intermittent pulsating brakes

[Dog Hauler]

I just replaced the front brake pads and had the rotors turned. Now the brakes pulsate...sometimes. Usually when I'm between 20-30 mph. But not always. I suspect the calipers since they are original. I've done every brake job on this truck including flushing the brake fluid and never had this problem. What do you think?

2001 2500 4x4 300K miles

Thanks,
Darren

 

[petersonj]

I just replaced the front brake pads and had the rotors turned. Now the brakes pulsate...sometimes. Usually when I'm between 20-30 mph. But not always. I suspect the calipers since they are original. I've done every brake job on this truck including flushing the brake fluid and never had this problem. What do you think?

2001 2500 4x4 300K miles

Thanks,
Darren

Auto transmission or manual?

The pulsation may be coming from the rear brakes. I was fooled a couple of times by pulsating brakes. I also have 300,000 miles on my truck.

The first event occurred at about 180,000 miles randomly. It turned out that the left rear caliper was randomly sticking causing the pulsation. I replaced the caliper but not pads on the left side and the intermittent pulsation went away. 6,000 miles later the same thing happened to the right rear caliper. I made the same repair and the pulsation went away. In each case the rotor became very hot during the pulsation event.

A few years later at 215,000 miles I replaced the original front brake pads and rotors as a maintenance procedure - they were working fine (I am sure the manual 6 spd and exhaust brake considerably extended the brake service life). A few thousand miles after the front brake replacement I started feeling a minor pulsation again when braking. It turned out to be the rear rotors (pads and rotors were still original) - who would have guessed? This time the rotors were never hot. More than likely the rotors developed hot spots when I had the rear caliper failures and then later the softer material on the rotors wore naturally, but the hardened hot spots created a varying thickness of the rotors.

This may not be happening in your case, but if it is, you can easily be fooled.

Oh, I also have the original front calipers on my truck.. The front brakes have always been smooth.

- John

 

[JR]

I agree on the assessment of the rear brakes. Its a more likely scenario if you just replaced the hardware in the front. If you have drum brakes and a functional parking brake, you can confirm or eliminate if it is the rears. Take your truck to a back road where there is no traffic and gently push on your parking brake until you start to feel the truck slow from it. If you feel the same pulsating you've found the culprit .

 

[Dog Hauler]

Thanks for the response guys. It's an auto trans with drum brakes in the rear. I'll give the parking brake test a try today...

 

[petersonj]

you have drum brakes and a functional parking brake, you can confirm or eliminate if it is the rears.

Good point, JR... I forgot about the drum brake application in the earlier models. Now that we know an automatic transmission is involved, it is likely to be a front brake problem.

- John