Broken disk brake rotor

Topic: Broken disk brake rotor (Read 2577 times) previous topic - next topic

Re: Broken disk brake rotor

Reply #25 – August 05, 2017, 12:25:29 pm

Bret, as craneman said everything has already extended as far a it will go. However as you are under there it takes 5 minutes to cage the spring brake just to be sure. The reason for capping the lines is to keep the assembly from trying to move. In the case of the service side if the line where still connected the slack adjuster would continue to try to adjust every time the brake pedal was applied, possibly damaging it. The caliper and slack adjuster are expensive items, it just doesn't take much to make sure anymore damage is notdone you are under there anyway.

Re: Broken disk brake rotor

Reply #26 – August 05, 2017, 12:46:41 pm

The question (I have no answer) is whether subsequent applications of the uncaged parking brake will cause the slack adjuster to continue to extend/over-extend (if the parking brake is not caged).

Re: Broken disk brake rotor

Reply #27 – August 05, 2017, 01:26:45 pm

Brett, I don't know if additional damage could be done, but property adjusted the parking brake travel is 2-2 1/2 ". Without the rotor in play the travel would bottom out the chamber travel 4-5" rather violently. It couldn't possibly do it any good. It will also transfer that travel to the caliper. The caging process is not a big deal 3/4 wrench remove the tool from the side of the chamber install it in the end of the chamber and tighten the nut until the it will not tighten any further. It's got to be done anyway before repairs can be made.

Re: Broken disk brake rotor

Reply #28 – August 05, 2017, 02:07:12 pm

So the concensus opinion is to cage the parking brake and to cap the line.

I think the pad(s) may be still in the caliper from a comment the mechanic made

Re: Broken disk brake rotor

Reply #29 – August 05, 2017, 02:10:26 pm

"Most conservative" answer:

Remove pads
Cage parking brake
Block off line to service brakes
Fix as soon as reasonably possible.
Remember if pads are replaced on that side to put new/the same ones on the other side. And I am a fan of the retract springs.

Re: Broken disk brake rotor

Reply #30 – August 05, 2017, 02:13:33 pm

Brakes had the assist springs installed.

Can the pads, if present, be removed with the inner wheel on?

Needs to go 1k miles at highway speeds safely

Re: Broken disk brake rotor

Reply #31 – August 05, 2017, 03:00:15 pm

I don't believe the slide pins will clear the wheel. I had to make a Rube Goldberg device to pull the pins. Here are some pictures.
helper springs

Re: Broken disk brake rotor

Reply #32 – August 05, 2017, 05:33:58 pm

One wheel parking brake and three wheel braking and two wheel retardation should get us from Idaho falls to so. cal carefully after caging the parking brake on that side and after removing and blocking the air line on that wheel.

Re: Broken disk brake rotor

Reply #33 – August 05, 2017, 07:07:28 pm

Cage the chamber before you remove and cap the air lines. Then you can use the air to compress the spring and save yourself several long minutes of cranking on the nut for the cage bolt against the tension of the spring for all of the travel.

Re: Broken disk brake rotor

Reply #34 – August 05, 2017, 07:11:44 pm

So I would need to start the motor and build air pressure then release the parking brake with the coach tires blocked?

with the tires remounted?

Then remove the brake air line?

Sounds like an expert job.

The shop might not be comfortable with being under the coach with the motor running and the one good parking brake off?

Re: Broken disk brake rotor

Reply #35 – August 05, 2017, 07:19:43 pm

Yes. Wheels still on and chocked. Build air. Insert cage bolt with nut all the way at the end. ( less spring tension so it's easier to get the bolt in the hole of the cage bracket sometimes it migrates when compressed) ( insert and turn 1/4 turn and pull on it to make sure it engages) push in park brake button. Run it down the spring is already compressed so it won't be hard until the last turn or two. Tighten with a wrench. Release park brake slack should not move. Remove lines and cap.

Re: Broken disk brake rotor

Reply #36 – August 05, 2017, 07:32:44 pm

You don't have to have the motor running, just the air pressure built up. After caging and releasing the parking brake there will be no pressure on the brake lines. If the shop doesn't have fittings for the lines, there are pipe threads where the AN fittings hooks to the hoses. Remove the fittings and install pipe plugs.

Re: Broken disk brake rotor

Reply #37 – August 05, 2017, 08:39:46 pm

I have not seen any mention of the rear service brake "compounding valve" that is there to prevent both the spring and service brake from functioning at the same time. Is it something that needs discussing?

Re: Broken disk brake rotor

Reply #38 – August 05, 2017, 09:22:28 pm

Barry the valve will not know the difference, the parking brake will be released while going down the road.

Re: Broken disk brake rotor

Reply #39 – August 05, 2017, 10:04:38 pm

Inside the chamber both the park and service circuits are still kept separate as far as the air goes so capping lines is no different.

The anti compounding valve has access to both circuits and could be looked at as a suspected cause of brakes dragging along with the chamber itself. It's designed to allow the park system and the service system to operate but not have both gang up on the brakes an apply excessive pressure. Never seen it but I have been told without that valuable you can actually apply enough pressure to fracture brake shoes. I have seen them fail and allow park brake air to seep into the service side and either drag the brakes or create a leak at a qr valve. If that was the issue you should see dragging on both sides of the drive axle.

Re: Broken disk brake rotor

Reply #40 – August 05, 2017, 10:25:22 pm

Quote from: its toby – August 05, 2017, 10:04:38 pm

Inside the chamber both the park and service circuits are still kept separate as far as the air goes so capping lines is no different.

The anti compounding valve has access to both circuits and could be looked at as a suspected cause of brakes dragging along with the chamber itself. It's designed to allow the park system and the service system to operate but not have both gang up on the brakes an apply excessive pressure. Never seen it but I have been told without that valuable you can actually apply enough pressure to fracture brake shoes. I have seen them fail and allow park brake air to seep into the service side and either drag the brakes or create a leak at a qr valve. If that was the issue you should see dragging on both sides of the drive axle.

That valve only comes into play when the parking brake is on and the treadle valve is pushed. It equalizes pressure in both chambers. With the parking brake off it does nothing. The issue you are talking about is when the seal between the chambers leaks. It used to be a problem with "California wheels" not being centered and shaking the chamber.

Re: Broken disk brake rotor

Reply #41 – August 05, 2017, 10:50:06 pm

I do some things that are calculated that many would argue are imprudent. However, I'm pretty certain I would not drive 1000 miles with one of my rear brakes not working at all.

A) Unlike a car, a truck or heavy vehicle gets much more braking form the rear axles than the front axles
B) If you have an air system failure, you now only have one spring brake to rely on. Even in good conditions, 2 spring cans for emergency stopping with air failure may not be enough.
C) Though retarder greatly reduces brake usage, it can fail.
D) Sh*t happens, and try explaining that when 30,000lbs is rolling down the hill with 30-40% of it's braking gone.

Going 20-50 miles to a shop....maybe. 1000 miles?!!???!!?

Re: Broken disk brake rotor

Reply #42 – August 05, 2017, 11:30:07 pm

Quote from: krush – August 05, 2017, 10:50:06 pm

I do some things that are calculated that many would argue are imprudent. However, I'm pretty certain I would not drive 1000 miles with one of my rear brakes not working at all.

A) Unlike a car, a truck or heavy vehicle gets much more braking form the rear axles than the front axles
B) If you have an air system failure, you now only have one spring brake to rely on. Even in good conditions, 2 spring cans for emergency stopping with air failure may not be enough.
C) Though retarder greatly reduces brake usage, it can fail.
D) Sh*t happens, and try explaining that when 30,000lbs is rolling down the hill with 30-40% of it's braking gone.

Going 20-50 miles to a shop....maybe. 1000 miles?!!???!!?

Had a similar problem and traffic stopped and I didnt.. I would not do it even at 45 mph all the way... it takes a long distance to stop.

Re: Broken disk brake rotor

Reply #43 – August 05, 2017, 11:34:04 pm

"If this stuff was easy, little kids would do it." My quote.

Not for a minute would I consider driving any distance with a disabled brake intelligent.

Like a lot of my posts I have stated what I may do is not reccomended and if you feel uncomfortable do not do this.

That being said the availablity of professional repair in this area is zero.

Parts too unusual. No chassis. No parts list. No experienced shops or mechanics.

I have built race vehicles for 50 years. Airplane tech.

The 25% braking loss minus the fully functional retarder offset by the fact that a incorrect repair percentage probably exceeds the less braking risk to me.

That its a rear versus the steer is a plus plus I have tested the three wheel braking on a short drive to the shop. Doable.

Unless you want to flat bed the coach a thousand miles? Two cats in coach. Tough to put them in a tow car for that long.

No black or white only shades of grey.

Two miles from I 15. Mostly flat ground.

All bad choices. No one within a long drive can fix this.

Oh, there is a camping world seven miles away. Oh joy. Should I have them learn how to fix a meritor disk brake system on my coach?

I almost kept driving after picking up the broken rotor but I may be crazy but not stupid. I hope.

That's why I stopped where I am at for a confab with my fellow wizards. And to look closely. My home work.

I have had a lot of unusual driving/race experiences in 2 million miles. Still here.

Coach actually had the left rear partially working for a period.

Slight braking pull was what I noticed. No idea why the failure but I will figure it out later.

The cautious answer, of course, cannot be wrong.

Offset by the odds and time of a remote repair I will have to furnish the parts for and watch while they learn how to install them.

The first shop said the not yet failed rear brake was stone cold. The other side hot. Worked ok. Three wheel.

Rotor failed in ten miles.

With the pro advise I have received and with the mods suggested I think I will limp home fine.

Fingers and toes crossed.

Again. Absolutely not recommended. Stupid.

Unless you think you have a feel for these things. Then you are probably wrong.

Bored here. Need to get down the road. Plus they are having trouble with the last inner wheel stud.

Better to put the wheels back on I feel. Block the parking brake. Cap the brake line. Pins are in the caliper so the pads are ok.

Calculated deal.

Way glad I stopped and am in a closed shops parking lot to juggle the choices.

Probably would have made it. Probably.

The way your help changes things make the probable almost a certainty.

For that thanks from all four of us.

Regardless of what happens.....

Re: Broken disk brake rotor

Reply #44 – August 05, 2017, 11:42:12 pm

Good luck with whatever you choose and drive careful ...

I see a camping world is close..

Id rather drive 1000 miles with no brakes than go there..

Re: Broken disk brake rotor

Reply #45 – August 05, 2017, 11:47:10 pm

That's what I thought. The fleetpride service local does not work on motorhomes nor does the kenworth shop or any local guys.

These people were nice enough to try to help and to hook me up to 30 amp in their parking lot.

Re: Broken disk brake rotor

Reply #46 – August 06, 2017, 01:27:17 am

Bob my personal opinion is run the interstate, at a slightly above posted minimum rate of speed. Let others pass you, so what. You have essentially have 2 braking systems and one axle out of four is compromised. Most vehicles have less to work with. Continue searching for a shop for a proper repair no doubt. If traffic should get congested exit and take a break and wait it out. Search out to find any construction zones. Know your current visual and braking limits and don't excede them.

Re: Broken disk brake rotor

Reply #47 – August 06, 2017, 11:35:12 am

Bob,
Been following the thread with interest but due to my advanced ignorance, I've kept my mouth shut - until now.
You, and the group here have gobs more experience than l - what ever way you decide to go, good luck and be careful!
If you do head out, I'm sure all your brothers here expect frequent updates so we know you and yours are safe.

Re: Broken disk brake rotor

Reply #48 – August 06, 2017, 12:11:11 pm

I changed my rear rotor myself. NAPA can get the rotor. Any reasonable truck mechanic can do the rest of the work. The hardest part is getting the hub off. And that isn't hard, it's just heavy.

Once the hub is off, the rotor just unbolts and bolts on. There is nothing special. Replace the oil seal while in there ($15 part?).

I did it with my friend in his front yard. I could do it along side the road with the tools I carry in my RV, if needed. In fact, taking the tires off was probably the hardest part.

Do as you choose. Rear brakes on a heavy vehicle are more than 50% of the braking.

Re: Broken disk brake rotor

Reply #49 – August 06, 2017, 12:16:27 pm

Quote from: Moby – August 06, 2017, 11:35:12 am

frequent updates so we know you and yours are safe.

Live Feed, Bob?
Y'all be careful.

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