I have a 2001 f150 4.6. I am having issues with the rear disc brakes. Anytime I apply normal brake pressure I hear grinding like I have bad pads. Light or severe pedal pressure there is no noise and normal braking action. After hearing the noise I replaced the pads and rotors and nothing changed. I have noticed 1/4" lateral play in the axle shafts but have heard this is completely normal.

I am looking for ideas before I start tearing into the diff as I pretty much hate rebuilding rear ends and haven't done one in very long time. I believe it is a 9" rear end.

Any thoughts or suggestions? The backing plate is intact. The slide pons for the caliper have been greased.

 

Whoa! You posted in the wrong Forum.

You need to post HERE about your truck:

1997 - 2003 F150 - Ford Truck Enthusiasts Forums

 

so your running down the road, fast/ slow and no problems......... you put on the brake and you have a metallic sound, so you thing the DIFFERENTIAL needs rebuilt ?
the noise is ONLY present when you apply the brakes... that is a dead give away.

 

so please tell me. What is the dead give away? Brand new pads and rotors... please tell me what the answer is.

 

The rear is an 8.8".
How did you determine it is grinding in the rear area?
Leave the differential alone for now and find the source first.
Check the fronts for an issue with bearings, worn pads, backing plate interference etc.
It has to show some where.
The way you describe the application vs noise does not make any sense for a carrier to act like that way.
The axle lateral movement is due to clearance/worn C clips and axle groves.
1/4" nothing to worry about.
If the truck is a 4wd, worn front wheel bearing paks will allow the disc to touch the rotors and move around when they should be stationary at all times.
To check for this, jack each front wheel up then move the wheel same as checking for worn ball joints but look at the caliper to disc relationship for movement.
It should not move very much if at all or the bearing pak is faulty.
Good luck.

 

check the front heat shields that go around the brake disc. Mine pretty much are rusted away. I had a piece of mine fall off and get wedged alongside the rotor..