Skip to main content ↑ ↓
Topic: Right Front Brake Pads Dragging (Read 4509 times) previous topic - next topic

Re: New Brake Dragging! Need Emergency Advice.

Reply #20 –
Quote from: rsihnhold –
You could crawl underneath and manually back the slack adjuster off a bit if needed.  You'll likely need the The selected media item is not currently available. if you aren't familiar with what to do.
As promised, here is what "the friendly truck driver" did to get me back on the road.  It is exactly what Robert suggested in his post (above).

First, he asked me if I had chocks, because he said it was safer working under the coach with them installed.  Being a well prepared owner, I did, and we put them in place at the rear wheels.

Then he asked for a screw driver and a Crescent wrench, which I was also able to provide.  We both slid under the front of the coach (so I could see what he was doing).  Looking at the brake (photo #1), he pointed out the auto slack adjuster (black greasy object in center of photo #2).  He used the screw driver to lift up on the "pull pawl" (spring-loaded button in photo #3).  Doing this disengages the gear in the slack adjuster, allowing you to adjust it.  Holding up the "pull pawl" with the screw driver (I had to drop the screw driver so I could hold the wrench and my camera), he then turned the square adjuster screw in a clockwise direction with the Crescent wrench (photo #4).  Doing this rotates the upper part of the slack adjuster away from the air chamber, and releases the excess pressure on the brake pads.

THAT'S ALL THERE IS TO IT.  ^.^d

WARNING:  This procedure renders the brake inoperative, so use caution when driving, cuz you'll only have 3 brakes!

The steps for doing this procedure are all contained in the Meritor Maintenance Manual mentioned in Robert's post (above), but they are not specifically listed as a "emergency procedure".  Instead, they are scattered around in various sections.  If you knew nothing about these brakes (pretty much described me before this incident), it might take you a while to figure out this solution.  Being shown what to do makes it simple!  I owe the "friendly truck driver" a big debt of gratitude.

While waiting to get back with MOT, I have been studying the manual (link below).  I now have a pretty good understanding of how these stoppers work.  The next time I have a "brake emergency", I will be much better prepared.  8)

The selected media item is not currently available.

Re: Right Front Brake Pads Dragging

Reply #21 –
Great Pics !

Thanks,

Carter

Re: Right Front Brake Pads Dragging

Reply #22 –
Chuck, something to think about is all the extra heat that your front tire has received. Might threw that in when you talk to MOT. Would be Big safety concern to me. Could have even damaged the valve core stem seals. 

Re: Right Front Brake Pads Dragging

Reply #23 –
Chuck, what a nice write-up and great images to "show & tell." I'm pleased to hear your saga ended safely.

Also, nice to meet you at Ft. FOT the other day. All the best. Paul

Re: Right Front Brake Pads Dragging

Reply #24 –
I find a 5/16 wrench works well on the square drive if you don't have a square socket to fit it. You can buy a ratcheting tool made for these adjusters it comes with a handy dandy tool to hold the adjuster out.

Please if you don't know what you are doing be careful with this. Adjustment is easy once trained. I prefer to tighten the adjuster until it stops and then back off 3/8 of a turn and measure stroke on a 90 psi apply then I jack it up and make sure the wheel turns free.

Re: Right Front Brake Pads Dragging

Reply #26 –
Quote from: its toby –
Please if you don't know what you are doing be careful with this.
I understand and concur with your concern, Derek.  I only posted this procedure as a emergency action to enable members with a locked up brake to get their coach off the side of the road, without resorting to calling a mechanic or a tow truck.

If this emergency procedure IS used, the coach should be driven (slowly and carefully) directly to a qualified service facility, where it should be inspected by a experienced technician to determine the cause of the malfunction.

The proper adjustment of the brake caliper and slack adjuster is clearly explained in the manual I linked above.

Re: Right Front Brake Pads Dragging

Reply #27 –
Is there a reason that a person would not want to degrease and wash off the dirt and grease residue in the pictures ??  ( sorry, another dumb question perhaps ).

Re: Right Front Brake Pads Dragging

Reply #28 –
Quote from: Bob & Sue –
Is there a reason that a person would not want to degrease and wash off the dirt and grease residue in the pictures ??
Robert,

Again, not a dumb question.  I share your feeling that wiping off the excess grease with a rag would be desirable.  However, in my experience very few "grease monkeys" (OOPS - I mean Professional Chassis Lubrication Technicians) worry about all those globs of goop, assuming I suppose that it will eventually fall off or blow off.

When we finally get back to home base, you can be sure I will be under the coach doing a little "housekeeping".

Re: Right Front Brake Pads Dragging

Reply #29 –
Cleaning excess grease off is not a bad thing however going crazy with heavy cleaners and brake clean can cause issues. The release can become seized also at the end of the slack there are two pins that go through the clevis and the slack to transmit the force from the chamber. If these pins do not rotate freely when not under braking force they can cause the brakes to not release correctly and can either wear out the pins or the clevis or the slack itself.

Re: Right Front Brake Pads Dragging

Reply #30 –
Chuck,
I'm back on the forum again for a bit, and am sorry to hear about your problems. I hope MOT does what is right by you and am glad you were able to make it back to NAC safe and sound.
Take care and happy landings!
Len

Re: Right Front Brake Pads Dragging

Reply #31 –
Update:

Well, today was a mixed bag.  MOT had us come to the shop first thing - got us right in a bay.  The techs pulled the RF wheel and inspected the brakes.  The first thing they found was the bearing "play" was a bit too tight.  On that corner they had replaced the inner oil seal last Wed., so the whole spindle assembly had been apart and back together.  They also determined that the brake caliper did not have sufficient grease due to a big air bubble trapped inside (?).  So anyway, they reset the bearing clearance (used a dial indicator), greased and purged the caliper, greased the slack adjuster, adjusted the slack with the correct yellow template, and buttoned everything back up.

I went out for a long test ride with Kieth (Risch)  He drove at varied speeds, exercised the brakes, and stopped several times to check the brake rotor temps with a infrared thermometer.  He said everything felt OK to him, and the temp checks looked normal.  He did ask me if our wheels had ever been balanced, and I said no because the coach had always felt extremely smooth to me at all speeds.  Otherwise, nothing notable was found.

This work took about 3 hours, and of course there was no charge.  Since it was too late to leave for home, we decided to take the coach for a extended drive around the loop and up and down Hwy 59 north of town.  The coach felt pretty good as far as braking, but I soon became aware of a pronounced "shimmy" in the steering wheel.  This occurred between 60 and 65 mph, and seemed to "come and go".  Since the coach was dead smooth with zero steering problems before this work was done, I decided the shimmy was not a good sign.  Got back to the FOT parking lot, and called Kieth.  I told him what I felt in the steering, and he agreed it was not "right".  He said they had checked the brake rotor runout, and it did not appear to be warped, but he wanted to take another look at it.

Bottom line - we're going back to MOT (again) first thing tomorrow and let them have another look.  I'm not leaving NAC until I'm convinced everything is correct.  So far, MOT has been willing to put me ahead of other service customers, and is trying to work with me.  Hopefully, tomorrow will be our last trip over to their shop, and we can soon head for home.

Will report again tomorrow!

Re: Right Front Brake Pads Dragging

Reply #32 –
My guess is the rotor got warped. When you drive it and lightly touch the brake pedal it would be more pronounced. Also after getting warmed up the steering would start to pulse.

Re: Right Front Brake Pads Dragging

Reply #33 –
Quote from: craneman –
Also after getting warmed up the steering would start to pulse.
That is exactly what I felt - the "pulsing" in the steering wheel.  But I did not detect any odd feel through the brakes under light application.

Re: Right Front Brake Pads Dragging

Reply #34 –
On the side that got hot, I would have expected new rotor and pads. Both would be suspect after being exposed to that heat. Did they re use pads? Definitely would ask for new rotor and pad on that wheel at no charge

Re: Right Front Brake Pads Dragging

Reply #35 –
They did install new pads.  We'll see about the rotor tomorrow...

Re: Right Front Brake Pads Dragging

Reply #36 –
Brake rotor should be checked for cracks, but are pretty durable, from what I've seen from your post they checked the run-out with a dial indicator to indicate a warped rotor, but it won't account for improper torque as they tighten lugs. Road racer's used to heat up the rotors until they were brilliant pumpkin orange at the end of every straight. Glazed pads or rotors can be hit with a scotch brite pad and rebedded. Wish for a positive outcome.

Re: Right Front Brake Pads Dragging

Reply #37 –
Coming through Colorado in oct I used our brakes hard without the retarder to keep the temp rise down in along grade.

Steering wheel shimmied.  Turned on retarder and with lighter use no brake shimmy.

Three thousand miles later I noticed the coach pulling to the left.

Took it in and the cummins shop said I had warped front rotors with the felt one being worse.

They said they were turnable so that's where we are today.

And I had front seal leaks. 

Re: Right Front Brake Pads Dragging

Reply #39 –
My rotor was also  brilliant pumpkin red (twice) when I had the slack adjustor issue, which is why Parliament in St. Pete suggested to change it out - not sure what they were worried about, but it was on their dime, not mine, and they wanted to change it to be safe. I forget what the IR meter said when I scanned the rotor when I stopped, but it was a scary high number -

My situation leading up to the initial brake repair was  - no issue with Brake operation, but one pad was excessively worn on passenger rear - probably because of light dragging over time in the past due to slow caliper release, but not enough to make the rotor smell or turn red.

Took in to shop - TN RV did both rear brakes. I drove 60 miles, turned around and came back to TN RV with hot smelly brakes. They "adjusted" the brakes, still hot smelling - but they swore that would go away. Drove to Parliament in St Pete. - they redid the brakes, TN RV paid them to do the job (Good customer service on their part). Stayed Winter in FL.

I drove to IL and back to FL, and the brakes stuck twice on that trip - both times I stopped on side of Expressway to let cool down. I was able to get rotor to release by pumping brake hard while stopped, and it didn't stick again. RED hot both times. Got back to Parliament, they scratched their heads and brought in a mechanic from outside,  The outside mechanic diagnosed the issue as a bad slack adjuster, ordered new slack adjuster, rotor and pads. Put it back together, not problems since.

All said, the inconvenience factor was pretty high, but both Tenn RV and Parliament made good on the costs, so I walked away OK with how it all turned out, and no hard feelings.

Any metals guys on the Forum with an answer as to if rotor is compromised in some fashion due to excessive heat?