[Lexacocca]

1997 Ram 1500 2wd
Hello all,
Like the title states I'm experiencing a strange brake caliper issue. For the past 2 weeks I've been experiencing a thumping sensation from the left front. This only happens when the truck has been sitting overnight and in cold temperatures. The thump only occurs when going forward under 35mph. However, after traveling faster, the thump disappears for the rest of the day. It doesn't pull under braking, nor are the brakes dragging. I replaced both calipers, rotors, and pads in November 2019. All suspension components were replaced last year. I have lubricated all caliper components and checked any loose items last weekend, with no change. Could it be an air bubble or binding piston?
Carquest Caliper # 18-4300 & 18-4299
Akebono ProAct Ceramic Pads # ACT369

 

[RaceHillFarms]

You sure it is not just a tire flat spotting over night in the cold weather and once the tire warms up the noise goes away, maybe a belt is starting to come loose inside the tire and is shifting so if could be a bad tire.

A caliper that does not release does not make a thumping sound but will instead continue to apply break pressure over heating that break wearing out the pad faster and maybe warping the rotor. Once you have a warped rotor you will get break pedal pulse when you apply the breaks.

Make sure there is not a hairline crack in the rotors as well as that can cause a thumping noise.

 

[Moparite]

Lift the truck off the ground and spin the tire. See if you can id what is causing it.

 

[Lexacocca]

You sure it is not just a tire flat spotting over night in the cold weather and once the tire warms up the noise goes away, maybe a belt is starting to come loose inside the tire and is shifting so if could be a bad tire.

A caliper that does not release does not make a thumping sound but will instead continue to apply break pressure over heating that break wearing out the pad faster and maybe warping the rotor. Once you have a warped rotor you will get break pedal pulse when you apply the breaks.

Make sure there is not a hairline crack in the rotors as well as that can cause a thumping noise.

Tires are new. Ironman All Terrain 265/75/16. Very smooth & very quiet. This only occurs when leaving my driveway or leaving work. As soon as I place the trans into drive and press the brake pedal is when the thump occurs. It's worth pointing out that this happens halfway through the brake pedal travel. Tuesday morning it thumped twice half way through pedal travel. As soon as I reach the end of the road at work about 200 yards the noise is gone. Not enough time for the tires to warm up. It sounds like a hammer tapping the right side or the beat of a drum.

 

[Lexacocca]

Lift the truck off the ground and spin the tire. See if you can id what is causing it.

That's the problem, it's difficult to duplicate because it doesn't happen everyday. I could take the jack to work with me and try it when it occurs.

 

[Lexacocca]

Problem Solved! And the winner is or in the case looser... The right front caliper!
Even though it was cold and rainy today, I decided to tackle this issue. With the wheel in the air, spun the wheel as my daughter pressed the pedal. Sure enough the piston was binding, causing the rear pad to shudder against the rotor. Fortunately I was able to do a warranty exchange. Greased everything, bled the brakes, took her for a test drive and she's 100% now! It's sad that parts don't last as long as they used to. The original calipers lasted 22yrs. before they gave up the ghost. This one only lasted 1yr. 2mths. It is what it is I guess.
Thank you all for your suggestions.