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Sam Powell
Supercharged
Joined: 04 Jun 2006
Posts: 3173
Location: Gaithersburg MD
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Post subject:
Why do trucks have drum brakes?
(Wed Mar 14, 2012 4:23 am)
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My brother asked me the other day why big trucks all have drum brakes. I could not answer him. I figured since old A bodies do have drum brakes, someone here might know why they are preferred on trucks. Anybody know.
Sam_________________ A REAL professional is someone who knows when to hit it with a bigger hammer.
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Ceej
SSRN National Champion
Joined: 31 Mar 2003
Posts: 6337
Location: Oregon
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Post subject:
(Wed Mar 14, 2012 5:40 am)
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Drums are cheaper.
There are disc brakes for OTR trucks. With the new braking requirements, you will start seeing more of them on the road.
CJ_________________ 
Tyrde-Browne Racing
I'm off to find myself. If I should return before I get back, keep me here. |
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SlantSixDan
Board Sponsor & Contributor
Joined: 31 Oct 2002
Posts: 21883
Location: North America
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Post subject:
(Wed Mar 14, 2012 9:19 am)
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Disc brakes have been on big trucks in Europe (and the rest of the industrialized world where the international, formerly "European", UN vehicle regs are recognized) for many years. The primary barrier to their adoption in North America has been US regulators moving with their usual molasses-in-January "speed" and odd priorities._________________ 一期一会
By birth & parentage: US citizen, 2nd class
By choice: Canadian citizen, 1st class
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65Dodge100
Turbo Slant 6
Joined: 08 Dec 2007
Posts: 593
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Post subject:
(Wed Mar 14, 2012 12:48 pm)
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I know I've had some as late as 72 where "flaky" is a good word for how they worked. Some brands of trucks you can buy the parts to convert them because some came with disc. Dodge doesn't have that eurika moment. They werent made with disc or AC or power steering. You have to make it all yourself.
There is a guy claiming he will sue you if you make your own but I wouldn't pay much attention to him. I intend to make the disc brake plates that bolt to the spindle and sell them for a decent price. Might be a long time before I get there but it doesn't take a brain trust to make them yourself. Got torch?
Danny
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WagonsRcool
EFI Slant 6
Joined: 02 Apr 2011
Posts: 305
Location: New Jersey USA
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Post subject:
(Wed Mar 14, 2012 1:42 pm)
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| I've seen medium duty 2 axle "box" trucks that have 4-wheel disc brakes. These are essentially just large versions of passenger car stuff- boosted hydraulic calipers. The BIG rigs have air brakes- do they make an air-controlled caliper/disc brake system? I'd be interested in how they accomplish that.
_________________
63 Valiant Wagon
225 - 4 bbl
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rlklaus
EFI Slant 6
Joined: 22 Mar 2006
Posts: 320
Location: Portland, Oregon
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Post subject:
(Wed Mar 14, 2012 3:05 pm)
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Air operated disc brakes are starting to come to the market.
What little I've heard from the people that have used them, it looks like it will be the wave of the future.
_________________
66 Valiant, 225.
84 Van, 225.
71 Maxi-Van, 318
60 Valiant wagon, 225
87 Maxi-Van, 318 4spd
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slantzilla
Board Sponsor & Moderator
Joined: 17 Oct 2002
Posts: 9366
Location: Park Forest, Illinoisy
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Post subject:
(Wed Mar 14, 2012 3:53 pm)
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| rlklaus wrote: | Air operated disc brakes are starting to come to the market.
What little I've heard from the people that have used them, it looks like it will be the wave of the future. |
Having been a truck mechanic back in the '80's when disc brakes first started making the rounds, I can honestly tell you that they sucked. Rotors warped like plastic, pistons stuck, and drivers hated them because they were hard to get to work without locking up. Trailers with disc brakes on them could be bought incredibly cheap because nobody wanted the frikkin' brakes.
Hopefully they have been improved.
_________________
Proud supporter of Mike Jeffrey Racing Engines since 1999.
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Joshua Skinner
Supercharged
Joined: 27 Jan 2005
Posts: 6465
Location: Portland, Oregon
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Post subject:
(Wed Mar 14, 2012 5:34 pm)
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| Correct me if I'm wrong, but I believe one of the main reasons for keeping drum brakes on big trucks is reduced maintenance due to the much greater mass of lining material.
_________________
Joshua Skinner
car nut, telecom tech, tool using mammal
'72 Dart Swinger
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rlklaus
EFI Slant 6
Joined: 22 Mar 2006
Posts: 320
Location: Portland, Oregon
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Post subject:
(Wed Mar 14, 2012 6:12 pm)
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I'm guessing that now that the parking braking situation is solved, and of course, air brakes now have a decent anti-skid system. The disc brake sets are now ready for prime time.
Having had a set of drums overheat on a 8% hill, and lose most of their effectivness. A set of discs that hold better when their hot would be nice.
_________________
66 Valiant, 225.
84 Van, 225.
71 Maxi-Van, 318
60 Valiant wagon, 225
87 Maxi-Van, 318 4spd
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Rug_Trucker
Supercharged
Joined: 23 Feb 2005
Posts: 2585
Location: Pertneer Nashville TN
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Post subject:
(Tue Apr 03, 2012 6:17 pm)
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I drove a '80 model Ford LT9000 with front discs. IIRC they had a master cylinder and the rears were air over drum.
Air brakes have lag time. Putting them on cars could cause problems.
As a driver I am required to check the brakes for wear on my pre-and post trip inspections. I can't see through the dust shields.
I can tell you one thing, they stop really good with the discs! If the ABS is malfunctioning and the trailer may or may not have ABS? Things could get weird._________________ '72 Duster 198 stock cam, 3:23's Hookers
'74Fart Dart 
'79 Maxivan 360 Offy Qjet Comp RV cam
93 D350 160HP Cummins Auto  Dually Clubcab
93 Corolla |
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