PD4106 Brakes

[richard5933]

I had the bus in the shop this week for some maintenance work, and they adjusted the brakes. In the process, it was discovered that I might need more than an adjustment. So far they've discovered that the clevis on at least one front brake might be binding due to rust, and that I've got one pad separating from the shoe. So, I've got a couple of questions so I can talk to them intelligently when I go back Monday. They only started to do full inspection before quitting time yesterday, so Monday will be the first time to really see what's going on.

1) Are the pads on the 4106 still replaced independently of the shoes and bolted on in the shop? Or, are the pads & shoes replaced in one piece like on a car? The mechanic seemed to think that they would need to replace them together, as this is how they do it on the newer coaches they service.

2) He mentioned that it would be advisable to replace the pads/shoes on both front wheels if one needs replacing? If there is lots of pad left on the other side, is this necessary? I know it would be done on a car, but I'm not sure here.

3) The mechanic said that he would recommend installing new brake drums even if these are still good. Is this typical? Can they be turned like brake drums on a car or is it normal to just replace drums?

4) Anyone have the correct part number for the pad/shoes? I want to make sure that they get pads intended for a bus and not something that should be on an 18-wheeler.

Any other advice for when I go back on Monday would be appreciated.

Thanks
Richard

[brmax]

If one knows by record the pad material can be obtained the same, its ok or has been in my carreer and fleet I serviced. Some shops have abilities to bolt or rivet some dont. Remember labor hours in this situation.
Scenario a wheel seal leaks, does one replace all shoes on that axle. Again as above on using same type shoes, this is a great reason to find if possible standard # for the equipment.. We as customers should only expect the safe method for repair, and with information available. To custom fit components to our coach, we need to try our hardest to find and record components. But unless a coach repair these types or older parts likely wont be stocked.
Fwiw a bit of oil and vise grip the slack adjuster rods clevis pin could be free'd. And remember any brake work on this wheel will need that done most likely anyway.
The drums have a stamped and or casting number to obtain a replacement. Some are cheap considering others, so 75-150 is cheap! Although needs considered if one thinks a machined drum is not worth it.
To be clear I am perfectly fine and have considered it my responsibility deciding if using machined drums. We have and use specifications, time is money.

Floyd

[chessie4905]

First, they should be shoes, not pads. The braking material is called lining on shoes. They should be replaced in sets per axle as only doing one side could result in different friction coefficient on the new set of shoes compared to existing shoe, resulting on brake pull by vehicle to one side or other on every brake application. In fact, here in Pa., brakes must be replaced on both sides of axle. The drums maybe able to be turned oversize, however this calls for shoes with oversize lining and oversize rollers. Otherwise the new shoes won't make complete contact.Think of putting a smaller bowl inside a larger one. The center of shoe will contact and ends won't. If it was my 4106, I'd get new drums while they are still available, and make sure any other worn parts, such as rollers, camshafts, camshaft bushings, pins, springs, etc get done at same time. Once done right, you won't have to deal with front brakes again. Oh, and make sure to get new wheel seals also. Don't know whether your new brake shoes will be prelined and riveted or you'll get new brake blocks that are bolted to old shoes, which is ok if shoes are in good condition. Anyway, they made/ make plugs of lining material to install in the bolt holes. These are then filed or rasped flush.Good to have these as it increases lining surface area and eliminates areas for grease or oil to accumulate incase of oil seal failure.These plugs were listed in the parts section along with lining in GM parts manuals for your model.

[bevans6]

Find all the parts before you make a decision.  I remember one guy had a GM that turned out to have odd drums, he went through a lot a trouble finding replacements and may have ended up converting to something different.  But yes, do both sides with identical material, and sometimes truck guys just throw new drums at everything.  On a common truck application, new drums are cheaper than de-rusting and painting old drums, even if the only thing wrong with the old drums is surface rust on the outside.

[richard5933]

Chessie4905: Thanks for the info. That pretty much confirms what the shop here was saying. Do you know if the shoes/linings should be available through normal supply channels for the shop or will I be calling Luke? Obviously faster if they can be found locally, but it is what it is.

I've got the parts book for the bus, so at least I'll be able to help them get started. I'd bet that the numbers have been superseded at least a few times, so if anyone has the most recent numbers I'd appreciate the info.

Thanks
Richard

[TomC]

When I took my truck in for a brake job, as I was leaving after dropping the truck off, the service manager stopped me and asked what brake linings I wanted. I didn't understand until he handed me a paper with about a dozen different linings available. Some of the choices I remember were: soft for cold stop-like for over the road trucks that need brakes when they are cold, normal medium linings, linings that work in dust, harder linings for hot stop and start, metallic for severe braking like loggers (but do destroy the drums that you need to replace after every lining replacement). I would suggest installing softer linings that work well when cold and are more powerful.
But to your point-yes all linings should be replaced on the same axle at the same time. You don't know what coefficient of friction the existing linings have. New linings only on one side could create a dangerous pulling. You'll find that relining or replacing the shoes should not be that expensive. I know on trucks, the standard 16.5" x 7" drum will cost about $90 and the upgraded Centrifuse brake drum about $175. Lining, roller and spring kits should be around $85 per wheel for standard up to $200 for more fancy linings. So realistically, you should be into new drums and linings for the front axle for around $500. Good Luck, TomC

[brmax]

Richard a tip I mentioned earlier, knowing the brake lining and or shoe component # is a key here. These items are found commonly on a "line sheet" as from a new vehicle purchase like this was and from the manufactures build of the equipment. Many times we don't know and so repair as a complete axle in best practice, and technical education.
This line sheet will list the exact part put on in the factory and designate its spec. briefly many times.
If one wants to change available types within rules that's normal. At this normal commercial, and or size level there are recording requirements of these and other repair with components as a mechanic or fleet.
You can be assured Luke will have the exact part numbers these coach's are standard with. So in listening to others I agree when in doubt do the safest thing and as important feel confident your getting a safe repair. As was mentioned by the tech the certain way they recommended to install as  keeping their standard for the vehicle and there business, this I always respected and never want to test a mechanic's safe call because I thought cheaply. 

In my cases I seen the vehicles when new, with line sheet and kept my "required records" and within the sheet specs. Its simple, its the rule.

Best regards
Floyd

[chessie4905]

I believe that the part number in the book also lists in the description letters like_ FF,FG,EF or something to that effect. The letters refer to the friction characteristics and will be helpful to the shop in ordering. Don't order anything from Luke or any other supplier before you clear it with your repair shop.Some shops don't like working with parts they didn't supply and be difficult to deal with. Also you can check with Mohawk bus parts if you have part locating problems.

[richard5933]

Update on this...

Long story short...the shop has been having some problems, not my brakes. I've been taking the bus to a large shop in Butler WI with really good results and only minimal problems, but this past visit has given me reason to start searching elsewhere. They were supposed to handle three things. 1) Adjust hand brake after my recent problems, 2) Adjust service brakes now that I've put a few hours on the bus, and 3) Find the cause of the air leak into my generator fuel supply and purge the air.

Hand brake has been adjusted fine. No problems there.

Service brakes created some definite confusion for them. First, when I picked it up the brakes were only marginally functional. I took it right back to have them investigate. Their initial thought was that I needed a brake job on the front, possibly the back. The mechanic saw some rust on the clevis and assumed it was binding. He also saw what he thought were cracks on the edge of the linings. In the end, after lots of time on the phone to Luke, the problem was that they adjusted the front and rear the same. The rear are supposed to do most of the work on a 4106, and since the fronts were adjusted as tight (or maybe tighter) as the rear they quickly faded after use. The 'cracks' were the wear indicator lines that are supposed to be there. After a thorough inspection and re-adjustment they are functioning properly.

The shop was able to get the air purged from the generator lines, but not before doing some damage to the electrical system. At least that's how it seems to me. In the process of trying to purge the air, new problems were a blown flyback diode, a blown fuse to the Murphy switch on the generator, a blown Murphy Switch (guess the fuse didn't protect it after all) and blown fuses on my new house battery charger. I believe that someone connected the house battery with reverse polarity at the shop, as the manual for the charger indicates that the purpose of the 3x 25-amp fuses is to protect against reverse polarity connections. They were all blown. Fuse to the house stereo was also blown, and my Echo Charger has ceased charging. Fortunately there was nothing else connected to the house system at the time and I think that the damage was contained to these items.

Before taking the bus to the shop I pulled the new house batteries and installed a single 8D. I knew that they'd have to remove the batteries to gain access to where they were working, so I wanted to make it as simple as possible. My guess is that someone hooked the 8D backwards when they put it back to test things.

I've asked the service desk to check with the mechanic to see what he was doing when the Murphy switch stopped working. I really hate to make any false accusations or to think poorly of a shop, but between the problems getting the brakes adjusted and the electrical issues I'm quite disappointed. Got a call this morning (9/14) to confirm that the mechanic did connect the battery reverse for a moment. Guess that was enough.

In case anyone is going to suggest that I should be adjusting my own brakes, I already know that. I have no problem doing it, but not until I've got a safe way to block the bus. Still investigating that and hope to have it figured out soon.

Richard