Hi.
I own a 2002 Dodge Caravan, 85,000mi. Often (but not always) when I brake, it makes a sound like ba-dump ba-dump ba-dump. The frequency of the ba-dumps is proportional to speed. However, this noise only happens at speeds less than 20 mph. So, for example, if I start braking while doing 40 mph, there is no noise until I get to 20 mph, then the noise strats at a relatively high frequency and gradully slows down with the car. The noise does not happen under any other circumstance.
Relevant maintenance history: Rear brake drums replaced at 79,000mi. Front brake pads replaced, rotors turned at 29,000mi and once again later. Front stabilizer links and bushings replaced at 63,000mi. Brakes and everything else appears to work fine.
Is this noise really a problem? If so, what is the underlying problem?
i couldnt tell ya without looking at/hearing it
you mention the rear being done 6000 miles ago. did this sound start after that?
does this have a vibration or feeling with it?
did you rotate tires then too?
if you didnt rotate tires, i would do that first. it doesn’t cost anything, and it may change the symptoms.
Thanks for your reply.
The noise was present before and after the rear brake job. I took it back to the garage after the brake job to complain, but they just gave me a story about rain water trapped behind the hub cap. I looked, there was no water, and anyway the problem is independent of weather.
There is no vibration, just a sound.
The tires have been rotated once since the noise started and are always routinely rotated every 10,000mi or so. They are quite new and in excellent shape. No uneven wear.
The problem might be that the rotors have excessive runout. This might be especially true if the rotors have been turned/machined in the past.
The rotors on todays vehicles aren’t as beefy as rotors were in the past. So anytime rotors are turned/machined there’s a potential for them to warp.
I bet if a dial indicator is placed on the rotors, you’ld find excessive runout. And this could be what’s causing the noise.
Tester
I would also check for chipping on the rotor. Turned rotors will not only warp but will sometimes chip. I once had a chipped rotor and could not see the chipping until I pulled the rotor off of the car since it was on the inboard side of the rotor. Before I changed it out I got the exact same type of noise and pedal feel that the OP described.