1999 2500 Weird brake issue

[woodland farms]

I inherited a 99 Extended Cab 2500 4wd from my wife father. It has around 120K miles. It was almost all highway used (oh, and it is a 5 speed).

I live on a long dirt road and have had a bizarre issue with the truck when it is cold. When I go down the hill and hit the brakes for the first few times the wheels lock up. I am thinking it is only the front but need to double check this. Once it is warm there are no lock up issues. No lights are on.

So, at first I thought it was an issue with the brake booster / MC. but now I am wondering if the calipers are not suspect.

On top of this all, I finally got the mechanical records (which were thorough) and the DOT3 has never been changed. Not sure if this could be part of the issue as well.

Any thoughts or testing guidance?

 

[Bill Lins]

My rear wheels (drum brakes) have always done the same thing, especially when the humidity is high. ABS on the rear only.

 

[woodland farms]

My rear wheels (drum brakes) have always done the same thing, especially when the humidity is high. ABS on the rear only.

We live in the PNW so that would make sense. Would be relieved to only change out the fluid and move on.

 

[B.G. Smith]

Don't think it is the fluid. If you drive the truck daily it nay not be the humidity. If you have a slight gear oil leak or brake fluid leak at the rear wheels that will cause lockup. bg

 

[brucejohnson]

As B.G. Smith stated, check the linings for contamination first. That is a #1 inspection - cleanliness.
One of the main causes I have experienced is with the brake lining materials. A high clay based shoe material was the cause of many an exciting moment in the PNW liquid sunshine state, as well as first stops in the early morning hours (condensation?). I researched which brakes had more mineral and metallic contents and went with them. MOST of the time it was very successful in significantly reducing, even eliminating the rear lockups. (Except on a D50 pickup )

 

[NIsaacs]

My rear wheels (drum brakes) have always done the same thing, especially when the humidity is high. ABS on the rear only.

Mine too.

 

[DavidC]

Guess I am odd man out. I can't recall mine ever doing any lockup like described.

 

[woodland farms]

When I start on a pavement, you would never know the issue. But the gravel it shows up. Again, only when cold and generally in the AM. I do need to bleed the brakes so I will dive into the contamination issue as well when I do this.

 

[DavidC]

That gravel maybe the difference as I am usually always on asphalt.

 

[BigPapa]

He said he thought it was the fronts. My bet is on surface rust that develops after sitting and cleans off after the first brake application.

 

[Joe Mc]

Big papa has a valid point. Try this, when rolling out of your parking spot ride breaks for 10 - 15" or so. I highly recommend flushing your brake fluid...I've replaced the line from front to rear on mine twice... BTW last time I used nickle-copper line (dosen't rust), a bit more $ than steel but way less than SS and much easier to bend. Let us know what happens.

 

[woodland farms]

First, I want to thank everyone for all their help. I honestly didn't expect such excellent feedback for a first question to the forum. It is appreciated. There are a ton more.

So here is one that mightbe to contentious to ask but I will. What sort of pads for brakes would you recommend? I do know that my front brake rotors have been swapped out with cross drilled and slotted disks. There appear to be some pad left before the warning indicators. I am unsure of the rears, last inspection had them good.

 

[fest3er]

My rear brakes would 'lock up' almost every morning when first applied ever so lightly. I think this may have been due to the leading/trailing edges of the shoes being worn (broken?) off. New shoes made the problem go away. The fronts almost never gave me a problem, though as BigPapa said, some surface rust will make the brakes especially grabby for an application or two of the brakes.

 

[GAmes]

https://s3.amazonaws.com/cdn.genosgarage.com/downloads/TechPDF/TDR51_BrakePadSpottersGuide.pdf

https://s3.amazonaws.com/cdn.genosgarage.com/downloads/TechPDF/TDR50_BrakeUtopia.pdf