2005 LS430, 140k miles. Our driveway has a decent slope and my wife backs up into the garage every day. A few months back my wife pointed out a faint rubbing/grinding noise while backing up the slope. It seems to be coming from the rear of the vehicle, but I haven’t been able to identify exactly where. The noise can not be heard while going forward or while backing up on flat roads. Only while backing uphill! It is not loud enough to really worry about, but obviously shouldn’t be there.

I just(last week) replaced the rear rotors, pads(well worn), and rear struts(leaking). The noise is still there! I walk alongside the car while backing and can’t locate the source.

Ideas? Just wait until it gets worse?

 

Could be the backing plate behind one of the brake rotors. When going uphill in reverse it could rub against the rotor.
Could also be the e-brake pads dragging as those are drum pads.

 

Did you use a torque wrench to tighten the lug nut bolts
Did you use OEM brake parts?
Were rotor faces cleaned before installation?
Were new rotors and pads "bedded" ?
Condition of emergency brake shoes?
Backing adjusts the emergency brake shoes so if unevenly worn then may not mesh with new interface surface on rotors without noise.

 

Seems like the noise existed months prior to the brake job, so the brake job is a non sequitur. I know on my car, the little lippy thingy mabobs were all destroyed when I took delivery in 2016. I replaced the right front (the little air deflectors in front of the wheel wells), and it's destroyed again under my ownership. I could see on a steep slope things rubbing. Can you back up on a flat and hear the noise?

 

Perhaps a certified mechanic can assist you with the non sequitur and the thing a ma bobs.

 

Yes, I’ll need a certified mechanic to assist me with those!

The sound was there before I changed the rotors and brake pads and did not change afterwards. I thought about the emergency brake, but lightly applying the parking brake while backing up the hill doesn’t change anything either. The parking brake works well.

No sound backing up on flat ground.

I’ll keep looking.

 

its your parking brake shoes contacting the inside of the rotor backing

 

Interesting that the incline seems to have something to do with the sound....is the sound not present, when going in the same direction of the incline, but forward, instead of reverse?

I don't want to say it, but everyone is thinking it so I will. You may need a new house.....