New Rotors created ABS Brake Problem HELP suggestions

[bruce119]

93 Ex 2WD XLT
I changed both sides pads bearings & new rotors (from Auto Zone). I throughly cleaned rotors exciter ring and all and I carefully inspected the rotors before installation especially the exciter ring for bends or anything unusual. Now the rotors that came off I think where original they had a solid metal tooth type ring where as the replacement had the open slot type ring. I cleaned the sensor good shiny clean. Only thing I didn't do was to actually sand off the paint of the new ring to expose bare metal. I figured that would be a bad idea as it would quickly rust and corrode.

Now I did this job before on a previous exact same truck with no problems. My problem now is the ABS is kicking in wile coming to a slow stop just before stopping under about 5 mph. The truck pulls slightly to the right, when the ABS kicks in, so that tells me the left brake is slipping.

So I am fishing for thoughts and suggestions. I did a search and came up with dirty sensors and dirty rings but this is all new stuff and the senors were nice and shiny. I am going back for a second look but I will take any advise I can get.

Thanks Guys
Bruce Egolf
Holiday, Florida

 

[Roadrunner777]

I can tell from your words you are a methodical type and surely covered all the trappings of a disc brake job. So, it seems unlikely, but is it possible your left brake actually IS slipping? Caliper piston hanging up on something inside, something like that?

I suppose I would get that corner off the ground lightly apply brakes and see if you are getting any brake action. (You will of course need help for this unless you are Stretch-Armstrong).

I'm not sure how accessible this is, but the gap from the sensor to the ring spec is 0.005 to 0.045 inches.

Also unsure, but maybe you need to disconnect battery for a while to reset the abs brake unit, maybe it will relearn sensor signal levels. I don't even know if it does this or not, just thinking out loud.

I wish I had something more definite, I have yet to pull the rotors off my explorer (sometime this fall, I think). You said you were fishing for thoughts... I don't know if I am Red Snapper or Rubber Boot. Good Luck!!!

 

[Jason94sport]

I cleaned the sensor good shiny clean

That may be the problem. You over did it & killed the sensor.

 

[bruce119]

"I cleaned the sensor good shiny clean"

That may be the problem. You over did it & killed the sensor.

First off I didn't use any abrasive on the sensor (I know better than that) I just clean the dirt off with a rag and solvent wile cleaning the spindle.

UPDATE
I took another look took the wheel off took a good look at the exciter ring it was a little high on one side just a hair out of round. So I took the rotor back off and reseted the ring now it is just about perfect. So I thought I had it put it all together and out for a test. SAME THING :thumbdwn:

Now to Roadrunner the brakes are working fine. Wile on my test drive I took the ABS fuses out to disable the system. The brakes performed flawless and felt great. Now the gap sounds interesting maybe the ring is pressed too far in and that is an issue. Boy don't know how you get in there to check that I am on a jack and jack stands.

So I don't know I was hopping someone encountered something like this before. Remember it only happens just before stopping. Maybe the sensor did get damaged would it react this way. I hate to start throwing parts at it. Guess maybe I could get another rotor tell Auto Zone there rotor was bad. I don't want to change that too many times.

Thanks
Bruce

 

[StryctNy9e]

Do you still have the old rotor to compare them. My stupid ABS does the same thing because I snapped some teeth off the exciter ring. Now my brakes do that annoying back pressure thing at 5 mph also. Oh wait mine did that before I snapped off the teeth. I will be changing my rotors and calipers when I get paid and maybe I will be able to help you better after the swap.

 

[Jason94sport]

IDK. I used autozone rotors. I didn't have any problems with the ABS. Went on like any other brake parts I've done. I didn't clean the sensors or mess with the rings. Just bearings & drove the new seal in them & on they went.

 

[matt0248]

Count the number of teeth on the tone rings to make sure they are the same. This may be your issue. I don't exactly remember how these are set up, if you were able to press the tone ring futher down, maybe it does not line up with the sensor properly. Also, it is possible for the sensor to fail. In doing the service maybe the sensor got hit or bumped enough to damage the sensor.

If the airgap is too large the output from the sensor will be low, especially at low speeds (less than 5 MPH). When the wheel speed slows, the sensor output may go to zero giving a false indication to the ABS controller that the wheel is locked up.

 

[Naasau]

I know that I'm stating the obvious, but it also might be worth looking at the wires and connections for the sensors to see if they are dirty/damaged/old. I did have a similar problem with my explorer a few years back and ended up replacing both front sensors and flushing the brake fluid. Not sure what was wrong with it, but the problem went away and hasn't come back.

 

[bruce119]

Now in diagnosing this. When the ABS kicks at low speeds it pulls to the right that is telling me that the left side brakes are letting go. So am I correct that it would be the left side where the ABS senor problem is (weather sensor or rotor). To me it's logical that if the ABS if failing on one side the system is thinking a wheel is locking up so it would restrict the flow of fluid to that wheel causing that side (the left) to ease up on the brakes. Am I correct in thinking this way I don't really know but I want to be working on the correct side. Because it will get costly and a lot of work to be looking at the wrong side.

Thanks