DD3 brake Chambers Rebuild or change to spring brake ?

Ed Brenner · October 01, 2009, 04:09:08 PM

Okay , This is a what would you do ?
the DD3 have not been touched I know in 15 years. I am going through everything that could possibly
go wrong on the road (murphy will stay at home !! ). I am either going to rebuild these units or replace them and convert to
spring brake chambers. If money is not the issue would you rebuild the DD3 or replace with spring.( rebuilt units for about $400 each
or mine for a little less as of today) Assuming I rebuild I would hope
they would outlast me, because I know a failure on the road would be awful hard if not impossible to get a replacement.
That is really my concern as I plan on taking several long trips, and all of us would like to not have to crawl up under these
beasts in a parking lot on a rainy dark night!!!!

Thanks for any input.
Ed 77 Eagle 05

Eagle Andy · October 01, 2009, 04:43:08 PM

Hey Ed , Iam sure more will chime in here , You can go to the Eagle board and Dreamscape has a thread there that will explain what it takes to change them out , check it out it might be what your looking for .

Eagle Andy · October 01, 2009, 04:50:15 PM

Eaglesinternational and click on the eagles form and open the tech section.

bobofthenorth · October 01, 2009, 05:23:19 PM

"If money is not the issue ...." it seems to me there's likely a good reason that industry has gone over to spring brakes so I'd make the switch too.

Chuck Newman · October 01, 2009, 07:46:58 PM

Ed,

I just went through the same anguish. Rebuilding both DD3's at Capital Clutch in Sacramento ran me $449. each as of yesterday. REI Braked Supply in IL has them for $525. new, not rebuilds. Will new outlast a reman? I don't know. Their was a big communications snafu with the local truck dealer that acted as the intermediary. Knowing what I know now I would have purchased new units. But I had to stay with DD3's, and you have a choice

Before I got to this point, I carefully measured a new 3030 spring brake chamber and it is 2" too long to fit my MCI. The price difference between the DD3 and new 3030 is phenominal, several hundred dollars each.

I read the conversion paper the other's have mentioned, and believe me I would have done that in a heart beat if I could have made it work. Check with other Eagle owners. I don't know if they are all the same, but get rid of the DD3's if you can.

I'm stuck with them. Hopefully, my new rebuilds will last my life in the coach. FWIW

Chuck

PS: I'm geared up to work under the coach day or night, but if a DD3 goes bad, it is now shop time. The 3030 brake chamber can be obtained at any truck supply store for under $100.00. The DD3 has to be rebuilt. The 3030 is a throw away item.

buswarrior · October 01, 2009, 08:25:48 PM

Swap to the spring brakes and send your DD3 remnants to me!

Seriously, there is some plumbing to do besides just swapping the chambers.

Dreamscape has done it recently.

happy coaching!
buswarrior

NJT5047 · October 01, 2009, 08:31:24 PM

Hi Ed,
You'll have to re-plumb the air system for spring brakes. Don't know how much of the OEM system can be retained. The park brake system is much simpler on spring brakes.
Another issue, which may not be a problem on an Eagle, is that spring brake cans are a good bit longer than DD3s. You may not have room to easily make the change. MC9s don't have room for spring cans...your Eagle might have?
IMHO, if you pull the DD3s and replace the two diaphrams in each unit, clean and lube the park lock mechanism, they'll outlast the rest of the bus.
Unlike spring brake pots, you can disassmble DD3s without risking life and limb.
They are a proven item. They work. And your bus is plumbed for them.
Spring brakes work great too....just a good bit of fab required to exchange the units. It ain't 'bolt-on' and go.
Post pix of your conversion if you install spring brakes. Be sure and compare the stopping power between the two designs. You'll want similar displacement.
Y'all coming up to Kyle's next weekend?
JR

Dreamscape · October 02, 2009, 05:35:25 AM

Hi Ed,

As others have said, you might be better off to change to Spring Brake Chambers. You can buy replacements anywhere they sell truck parts, not so with DD-3"s. On my Eagle 01 it really was an easy task, lots of room to work with and they bolt right onto the existing brackets. Yes you have to change some plumbing, no big deal. They are about 40 bucks a pop. Don't use any thread tape on the fittings, use pipe dope. Replace any old air lines and fittings if they look suspect. Use DOT stuff, which is available at any truck shop or store.

The post Andy is referring to, actually there are two, one for switching out on an 05 and the other explains what I did on our 01.

Go "Down Under" and measure the distance from the existing DD-3's to anything forward that is close, get out your brake plumbing schematic and study it, get familiar with the terms used. You may or may not have a dual brake system, find out. Maybe a PO did some modifications that you are not aware of.

If you have any other questions I'll be more than happy to assist you.

I really like the new setup, you don't have to apply the service brake to disengage the park brake, release park brake and go.

Clifford talked me into doing it, sure glad he did!

Paul

luvrbus · October 02, 2009, 05:47:36 AM

Ed,spring brakes swap on a Eagle is not brain surgery no fab work to do cost around 250 bucks for both cans and the valves you need and that is a high estimate.
Are your cans mounted on the front of the rear axle or the back if on the front the passengers side has to be rotated to clear the the torsion tube not a big deal and the price of spring cans new why would you even want to open one .
Go for the spring brakes you will like not having to wait till the air pressure is just right and pumping the pedal to release the brakes push the application valve off you go.
For you MCI guys I under stand MGM a manufature of spring brakes in Charlotte has a can that will work for you guys nows they have over 20 different models of the spring brakes
Ot here but how did the new radiator from Altas work out for you.

good luck

bevans6 · October 02, 2009, 06:36:49 AM

I'm more than willing to be schooled in this area, but here are my thoughts. the DD3 and the spring brake both serve two different functions - parking brake and emergency brake. leaving the parking brake function aside, since they both work fine, they act in an emergency brake situation completely differently. DD3 has a separate air tank, hose system and diaphragm that allows a driver to have a couple of decent brake applications if the primary system goes away. I think the emergency diaphragm is smaller, but you would still get driver-controllable braking on the rear wheels. The spring brake system relies on air pressure to keep the emergency brake function from not operating, and when the air pressure goes away, it applies itself, not under driver control, based on the ratio of spring pressure to residual pressure inside the diaphragm. With different failure scenarios you would get different reactions of the spring brake. The spring is apparently sized to apply 60% of the force of a normal full brake application. anecdotally, that results in a smooth, relatively normal stop from highway speed, but it doesn't send you thought the windshield or anything, and you can't control it. In a modern system, there would be separate front and rear tanks giving a dual system, so you might have front brakes working still, but no rear brakes and a locked drive axle.

NJT also brought up a real interesting, to me at least, point the other day about a pin-hole leak in a spring brake diaphragm possibly allowing a brake to apply sufficiently to cause a fire, but not otherwise be terribly noticable. He said that may have been one reason for the DD3 system in the first place.

So I think there may be more to it than parking brakes, and i don't know which is actually better for us in the various failure modes that air brakes might be subject to. i do plan to rebuild or replace my DD3's as part of a running maintenance schedule, and I don't see, in the greater scheme of things, a problem with carrying a spare or knowing where to get one shipping in overnight from. It's less than the cost of a spare tire, after all, and I am getting one of those pretty soon... On the other hand, my local truck parts place has brand new 30/30's on sale for $49...

Yours in confusion...

Brian

Brian

luvrbus · October 02, 2009, 07:14:55 AM

Brain,if you have air leak large enough to apply spring brakes your DD-3 brakes are not going to work either.
And a dual air system is not that hard to do the foot treadle valve being the most expensive and hardest part of the change over. The tanks are there it is a matter of pluging lines
If you guys ever get a chance to attend a Bendix air brake school in your area it is well worth the money the instructors for Bendix will tell you to rid yourself of the DD-3 systems if all possible and like one told me " WE DID".
I am not saying Larry doesn't know but him and Bendix have a different opinion on the matter and I will go with Bendix on this one

good luck

bevans6 · October 02, 2009, 08:08:21 AM

You don't happen to know which model can be fitted to MCI, do you? they don't seem to have a tech support line to call.

Brian

Ed Brenner · October 02, 2009, 02:04:56 PM

Okay guys , Thanks for the input. I will replace with the spring brake chambers.

Clifford : Cans are on back side no clearance problem.
Radiator goes in Monday I hope. While it is out I did lots of other work
on that side. ( exhaust manifold, new muffler, valve cover gasket, spin on oil filter adapter
new bearings in fan block and belt tensioner.)
Let you know in a couple of days if it fits looks and measures right !!

JR : Wish I was going to be at the cove, but the Eagle ain't quite ready.
As long as I'm done in time for Jack's I'm okay. I know that is no problem
Going to do it all while it's down
Brakes and brake lines rear shocks next. got new tires on accuride wheels sitting ready to go on.
Thanks all Ed

buswarrior · October 05, 2009, 07:47:36 PM

I'd be pretty sure that Bendix is not paying their "instructor" to express his personal opinions about different brake systems, and shouldn't be spreading what sounds like a dose of self important ignorance, while being paid by them/you to be an "authority" on brakes.

It has been experience that precious few understand how all the variations work, yet there are many people who will give you a negative opinion about them.

Human nature at its finest?

Popular current wisdom, there are no spring brake chambers that will do the job for the MCI DD3 owner to swap to.

If this has changed, we need specifics, and we need to know they are not a compromise in stopping performance in order to fit.

happy coaching!
buswarrior

luvrbus · October 05, 2009, 08:14:24 PM

BW, I was at the school in Phoenix and on break one instructor told me that and I have no reason to make it it up and Fwiw we did not cover the DD-3 brakes system it is in my manual but the system was not covered in any depth maybe 5 minutes total nothing about rebuilding only the operation.
BTW the manual is worth the price of the class
And for the spring brakes on a MCI check with MGM they have different models now and working on others measure yours and call one of their dealers you may not know what is out there coming to a theater near you soon

good luck