Thread: Pulsing Brakes?
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Old 04-03-2012, 11:33 AM   #1
jerroldk
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Join Date: Oct 2007
Location: Longview, Texas
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Pulsing Brakes?

All,
My father-in-law has a 2006 Ranger with maybe 45K on it (never had a brake job). Over the last number of months it has developed a pulsing action when braking the vehicle. It can be noticed/felt during an abrupt stop from high speeds or during a very gradual stop from low speeds. I automatically assuming warped rotors - easy fix.

When I pulled the front wheels, I dial indicated the rotors' interior and exterior faces at a few locations near the OD. One rotor's worst runout was .0015" and .0005" and the other's was .0025" and .0010". I'm not sure what the runout spec limit is for this vehicle's rotor is, but I've never seen a vehicle requiring less than a .0030" spec limit. I realize .0025" is a little high on one of the surfaces, but if you felt how bad this thing is pulsing you wouldn't think .0025" would be the culprit either. Both rotors and all pads had tons of life left on them, so let them be and I moved to the rear drum brakes thinking the cause might be there.

I lifted the entire rear end, put the truck in gear, and let the wheels turn as it idled. I then applied the brakes mildly braking expecting the to see/hear the drums grabbing every half rotation or so if one of the drums was out of round, but no such luck. I removed the drums and inspected everything. I didn't have a mic capable of measuring the drum's ID. Again everything was in order and the shoes had plenty of life in them, so I put it all back together and scratched my head.

I'm stumped, there is no ABS light, no weird noises, and no pulsing/shimmying unless the brakes are applied. Does anyone have any ideas as to the cause for the pulsing? I could have the rotors turned to true them up a little more, but really feel like I'll still have the same problem when I'm done.

Thanks for any help,
Jerrold
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