This started a couple of weeks ago and I cannot find any reference like it on this site; when I apply the brakes, I hear a pulsing sound only on the last few feet as I come to a stop, it sounds like the ABS system activating from a slipping wheel but I don't feel it on the brake pedal. I hear it only when the brakes are pressed, it feels almost like running over the rumble strips on a highway, the pulse frequency is related to the wheel speed. The ABS bulb passes the light test on start up so it is working, but the light does not come on to indicate a brake issue. Anyone have any ideas what this is?

 

her is the thread I saw on installing zerks on the unit bearing. http://forum.mopar1973man.com/index.php?/topic/7879-just-did-front-brakes/#entry82535 It was Diesel4life. What he did is about halfway thru it.

People have done the 4x4 hubs. It takes a lot of work though. They are pressed together so unless you have the equipment to handle that you just have to replace them as a unit.

Well, I will just replace it this time, that way I will have a part that I can play with when I get more time.

OK, finally had time to check the wheel bearings; jacked up both front wheels, one at a time and using a bar tried to move the tire by putting the bar in the spokes of the rim and rock the wheel. I was not able to detect any movement, I put one hand on the wheel to try to feel any shifing motion and could not, I then tried to move the wheel by hand to get a better sense of movement and agian nothing. I did this on both front wheels, they both seam solid. I slowly rotated the wheel and do feel/hear a slight "clunk" (did not sound right)  much like the pulsing I heard before, I wonder if a u-joint would cause this. Any more ideas?

You can try prying the Ujoints back and and up/down. If you get any kind of movement out of them, replace them. Also, they should turn as one complete unit. If one side of the joint turns at all without the other side going with it, time to replace.

FOUND THE PROBLEM: I was running out of time so I took my truck to Les Schwab Tire and brakes, to see if they could find something. They did find the front brakes needed to be replaced, and the rotors were too far to surface, so I had them do the brakes which included fluid flush etc. a little while later he came in and showed me cause of the pulsing; the rear rotor was worn down so far the vent vanes where showing through! The vents that where protruding where rubbing on what was left of the brake pad and causing the pulsing, the weird part is we both thought the problem was in the front axle area.

I know, I should have checked the brakes sooner, had that nagging voice in my head for the last year or so. So, that's one for the books, brakes can be the cause of all kinds of noises and vibrations.

Thanks to everyone for the help!

Ouch... Might be a good idea to step up the maintenance / inspection schedule. I typically inspect my vehicles once a month and check basic things like this.

Yeah, I kept meaning to check the brakes, I change the tires out every winter and spring (snow tires) but forget to check because it's less than ideal weahter conditions, cold and raining. From now on I will be checking them! Live and learn.