Front rotor scored. My mechanic said they no longer grind them.

[nitroman58]

The right front brake was squeaking, so I took a look at the what was going on.   It looks like something must have gotten between the pads and rotor, and caused some scoring.  I called my mechanic and asked if they could grind them.  He said that they just replace rotors these days.  

I was looking at rotor prices on Amazon, and they are fairly reasonable.  Does it seem like replacing them is the best option?

 

I have done pad replacement before, but have not done rotor replacement.  I was watching a few video's on you tube, and the job seems pretty straight forward.  I would guess that it worth changing the pads even if they do not need them?

Thanks.

[Rooster2]

The rotors just bolt on, really easy to do. As cheap as rotors are, it is far easier to replace. I don't think there are many shops around any more that turn drums or rotors.

[ocei77]

Yes, replace the rotors. Check pads, if worn a lot or scored, might as well do it all at once.

 

Only two extra bolts per side.

Depending on the year of car, most bracket bolts are 17mm. An extension and 1/2" ratchet would be best. Spray with PB beforehand if you can.

Sometimes the rotors are stuck. Since you are replacing them, a good whack with a BFH will shake them loose, though there are two threaded holes that take an 8x1.25 bolt to push them off.

If you have it , wire wheel the outside of the hub that the rotor centers on and a little of the face.

I generally put a little anti seize on the circumference of the hub and a little on the face. This to minimize sticking in the future.

Anti seize all the bolts before reinstalling.

 

O.

[wtdash]

Usually?? It's suggested to replace pads w/rotors so they 'wear (bed-in) together', but I've done it both ways and seems to work fine. I'd still bed-in the new rotors w/the old pads if  you do that. 

 

To add to the above.

 - The rotors are not bolted on directly (NO offense, Rooster), they're held on by the wheels+lug bolts, but they do get 'sticky' so follow the above. - This is for '90-2004 Subies (I've not worked on anything newer).

 -  The calipers should be supported by some wire, rope, etc. so there's no strain on the brake lines.

 -  Remove the cap, or @ least loosen it (to keep out water, etc) on the Brake Master Cylinder as you'll need to compress the calipers' pistons to make room for the new, thicker parts, which pushes the fluid back in the MC - this applies to both rotors only and rotors+pads. Make sure it's not already full.

 - You do NOT need to bleed the brakes as you're not disconnecting the brake lines, but if you don't know the age of your brake fluid now's a good time to bleed them - If you have a helper. Bleed: RF, LR, LF, RR (Not like most cars). But since you live in the Land of Rust (PA), you may not want to even touch those bleed screws if they're rusty.

 

GL,

td

Edited October 8, 2016 by wtdash

[Rooster2]

Usually?? It's suggested to replace pads w/rotors so they 'wear (bed-in) together', but I've done it both ways and seems to work fine. I'd still bed-in the new rotors w/the old pads if  you do that. 

 

To add to the above.

 - The rotors are not bolted on directly (NO offense, Rooster), they're held on by the wheels+lug bolts, but they do get 'sticky' so follow the above. - This is for '90-2004 Subies (I've not worked on anything newer).

 -  The calipers should be supported by some wire, rope, etc. so there's no strain on the brake lines.

 -  Remove the cap, or @ least loosen it (to keep out water, etc) on the Brake Master Cylinder as you'll need to compress the calipers' pistons to make room for the new, thicker parts, which pushes the fluid back in the MC - this applies to both rotors only and rotors+pads. Make sure it's not already full.

 - You do NOT need to bleed the brakes as you're not disconnecting the brake lines, but if you don't know the age of your brake fluid now's a good time to bleed them - If you have a helper. Bleed: RF, LR, LF, RR (Not like most cars). But since you live in the Land of Rust (PA), you may not want to even touch those bleed screws if they're rusty.

 

GL,

td

Thanks for correcting me. You are right the lugs hold them on. Been a while since I have done brake work. I would have recognized how to remove them. Small fastening bolts from caliper, I think, are used to screw into the threaded holes on the rotor. Upon threading in, the rotor gets pushed forward for easy removal.

[gbhrps]

nitroman58,

 

If your present pads have the reverse ridges that match the scoring on the rotor, but there is lots of pad material left on them, you can sand the pads material down to make them perfectly flat, to match the new rotor faces.

 

BUT: .... wear a dust mask if you attempt this!

       ...... place 100 grit sand paper on a hard flat surface, put the pad surface on the sand paper and sand the entire pad material surface flat. Be certain to make it parallel to the backing plate of the brake pad in all directions!

       ....... or grind the brake pad surface on the side of a grinding wheel, ensuring its final surface is parallel to the brake pad backing plate in all directions.

 

If done carefully, you can extend the life of the pads that were grooved or ridged by the rotor but still had 65% or more pad life left.

[Fairtax4me]

How bad is it scored? I would just remove whatever was caught in there and keep running it.

[Rooster2]

How bad is it scored? I would just remove whatever was caught in there and keep running it.

Yes, I have done that before, if scoring is not that bad.

[nitroman58]

How bad is it scored? I would just remove whatever was caught in there and keep running it.

I took the pads off, and sprayed the rotor with brake clean. It is better, but still some squeal. It is just the right side.

BTW, it is an 2011 forester.

There is a good video on you tube, showing how to do the rotors. The pads have plenty of life too, but replacing them is not cost prohibitive.

[idosubaru]

Don't replace anything.

 

You can always call around and find a place that turns rotors - there's usually a few in town. If you do the brakes yourself just have a place turn your rotors and finish up.

If they're the original Subaru rotors, they're higher quality materials than low price aftermarkets. keep original OEM rotors as long as possible.

 

I wouldn't even turn your rotors though. rotors are waaaaay overrated and mis-understood in daily drivers.

 

Scored rotros - there's no need to replace those. I have no idea where the notion comes from to replace rotors that are scored or wavy. It matters not. The new rotors and old ones will do the exact same thing, they are very simple in function.

They increases effective surface area for more pad/rotor contact = effectively "larger brakes" and more cooling. So physically speaking scored rotors are only "better" than stock.

 

There are two conceivable downsides - the pads won't last as long - and initial contact would be lessened, but that is mitigated by practical considerations:

1. we don't buy pads for longevity usually anyway

2. the amount by which some light surface roughness would cause additional pad wear isn't within the *margin* of typical replacement or concern - it's not like most people are drilling through their pad material to get every thousandths of a millimeter of pad material use from their pads.

3. they'll quickly wear into place when new - and tires stop the car, not pads, the initial wear in isn't going to prevent the ABS from locking up or change stopping distance.

 

I'll run rotors all the way to 300,000 with waves, scores, it doesn't matter. I only turn or replace them if they vibrate when braking.

Edited October 10, 2016 by grossgary

[idosubaru]

In general it is true though - shops typically just replace rotors.  That is the norm. 

 

it's a pay-to-play system now - the automotive economy is way different than it was 20 or so years ago.  people are very uninformed about cars, pay whatever is asked, aren't very economical with cars (they pay a lot for them, buy newer cars more often/quicker, love spending on gadgets and latest novel items, and thus pay higher and more frequent maintenance costs).  so it's not in a shops interest to turn rotors, people don't care, and it's a win-win for shops.  replacing rotors is super easy/quick, no machine needed, and they can make more money.