chevy Volt

Re: Intermittent Hot Brake

Reply #3 –
Thanks Peter and Jerry  for your rapid replies.

I sprayed rotor and caliper with a hand sprayer, not a water hose because I could not touch them when I stopped. After the heating there is no pulsing but I will check the rotor runout (with a dial gage) on all rotors after I get the tool which will allow me to remove/reinstall the wheels.
I will check the pins & bushings with brakes applied also - great information.
 
There was a barely perceptable pull to the right which may have been there before. I suspect that the left brake pads have been damaged and will be watching for overheating on future trips. My airbrake manual indicates that brake components will be damaged at above 570F.

Wyatt
Wyatt
96 U320 40 WTFE, build 4943
84 Toyota Supra towd
2015 Jeep Wrangler towd
Victoria, BC, Canada

Re: Intermittent Hot Brake

Reply #4 –
When I first drove my coach home from Nac about 3 yr ago.  THe front left ran warmer than the right front, upon getting back to my shop, pulled front wheels,and brakes, cleaned and lubed per instructions, and no sign of heating since.  So I am guessing my problem might have been a build up of dirt, that is a guess.
Dave

Re: Intermittent Hot Brake

Reply #5 –
It was probably a stuck caliper. FT has issues with them because of the retarded, we use it instead of the brake.  I changed my pads and rotor for that issue and now follow James Triana's suggestion to start out and oust the brake done and to use them every so often. 
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Intermittent Hot Brake

Reply #6 –
John,

Could you explain James Triana's suggestion?

I may be a bit on the dense side as I don't understand what was meant or intended.

Dave M,

Could you PM me. I tried to PM you but, it didn't work. I live in Powhatan.

Thanks,

John
Just enjoying life &  friends wherever we  park


 '91 Foretravel U300/'94 Foretravel U280

Re: Intermittent Hot Brake

Reply #7 –
Quote
Could you explain James Triana's suggestion?
John,
I think he is saying you should push the brake pedal down all the way to the floor after starting the coach periodically to keep the slide pin from corroding and the brakes from sticking.
Thats what James T. told me also.
Since I always use the retarder and rarely use the brakes I try to do this every time I start the coach as part of my start up procedures as a habit.
The selected media item is not currently available.Barry BEAM #16014
2003 U320 40' AGDS
Beamalarm, Foretravel technical help and specifications
"Whatever the mind can conceive and believe, it can achieve"

Re: Intermittent Hot Brake

Reply #8 –
Quote from: Barry Beam –
Quote
Could you explain James Triana's suggestion?
John,
I think he is saying you should push the brake pedal down all the way to the floor after starting the coach periodically to keep the slide pin from corroding and the brakes from sticking.
Thats what James T. told me also.
Since I always use the retarder and rarely use the brakes I try to do this every time I start the coach as part of my start up procedures as a habit.


John, Barry is correct. You need to move the pads and the caliper or it will stick. Also backing up will unlock them usually. Also, you should know how to cage your brakes too.
2025 Wanderbox Outpost 32 on F600 Expedition Motorhome
2015 Born Free Royal Splendor on Ford 550 nonslide version  for sale
Former Coaches  covering. 360,000 miles
1999 34 U270
2000 36 U320
2001 42' double slide U320
2018 Jeep Rubicon

Re: Intermittent Hot Brake

Reply #10 –
John,

Simply stated:  use the service brakes occasionally or you may inadvertently cause them to be less effective. There are more technical explanations, but

I can't supply one.
George Stoltz.  Retired from full-time living in a great Foretravel and now are back to living in a traditional sticks and bricks in Florida.

Re: Intermittent Hot Brake

Reply #11 –
Thanks for these suggestions.
I will add pushing hard on brake pedal after air pressure reaches 90 psi on startup to cycle brakes.

These suggestions are consistent with what the mechanic who inspected my motorhome (for registration in BC) said:
"The pads are all 90% but the rotors are glazed because of very light brake application - use the service brakes firmly at least once on every trip to remove the glazing."

Wyatt 
Wyatt
96 U320 40 WTFE, build 4943
84 Toyota Supra towd
2015 Jeep Wrangler towd
Victoria, BC, Canada

Re: Intermittent Hot Brake

Reply #12 –
Since brake pedal pressing will usually activate retarder, we periodically drive with side panel retarder electric switch turned off.

We then stop a few times hard forward and backward to activate brake pads without retarder assistance, to try to remove all glaze & rust from pads & rotor.