Question to anyone who has rebuilt one partial or complete.
How hard is it to just replace the diaphram on the parking brake?
Do you need any special tools?
Or just undo the back part of the can and replace the diaphram?
Waitng for your replys
Cliff
Cliff, I rebuilt one a few years back for an MC8 I had briefly. Ordinary tools will be all you need. If you don't have an exploded diagram to work from, take lots of digital pics as you go, since there's a lot too 'em. I'd also recommend digging into the whole can and taking each part out prior to ordering parts. You might find springs and such that need to be replaced. Some of the ball bearings might be too flat, etc. Order new breathers and cotter pins, too. You might consider replacing the service side diaphram while you're at it. That way you'll never have to touch the can again. Plan at least 4 hours for the job and don't feel rushed.
For the rebuild, I got my parts from Mohawk Manuf. and they were awesome to work with. Since I was in a hurry, they overnighted the parts to me for only FedEx rates (no "rush" charges). Luke is great, also. I spent about $120 or so a lot of the guts. On mine the can had been exposed to water and road salts and had major rust/ corrosion.
Do you have a parts manual? I did for the MCI can I was rebuilding, and made it much easier on myself and the Mohawk folks to have the proper numbers.
HTH,
Brian Brown
4108-216
Longmont, CO
Cliff, I'm so glad that you broached this subject, no only because we're having a similar problem with releasing our Parking brakes but because I had a discussion with my bus mechanic, David, today about brake actuators. New DD-3's are going for over $500 bucks now and David feels that instead of replacing mine with DD-3"s I should replace them with the 30-30's which the trucks use...for the reason that once you push the button to dis-engage the parking brake...it goes off...you don't have to do the Potomac Two Step on the pedal to get them to release.
Initially I thought he was talking about the spring brake actuators but from what I was led to believe the 30-30's are smaller than the spring brake actuators and can be bought re-built for around $80 ea, exchange.
Now we're going to have to be patient and hear from our experts on the subject.
Also, Uncle Ned and I have asked David if he and his wife, Roxie, would join us at Dallas' bash in October. We're happy to have a man of his talent and knowledge of buses so close to us and I'm sure he would, if we could arrange it with Dallas and Cat, talk to us about buses in general and share some of his knowledge and have perhaps a Q & A session.
Bob
Gosh, I stepped in this one.....Bob wanted an 'expert'....... info is valid, just not my credentials!
Bob, On MCI buses, Due to the way the mounting bracket is made, there's not enough room to replace the DD3 with 30/30 chambers.
Clifff: It is a long time since I took a DD-3 apart. Get a big felt pen and mark the orientation of all the fittings and draw a line down one side of both cans so that you get everything back in the right position the first try. IIRC the clamp ring needed a 12 point socket to remove it. The spring is not as powerful as a spring brake but will still make things come apart rather quickly if you don't have some method to control it.
NCBob: Can you get some more info from your mechanic on the brake cans he proposes - make and model?
Cliff, have you checked the Bendix website? There are some pix located at this address.... http://www.bendix.com/downloads/air_brake_handbook/Control_section_3.pdf
If this doesn't load correctly, just take the link back to Bendix.com and look around. There's a troubleshooting chart on this site also. I've never had a lot of success using diag charts, but they help build a knowledge base that is useful.
Here I go again .... modifying brakes systems can be problematic. This ain't directed at you Cliff...you're not modifying anything.
These various brake systems have many interdependent components that may cause problems if modified...and death and dismemberment once the operator notices something doesn't work quite right.
Bendix DD3s are proven brake chambers. Spring brakes and 30/30s fail too. Fix your DD3s and get on with other things....May I suggest that before any brake systems are altered, that schematics of both the existing bus system and the system that is used with (in this case brake chambers) be overlayed and compared. Compare part numbers and valves. Then an idea of the level of difficulty required to correctly change the bus brake systems will become more apparent...maybe they aren't as different as I think?
If parking brakes don't release correctly, there's something wrong with the system. Fix what ails it. Just disassembling the drive axle chambers and cleaning and lubing may work wonders...or an inexpensive valve is not working. Could also be the result of years of moisture crud and corrosion buildup. DD3s are not difficult to repair...IMHO what's gonna be hard to work on is a bastardized system with no manuals or absolute replacement parts. I don't doubt that a good brake man couldn't rig something that may work...but who's going to followup later? An unknowing mechanic that knows buses may make inappropriate repairs without understanding that the system has been modified. Just sooo many ways this could go bad. :o
Last but not least, anyone with parking brake release issues should be certain that they are following the correct release process.
Alas, I doth prattle too much! But I did get the grass mowed tonight! JR :)
Cliff, I rebuilt mine also. I would suggest you tear completly apart and replace rubber and worn parts.
NCBob, The 30-30 is a spring brake. 30 is the surface area of the brake and spring area (sq in ). You can buy 24-24, 30-30, 30-24, 36-30, 30-30 etc. The 30-30 is the most popular. I have a MCI 5C and COULD NOT fit spring brakes in. Hope this helps. Tom Y
If you go to mybendix.com (you may have to register, but it is free), you will find a service data sheet for the DD-3. It has all of the data I think you will need. It is: 024600.pdf
We modified the mounts and went with spring brakes. While there are liability issues, we made a point of doing two things: we have exactly what is used on a truck tractor and we were careful to make sure that we did not develope any weaknesses in the braking system.
We also kept the original hand brake.
To each his own.
Tom Caffrey
Suncatcher
Ketchikkan, Alaska
Thanks for all the replies
As some of you may know I replaced my drivers side DD3 before a trip I was going on.
Since timing was very important in that situation I ordered a rebuilt DD3.($400.00)
Now that I have a little down time I want to rebuild the passengers side, as I have a leaky parking diaphram which can make it difficult to release the parking brake.
I remember Brian talking about rebuilding his and I wanted to get some opinions on the difficulty factor involved.
I would hate to spend $200.00 for a full rebuild kit and then find it was a major ordeal and as we all kow sometimes it easier to
let the rebuilders do it. And of course I get a 1 year warranty from them.
Jim-Great website, downloaded all the stuff I needed.
Brian-I do have the Coach Maint manuals too.
Bob-As Chuck said regarding your MCI5, is also true on my GMC, not enough room to go to spring brake.
Thank you all
Cliff
have replaced the old type on my 04 with spring brakes the 4905 should be about the same. i will talk with some one more knowledge before monday
uncle ned
"huggy bear"
Cliff, I'm not sure which "Brian" you are referring to, but yes I did rebuild my cans.
However, I did not rebuild the internal locking guts of my cans because the shafts were completely worn out. I ended up getting used DD3 cans from Luke @ US Coach and then put new diaphrams in them. Let me just say putting the diaphrams in is really easy. Basically nothing to the job if you are careful and take your time. Also, it is really easiest to do the job with the tires off, but you might be able to do it with the tires still on. Just make sure to block up the coach body and chock the wheels so the bus can't move when you release the parking brakes.
-Brian Diehl
Hi Brian D.,
I was replying to Brian B's earlier comment. Have to get my Brians right. ;D
Thanks for the information on your experience.
Having a 30 year old coach I am leaning to buying the rebuild again.
I keep thinking that I if I buy a kit(half of new) and find something worn or damaged not included, and then I have to that,
I might as well buy a rebuilt unit with the warranty.
Plus, these are the original cans and I doubt will wear them out again.(rebuilt)
Decisions, decisions...
Cliff
Quote from: FloridaCracker on July 28, 2006, 09:41:07 AM
Decisions, decisions...
$200 to do it yourself and $400 for a bebuilt can? I'd go rebuilt and save that $200 on a less critical project. If I could save $500 or so, I'd definitely do it myself.
I dont know where the $200 for parts comes from..the diaphrams are $64 for the pair on each side (from Mohawk). My locking components (rollers and brake shaft) were fine...so ..where is the other $140.00 ?
Quote from: ChuckMC8 on July 28, 2006, 02:14:32 PM
I dont know where the $200 for parts comes from..the diaphrams are $64 for the pair on each side (from Mohawk). My locking components (rollers and brake shaft) were fine...so ..where is the other $140.00 ?
Don't know, I was quoting Cliff...
"I would hate to spend $200.00 for a full rebuild kit and then find it was a major ordeal and as we all kow sometimes it easier to let the rebuilders do it. And of course I get a 1 year warranty from them."
Personally, I'd buy rebuilt. Never even priced the parts to rebuild one. Steers and tags I would rebuild in a second. Just too much to screw up in a DD3. It's worth it o me to have someone else rebuild it. I replaced my left side last year with a rebuilt.
Quote from: ChuckMC8 on July 28, 2006, 02:14:32 PM
I dont know where the $200 for parts comes from..the diaphrams are $64 for the pair on each side (from Mohawk). My locking components (rollers and brake shaft) were fine...so ..where is the other $140.00 ?
Chuck,
That was what I was quoted for a COMPLETE rebuild kit or what Bendix replaces when they rebuild one.
All new springs, valves, clamps, rollers, push plate and shaft, exhaust ports, gaskets, dust boots, o-rings, seals, dust boots, and probably some other stuff.
Is it worth 140.00 dollars, I guess thats open to opinion. :-\
Cliff
Sounds like a case for disassembling the chamber and see what you need? I'd probably use the complete kit so that issue would not have to be revisited. However, if I found the rest to be in good condition, may just go wiith the flexible parts. Mechanix choice! Post some pix of what you find in the can. I'd like to see exactly what it looks like before mine cause problems. I have one new chamber (probably rebuilt) but the other looks a little "original" but they work great...for now. NJT was pretty good about keeping the brakes in good condition.
Cliff, you still planning on coming up to Timmonsville? Hope so!
Cheers, JR
Quote from: FloridaCracker on July 28, 2006, 09:41:07 AM
Hi Brian D.,
I was replying to Brian B's earlier comment. Have to get my Brians right. ;D
Thanks for the information on your experience.
Having a 30 year old coach I am leaning to buying the rebuild again.
I keep thinking that I if I buy a kit(half of new) and find something worn or damaged not included, and then I have to that,
I agree, once rebuilt, will probably not have to do that again.
I might as well buy a rebuilt unit with the warranty.
Plus, these are the original cans and I doubt will wear them out again.(rebuilt)
Decisions, decisions...
Cliff
JR,
Yes, I am still planning on making it to Timmonsville.
Just can't make a firm commitment yet.
Depends on what happens with the Hurricane season around that date.
I have scheduled time off for a 5 day weekend though ;D
Cliff
Are you a FEMA inspector? My SIL spent a couple of months in Texas and Florida last year doing this, is the rason I ask.
Richard
Quote from: FloridaCracker on July 29, 2006, 04:19:24 AM
JR,
Yes, I am still planning on making it to Timmonsville.
Just can't make a firm commitment yet.
Depends on what happens with the Hurricane season around that date.
I have scheduled time off for a 5 day weekend though ;D
Cliff
Richard,
Not a FEMA inspector.
I am Systems Engineer for a large privatley owned utility.
With over 3 million customers in Central FL.
So all vacation is subject to change during storm season. :'(
Quote from: FloridaCracker on July 29, 2006, 04:19:24 AM
JR,
Yes, I am still planning on making it to Timmonsville.
Just can't make a firm commitment yet.
Depends on what happens with the Hurricane season around that date.
I have scheduled time off for a 5 day weekend though ;D
Cliff
Very good! See you there, JR
Cliff, I vote for disassembling the unit and seeing what needs replacing. If it's just a diaphram and a spring or two, you'd likely pay less than $100 for parts to DIY without too much effort. If there's a lot of work to do in there, rust/corrosion, etc., put it back together and send it in as the core for the rebuilt can (and warranty) for the $400.
The biggest thing to watch for is damage around the sealing rings. If they're chipped or gouged at all, go ahead and pony up for a rebuilt can.
For the kinds of work you've done on your conversion, you obviously have the skills to rebuild one of these. Whether you have the time, is another thing. And whether you're comfortable doing the job (life safety, etc.) is something else. And only you can answer those questions.
Keep us posted either way... and good luck!
Brian Brown
Cliff,
Just my personal touch on this subject, if Sonnie Gray can take off his DD3 cans and install regular spring brake cans and system and he had driven over 30,000 miles if I recall for sure, then I say to heck with these bandits with the high priced DD3 which are antiquated and just plan suck.
You know I love to rebuild things and save $$ but I believe these DD3's are not worth the price they have put on them and absolutely refuse to use them. I would rather use a 2 X 4 through the floor board that the wife can pull on when we need to slow down. (A little humor there). Again, there is not one, not even one excuse I can accept why these DD3 are so expensive. Let them eat them as far as I am concerned. I will change every valve, every air line, and every brake can to run with spring brakes and take that to the bank on my 1973 model 05!!
Now this is my personal position on this, enough is enough to me for this high priced stuff. If I could come up with a safe, rebuild of these cans for all to consider doing with instructions I would do it in a hear beat to help anyone save the money. I cannot accept even one excuse for the cost!!
Good luck in your decision buddy,
just make a safe decision for you and family.
Gary
Gary,
Yeah, I dont like the price off the DD3 rebuilts or parts either.
Especially when you compare them to the spring brake equipment.
But I do accept the fact that it is supply and demand at work.
Bendix makes zillions of the spring brakes and rebuids the old DD3's in a very limited prodution at a premium.
Heck the core charge is 200.00, these things are in a limited supply, they want the core back.
Anyway, I will bite the bullet and rebuild them or buy a rebuilt unit and hope I get 30 years out of this set, A little above my comfort level to redesign brake mounts at
this point.
Cliff
I am sure you are making the right decision for you and your family Cliff, take care.
Gary
First off, I'm not directing this at you specifically, Gary. But this issue with DD3's comes up on the boards every so often. So for the DD3 neighsayers, I say, take one apart sometime and you'll see why they're so expensive. It's not only 'supply and demand' at work making these cans so pricy... there's a lot of engineering at work in a DD3 can... not just a big fat spring that can kill somebody from taking apart a spring brake without caging it.
Better yet, pull the emergency brakes at speed in a DD3 coach compared to one with spring brakes and you'll see how much better air stops a coach than springs. A DD3 is a redundant airbrake, folks. And those extra set of airbrakes cost more than a set of big springs. Why act like it's a consipracy or something?
There's a reason MCI and GMC spec'd these things long after spring brakes were found on every other piece of heavy machinery... safety. And $400 a can is a small price to pay for that, friends.
And for those that moan about their DD3 systems not working properly... fix 'em. These systems worked in day-to-day revenue hauling service for decades and millions upon millions of miles, given proper maintenence and upkeep. Spend a weekend and a few bucks getting your system working to proper specs. and the system could outlive you.
There's no way in heck I'd willingly trade out my DD3's for springs. No way.
Climbing off of soapbox now,
Brian
Yes, Sonnie did replace his DD3s with spring brakes. But he also installed a CAT engine and removed the bogies replading them with a tag axle. He is way ahead of me in engineeering and modifying abilities. Jack
Brian said "there's a lot of engineering at work in a DD3 can... not just a big fat spring that can kill somebody from taking apart a spring brake without caging it."
Brian, you are so right.
You can't really compare them dollar for dollar, as one is at least twice the componet of the other.
Thanks for stating what I was thinking, just not typing.
Cliff
Cliff,
I have just one more question about this (horse beating subject), why isn't the DD3 used any more today on our newer rigs that go faster, haul heavier loads and go further distances than ever and over the same roads as the earlier brake systems used?? I don't mean to be so stubborn at this to keep it going but I truly don't understand why they aren't used more if they are so much more dependable and safer for the same reasons stated above?? As far as safety, I am all for that as you all know, but traveling safe speeds, traveling safe distances from the vehicle ahead of you having a safe braking system for your toad if used is being done by thousands of others right this moment is truly the way to travel and many of these buses do not have the DD3?? This is my last post on this so as not to bore you or peave you off on this but I can't help wondering. Are all the buses out there now with spring brake systems at a danger to the rest of us??
I finally am putting "MY" comments on this particular post to rest, thank God right??
Best of luck,
Gary
Gary,
I enjoy when we ALL get into a discussion on a subject like this.
Everyone is stating what they know, being cordial, expanding on each others posts as other information is added or commenting on
anothers post.
This is exactly how this BBS should be used.(My humble opinion)
I am also curious the reason why the change to the spring brakes.
My guess is that they were looking for a cheaper alternative that met there specifications. Or the specification changed.
Maybe the DD3 was considered overkill!
Of course this is not just with brakes , but all the componets of there assembly process
I would love to hear from someone who has first hand knowledge of the reason.
Interesting topic and I have enjoyed your contributions to it.
Cliff
Cliff,
You would make a good politician as you know the right things to say to calm down a Yankee-Rebel. Just don't get into politics, I like you as you are and you know how I feel about them right now anyhow. Maybe I will feel better when our troops come home before we lose any more and when the price of fuel comes down so that everyone can make a living and afford to get there to do it.
But I would seriously also like to know, why all the many millions of vehicles out there now all have the spring brakes and there are only a few old timers left, (Buses I believe only left now) that still have these dinosaur DD3's on them. Straight skinny now, no thoughts of how wonderful they were in the old days, straight stuff why they are not used today. Cost to manufactuer, not in an assembly factory once designed and parts fabricated in large lots, at least the cost would not be like we are led to believe. Good grief, 10 years ago you would pay abut $3,000 for a computer system that you can now buy for $499 at Best Buy. Why?? Competition which is great. Why can't these DD3's be manufactured in a competitive way or is it they are not really needed after all if you are safe.
Good grief, I said in my last post that was my last post on this subject but the (politician) here, (Cliff) calmed me down to more reasonable conversation, can't you tell??
Gary
Gary - Simple answer to your question about why DD3s are no longer OEM on most equipment:
$$$$$$
Spring brakes are much simpler and less expensive, not to mention fewer air lines and associated plumbing.
And, since the manufacturing philosophy nowdays seems to be more of "maximize the profit, forget the quality" (example: MCI's G4500), every penny saved makes the shareholders happy. Not to mention the Wall Street analysts, who really screw the system up with their short-sighted short-range predictions.
FWIW. . .
Gary, I truly suspect that some bean counter somewhere along the way figured that spring brakes stop a coach half as fast as DD3s... but cost one-quarter as much. Or something like that. Choices like this get made all of the time. Same reason Ford execs took "acceptable risks" leading to exploding Pintos everywhere. And Morton Thiokol saved a few bucks on an o-ring that led to the Challenger disaster.
And, no, there's not a rash of motorcoach accidents due to failing air systems. Maybe spring brakes are "good enough" if they do fail. Or maybe loss of air pressure is almost non-existent anymore, especially in the well-maintained fleets of the daily haulers.
But I do know that a cyclist was killed in Boulder County just a few weeks ago due to failed brakes on a gravel truck. Similar accidents happen in the trucking industry all of the time, usually due to maintenence issues. And the most-advanced brake cans in the world won't stop a vehicle if the brakes are out of adjustment or over-worn.
What we can do, as a "pleasure" class of heavy-vehicle users, is maintain our coaches regularly, and deviate from the manufacturer's designs and specs only when the "acceptable risks" are tolerable and well-researched and engineered.
Speaking of deviations: Would I upgrade a Johnson Bar system to spring brakes? Most definitely. Would I retrofit spring cans onto a DD3 system? You already know the answer to that. ;) But someone else's "acceptable risks" might be different than mine.
And please don't make any post your last post on any subject, if you still have something to say. I learn stuff here every day from posters just like yourself who take the time to post information and ask meaningful questions. As long as we keep it civil... and I think we have here... we all benefit.
Cheers,
Brian
Since there have been many viewpoints on this subject, I might as well add another.
When you lose your air so that the dynamite button pops, the springs on the drivers are released and provide as much stopping pressure as is required to cage the springs. On our coach, that is about 45 psi.
If you lose your air on a DD-3 system, and the button pops, then air is applied from a storage tank and the locks on the pushrods are set. What pressure is applied by the emergency air tank?
I ask this because I know that 45 psi represents quite a bit of stopping effort, but not as much as you would get from a full treadle application (over 80 psi). What is the chance of a collision or loss of control if that much braking effort were suddenly applied? We drive in icy conditions every now and then, and I sure wouldn't want them setting under those conditions.
Would the braking effort from a DD-3 system be much higher? What is the chance of a collision or loss of control with that pressure?
Maybe most of the above is academic, because most cases might involve some driver warning, and not be so dangerous. But I can think of some scenarios that would make loss of air pretty sudden. For example, what if a blowout ripped the hoses off of one pot? Would you prefer DD-3 or springs in a case like this?
The only kind of case that I can think of that I might want more pressure is if a hose blew when I was already standing on the treadle to prevent an accident. I would have to try to steer around whatever I was trying not to run into.
In most other cases, 45 psi would be more than I would care to have. What if the DD-3s applied a lot more pressure? It seems to me that a stackup on the freeway might be a real possibility, if there was no shoulder where this occurred.
Quote from: pvcces on July 30, 2006, 10:17:23 PM
If you lose your air on a DD-3 system, and the button pops, then air is applied from a storage tank and the locks on the pushrods are set. What pressure is applied by the emergency air tank?
Since the poppet is also supposed to apply the emergency brakes at 45psi on a DD3 system, I'd think that it would be the pressure of the emergency tank less the pressure on the service side diaphram of the can (albeit, rapidly decreasing in most cases). So, something like 120-45=75psi on the absolute high side to 90-45=55psi on the low side.
So, yes, the DD3's do stop the coach faster, because of the extra psi given at time of application over the 45psi you mention for springs. But, don't forget it's only applying the brakes to the drive axle cans (springs OR DD3's), whereas a treadle application applies to all axles, so stopping distances are even greater than the pressure would indicate. So I can't imagine a loss of control in this instance, esp. since the steering axle is unaffected. Unless you're on ice or slippery roads, like you said.
In most cases, however, I believe that I would want to stop sooner rather than later in an emergency air loss situation. Especially if headed downhill. :o
However, you do bring up some interesting points for discussion.
Thanks!
Brian
To avoid a lot of mis-information, if you are working on DD-3 chambers go to
http://www.bendix.com/downloads/service_data_sheet/024600.pdf
for a detailed description of operation and repair. Pay particular attention to the fact that all DD-3 30 chambers do not use the same diaphragms.
???
Intelligent question designed as a dumb one:
Have any of you ever popped the emergency brake at 50+ mph to actually see what happens? :o
I don't care if it's a spring brake or a DD3, if you've done it, what's been your experience?
If you haven't done it, why not?
Fire away! ;)
Quote from: Russ on July 31, 2006, 08:21:12 PM
If you haven't done it, why not?
Fire away! ;)
Sounds like a good thing to do... in the name of science, safety, and driver training. Why wait until an emergency to know how the coach will respond?
I'll give the poppet a pull at speed in the next few days and report back...
Brian
I've pulled the e-brake on a dirt road at 20mph. It locks up the drive axle NOW! I personally would not do it at 50mph on pavement unless I had a set of tires I was ready to replace as the resulting flat spot on the tires will make for a very rough ride afterward.
Correct me if I'm wrong, but spring brakes on trucks lock on both the trailer and both rear drive axles (where there are two rear axles). While a bus has only two emergency brake chambers for what could be more than half the weight of most trucks.
Any, or all, of the eight spring brake chambers will lock with loss of air...is the stopping force of a DD3 greater?
An aired up bus with DD3s won't roll off even if the park brake button was inadvertantly pushed, without releasing the park brake with the service brakes. Seems as though DD3s may have been designed with safety in mind? Just wondering why so many coaches were fitted with DD3s when trucks went to spring brakes? Got to be a story somewhere.
JR
Quote from: Brian Diehl on August 01, 2006, 06:18:32 AM
I've pulled the e-brake on a dirt road at 20mph. It locks up the drive axle NOW! I personally would not do it at 50mph on pavement unless I had a set of tires I was ready to replace as the resulting flat spot on the tires will make for a very rough ride afterward.
Brian - Try it on dry pavement at 50 mph - the coefficient of friction is quite different than dirt. . . ;)
I did it once on my 80 Eagle which I assume had spring brakes. I did it at about 35 mph and there was no jerk, no skidding wheels. Just a short controlled stop.
Richard
Quote from: Russ on August 01, 2006, 04:56:01 PM
Quote from: Brian Diehl on August 01, 2006, 06:18:32 AM
I've pulled the e-brake on a dirt road at 20mph. It locks up the drive axle NOW! I personally would not do it at 50mph on pavement unless I had a set of tires I was ready to replace as the resulting flat spot on the tires will make for a very rough ride afterward.
Brian - Try it on dry pavement at 50 mph - the coefficient of friction is quite different than dirt. . . ;)
Quote from: Russ on August 01, 2006, 04:56:01 PM
Brian - Try it on dry pavement at 50 mph - the coefficient of friction is quite different than dirt. . . ;)
You know, if 20mph is okay and 50 mph is good, then trying it at 100mph is even better! I gotta do that sometime. I'll let you know when I plan to as the rocket assits on the rear of the bus to get to 100 should be very loud and visible for miles to come. Sounds like fun! :)
Experimenting with the park brake at 50 MPH (or 30 or even 20 MPH), on pavement, could be counterproductive on an old coach. If the park brakes work really well, you may pull the drive axle and associated components loose. May not either...ya'll let me know. :o
This is something to test at a barely rolling speed....I would think. ???
On a wet street, this activity would assure loss of control. Reckon one cannot always predict failure induced emergency brake applications, but deliberately setting the park brakes at any speed could be dangerous.
I will be too happy to evaluate all data available from those that attempt this daring feat! ;)
My does centavos, JR 8)