MCI Parking Brake Question - Update

[Dreamscape]

According to information I have heard, Bendix no longer makes the DD-3 or the parts, as of Dec 2008. That is one reason why I switched to spring brakes on our Eagle, the other was the cost. New, if you can find them, DD-3's were around $1400, rebuild kits were around $90 per chamber. New spring brake cans size 30/30 are about 40 bucks total. DD-3's are getting scarce and so are the parts. You can get spring brake cans at any truck parts place.

Clifford talked me into switching over, sure glad I did.

Keep in mind this was on an Eagle, MCI's might not have the additional room required to cage the brakes.

FWIW,

Paul

[belfert]

I strongly suggest anyone who doesn't have a strong background in air brakes get their brakes inspected like Paul at a bus garage on a regular basis.  I have mine checked once a year at C&J Bus Repair when I have my yearly oil change and service done.

[Dreamscape]

I strongly suggest anyone who doesn't have a strong background in air brakes get their brakes inspected like Paul at a bus garage on a regular basis.  I have mine checked once a year at C&J Bus Repair when I have my yearly oil change and service done.

I agree, but everyone who drives a bus needs to know how they work so he can be smart when he does take it to a shop.

[cody]

Thats one thing I'm hoping to do when we get to BK's rally, with that huge pit in BK's shop it really makes it a lot easier for an old guy to crawl around.

[Chuck Newman]

Paul,

I agree with Jack and others, your slack adjusters probably need adjusting.  If you have an MCI 102A3 (per your BB name), it is doubtful you have automatic slack adjusters.  They may have been available as an option, and you may in fact have them, but most MCI's of that era used manual slack adjusters.

"Paul, the dd-3 parking brakes set at the air pressure you have built up in the system try 110 0r 115 lbs before setting the parking brake."

Partially correct.  The DD3 brake chambers, via the park brake system on an MCI, do set to the applied service brake pressure, but only up to 85 psi.  The park brake pressure regulator limits the park brake set pressure to 85 psi, and MCI has a service bulletin out stating the importance of that pressure for proper operation of the DD3 chambers.  I'm out of town a few days but if this board accepts .pdf files, I will post it when I get home. 

"So does that mean that they don't have the "spring applied air released," system anymore, or does that just mean that they stopped making the DD3, but still have that system."

John, yes hundreds (maybe thousands) of DD3 brake chambers still are in use and will be for years to come.  The local college has D series buses purchased new in 1999, and they all have DD3 brake chambers.  Parts will be available for a long time.  In fact, factory new DD3's have been offered on Ebay for that last several weeks.

Yes, they cost more than a spring brake chamber and always did.  And like many bus parts that went out of production (and more that will), maintaining/repairing these machines will be more expensive.  But the picture painted by some that DD3 owners will have no brake parts available soon is simply not true.  When I got into this bus thing 10 years ago, I had people telling me the same thing about dwindling 2 stroke engine parts availability, lack of proper oil availability, and dwindling numbers of "2 stroke mechanics."  But today I'm not hearing about bus nuts that cannot get their 2 stroke engines repaired due to any of the above doom and gloom scenarios having come true.

Have the shop adjust ALL your slack adjusters (you have 6 with an A3 model), and test service brake and park brake functions before you leave the parking lot.  And then, have a wonderful trip!

[John316]

Thanks for the explain, Clifford. Makes sense, and I am glad that we have spring brakes, with auto adjusters (I still get under there and check them).

God bless,

John

[luvrbus]

Chuck, my reference was made to the DD-3 in general MCI was not the only vehicle that used the system there were trucks, trailers and on some heavy equipment and the 85 lbs wasn't for all applications Eagle used 105 lbs Peterbuilt used 115 lbs and who knows what valve he has.

Paul was right about Bendix not servicing the DD-3 any longer that stopped in 2008 and a little difference in stopping production and the 2 strokes with parts and engines still being to day by MTU with after market parts by Fedaral and others with parts available for every series of engine except the 51.(over 5 million 2 stroke in use today per MTU)

If Midland or others don't start making parts and I am told that won't happen you guys are going to find out it is going to hard to find and pricey as the stock dwindles.  

David and I changed 4 of auto adjusters on his MCI 102A3 Wed. because they froze and his manual showed the auto adjusters for his serial number I am sorry but I thought they all had the auto adjusters.
A 1999 year model bus is 10 years old now times have changed  

oops forgot to tell you guys the other 2 on the front were only 2 months old



good luck

[Chuck Newman]

Luvrbus,

I agree with that.  Especially that this is a new era of mergers and closed doors.  But historically, where their has been a market, and their is a large DD3 market out there,  someone has come along to fill that need.  Obviously to their profit.  It's called free enterprise.  I'm hopeful that is not wishful thinking in this instance.

Now am I at ease with that?  No.  In fact last week with the wheels off I took measurements to see about switching to 30-30s.  I don't know about earlier or later MCI designs, but the 102 series are just 2" short on getting spring brake chambers to fit.     And that would have required moving and rebuilding the height control valve brackets.  Not counting the caging bolt requirements.

So I am having my DD3's rebuilt now, and I may purchase a new one ($525.) for backup. More likely, I'll purchase a parts kit (or two) for the future.  Just in case. 

Hopefully, those plans will outlive my busing adventures.

Chuck

[belfert]

Parts for the older buses will probably be available for some time to come, but they will not be on the shelf at every parts house.  you'll probably have to order them and wait unless a local Detroit or Freightliner dealer has the two stroke part you need.

There is a large Napa store that opened in the last year or two that has both truck and auto parts.  They have spring brake chambers sitting on the shelf in the customer area while the counterman might not even know what a DD3 is.

[NJT 5573]

Most housings have a bolt on spider that is reclockable. It lets you rotate the brake chambers to a more favorable position if needed. I would spend a few bucks and get the chambers rotated and switch to spring chambers instead of trying to maintain the old technology.

[Tom Y]

Guys, I talked to Mohawk last week. I think the owner Jack Brown. He claims to have a contract with NYC Transit to supply DD3 parts into 2011. They have someone make their parts, Not Bendix. If the demand is still there, he claims to keep the parts after that date.  Hope this helps.  Tom Y

[Chuck Newman]

That's good news Tom.  Mohawk designs and manufacturers quite a bit of items for the transportation industry.  During the discussions concerning Bendix dropping production of the DD3 brake chamber, I had a feeling Mohawk had or would pick up the slack in that area.  Simply because they are deeply entrenched in the business.

Chuck

[luvrbus]

The Mohawk guy is on the board here perhaps he will answer for you guys because I don't know of any modern transit buses that use the DD-3.
Eagle stop using the DD-3 in 80's and Prevost in the early 90's or before Bendix gave years of notice they were not going to make the DD-3 it just didn't happen overnight. 
I remember the last DD-3 can I bought from Chalks in Houston in the late 70's cost me 55.00 dollars and I complained big time
Let's face it guys we are the only people that keep these old buses from going to the crushers and there  
is not that many of us    


good luck

[paul102a3]

I dropped the bus off at the shop this morning and the news was not good.

The drive brakes were completely worn out with about 1/16 inch of lining remaining. The slack adjusters (manual by the way) were way out of adjustment and I have the start of a leaking seal.

On the bright side, dd-3s are in good condition as were the drums so I saved some money there. The front and tags brakes were both in good shape but did need some adjustment.

While they are under the bus, I decided to have the shop replace the sway bar bushings as they were pretty worn.

It will be interesting to see how the bus stops once the brakes are up to snuff. From my perspective, I had no issues (other than the parking brake), the bus stops in a reasonable distance and there was no pulling left to right under braking.

I think I will have to have a talk with someone at ABC bus. As I mentioned, they inspected the brakes in April of this year and gave the entire braking system a clean bill of health.

Paul

[Len Silva]

You must do a lot of driving to wear out the brakes in five months.