| Author | Message | ||
| Bill Holstein (Billmoocow)
Registered Member Username: Billmoocow Post Number: 23 Registered: 5-2009 Posted From: 98.232.218.68 Rating: N/A |
I fianally got the inside operational for coming of summer camping. All plumbing done or almost. Went to dmv to register as a motor home instead of a commercial rig. Anyway, decided to take it down the hiway because it had not been ran for a long time. Smoked like a son of a gun because it hadnt been run for a while. The smoke cleared after 3 miles and wouldnt smoke no matter how hard i drove it. I was pleased at that moment. No smoke, drove like a dream. Until.... I decided to take a left turn which was my turn around to go back home route. I got into center median, ready to turn... Pressed on the brakes thinking i had plenty of stop distance and by the way, it should have been..! Under normal braking it would have. But noooo, it didnt slow enough to even thinking of turning. Kept going. Put my right blinker on to merge back onto hiway to find another exit stage left. This time i babied to stop if you know what i mean. Babied all the way home... The question is; What the heck! Does not driving, leaving sitting too long affect the brakes? Shouldnt i be able to lock up the brakes if i really hammered down on the pedal? I will take to shop when i get a chance but what a bummer. | ||
| George M. Todd (George_mc6)
Registered Member Username: George_mc6 Post Number: 833 Registered: 8-2006 Posted From: 76.171.79.185 Rating: N/A |
Questions before comments, Do your low air alarms work? Have you ever checked your brake adjustment? Have you ever applied your parking/emergency brake at about 5 mph to see if it works? MC8s were equipped with DD3 type park/emergency brakes, and a dual circuit treadle valve. One tank & circuit does the front + tags, the other does the drive axle. The parking brake will apply when air drops into the 50s, and the low air alarm should sound in the 70s. Driving thru standing water would cause loss of braking, while improper adjustment would have been noticeable for this trip and before. Rust powder on the shoes? If you can't give a good answer to the questions above, consider having the shop come to you! Strange occurrence, George | ||
| RJ Long (Rjlong)
Registered Member Username: Rjlong Post Number: 1558 Registered: 12-2000 Posted From: 98.192.173.82  Rating: |
Bill - I think now you see the value of doing a proper pre-trip inspection before leaving the yard. If you had done so, you would have discovered the brake problem right away. Pre-trip's posted in the "Articles of Interest" section of this BBS. FWIW & HTH. . .  | ||
| Tony LEE (T_lee)
Registered Member Username: T_lee Post Number: 57 Registered: 11-2007 Posted From: 59.154.2.62 Rating: N/A |
Yesterday I did the same after the bus had been sitting for 5 months while I was overseas. Did drive it around town a bit (but only light braking) before taking it 60km for an official safety check. Went to turn off the highway and needed to brake a bit harder than during the rest of the trip and found the brakes were very very poor. Knew what the problem was and while the road was clear, did a few hard(ish) stops until the brakes started working properly. Guessed that the drums had developed a coating of rust and the friction was way less than it should be. The bus went through the test - including an automatic braking force/efficiency test - with no problems. Pretrip inspection while stationary would have shown no fault - needed to check with the wheels rotating so the check needs to be the same as after wading through deep water. | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 474 Registered: 3-2007 Posted From: 71.55.197.237  Rating: N/A |
Bill; check the brake adjustments REGULARLY!! For my adjustments I FIRST; block the coach, Air it up, release the parking brake, DO NOT CRAWL UNDER TO DO ANYTHING UNTIL YOU HAVE PUT BLOCKS UNDER THE BODY, crawl under and turn the slack adjuster all the way in and back it off 1/4 a turn. That will get you out of trouble. Gomer | ||
| Bill Holstein (Billmoocow)
Registered Member Username: Billmoocow Post Number: 24 Registered: 5-2009 Posted From: 75.170.68.136 Rating: N/A |
Rust powder is what i am thinking. Anyway to take care of that without taking off wheel? | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 1080 Registered: 12-2000 Posted From: 71.3.157.139  Rating: N/A |
Perhaps, ride the brakes to clean the drums. BUT, You still need to adjust the brakes and check operation of both service and parking brakes. Also check condition of linings, S cams (and bushings), and slack adjusters. As you almost found out, brakes are definitely one of the major "safety systems" on our coaches. Jack George, Not sure about late model MC-8s, but our early MC-8 ('73 model) does not have the dual braking system. | ||
| Tony LEE (T_lee)
Registered Member Username: T_lee Post Number: 58 Registered: 11-2007 Posted From: 59.154.2.62 Rating: N/A |
"Shouldnt i be able to lock up the brakes if i really hammered down on the pedal?" Not with full air brakes on a bus. The pressure is limited so once you reach that point, pressing harder on the pedal does nothing - unlike hydraulic brakes. | ||
| Clint Hunter (Truthhunter)
Registered Member Username: Truthhunter Post Number: 192 Registered: 1-2009 Posted From: 24.129.232.82  Rating: N/A |
...or if you have anti lock brakes , my 75 MC 8 did, switch is abou;ve left knee on front dash with test swtich. | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1610 Registered: 12-2000 Posted From: 76.68.132.83  Rating: N/A |
Safety point: don't be driving that bus anywhere of significance until you get this sorted out. First check, are all the brakes applying? a stuck relay valve would take the rears right out of the picture. As for brake adjustment, MEASURE your adjustment before you start fooling with wrenches, and MEASURE it afterwards. If you don't know what you started with, how you gonna know if that was a problem? And you measure when you are done to make sure you did it right, and to uncover other more serious problems like worn bushings or cracked drums. To get the rust off, on a piece of deserted road, out front of the house, otherwise, think hard about point #1 above, run it forwards and backwards and apply the brakes hard both ways, half a dozen times or so, see if it starts feeling any better. In reverse to the governor, much the same speed forward, if you can. Slower speeds, just do it a few more times, you want lots of "sanding" time. You also need to be VERY worried about sticking brakes. The longer they sit, the greater the chance for some part of the brake mechanicals to hang up, dragging the shoes and ultimately setting your tires on fire. You must carefully monitor brake drum temps as you return the coach to operational. You have an infra red temp gun? An odd drum being hotter than the rest must be investigated as to the cause. A full lube job on all your brake components, depending on your last service, should be highly considered. The best thing we can do is drive the coach monthly, the worst thing we can do is leave the coach sit. Don't feel too bad, I'm in much the same position, life and employment getting in the way of getting the preventive maintenance caught up and not using the coach enough. No different than re-commissioning a mothballed warship, pretty much nothing can be expected to work properly without a great deal of attention, time and preventive maintenance carried out. happy coaching! buswarrior | ||
| FAST FRED (Fast_fred)
Registered Member Username: Fast_fred Post Number: 784 Registered: 10-2006 Posted From: 76.214.45.118 Rating: N/A |
""Shouldnt i be able to lock up the brakes if i really hammered down on the pedal?" Not with full air brakes on a bus. The pressure is limited so once you reach that point, pressing harder on the pedal does nothing - unlike hydraulic brakes." This was the norm for a passenger bus , BUT over the years even brake treadle valves wear out and the camper replacement might not have the regulation feature. IF mine ever dies , I will sure avoid the pressure regulated valve. FF | ||
| larry currier (Larryc)
Registered Member Username: Larryc Post Number: 222 Registered: 2-2007 Posted From: 205.188.116.203 Rating: N/A |
Bill, Your bus was mfg in the era of the first computer anti skid brakes. I have no idea if they were used on buses or not, but what you describe is the most common symptom we had with them in their day, Sometimes they just don't work and no one knew why. If you have some unusual looking air valves then you may have that system. Sometimes I remember the problem could be as simple as a fuse. For many years, you could just butcher them in different ways and bypass the anti skid and DOT looked the other way. Hope thats not what is going on here, but with regular service brakes, you should have at least a small brake movement somewhere. Have someone push on the pedal and look at a slack and see if there is any action. Call the factory and see what is was built with. | ||
| Peter River (Whitebus)
Registered Member Username: Whitebus Post Number: 70 Registered: 4-2009 Posted From: 204.62.111.51  Rating: N/A |
what about self adjusting brakes? I was told that mine has a self adjusting ones. I haven't adjusted it once, and I went down some hills that made my hairs stand on end... | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1478 Registered: 10-2003 Posted From: 71.58.110.9  Rating: N/A |
don't assume you have self adjusting brakes. You need to know for sure. If you don't, you could run out of brakes when they get too far out of adjustment. Without self adjusting slack adjusters, there is only so much travel from the brake chamber rod which is attached to that slack when applied. Once near out of range, they can't apply enough pressure to shoes. Going downhill, the drums start expanding from heat and aggravate the situation. Frequent periodic adjustment of manual slacks is mandatory. You can't "pump up the brakes" to improve pedal on manual slack airbrakes, like you can on hydraulics. I hope you have or are getting a shop manual for your coach asap. | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 1086 Registered: 12-2000 Posted From: 71.3.157.139 Rating: N/A |
Make sure before you try to adjust. Manually adjusted slack adjusters require tightening until the wheel will not turn then backing off about 1/4 turn. Make sure the lock ring pops back up to prevent the adjustment from changing. IF you have automatic slack adjusters, they cannot be back off once tightened. So if you tightened them to the point the wheel will not turn, you will not be able to back them off. | ||
| David Guglielmetti (Daveg)
Registered Member Username: Daveg Post Number: 59 Registered: 2-2009 Posted From: 64.163.110.102  Rating: N/A |
Regarding auto slack adusters, there are more then one manufacturer, and different ones operate differently...that said, they don't all work all the time properly. Just 'cause you got 'em doesn't mean they work. So you still gotta check brake stroke once and a while to confirm that your ASA's are working. Generally speaking, if it doesn't work and you have to adjust it manually more than once, it is probably shot. For more in-depth information on Auto Slack Adjusters, PM me. | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1481 Registered: 10-2003 Posted From: 71.58.110.9 Rating: N/A |
They also make automatic adjusting slacks now that will also back off if too tight. Don't know if they are used on coaches though. | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 1091 Registered: 12-2000 Posted From: 71.3.157.139 Rating: |
My personal choice is non automatic slack adjusters. While I am under there adjusting the brakes, it gives a chance to inspect suspension components, check for leaking seals, grease chassis, check rear end lubricant level, etc. With auto adjusters it is too easy to develop an "out of sight, out of mind attitude". YMMV, Jack | ||
| Tim Brandt (Timb)
Registered Member Username: Timb Post Number: 332 Registered: 10-2003 Posted From: 74.244.14.221  Rating: N/A |
Very good point Jack. Everytime I check the slack adjusters I bring my grease gun with me and also check the diff and drop box level. | ||
| Paul Lawry (Dreamscape)
Registered Member Username: Dreamscape Post Number: 500 Registered: 5-2007 Posted From: 64.40.215.214  Rating: N/A |
I aggree with Jack, manual slacks are the best for the reasons he listed. | ||
| Tony LEE (T_lee)
Registered Member Username: T_lee Post Number: 61 Registered: 11-2007 Posted From: 59.154.2.62 Rating: N/A |
"and I went down some hills that made my hairs stand on end..." Best to go down in a low enough gear that you don't need to hammer the brakes. | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1614 Registered: 12-2000 Posted From: 76.68.121.33 Rating: N/A |
The important thing is to CHECK your state of adjustment, before you do anything, and after you do anything. Measure the applied pushrod stroke, which is a snap with a partner and a couple of radios, (or shout at one another, if you like!) How do you know what you had, and what you got, if you don't measure? Auto slacks are a lovely creation, if they were greased regularly before you got it, and you kept it up. An auto slack that does not automatically adjust, allowing pushrod stroke to exceed the adjustment limits, is defective and should be replaced. You still need to CHECK the brake adjustment just as frequently, an auto slack takes care of the wrenching. On the original mid 70's era anti skid controls...following the horrific on road misadventure of these systems, stops when it wants, doesn't stop at all...after great screams from the manufacturers and users, the regs were unceremoniously removed. The technology simply was not ready. fast forward to mid 90's and the regs were returned to force. When the regs were removed, the story I heard was that MCI sent word to all the purchasers of coaches so equipped to immediately disconnect and otherwise render the anti-skid features ineffective. Failure to do so would not be viewed well from a liability standpoint. I'm thinking that we'd be hard pressed to find one of these systems intact, but who knows? Anyone got one? happy coaching! buswarrior | ||
| Peter River (Whitebus)
Registered Member Username: Whitebus Post Number: 72 Registered: 4-2009 Posted From: 204.62.111.51 Rating: N/A |
"I'm thinking that we'd be hard pressed to find one of these systems intact, but who knows? Anyone got one? " 1998 was the first year that made the ABS mandatory for all air brake systems, or so I heard. I have one, but I never had an opportunity to test it out yet. but whenever I turn on the bus, the little red check light that says ABS gives me a warm fuzzy feeling | ||
| Peter River (Whitebus)
Registered Member Username: Whitebus Post Number: 73 Registered: 4-2009 Posted From: 204.62.111.51 Rating: N/A |
"Best to go down in a low enough gear that you don't need to hammer the brakes." it's harder when you are driving an automatic. although it seems the allison built this feature into their transmission that locks into each gear at certain RPMs. so I find that when I am going downhill, I have to get the RPM high enough to the shifting point in order for the bus to get shifted into the higher gear. it provides some braking. | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 1095 Registered: 12-2000 Posted From: 71.3.157.139 Rating: N/A |
If the engine RPM gets to high, the transmission will shift into the next higher gear, giving less engine braking. You have to use the brakes just enoough to keep the RPM below the shift point, after manually selecting a lower gear. | ||
| Peter River (Whitebus)
Registered Member Username: Whitebus Post Number: 75 Registered: 4-2009 Posted From: 204.62.111.51 Rating: N/A |
actually, in my transmission (auto allison) the engine /trans seemed to lock itself going downhill, I actually have to rev the RPM higher for it to shift into higher gear. in one particular hill west of Reno, I had it going at 2400rpm in lower gear until I jabbed the accelerator to let it go to higher gear at lower rpm (I like to keep my RPM at 2000max) is that normal, or is my tranny screwy? | ||
| Ralph Peters (Ralph7)
Registered Member Username: Ralph7 Post Number: 17 Registered: 3-2004 Posted From: 66.59.120.171 Rating: N/A |
Peter your antilock brakes are totally different than earlier brakes. You have sencers on each wheel, if your light comes on, the brakes will work as normal. You will loose the anit skid portion of the systen, not loose brakes. Your system will not tell you if you need adjustment, that you must check visually. | ||
| john w. roan (Chessie4905)
Registered Member Username: Chessie4905 Post Number: 1496 Registered: 10-2003 Posted From: 71.58.110.9 Rating: N/A |
Having Jake brakes is a plus. They should have a brake adjusting seminar at the next Arcadia. If you own a conversion, you should know how to inspect/adjust your brakes. | ||
| Jack Conrad (Jackconrad)
Registered Member Username: Jackconrad Post Number: 1118 Registered: 12-2000 Posted From: 71.3.157.139 Rating: N/A |
"They should have a brake adjusting seminar at the next Arcadia." John, That is an excellent idea, thank you. I will set up a brake adjusting seminar. BusWarrior, are ya'll coming next years? Jack | ||
| marvin pack (Gomer)
Registered Member Username: Gomer Post Number: 509 Registered: 3-2007 Posted From: 71.55.197.237 Rating: N/A |
Jack; Did you see the picture of BW? That is SNOW and I forgot what it looked like until BW posts a comment. From the looks of things it will be a LOOOONNGG time to thaw that out. But you never know what will happen to it, I hope to come down this time since I retired this year. Gomer | ||
| Buswarrior (Buswarrior)
Registered Member Username: Buswarrior Post Number: 1631 Registered: 12-2000 Posted From: 76.68.122.128 Rating: N/A |
I'm working, I'm working, I'm working.... Yes, a brake inspection seminar would be a lovely idea! After another snowed in winter, our coach pulled itself out of its winter sinking far more easily than I expected... Has to go in the air for some major PM to the air system, the DD3's and the wheels ends, oh, and an exhaust mixing chamber needs installed.... If only my employer would understand how important this work was.... they'd send me up there for two weeks to get it all caught up... And someone wants this all caught on video....? Bussin' 2010 is on the calendar, as long as enough calendar stays between then and the coach maintenance.... happy coaching! buswarrior |
