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Author Topic: Baby's back and (almost) all's well!  (Read 3252 times)
NCbob
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« on: July 01, 2006, 12:16:41 PM »

I picked up the "Road Princess" this morning and the ride back was like "sippin' Moonbeams"!  The old girl had the bit in her teeth and wanted to run!

I checked the driver's seat before I left the shop and again when I got home and there were definitely no 'pucker marks'. Grin

I knew, going in, that the new Jakes weren't going to have as much authority, because she's got the 2 stroke 8V71, as they would on say a Cummins 6, but as long as I keep the engine within it's working range...they're great.  Well worth the money!  Grin

All the work Dave did was top drawer. Not a moment of specultation about the punch list I brought in when he accepted the job.
Everything was done to a high and acceptable standard (and I'm a fussy individual).  The rebuilt compressor now send the A/P right to 120# and maintains it within +/-30#.  A new problem seems to have developed though, for which I cannot blame Dave.  The parking brakes, which were cussed prior to my bringing it to him, are now even more cussed.  It takes an act of Congress to release them. Shocked

He suggested that I change from the DD3 actuators to the spring brake actuators.  That's on my Christmas wish list in the hope that Santa might be benevolent. Huh

Anyone with MC5 experience who might have a bit of insight as to where I might look for the solution to the parking brake release problem...I'd be most appreciative.

Have a great Holiday...stay sober Shocked and Keeep on Bussin'! Tongue
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NJT5047
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« Reply #1 on: July 01, 2006, 12:45:27 PM »

Glad to hear that you're happy with the coach! 
Regarding your DD3 cans, installing spring brakes is not the best way to repair the rear brakes...but, if you decide to try, before you buy anything or remove your DD3s, be sure and measure the length of spring brake cans vs the shorter DD3s.  Later MCIs don't have room for springbrake's spring cannister.  I'm unsure of an MC5.  You may have to rebuild your DD3s, or you may find a valve or other component not working...but the DD3s generally work well. 
Another thing, our litigeous habits these days would cause one to be very cautious about re-engineering the braking system.  You may find yourself exposed should an accident occur (even if the brakes are not at fault) and some smart lawyer discovered the brake mods.  Maybe not...? Huh
Are you familiar with the brake release method?  Air it up until the compressor cuts out, firmly depress the service brakes, and then push the park brake button down.  You can also push the park brake button down and then depress the service brakes....the goal is to apply max air to the brakes for release.  Then just lightly move the coach and verify that the brakes are off...this is esay with an automatic...have to put it in gear with a manual...unless it rolls down a hill.  The brakes will not release by just pushing the park brake off...such as in a big truck.
You may have a brake cam hanging too...did Dave look at your brakes while he had the coach in his possession?
Maybe just be one wheel is causing  your problem...if both drive park brakes are not releasing, the DD3s are likely not your problem.  Some control valve could cause the brakes to fail to release. 
See you at Timmonsville!  Now get them brakes fixed!  Wink
  JR
   
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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

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ChuckMC8
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« Reply #2 on: July 01, 2006, 01:30:31 PM »

To maintain bus equilibrium, it is necessary that when one thing is fixed, something else of at least the same expense and trouble should present itself.  Shocked
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JackConrad
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« Reply #3 on: July 01, 2006, 03:52:54 PM »

Bob,
  Per the MCI insstructions on the panel to the left of the Driver's seat in my MC-8 "RELEASE PARKING BRAKES, APPLY SERVICE BRAKE AND HOLD FIRM PRESSURE FOR 5 SECONDS.  I have found on my MC-8, the DD3s do not always release with a quick hard stab, but if I hold the firm pressure while counting slowly to 8, I have no problem. Of course this is done will full air pressure.  Hope this helps, Jack
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RJ
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« Reply #4 on: July 01, 2006, 03:55:08 PM »

NCBob -

The correct procedure for releasing DD3 parking brakes is as follows:

1)  Build air pressure up to governor cut-out (about 120 psi)

2)  With your right foot GENTLY on the service brake pedal, release the parking brake button (push it in, or down)

3)  Once you've released the parking brake, make a full service brake application, holding the pedal floored for 3-5 seconds.

4)  Release service brakes, and you should be good to go.

5)  If brakes don't release, repeat steps 1-4.


If you apply the service brakes first, then release the parking brake, all you'll do is confuse the system and keep 'em locked up - especially if you do both at the same time, which often people in a hurry attempt.

I taught over 250 bus drivers during a 25+ year career in the bus industry this procedure.  I'm sure if BusWarrior chimes in, he'll agree with the steps involved, as he, too, has been a driver trainer for many years. . .

All of the above, of course, is based on the assumption that the brake system is in good condition and operating properly and is, in fact, a DD3 system.  (Which can be easily identified by the three air lines coming off the brake cans on the rear axle.)

Then again, we all know what happens when we assume something!   Shocked

HTH. . .
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RJ Long
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« Reply #5 on: July 01, 2006, 05:01:01 PM »

OK Bob, you got a good bit of brake release data....did any of the below help?   We're waiting!  My guess is that you have some sort of issue with the brakes....it really doesn't seem to matter how I release mine, they always release.   Occasionally I want to get out of the barn and the brakes will release at somewhat less than cutoff....anything above 90 lbs...this may only reflect what the air pressure was when the park brakes were last set.    I suppose most do, although, some may require special care...I'd think that if you have to repeat the brake release routine more than twice, something's not working correctly.  However, the brakes must release completely before the bus is driven.
Let's fire that puppy up and see what happens!   
A bus sitting out in the weather and not used for long periods begs problems.  The more you use it, the better almost everything will work.   
Your bus came from up North?   May need to lube that sucker really good. 
Regarding the above "brakes release at less than 120lbs" thing...be certain that your brakes are released before you hit the highway.  My bus sits on concrete and once dropped into gear it rolls easily or it doesn't.  If it rolls easily, the brakes are off...if not...well, now we got a problem.   I've never had a problem with the brakes, but my turn's coming...when I say "rolls easily," I can "bar" the bus to move it with the tire iron...no problem.  I rolls easily.   Whenever I jack the bus up in the barn, the ACs have to be located between the rafters, or something's gonna get broken...I just bar it in place. 
Interested in your outcome!
Best, JR
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JR Lynch , Charlotte, NC
87 MC9, 6V92TA DDEC, HT748R ATEC

"Every government interference in the economy consists of giving an unearned benefit, extorted by force, to some men at the expense of others.”

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NCbob
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« Reply #6 on: July 01, 2006, 05:05:11 PM »

After getting home and re-thinking all of the events leading up to this situation, and drinking volumes of water (it was HOT in the bus on the trip back and I didn't want to stop and apply the parking brakes to start the generator for the A/C) it dawned on me as to what the problem might be.....

Dave had a problem releasing the parking brakes in the shop after putting the bus over the pit.  He suspected that the problem might be the inversion valve.  Not having a new one he replaced the IV with a used one he believed to be OK.  Worse!

I suspect that my original IV might have been a bit sticky and the one he installed, with all good intentions, was worse.  A new one is
$125.00 and considering the age of the bus should probably be replaced anyway.

As the old adage say, "In for a dime...in for a dollar".  I'll probably order a replacement and put it on and see.  There's been a history of more than enough moisture in the system (although it's as dry as I can make it now) so it makes sense to change that valve out.

I thank you for your advice and will report the results.

Bob
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Stan
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« Reply #7 on: July 01, 2006, 05:13:21 PM »

Unless there is something new  on the market, there is not enough room on a MC-5 for spring brake chambers.

To release a DD3 brake you have to move the brake rod furhter than it was moved when the park brake was set. Two things that affect this are (1) the air pressure regulator that supplies the DD3 brake and (2) if the service brake was  fully applied when the park brake was set.
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gm4106
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« Reply #8 on: July 01, 2006, 05:17:01 PM »

Hi Bob
you do live in North Carolina? Who is this Dave person you talking about?
Could it be Dave's Coach and truck service in Connelly NC
He has worked on my 4106 and very happy with his work.
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GM PD4106-1689 8V71TA  V730
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NCbob
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« Reply #9 on: July 01, 2006, 05:23:57 PM »

In reading all of your fine advice, sometimes my mind works like a trip-hammer...but there are days...... Undecided, I keep thinking about all the previous moisture in the system and that teeny-tiny little locking mechanism which holds the actuators in the locked position.

Yes, the immediate problem might be the inversion valve, but I agree that it just might be time to overhaul or replace the DD-3 actuators.  JR made a great point about remanufacturing the system by using spring brakes.  You've given me sufficient food for thought in that regard...I'll stay with the DD-3 system.

It follows though that if there had been sufficient moisture in the system and subsequently in the actuators the locking ball mechanism could certainly have been affected as well.  It might not be inclined to release the rear chamber no matter what I do with the treadle.

It looks like Daddy Rabbit is going to be doing some brake work in addition to the zillions of other items on Sarge's wish list.

Thanks again guys....you're priceless!

Bob
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NCbob
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« Reply #10 on: July 01, 2006, 05:32:21 PM »

Yes, GM 4106, it's the same Dave and he's a gentleman to deal with.  There is no way that I'm putting any blame on Dave.  What we're dealing with here is a 38 year old broad with, it seems, a mind of her own.  She'd been sitting in a barn for the last 5 years and little problems like this are not unexpected.  Just a little inconvenient. Huh

As far as any work David did....it's all A1, Top Drawer and I'm 100% satisfied that he did everything in his power to make a silk purse out of a sow's ear! Grin

I would heartily recommend David to anyone who is in need quality service on their Bus!  Kiss

Needed to set the record straight on that in the event someone misinterpreted my writings as sour grapes.  Smiley

Bob
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« Reply #11 on: July 01, 2006, 06:08:46 PM »

It also helps not to stand on the pedal when setting the brakes.  Most of the time all it takes to hold the bus on level ground is 1/4 or so pedal.  Like Stan said, if you stand on the brakes to set the park brake, you'll have to go just a whisker more to release them.  That can be a problem if you set them hard at full system pressure.
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NewbeeMC9
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« Reply #12 on: July 02, 2006, 05:01:44 AM »

I don't think there is any level ground where NCbob lives. Cheesy
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« Reply #13 on: July 02, 2006, 06:05:02 AM »

I don't think there is any level ground where NCbob lives. Cheesy

The only level ground within 100 miles of me is the spot I leveled to park the bus. Smiley
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Dallas
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« Reply #14 on: July 02, 2006, 07:58:37 AM »

I don't think there is any level ground where NCbob lives. Cheesy

All the cars and trucks where Bob lives have bigger tires on one side than they do on the other.
I saw one bus up there, I think it was a 3751 Queen City Coach that had 19.5 RV tires on the left and 455X24.5.s on the right. When they got to the end of the run, the mechanics swapped the tires right with left while the baggage guys were swapping luggage.
When they butcher a cow, they get more money from selling the short side first and saving the long side for stew!

Sorry Bob, I was only funnin' ya! Where I lived in Idaho, they had horses that could only walk north on the west side of the hill and south on the east side. If you tried to go the other way, you'd fall out of the saddle.

Dalllas
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