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What cause all 4 Brakes to be Draging? Anti Lock light on too?


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I've had this problem for awhile with all 4 brakes staying slightly on and dragging. The Antilock light is on.

 

Here is what we've done that it needed

 

       

 

       changed out both front calipers 2x's

 

     New rear shoes

 

     New springs and clips

 

     New rear brake self adjusters

 

   New  Emergency brake cables all adjusted

 

   Both Drums turned

 

  Both front disks turned

 

   new front pads

 

  Rebuilt master cylinder primed properly in a vise

 

  All new fluid flushed thru

 

  New front brake lines

 

New rear wheel cylinders

 

Any speculation as to why all 4's are dragging, ruining fuel mileage, is greatly and so very much appreciated. :broke:  :doh:  :)

Edited by JAG1
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Something I have heard about but never experienced is the vacuum booster failing and applying a slight amount of pressure to the master cylinder. Try putting it in your shop. With the engine runing try to rock the truck and see what it feels like. Next shut the truck off and pump the brakes until you bleed off all the vacuum. Try rocking the truck again. If it is a lot easier without the vacuum, then you know where to look.

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Thanks to both you guys. At this point the only thing left, I think, would be the vacuum booster. MnTom, that truck is a rock there's not much rocking it'll do. Don't know what the reasoning is there.

I've even thought the dragging was coming on by itself sometimes without pressing the brakes.

Just checked the vacuum and is around 30. Disconnected the booster and as suspected, is a lot harder to get the brakes to work. So that won't work. Amount of times I've changed the booster I have to dislike the thing.

Has to be the check valve putting slight pressure on the brakes somehow, don't understand.

Edited by JAG1
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'Rocking' is a method big rig guys use to 'see' if their brakes are completely released.

They just roll a couple feet, push the clutch in, and feel how the truck comes to a stop. (in both directions) if the truck comes to a stop, and the driver 'feels' even the slightest drag just as the momentum stops- viola; hanging brake(s)

Sometimes going up a slight incline will help. The exact instant the truck comes to a stop, you should feel zero 'hang time' as the vehicle immediately reverses direction. You'll see them stick their head out the window too to watch and listen for a tight spot of the rotation on the tires.

I like to get just enough speed to get a full rotation or two.. just in case there's an out of round drum.

sometimes a hanging brake will sound a slight 'eeek' noise just as the truck momentum stops.

As far as your situation.. I've never been that deep into mine yet, are these trucks equipped with an adjustable pushrod coming off the brake pedal? The thing may be screwed in too far..

I think what MnTom was getting at was to 'rock' the truck with and without the vacuum attached to see if there was any difference in the 'glide'.

Try putting your foot UNDER the pedal with pretty good force too, and see if that helps

Edited by rancherman
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The Antilock light is on.

 

I know those trucks its just a dump valve on the rear brakes to prevent locking of the rear brakes. You might check over that assembly in the back as well.

 

As you get measurable heat from the rotors and drums? Just want to verify actually is all 4 wheels.

 

I would tend to agree with MnTom to check the vacuum booster.

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What I meant by "rocking" the truck is just grab a tire and try to move the truck, hence 'rock the truck'. You can leave it in gear or park if you have an auto. You only need to move it an inch or so to find out if there is a drag or not. In other words if you can't move the truck with vacuum on then you can with vacuum off you know where to look.

What truck are we talking about? Your sig says you have a 2002 and this is the First Gen section.

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Mn Tom, Thank you for explaining that. Some days my skull is bullet proof thickness. Yes I have done that and it holds on hills sometimes and sometimes not.

 

Mopar Michael, This problem is on my first gen. Just never listed it cause it's usually very reliable.

 

With all the new parts that this 92 actually needed to get everything up to par, it is not like just throwing parts on it. It needed al new brake parts so easier to narrow this problem down.

 

So it could be the booster, rear brake dump valve, or I've come up with another possibility on the new front brake pads as they have a very thin metal shim attached to the back sides and I know that shim warps and expand. Could be causing pressure against the rotors when getting hot/ warm.

 

Thanks to you all.... this weekend I will do some tests and looking at it some more. Will report back.

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MnTom,  to find and put that information up for me. That's some good reading right there........you are one cool person. I owe you one bud. Or a breakfast or something.

 

Will work on it again this weekend and report back.

Edited by JAG1
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MnTom,  to find and put that information up for me. That's some good reading right there........you are one cool person. I owe you one bud. Or a breakfast or something.

 

Will work on it again this weekend and report back.

All you owe me is a detailed report for what you find wrong with your truck...... Deal?

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Yep, Deal!

 

Had to haul free firewood today but will check out my truck against what the link says tomorrow

 

 

UpDate; I found out it's the two fronts that are dragging. Not the rear drums at all. Antilock system applies only to the rears And I got the ABS light to stay off by messing with some wires and disconnecting the battery for a short time. Thanks MnTom.

 

The fronts are not dragging as much the last two firewood trips because everytime I feel it starting to drag I hit the brakes with a light tap and it goes away. Before without the taps they get worse and worse without even using the brakes.

 

Will be checking the one way check valve on the booster, maybe even change the booster and master cylinder next weekend.

Edited by JAG1
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  • 2 weeks later...
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Thank you MnTom, It was as you suspected that the brake booster was causing the brakes to activate on and off.

 

So nice to have it working again just need to adjust the booster push rod a little longer is all'

 

It's funny how a guy loves his truck the longer he has it. This 1st gen has been a work truck running almost every business day for 18 1/2 years I've owned it.

 

I can't tell you guys how much it has meant to me.

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