Brake troubles

aaronjweiss · February 20, 2017, 04:11:58 PM

Yesterday driving through California mountains in the rain in my MCI 102c3 I noticed my brakes were drastically less responsive than usual. We had a very scary moment when our bus wouldn't come to a complete stop on a downgrade. Even the parking brake wouldn't keep it still. I pulled over and tightened the slack adjusters on the steer and tag axle (couldn't move them on the drive axle, I'm assuming b/c the parking brake was on?), which helped a lot, but the experience has left me a bit rattled, and with a few questions:

Does this sound like merely an adjustment issue? Or possibly related to overheating? Probably exacerbated by the rain?

And finally, does anyone know a repair shop around San Diego I could take it to?

Thanks so much!
Aaron W.

Zephod · February 20, 2017, 04:55:25 PM

Check the depth of the brake pads. I'm assuming since you have slack adjusters that you have air brakes and drum brakes.

The pads should not be unevenly worn nor should be excessively thin. The drum should be clean and clear of grease and dirt.

Brakes cool fairly quickly. Overheated brakes have a definite odor about them. Just a thought... do you have brakes that don't have an emergency brake built in? Could it be that you have a leaky air line?

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Iceni John · February 20, 2017, 06:16:14 PM

After you've correctly fixed your brakes, you may want to consider installing a brake application force dual pressure gauge. It will tell you if your brakes are overheating (because you'll need increasing amounts of air pressure to hold a constant speed on a constant downgrade), and if you have a leak in either the front or rear system (because the two needles won't move the same amount). I check mine whenever I descend long grades, even when using the Jakes - it's just another way of knowing what's happening before things could get bad.

John

Utahclaimjumper · February 20, 2017, 06:34:37 PM

How often do you drain your air tanks?"?when they get near full of water and oil there is no room for AIR,,and after an application (or two) you got nothing to work with!!>>>Dan

Zephod · February 21, 2017, 01:10:51 AM

Quote from: Utahclaimjumper on February 20, 2017, 06:34:37 PM
How often do you drain your air tanks?"?when they get near full of water and oil there is no room for AIR,,and after an application (or two) you got nothing to work with!!>>>Dan

Good point. I forget about draining air tanks because it's automatic for me. Every time I park, I drain the work bus air tanks.

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Scott Crosby · February 21, 2017, 07:09:09 AM

Is there any oil on any of your brakes? Bad wheel seals make for slipping brakes. Block the wheels and body and then release the parking brakes and then you can adjust the slack adjusters on the drive wheels. You really should inspect your entire brake system and learn how it works before driving it again. I have seen people turn the slack adjusters the wrong way and accidentally disable their brakes thinking they were tightening them before so make sure you see the shoes tighten against the drum. They are not always the same direction.

luvrbus · February 21, 2017, 08:19:04 AM

Sounds more like you just overheated your brakes to me MCI buses have good brakes,unless they are over heated.I would buy a $10.00 scope camera that works on a cell phone or lap top and inspect the drums for cracks.
A drum with cracks when hot will expand and the shoes will not make the correct contact,cracked and out of round drums are the worst culprit for bad braking especially when hot IMO and Bendix and FWIW rain will have a huge affect on braking. .
If you really want to know about brakes take a Bendix course either in person or do their online schooling draw back is they don't cover much on your DD-3 brakes.
Bus people don't seem to want to spend the money on brakes because of cost like a complete brake job on yours with new drums can exceed 5k in a hurry

buswarrior · February 21, 2017, 08:34:31 AM

Quote from: Scott Crosby on February 21, 2017, 07:09:09 AM
You really should inspect your entire brake system and learn how it works before driving it again.

And that's the best advice.

With your DD3 brake system, ignore all the spring brake info, it doesn't apply to your coach. Focus on the wheel end mechanics, how to inspect, measuring, tightening and measuring again, slack adjuster applied stroke, and proper operating procedures for descending hills.

happy coaching!
buswarrior

daddysgirl · February 21, 2017, 08:45:49 AM

I agree with the overheat...and the seals, possibly.
In my experience (because some jackass failed to listen and check the rear seals, the front breaks had 1/8" cracks and were doing all the stopping for 44,000 lbs) heat and tires are not a good mix.

Lin · February 21, 2017, 08:48:19 AM

I do not know of specific shops in San Diego, but truck shops should be able to take care of you on brakes. You may even be able to get them checked at a truckstop along the way.

TomC · February 21, 2017, 10:00:58 AM

In the rain, it is hard to overheat brakes. Your brakes are just plainly out of adjustment. Tighten the slack adjuster down till it stops, then back it off by 1/3 turn. Bang the drum brake with the wrench and it should ring like a bell. If it just clunks, then back it off a bit more. Good Luck, TomC

luvrbus · February 21, 2017, 01:38:05 PM

Brakes will steam in the rain it happens all the time in the mountains,reading the post this was a 1 time deal his brakes were fine up to that point

gumpy · February 21, 2017, 03:57:52 PM

Well, I'm just going to throw this out here.

Do you actually know how to properly adjust your brakes, and have you been doing it on a proper maintenance schedule?

The reason I ask is because anyone who does would know that you cannot adjust the drive axle brakes when the parking brake is applied!

Next question, how many turns did the steer and tag brakes require to tighten up?

Zephod · February 21, 2017, 04:08:24 PM

Quote from: gumpy on February 21, 2017, 03:57:52 PM
Well, I'm just going to throw this out here.

Do you actually know how to properly adjust your brakes, and have you been doing it on a proper maintenance schedule?

The reason I ask is because anyone who does would know that you cannot adjust the drive axle brakes when the parking brake is applied!

Next question, how many turns did the steer and tag brakes require to tighten up?

Omg! Took the words out of my mouth. I read somewhere about somebody complaining their hydraulic brakes went out due to corrosion of a brake line. Clearly somebody that hadn't been under their bus to give it a good check over in a long time, if ever.

Part of the problem is that the drivers of most busses converted to RVs just don't have a CDL and have never had the benefit of CDL inspection training.

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luvrbus · February 22, 2017, 07:12:06 AM

He did make a mistake by trying to adjust the drive with parking brake applied.I still think the rain and heat caused his problem.You never adjust brakes when they are hot anyways and his bus should have automatic adjusters that need some TLC.

That was they were installed people are just accustom to automatic adjusters how many of you here adjust your brakes on your auto or pickup

You go into a shop and the new guy with the clean new uniforms,new tool box, walking around guess what he is going to be the one working on your brakes some shops will keep a eye on him.

So don't think for a minute you get a guy with a lot of brake experience,later on the shop may enroll him in a Bendix or Midland course you never know.Free info is out there he just needs to read