Rear Brake Questions

[woodyNwoodinville]

I knew my rear pads were starting to get thin. Had my 2011 LR4 into the Rover shop last fall for a vacuum issue. They told me I was down to 4mm remaining. I checked them in the spring when taking off my snows and there still seemed to be a good bit of material left. Decided to wait until fall when the snows go back on to install new pads. I haven't driven it much this spring/summer, but earlier this month the Brake Wear indicator started flashing on the dash. I got new pads ordered and got them installed within 200 miles.

When I got the pads off I discovered the inner pads against the piston had much more wear than the outer pads. This was the same on both the right and left side of vehicle. Is that a normal occurrence? Don't remember noticing that last time I changed them out.

Also it seems that the thin inner pad had created wear on the brake sensor. I could see a bit of the material was worn of the side against the rotor. Unfortunately I neglected to order a new sensor so had to reinstall the old one. So far the brake pads warning light on the dash has not gone out. Will it go out on its own, or do I really need to get a new sensor? I have an OBDII with the LandRover app. I don't see anywhere on it to clear a brake sensor code.

Thanks in advance!

 

[f1racer328]

You need a new brake pad sensor. I've bought cheap ones ($15) from Amazon and had no issues. If you want to reuse them, you need to replace the brake pads before they trigger the sensor.

Also make sure your caliper pins are clean and lubed. Do this everytime you do brake pads. The calipers seem pretty sensitive to dirty caliper pins.

 

[Longtrail]

Agreed with f1racer328; the higher level of wear on the piston side of the pads is likely caused by the caliper not moving as freely as it needs to; the net result being uneven brake wear. I'm facing the same with my wife's Toyota Sienna despite always checking and lubing the caliper.

 

[ftillier]

The brake pad sensor works by wearing off once you reach the wear limit and opening the circuit, so once it's worn through you have to get a new one to get the light to turn off.

 

[woodyNwoodinville]

Thanks for your input!
I was hoping that the sensor would only fire when it was in contact with a rotor, creating a circuit. But sounds like that's not how it works :-(
The caliper pins seemed pretty loose and free. Could it also be that the caliper pistons are getting stiff? I did previously have a front caliper piston freeze up...

 

[ftillier]

Piston shouldn't really freeze up if the seal is doing its thing. Only thing I can think of is if the brake fluid wasn't flushed and got enough moisture in it to lead to internal corrosion, but not sure how likely that is. I believe the piston is steel.

 

[f1racer328]

I would still clean the caliper pins every time you do brakes. Not sure what the dealerships do, but I’ve been doing that and have had no issues over 90k miles (130k on the truck) and a few sets of brake pads.

 

[Longtrail]

Piston shouldn't really freeze up if the seal is doing its thing. Only thing I can think of is if the brake fluid wasn't flushed and got enough moisture in it to lead to internal corrosion, but not sure how likely that is. I believe the piston is steel.

Pistons are steel given the loads they see. If they are corroded, or stuck for some other reason what's the best way to proceed? I realize they're relatively simple devices and people often choose to service them by removing the piston, installing new seals, etc... For me, this means bleeding the brakes which is one of my least favorite jobs! I wonder if there's some sort of anti-seize fluid for brake pistons? I can imagine gently exercising the piston while the brake is removed being very carful not to push the brake pedal so far that the piston comes out (use a clamp to press it back in). Any thoughts folks?

Agreed on lubricating the pins and also any surface where the pads slide within the caliper. I also lube between the piston surface and the pad; and the caliper surface and the outboard pad (helps with brake squeal).

 

[woodyNwoodinville]

Yep. I replaced the brake wear sensor with an Amazon special replacement. Fit fine and worked fine. The "Brake Pads Worn" light on the dash went out.

But.. Ive had a "Spare Tire Pressure Low" warning on the dash as well. I dropped the spare while I was back there working on the rear brakes and filled it to the designated 60 psi (it was already at 56psi). But that light has not gone out. Suspect I need to replace the TPMS in the spare. And maybe replace the tire too since its 15 years old now. I don't think shops will install a tire over 10 years old.

 

[ftillier]

Yeah, you probably should replace the spare. TMPS sensors have a lifespan of about 10 years, so you're likely due. I ended up disabling mine using the IID Tool.