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self adjusting brakes

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What's involved to update my slack adjusters to self adjusting on my 87 superliner with Rockwell rears?

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You can install automatic slack adjusters in place of your original slack adjusters. Any that you purchase will come with instructions for installing and initial setup.

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The push rod coming out of the brake chamber may need be longer then the one in use now .

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Get the right size slacks and the pushrod length should not change. The operating angle must be maintained. Some adjusters will have a new style clevis included in the kit.

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Thanks for all the info guys.

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On December 3, 2016 at 8:38 PM, davehummell said:

When  city driving I found I still had to adjust them. The other place I worked had long haul rigs and I didn't have to adjust them  as much. 

Far from an expert am I but I've had exactly the opposite experience with auto adjusters here in MT. With the flat terrain and virtually no stop lights in my daily 330 mile round trip I rarely step on the brakes except to take the cruise off or lightly breaking down hills to help the jake. From what I can tell I don't put enough applied air pressure to the brakes which actuates the adjuster. I believe it takes 60 psi for them to actually adjust at all. To remedy this every night the last thing I do on my post trip is shut the truck off and depress the brake once and hold it to listen for applied air side leaks and to help the slack adjusters stay adjusted. My experience Could be an anomaly too for that matter. 

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the issue I was fighting was we ran 30+ dump trucks and pups with a lot of seasonal drivers (steering wheel holders) every so often I would have one who took a white knuckle ride would come in cussing me out about the truck having no brakes, and I would find auto slacks that wouldn't hold adjustment, one truck I replaced 5 adjusters before I would let it on the road again. The thing I don't like about them is drivers get lazy about checking "over stroked" push rods and thus miss the warning sign that they have a malfunction.....but to make the other point I have also had "drivers" adjust manuals the wrong way and had BAD THINGS HAPPEN TOO!     

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Gearhead, I agree with you I can't count how many of them I changed when they would not self adjust. Boy does the dot love to write up out of adjustment brakes, I don't think a lot of drivers really understand anything about the trucks they drive down the road and I have seen them time and time again get in and go without looking the truck over I found some didn't care if it had oil or antifreeze in the engine . I spent more time keeping an eye out for stupid shit they didn't see like flat tires, lights out. Underdog as I said before if your cam bushings have some slop they will not adjust as good. I think you are right about over adjusting them, I had one guy that drove like a madman with heavy loads and he adjusted his slacks all the time and I had to change his more often.

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Guys, problem is that we're dealing with a legacy technology (drum brakes) actuated by an oddball technology (air pressure) that's darn near completely outside the knowledge of young drivers. To make matters worse, the CDL mills ain't gonna teach drivers anything about slacks other than "take a look at the brakes on the CDL test". So were stuck with an increasing population of drivers who don't know how to inspect slacks, and in no way should be allowed near them with a wrench!

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If the newbie drivers are familiar with any brakes, it's disc brakes... Almost every new vehicle comes with discs all around, except big trucks...

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If the newbie drivers are familiar with any brakes, it's disc brakes... Almost every new vehicle comes with discs all around, except big trucks...

I must admit, I am old school, not familiar with disc brakes... Do they have a slack adjuster or are they like a car, no adjustment necessary?

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1 hour ago, Underdog said:

I must admit, I am old school, not familiar with disc brakes... Do they have a slack adjuster or are they like a car, no adjustment necessary?

They have an internal automatic adjuster set up that compensates for pad wear. No fade, shorter stopping distances, no pull and pad wear is at least 2 times better shoes.

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They have an internal automatic adjuster set up that compensates for pad wear. No fade, shorter stopping distances, no pull and pad wear is at least 2 times better shoes.

Seems a worthwhile investment to me.

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12 hours ago, TeamsterGrrrl said:

If the newbie drivers are familiar with any brakes, it's disc brakes... Almost every new vehicle comes with discs all around, except big trucks...

The option for disc brakes is available from every truck, bus and trailer manufacturer.. the buyers seem to be content with old foundation brakes...

I've been working on Knorr Bremse brakes since 2007, just about all transit buses and highway coaches use disc brakes today... the capacity and fade resistance is what we install them for...

we have 1200 transits, about 70% are now disc brake, all new purchases are to be disc..

as far as maintenance, pad replacement is pretty simple... yes, just like a car... however, there are other inspections that take place at that time so as to confirm serviceability of the caliper and other systems that need to be done.

even though the caliper has a provision to visually check the pad wear, on a bus it is simpler to utilise electronic dash info from a sensor built into the caliper...

caliper rebuild is more complicated than on a car, especially to piston boots and adjuster system

cost benefits?... so far the company seems happy with no increase in per mile costs even though the pads wear faster, about 3 times the rate of shoes, rotors and drums seem to have the same life and cost.

for a truck driver, and the dot, all that can be visually examined is the pad wear indicator or condition of rotor, no slacks as the actuator/maxi is directly bolted onto the caliper.

for the techies, I have added a link to the component manual... there are many videos on youtube

http://aus.hendrickson-intl.com/getattachment/4c5a1926-acc7-4035-aab0-7fcc8265eec3/Knorr-Bremse-Disc-Brake-Service-Manual.aspx,.pdf

hope this helps you all get ready for the future..!!!

BC Mack

 

 

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On 12/7/2016 at 5:39 PM, Underdog said:

I must admit, I am old school, not familiar with disc brakes... Do they have a slack adjuster or are they like a car, no adjustment necessary?

From the few disc brakes (on a semi) that I've changed the inside pad that is directly against the push pistons wears out twice as fast as the outside pad that gets "pulled" into the disc by the caliper. Other than that they're great unless they get frozen in the winter. 

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we had one rd 688 late 80's or early 90's that had disc brakes, we couldn't find pads locally  so we changed it over to shoes and drums from a wrecked truck. so I didn't get to play with them much.

 

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Never seen disc brakes on semi; but would've figured they would have been Pistons on both sides

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slobber the the grease all over its like putting the crank handle on the passenger to get the driver on that side of the truck to visual inspect that side.

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