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Air Disc Brakes

Discussion in 'Trucks' started by redneckracin, Jun 13, 2016.

  1. redneckracin

    redneckracin Senior Member

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    So, I don't run a truck full time and I certainly have no need to buy a new truck, but I do like keeping up with the trends in the industry for fun. I was listening to Road Dog on Sirius the other day and they were talking about disc brakes. I was thinking big deal, but they were air disc brakes. I never knew they existed before that point. I had to chuckle because it was giving the DOT guys fits because they couldn't check the slack adjusters for out of service violations. Oh darn! So has any body been using them? Likes? Dislikes? It seems like a disc would be a huge upgrade over the old drum brakes. Not to mention they give the DOT guys problems....:usa
     
  2. walkerv

    walkerv Senior Member

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    I been mostly in truck repair for my 16 years wrenching, Air disc brakes have been on tour busses for years , the oem's I'm told are already starting to put them on steer axles as standard equipment now or will be very soon in all applications. All of the air discs that I have seen ran a standard slack adjuster and brake chamber so dot should have no problem checking stroke , But i do beleive there are some out there that dont use a slack in that case that have to check pad to rotor clearance like they used to have to do on wedge brakes . Back in the 80's I think they tried them out on trailers for awhile(this was before my time) but I dont think they ever caught on for some reason . They tend to be expensive if you chew up a rotor and last I knew the calipers cost a pretty penny also if they go bad .I'm pretty sure that european trucks have been running disc's for awhile but I'm not sure on that one I never looked at there trucks but I do like the way there trucks look .
     
  3. old-iron-habit

    old-iron-habit Senior Member

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    My old 1978 406 UNIMOG has air disc brakes from new. No issues at all in the 15 years i'v owned it. Emergency brake cable pulls a manual lever on them for parking.
     
  4. fast_st

    fast_st Senior Member

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    I think there is a substantial weight savings with discs, so likely they'll keep showing up. Our fire trucks have been coming with and without disc brakes, seems random as to application.
     
  5. Birken Vogt

    Birken Vogt Charter Member

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    On the fire truck mechanic forums all I have seen for the past 10 years has been them complaining about constant unresolved problems with disc brakes.

    I have never seen them myself so I don't know. I am not in that scene any more.

    Maybe they have gotten better of late.

    The reason for going to discs is federal stopping distances. Basically they are trying to make a truck drive like a car because of some of the seat warmers out there. But I always thought modern drum brakes were pretty good. And their reliability and simplicity is one of the best systems going.
     
  6. Junkyard

    Junkyard Senior Member

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    The two best things about disc brakes are weight savings and lack of fade. They're expensive to work on but do last a long time. Rotors are spendy. The early trailers we had with them had rotor issues, poor materials best I could tell. Loved my last rig, 13 axles, all disc!

    Junkyard
     
  7. fast_st

    fast_st Senior Member

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    Well, yeah, they stop well but with the new 450+hp ISC motors and Jakebrakes, honestly its rare to use the service brakes save for final stopping. A big firetruck with overheated drums really sucks! Its not how a road truck was meant to be driven.
     
  8. redneckracin

    redneckracin Senior Member

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    So no brake fade and better service life as well as lighter? Sounds like a decent deal to me?
     
  9. Junkyard

    Junkyard Senior Member

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    Overall it was worth it to us. Less crap to grease too. Easy to change pads. If you run a lot of miles, have a weight sensitive cargo and use them hard say in the mountains they're hard to beat. I tried to smoke them, make them fade on the 13 axle I had and couldn't do it. I could see where a hard long grade of braking and a nice big puddle could result in a cracked rotor. The setups have gotten so much better over time. Lifespan is better than drum in most instances as well. Don't seem to grow stuck as bad as drum brakes do when sitting a long time either.

    Junkyard
     
  10. Old Doug

    Old Doug Senior Member

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    They just got a new truck with them were i work. I wouldnt have got them my self because if there so great why has it taken so long to put them on all trucks?, most new stuff now days isnt better just diffrent and on cars and pickups salt and age are hard on disc brakes 2 things that a truck will see alot of.Time will tell.
     
  11. Truck Shop

    Truck Shop Senior Member

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    It will be great until labor and parts bills roll in to the office. Freightliner uses 9" wide shoes and long stroke cans from the factory for the last two years. In our shop
    all four corners of drive shoes takes 25 minutes with drums and hardware. Some how I'm not seeing the advantage of the disc. Besides that the cost of drums has
    fallen to $68 bucks. And as fast_st said the jakes are so strong shoes are lasting way longer, depending on the driver of course.

    Truck Shop
     
  12. Junkyard

    Junkyard Senior Member

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    The majority of our rigs are drum. Our heavy trucks are disc for two main reasons, weight and stopping distance. When you're 260k gross or more every little bit makes a difference and virtually no fade is the biggest asset in my opinion. Not to mention getting somebody to properly grease a trailer is a big issue from time to time. On my 13 axle you're talking 6 less zerks per axle depending on how your drums are setup. All depends on what you're doing with them, budget and personal preference. Air disc was the main reason I was able to build an 85 ton 13 axle with an empty weight of 53,000. An upside to one may very well be a downside to another.

    Junkyard
     
  13. BlazinSS934

    BlazinSS934 Well-Known Member

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    All of my fire trucks have air disc in the front and drums on the drives. Never had a problem, work great


    Sent from my iPhone using Tapatalk
     
  14. monster76

    monster76 Senior Member

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    My 92 volvo has air disc brakes all the way around
     
  15. Truck Shop

    Truck Shop Senior Member

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    260 is a hell of a load, where do you run to. Oklahoma is fairly flat along with most of the mid west. Brake fade? The company I work for operates 43 tractors and seventy trailers
    all seven axle units. In the northwest there are grades everywhere you go 6,7 and 7.5% up to seven miles long or longer. Our trucks never suffer from brake fade. As far as greasing
    that's not much extra time, besides your looking the equipment over while your doing it. For a unit like yours I can see the weight issue but we have that too. Usually It is the driver
    packing in a kitchen, tv and a steamer trunk full of crap into the sleeper. LOL

    Truck Shop
     
  16. Junkyard

    Junkyard Senior Member

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    At out peak we ran all 48 and Canada. Now we seem to run laps around the yard lol. We ran daycab trucks and you'd think weight wouldn't be an issue but it always seems to be. Starting adding the weight of 52k rears, an auxiliary blah blah before you know it a daycab heavy haul tractor is pushing 30k empty. When things were good they were great. Cheap oil had a lot of trucks sitting and what is being hauled isn't worth firing the motor up for. There's the occasional exception of course. The difference between 7 axles around here at 135k gross and being 260 or more on 13 almost feels like an exponential increase when it comes to creating or reducing momentum. There's a grade going south on I-540 in AR that will bite you in the butt if you start down in too fast. It's that little extra safety factor sometimes.

    Junkyard
     
  17. old-iron-habit

    old-iron-habit Senior Member

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    Like every else when more trucks have disc brakes the price of the rotors will come down. Need to generate enough market for the after market suppliers to get aboard. Our local trailer repair shop had a disc brake cutaway setting on the counter the other day. He said that there was a proposal in our state legislature last year to require discs on new trailers but it failed to pass. He also said they are seeing more and more discs on rigs and The biggest majority of the owners are liking them. Doesn't sound like there is any frozen brakes issues with them either. If they are being used hard enough to crack the rotors using drums in the same scenaro may have had a different outcome. Driving conservatively still out weighs all else.
     
  18. 712alberta

    712alberta Active Member

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  19. old-iron-habit

    old-iron-habit Senior Member

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    Good video. I would like to see one like that with full loads on board.
     
  20. fast_st

    fast_st Senior Member

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    A great looking demonstration, some kind of crazy test track they have there.