DD3's to spring brakes, comments?

[John316]

Anybody want to guess what I am planning for this summer? I know, I don't have the time, but I figured that I won't have anymore time then now .

Does anybody have any suggestions for the conversion? Paul (Dreamscape) I know that you had a write up on that (I heard that it is on the Eagles board, I will have to look).

Otherwise, I am mostly trying to figure out the plumbing on those. I know we will need different relays, but I am not sure which right now.

This post is my first step in the gathering information process.

Thanks.

God bless,

John

[Dreamscape]

John,

The plumbing on our Eagle was pretty simple. Read the article and if you have questions let us know. Just remember that the article is for information only. I'm not a brake expert, don't rely on that information without having an expert check it out. You know, the usual disclaimer stuff. 

Just be safe!

Paul

[buswarrior]

The later D coaches optioned/changed to spring brakes over time. Is there space for them to fit in the current configuration on the axle?

If so, use the materials in the Maintenance and Parts manuals to substitute the spring brake components for the DD3.

You must pay close attention to getting the circuits that save your bacon under an air failure to work right.

Distinctly, you need parking, service, and emergency components interacting as stock would.

A bit of available parts acquisition and some re-plumbing.

keep the questions coming!

happy coaching!
buswarrior

[John316]

Paul,

I am going to look up your writeup. The more ideas, the better.

BW,

There is loads of space under there. Not a problem. I will check MCI out, and see what they have. That would certainly be the easiest. But that will co$t me the most . My goal is to have as much of the conversion as possible, be simple truck parts that I can get from NAPA. Time will tell if that is actuality.

I am certainly going to get the alarms working.

I wonder if I will be able to tie my current parking brake tank back into the general brake system (convert it to a regular air tank to feed the service brakes)....

Thanks.

God bless,

John

[buswarrior]

This is a good project for a 102D coach, and will be repeated many times in the future as they become part of the hobby, but...

By emergency components, and saving your bacon, I meant the emergency valving and plumbing, which will automatically compensate for some air losses. Alarms are a given, but far from enough!

A spring brake relay valve figures prominently in that functionality, a part that isn't in a DD3 system. The existing plumbing will be mostly available for re-assignment to make these work.

Also, a faithful re-plumbing is required where you don't re-use the parking tank in a way that allows the spring brakes to be released with no service air to stop the coach!

This is no place for roll your own, you need to follow a whole system design, with valving sourced that will perform the way the system intends, or there can be disastrous consequences when the brakes don't do what is expected of them, especially under partial failure.

Yes, you may get the parts at the local NAPA, as long as it is the right parts.

happy coaching!
buswarrior

[Len Silva]

Probably the best single source of information is the Bendix Air brake Manual available here:
http://www.wsafc.org/WSFMA/Shared%20Documents1/Bendix%20Air%20Brake%20Handbook.pdf

If you are going to make this change, I would replace all the various valves, even the treadle valve.  They are relatively inexpensive.

On an Eagle, it's fairly easy to replace all the tubing as well as it runs in a conduit from front to back. Do not splice or extend any tubing, replace it. Be sure to use DOT fittings and ferrules.  Don't know about MCI.

[lostagain]

Why change? What's wrong with the stock system? What am I missing?

JC

[John316]

Why change? What's wrong with the stock system? What am I missing?

JC

JC, I figure that I am just going to get more busy in the future, so I am just going to take time to do it this summer. As to why change, personally I like the springs better. Nothing necessarily wrong with the DD3. Except they aren't the standard anymore. If something goes wrong with the DD3, it is pretty much an automatic teardown and rebuild. If something goes wrong with a spring brake, run to Napa and get a new chamber. On the road, the springs are more readily available too. I don't know, I like the idea of knowing that the parking brake is on, no matter what the air pressure is. Just my thinking....

BW,

Thanks for the information. Good points. I want to make sure that this system will be good. I will work very closely with my buddy at MCI tech support.

Len,

Thanks for the link. Good reading.

I appreciate the replies.

God bless,

John

[bevans6]

A lot of people think spring brakes are better than DD3's.  Certainly spring brake cannisters are a lot cheaper than DD3 cannisters, and DD3's are no longer made.  To me it's a bit of a wash, I can get rebuild kits for the DD3's I have, or new ones for what I consider a reasonable price, and this summer I plan to do both - install new DD3's and rebuild my old ones as spares.  Just my way.

There are advantages and disadvantages to either system in use.  I think the only reason DD3's got left behind is that spring brakes are simpler to manufacture on the vehicle and match the vast majority of OTR air braked vehicles, so spares, mechanics, repairs are a lot easier.  I think that there are advantages in certain emergency braking/air loss situations that may sometimes favor the DD3, but there is a certain elegance to the spring brake's "no air, no roll" operation.

For me, the major objection to going to spring brakes is the potential liability resulting from unauthorized radical modification of the manufacturers braking system.  I have no idea how one would go about getting the modified system "approved" or even who you would ask, but I bet that a lawyer would know if you ever have an accident, even one not resulting from any failure of the braking system per se.  I also have no idea how that would actually play out in the US.  Or in Canada, for that matter.

Brian

[John316]

Brian,

Now that you mention it, that is another good reason to use MCI parts. Thanks. I agree, the DD3's can be rebuilt, and they have worked nicely.

God bless,

John

[lostagain]

When I was looking after the hockey team's 102D3, I replaced one front chamber, and both drive axle DD3 chambers. No problem getting them. Yes a little more expensive. But that will last a long time. And is a LOT cheaper than converting a whole system.

I have DD3s on my 5C, and will replace parts as necessary when the time comes. I suppose if parts became totally unavailable, one would have to convert, but we are not there yet I don't think.

JC

[artvonne]

  If you pull into a highway truck stop with a DD3 problem, are they able to get it working, or have spring brakes so taken over the industry that DD3 is yesterdays techology, and they need to kick old Bobs chair and get the grey hair out there to figure it out?

  Mechanics is a hard life, and hard on your back, most are out of it by 30 or so, if their smart. If the 20 somethings dont know the system you really dont want to be paying on the job training if you find youself in a bind. I could see the desire to have current technology for that reason alone.

  We could build our own coach from scratch in this country, including the air brake system if we want, and it can be DOT'ed by anyone if its put together correctly.

[luvrbus]

You can change over to springs with the valves cheaper than you can buy the parts for a rebuild on a DD3 and Bendix does not support that system any longer they are not making parts for DD3.
Brian I have to disagree on the modification of brakes when I was a kid I replaced a lot of mechanical with hydraulic brakes on old Chev's and Ford's was that for the better or worse ? today I have friends with buses converting over to disks on the their buses good or bad ? my take on it why use a obsolete system when there is something better



good luck

[lostagain]

Replacing brake chambers isn't rocket surgery! Any greassy monkey can do that. Getting DD3s to your truck stop might take overnight or so. If you're worried about it, do like Bevans6 and carry spares with you.

JC

[artvonne]

when I was a kid I replaced a lot of mechanical with hydraulic brakes on old Chev's and Ford's was that for the better or worse ? today I have friends with buses converting over to disks on the their buses good or bad ? my take on it why use a obsolete system when there is something better

  Like the old Fords and GM's with single line master cylinders? Switching them over to a tandem master cylinder system with a propotioning valve is a lot of piece of mind.

  I dont know enough about DD3 vs Spring brakes to have an opinion, other than the knowledge of trying to repair obscure things when off the edge of the map. Having the most currently available equipment with readily available parts and a knowledge base that understands it, is nice to have when your in the middle of nowhere. An Audi Quattro is a nice car. But it can become worthless when your out in the middle of farm country and the locals only have domestic parts and knowledge. Youll either be flatbedding it back to civilization, or walking.