Just a theory..
After reading many posts with regard to the mysterious grinding following new rear brake/rotor install, and trying to figure out the source of mine.. I may have a solution for those still scratching their heads. There are so many variables involved that it's hard to say what is causing the issue, let alone determine the proper action. I installed new OEM rear rotors, remanufactured OEM calipers, and those fancy Napa pads. Immediately following there was a new metal on metal grind/rub.. heard mostly from the passenger side. I removed the complete install numerous times, inspected pad spring clips, straightened the dust shield, and removed the parking brake all together. I noticed there was a mark on the inside of the rotor where the parking brake backing plate lip would possibly touch.. so i shaved down the lip. Each time I bolted up the wheel and drove it, and it always seemed the same or got worse.
Now, if you are like me and have an 'all previous owner neglected' LC.. one which you are removing original factory parts from.. then it is safe to assume that the vehicle had rarely [if ever] been jacked from the rear diff. That being said, my theory is that the never seen stress [in 20 years] is straining the rusted and never greased drive shaft or u-joints. When it occurred to me that the sound is more of a pulse rather than a solid sound I greased the shaft and joints and the sound is 90% gone [I ran out of grease, and the shaft wasn't full].
Could it be a coincidence, absolutely! It is possible to have finally smoothed what may have been rubbing the rotor.. but all of these tests were isolated and I am fairly certain the driveshaft was the issue. Anyhow, I hope this helps those at the end of their rope. Lube your shafts boys.
*Update: just drove it some more, and though all straight line driving is noise free, it re-engages upon turns. Took 4 right turns and then 4 left, all the same. Sound lasts as long as it takes for the vehicle to level out [5 seconds]. Also, never has the sound occurred in reverse.. even 25+ yards. So, still just a theory.
After reading many posts with regard to the mysterious grinding following new rear brake/rotor install, and trying to figure out the source of mine.. I may have a solution for those still scratching their heads. There are so many variables involved that it's hard to say what is causing the issue, let alone determine the proper action. I installed new OEM rear rotors, remanufactured OEM calipers, and those fancy Napa pads. Immediately following there was a new metal on metal grind/rub.. heard mostly from the passenger side. I removed the complete install numerous times, inspected pad spring clips, straightened the dust shield, and removed the parking brake all together. I noticed there was a mark on the inside of the rotor where the parking brake backing plate lip would possibly touch.. so i shaved down the lip. Each time I bolted up the wheel and drove it, and it always seemed the same or got worse.
Now, if you are like me and have an 'all previous owner neglected' LC.. one which you are removing original factory parts from.. then it is safe to assume that the vehicle had rarely [if ever] been jacked from the rear diff. That being said, my theory is that the never seen stress [in 20 years] is straining the rusted and never greased drive shaft or u-joints. When it occurred to me that the sound is more of a pulse rather than a solid sound I greased the shaft and joints and the sound is 90% gone [I ran out of grease, and the shaft wasn't full].
Could it be a coincidence, absolutely! It is possible to have finally smoothed what may have been rubbing the rotor.. but all of these tests were isolated and I am fairly certain the driveshaft was the issue. Anyhow, I hope this helps those at the end of their rope. Lube your shafts boys.
*Update: just drove it some more, and though all straight line driving is noise free, it re-engages upon turns. Took 4 right turns and then 4 left, all the same. Sound lasts as long as it takes for the vehicle to level out [5 seconds]. Also, never has the sound occurred in reverse.. even 25+ yards. So, still just a theory.
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