I finally got my front brakes completed, but while breaking in the brakes I started getting an odd spring noise and loss of brake pressure in the last few feet of my stop. I thought I had some air in the ABS system, but I have another theory after some research that I would like to get some input on before I move forward. I did notice damage to the ABS ring where it looked like the sensor had impacted it for many miles. I flipped the ring over to the undamaged side and installed it on the new hub. I did not replace the ABS wheel speed sensors, but assumed that could be necessary. Before replacing the sensors is there something I can do to confirm they are the problem? I'm going to try checking codes in the ABS system and removing the fuse to see if the sensation is still there when the abs is disabled.

I would also like to note that I made sure to press the ABS rings all the way down onto the hubs because of the previous damage. Is this correct?

Thanks again all!
1994 Bronco XLT 5.0 E4OD 4x4

 

Here is what I have done so far.
1) Disconnect rear speed sensor to shut off abs system - Everything worked perfectly
2) Re-attach rear speed sensor and disconnect both front sensors - Everything worked perfectly
3) Install new front speed sensors - Noise is gone, pedal feel is ok, some front end lockup and ABS light is on
4) Drive for 15 minutes on last hard stop the ABS light went off
5) ABS light comes on as soon as I hit 15 mph
6) Ground white/blue wire in ABS connector to read codes - No codes because the ABS light only comes on over 15 mph and you read the codes with the engine off.
7) Disconnect battery for 15 minutes to reset the system - ABS light as soon as I hit 15 mph

I can not find a specific bleeding procedure for a Bronco with 4 wheel ABS, but I did find mention of needing an ABS code scanner so that the valves of the ABS unit can be cycled as you bleed them. Is this correct? I can not find an OBD1 ABS code reader for less than $200.

I did not bench bleed the master cylinder because I am using the Motive Products Power Bleeder. I also got lucky and had the master cylinder at perfect level while on stands, but I do not know if I should have pressed the brake pedal to cycle the cylinder. Am I correct that these Broncos only have bleeder valves on the calipers/pistons?

 

The ABS codes are
32 - Right Front ABS Sensor
33 - Rear ABS Sensor
42 - Right Front ABS Sensor (Dynamic)

I am not surprised by the right front codes, but the rear code was unexpected. This led me to search for how to clear the codes. It basically stated that the codes will clear after all codes have been output, fixes made, and vehicle driven over 25 mph. It also stated that codes will be automatically erased after 50 ignition cycles without the problem present.

If you read all the codes prior to the repair do you have to read them again after the repair and before driving to 25 mph for them to clear?
Wouldn't that mean all these codes have been from me disconnecting sensors to test the ABS system since that was less that 50 ignition cycles ago? That may explain the rear code.

What is the preferred air gap for the front abs sensors to the toner ring? Can it be checked without removing the hub?

While hunting down the bits I have so far I stumbled across what I believe to be a way to cycle the ABS valves during fluid bleeding without an ABS scan tool. If you unbolt the acceleration sensor from the frame and tilt it forward and backward it should cycle all the valves to let air out. I have not had a chance to test this yet, but the theory is sound.

 

Link: abs tone ring question - Ford Bronco Forum

 

The tone ring was a little crooked because my press had a slight bend that I was not aware of. So I took the hub back off and pressed it straight. Put everything back together and everything was perfect, except the abs light was still on. I figured I needed to read the codes so they would clear. After a bit of driving the light went out, but immediately after that the sound and loss of braking pressure came back. I had to do a few hard stops to get the light back on so I could read the codes. I still have code 32 and 42...

There may be some grease in the area from putting the hub back on, but I sprayed the area pretty hard with brake cleaner. I also noted that the rear abs code is now gone, but persisted in the memory after multiple code readings. Before I think about taking the hub off for a 3rd time I would like to be 100% sure the code is clearing and coming back. I have heard disconnecting the battery will clear the ABS code memory. Is this correct? Is there a recommended time for the battery to be disconnected for it to work? Could these codes be caused by air remaining in the Hydraulic Control Unit? I ask this because I have yet to try rotating the Acceleration Sensor while bleeding the system to see if that helps. I figured my Motive power bleeder would not require this step.

Thanks in advance!