Bought ST from big dealership recently, rotors grooved/worn?

[smneufell]

Props on knowing how to use a micrometer lol also I’m not sure what the rotor spec is for our cars. Maybe the rotors were bad and the dealership had them redone and fucked them up bad bc .825 is pretty horrible for a new car. I can check what the spec is on Tuesday, but that isnt doing you much help. I would measure all four rotors and write it down. Anyway, did you check your pads? Master cylinder for leaks? Any loose fittings or kinked/bubbled brake lines? Bleeding the brakes, could be some air in the system if you have soft pedal pressure.

Hell, did I mention Im a machinist? If I remember correctly factory spec is .827. Sounds about right, the lip feels about 1/16th wide on each side of the rotor. Everything else is good. In terms of pedal feel, if I had a pic of my actual rotor you'd see exactly why it feels the way it does. Hopefully its not an underlying cause, like a caliper issue. You touch the pedal from a low speed and it stops quick, like it should, but then there's another inch or so of softness before it starts to stiffen up again as the bad rotor finally starts to grab. Almost like the outer pad is pushing from one side at the top of travel, then the other pad finally squeezing towards the bottom. I can picture it, cant really describe it. I know what a bad, leaky, or airy system feels like (referencing my old buick again), this car aint it.
I appreciate the responses, but the main goal of this question was to determine the legal/liable aspect of the situation. A curiosity to people with dealer experience. No time wasting/disrespect intended, but I can call this thread as "solved".
Thanks to all for the help!

 

[OggiSiMangia]

Hell, did I mention Im a machinist? If I remember correctly factory spec is .827. Sounds about right, the lip feels about 1/16th wide on each side of the rotor. Everything else is good. In terms of pedal feel, if I had a pic of my actual rotor you'd see exactly why it feels the way it does. Hopefully its not an underlying cause, like a caliper issue. You touch the pedal from a low speed and it stops quick, like it should, but then there's another inch or so of softness before it starts to stiffen up again as the bad rotor finally starts to grab. Almost like the outer pad is pushing from one side at the top of travel, then the other pad finally squeezing towards the bottom. I can picture it, cant really describe it. I know what a bad, leaky, or airy system feels like (referencing my old buick again), this car aint it.
I appreciate the responses, but the main goal of this question was to determine the legal/liable aspect of the situation. A curiosity to people with dealer experience. No time wasting/disrespect intended, but I can call this thread as "solved".
Thanks to all for the help!

🙂🙂🙂

 

[Intuit]

Thanks for replies. I know for a fact they (rotors) need replacing, it's definitely not surface sitting rust, it's just a matter of whether or not they're bad enough to be considered a safety defect in the eyes of the law. The car did pass inspection, that's why I'm hesitant to go back there. The pedal even feels like a stuck pin/piston, inconsistent soft pressure. Stopping from 40 feels ok, but say from 60, it slightly pulls and most definitely does not stop the way these cars should. BUT, like I said, it's driveable so I dunno. For pics, it was hard to see even with the car jacked for an oil change, never mind now that it's raining/snowing a mess. For a best comparison, https://i.stack.imgur.com/kot2t.jpg, just the inside of a front instead, can't remember which side, but the opposite side had the whole surface used. I know the rear rotors on my buick only use maybe half the surface and result in the same type of wear as the pic shows, but that's normal. Here's another pic which applies to all the other rotors having the wear lip, uneven surface, https://carfromjapan.com/wp-content/uploads/2016/12/brake-rotor-replacement-grooves.jpg Without a doubt this thing was pad slapped, pads are at least 75%. I hate whining about something, I'd rather just fix it myself and get it over with, but at the same time I feel like I shouldn't be doing the same repairs within a week of purchase as I would with my old $1000 beaters. As Ive mentioned, love the car, just certain things like this which bug me. Im thinking next time Ill stick to certified preowned cars...

It is normal to have some inner and outer portion of the rotor that doesn't make contact with the pad and therefore doesn't receive any wear; rusts up.

My prior car came with 14" steel wheels. Selling options included 13" steel and 15" alloys. Never taking my original part in, the AutoZ*** store clerks were handing me pads that were suited for the 13" wheel with smaller calipers and rotors. As a result, there was a rather large inner and outer ring on the rotor. It was my first car and really hadn't noticed that these larger rings were unusual. It didn't click until I started getting parts from CarQuest and mounted their pads instead. Needless to say, braking was unusually rough and noisy for a short time until the pads wore off that layer of rust and adapted to the rotors. (this doesn't take many stops/time)

This car did not have ABS. The smaller pads did not seem to reduce stopping performance, but it did make it less safe. Post replacement and adjustment period, I noticed two key benefits to breaking performance. Braking was more "granular"; you had finer control over braking. The notably larger surface area pads afforded the same stopping force with less pressure applied to the rotors. In short, it was much much much easier to avoid wheel lockup on both hard stops and on slippery surfaces. So the smaller pads made driving significantly less safe by increasing the propensity for wheel lock-up during hard braking and/or braking over slippery surfaces.

Regardless, just take it back to the dealer. You've had the car a very short time, are within the "renege" period on the contract. They should make it right, no questions asked. This is by no means an expensive job for them, or for you.

 

[M-Sport fan]

The wear and tear part is what I was afraid of, I just figured since Ive only had the car for 4 days and 200 miles it'd fall under the used car warranty implied by the state. I guess really I'm just looking for an excuse to do them myself. I ALWAYS do brakes as a full set. I'm actually kinda looking forward to doing brakes on a car only 2 years old. SHOULD be cake compared to my '98 Riv with over 200k on it. I usually do EBCs on my bike, but I've heard mixed things about them. Not looking for extreme performance, I'd be satisfied with oem performance/quality (without the oem price). Especially since my 15" steelies just came in and will be getting some xice3s in the next week or 2.

IF it was the dealer who gave it a passing state safety inspection sticker with the rotors below manufacturer (and state) specs, they could be liable for replacing them, as it should not have passed, and been let out of their dealership for sale, with those readings (especially in MASS!).

 

[TrickSTer]

Courtesy D1JL (3/10/2016):

This is from the Service Manual.
Also covers non FiST


General Specifications


Item Specification
Front brake disc minimum thickness 0.827 in ( 21 mm)
Rear brake disc minimum thickness 0.354 in ( 9 mm)
Brake drum maximum diameter 8.661 in ( 220 mm)
Brake pad minimum thickness 0.059 in ( 1.5 mm)
Brake shoe minimum thickness 0.039 in ( 1 mm)
Brake lining maximum taper wear (in any direction) 0.059 in ( 1.5 mm)




Dave