96 328is Passenger Rear Brake Issue

[Earl]

This is proving to be a fun issue to try and diagnose....not. Roughly two weeks ago I did my RTABs and on the way home, I was hearing a very faint dragging sound from my passenger rear brake. When I would press on the brakes the dragging would get louder, as if the caliper wasn't grabbing hard enough. I figured I tweaked a hose during the RTAB install or I had a sticking caliper. I replaced the caliper, pads, rotor, and brake hoses. This issue still persists. I removed the hand brake shoes just to rule that out and the noises are still there. I also looked over the hardlines and do not see any kinks or damage to them. At this point I am grabbing at straws to figure out what the issue is. I figure it has to be from the rear tee to the caliper at some point. If it was anywhere before that, I would assume both rear brakes would be having similar issues. Has anyone ever experienced this or may know of what is causing it? 

[B C]

Did you try turning it off and on again?

My first attempt would be bleeding that caliper, not to bleed out any air, but just to confirm you have a strong fluid stream getting to the caliper.

[patsbimmer1]

Come visit me on Friday and we'll figure it out.

[Earl]

2 hours ago, Snap said:

Did you try turning it off and on again?

My first attempt would be bleeding that caliper, not to bleed out any air, but just to confirm you have a strong fluid stream getting to the caliper.

Did that and it seemed normal

[Earl]

1 hour ago, patsbimmer1 said:

Come visit me on Friday and we'll figure it out.

Friday I will be taking out the diff and subframe to install new bushings and chassis reinforcements=/ 

[m42b32]

Is it possible your dust shield is contacting the rotor and dragging on it? Are you getting more brake dust on that wheel than the other side? 

[Earl]

4 minutes ago, m42b32 said:

Is it possible your dust shield is contacting the rotor and dragging on it? Are you getting more brake dust on that wheel than the other side? 

I forgot to mention there is no noise when the car is on stands and I rotate the wheel. The dust shield has tons of clearance. There is also no extra dust which is odd. 

[patsbimmer1]

You should probably run through what you have tried already lol.

[Earl]

Why would I do that? The issue never changed and everything else has besides the hardlines

[KaiserRolls]

Why would I do that? The issue never changed and everything else has besides the hardlines

So we don't mention shit you already tried

[m42b32]

Maybe an early wheel bearing failure? Its possible to not have noise or noticeable play when rotating it on a stand, but under the weight of the car it could potentially make a faint noise and hitting the brakes could affect the sound. 

 

Ooor, do you have access to one of those infrared thermometer things? You can use them to take the temperatures of each rotor after a long drive. One being hotter than the other would indicate dragging pads. 

 

Just throwin' some ideas out there

[KaiserRolls]

I know you replaced the wheel bearings right? That's the only thing that's changed correct? If it was at a goofy angle, could the hub be cocked causing one side of the rotor to make contact with a pad?

[Earl]

Wheel bearing is tight and was replaced in November. The noise sounds like metal being taken to a grinding stone so I am not sure what else would cause that noise when you touch the brakes lol

[KaiserRolls]

Maybe it's the 17x11 wheels =)

Any debris in the shield?

[straight6pwr]

shooting in the dark here, as it seems like you've eliminate almost everything to do with the brakes/rotor/ebrake/wheels/etc.

the dust plates on the rear diff inputs/outputs can make that noise if they start rubbing on the case or something becomes lodged in them. i guess braking could cause just enough driveline movement to make the sound increase?

[Earl]

1 hour ago, KaiserRolls said:

 

Maybe it's the 17x11 wheels =)

Any debris in the shield?

This is on stock wheels

[KaiserRolls]

Hm

100% positive the hub is in perfectly

[Earl]

25 minutes ago, straight6pwr said:

shooting in the dark here, as it seems like you've eliminate almost everything to do with the brakes/rotor/ebrake/wheels/etc.

the dust plates on the rear diff inputs/outputs can make that noise if they start rubbing on the case or something becomes lodged in them. i guess braking could cause just enough driveline movement to make the sound increase?

I'll take a peek at that. I just find it odd that this happened the day I did RTABs but it has had nothing to do with anything I touched when I replaced them 

[straight6pwr]

well if you replaced rtabs, then the whole trailing arm could be slightly moved compared to before, what might this effect? axles/stubs/wheel bearings would be on that list.

[patsbimmer1]

[Earl]

11 minutes ago, straight6pwr said:

well if you replaced rtabs, then the whole trailing arm could be slightly moved compared to before, what might this effect? axles/stubs/wheel bearings would be on that list.

It's definitely a brake related issue.

[Earl]

3 minutes ago, patsbimmer1 said:

The only thing it could be from that list is that the vent bore of the master is clogged. 

[KaiserRolls]

Guide pins all lubed and crap?

[Earl]

Brand new caliper lol. Lubed to the T. Let's put it this way. From the hardlines to the caliper, there are no issues. 

Just noticed if I lock my brakes up to stop, my caliper sticks pretty good until I start to move. Something isn't allowing the pressure to relieve normally. 

[straight6pwr]

coincidence it started when you did your rtabs?

[KaiserRolls]

Anything in the union? Maybe some crap in there?