Weird brake problem?...

[kiwifoz]

When I bought my Foz, I was told the brakes had been done (new pads and rotors machined) less than a year prior, and I have a receipt to show this.

However, I don't know if the work was actually done. The rotors appear warped as I have brake pedal pulse under moderate-heavy braking. This is liveable though.

More concerning is my other problem. For some reason, the right front wheel seems to lock up and trigger the ABS before the other wheels. Oddly though, I can take my hands off the steering wheel and it still brakes straight. I've got no idea what could be causing this, but I have no warning lights and my OBD scanner shows no codes. Could it be the front calipers need rebuilding or are sticking, or is the brake balance out?

Any ideas? Cheers.

 

[Ratbag]

^ Doesn't sound as if the job was done, or done properly, to me.

Maybe the caliper is binding, causing uneven pressure on one pad vs the other pad? I'm just guessing.

When I have had to have brakes done, they have given no problems within about 80-100K, and that's only been a pad change ...

Shouldn't be giving any problems within a year of a major brake job, unless something has broken, IMNSHO.

 

[kiwifoz]

I agree it shouldn't be giving me problems. I'm very doubtful that the rotors were machined, the brake pads were probably replaced though as they have plenty of meat left.
I suspect you may be correct with the diagnosis of the sticking caliper. Damn.

 

[Ratbag]

Hope you find the cause of the problem, KF. Those sorts of things are bloody annoying. So is being ripped off ... .

 

[kiwifoz]

Well, at least I didn't pay for the brake job! But that was still one of the reasons I bought the car. My dad didn't pick up the brake probs on the test drive. Which is annoying, considering we went down a steep hill (car wasn't insured for under-25 drivers by PO so she wouldn't let me drive it till I bought it).
In all fairness though, she did ask me to treat it nicely and I've flogged the tits off it, so it's probably karma biting me.

 

[zippo]

I'm very doubtful that the rotors were machined.

Generally when they machine discs, the ridge around the outer edge - the unswept area - is ground back to flush with the working face. It's a piece of proverbial to check that.

If your issue IS a disc, there should either be (a) visible runout; or (b) enough thickness variation that a vernier caliper would show it without needing to resort to a micrometer.

Incidentally I have had (not on a Foz though) pedal pulsation from a front brake disc where the disc was innocent. It was a shaft bearing with excess play.

 

[kiwifoz]

Okay. So considering the brakes were done less than 15,000km ago, there is already a decent ridge around the edge of the front discs. This is reasonable though as it is a lot smaller than the ridge on the discs of my dad's pathfinder which hasn't had the discs machined in 140,000km.
Thanks for clearing up what they actually machine. It seems I may need new rotors/rebuilt callipers.

 

[zippo]

How deep is the ridge? (That sounds back-arsewards I know, but you know what I mean). A 1mm ridge in 15,000 sounds a bit extreme unless your pads are uber-abrasive like emery stone.

Rip the wheel off, and check the rotor for runout and thickness variation. Eliminate them first. Try to get the pads backed off and see if there is any play in the hub bearing. If that's OK then IMNSHO it's either a wacky disc or frozen piston(s) on one side of the caliper, or the caliper body itself is frozen and can't slide.

 

[Kevin]

Have you crossed water with overly hot rotors by chance? That could warp it.

 

[NachaLuva]

Have you crossed water with overly hot rotors by chance? That could warp it.

Yep, always stop for a minute or 2 after a descent down to a water crossing. Hot rotors & cold water dont mix!

If you jack up the front and rotate the wheel, you should feel/hear if the disc is warped