I just had my brakes installed today, I stuck with OEM breaks, so I go to pick up my car and i notice that the Rotors are still shiny. So i go back inside and ask the guy, I thought you were going to cut my rotors! He replies ; I put it on the lathe and there was not offset so i did not cut them. So whatever i take my car back to work and park it. When i leave work to go home i notice that the brakes are feeling a bit weak. I know they are not broken in yet but, I also know that everytime you change the pads your supposed to cut the rotors, to help brake in the pads. Should I have them cut anyways or just wait it out and see what happens once the Pads break in?


Thank You

 

Why would you want to remove material from your rotor? It will just make it warp faster. Most rotors these days should be replaced if they're out of spec, not stuck on a lathe. Bed your brakes properly and don't worry about the rotors unless you feel them starting to get warped.

 

Thanks Socket7, I guess I was just a little worried about braking performance. Guess ill just follow the guide to braking in the new pads. Thank Again!

 

I think you should turn your rotors to remove the material with the old brake pad compound so you can bed in your brake pads on clean rotor material.

Also you need to properly bed your new pads. Search on how to do that.

Basically you need to do a series of hard stops from 50-10 without stopping completely to get them up to temperature so they can transfer some material to the rotor. Then they will start stopping like crazy.

 

Are you breaking in your brakes or braking in your breaks? I'm confused

 

Okay, I took it around block got pulled over by my next door neighbor (hes a cop) so for the next 15min i had him riding in the passenger while i accelerated to 60 mph then broke all the way down to 10-15mph i did i a couple of times and noticed a difference in braking now. HOWEVER now when ever i brake hard it makes a very high pitch sound as if my brakes were worn....Now what?

 

just put some grease on ur rotors that will take car of the squeak!! Just Kidding

To measure rotors you measure the runout of the rotor and paralellism of the rotor to see if it needs cut you do not HAVE to cut the rotors on every brake job but personally i do even if it's just some becuase ur old pads wear in a certain groove and cause grooves in the rotor so when ur new pads get installed they are not completely flat against the rotors becasue of the grooves and will wear to ur grooves... I would have them cut at least just some 2/10" at least....

All this depends on if they will b in spec etc

 

But that high pitch sequel, that cannot be good. I guess ill just take it to the dude tomorrow and ask him to take a look at it, its to dark outside now and i cant see anything.

 

^^ make sure they put the right amount of grease in the shims area. If you don't grease the right area's your new brakes will start making noise. Mazda has an TSB for this issue. GL.

 

Right thanks

 

IMO, rotors don't need turned unless they're out of spec. However, he should have taken something like a disk sander and "roughened up" the rotor surfaces a bit so the new pads would have a fresh surface to bed in to.

 

Yea, that what i thought they were supposed to do to the rotors, so that the brake in process would be better.

 

I once swapped through 3 different pad compounds in one weekend during a track weekend and simply cleaned the rotor surface between swaps and bed the pads. Turning your rotor is not necessary unless there's serious amounts of uneven pad deposit.

Noisy OEM brakes are most probably due to not using silicone brake grease between the shim and pad backing plate.

FWIW, track pads sound like whistles under hard braking- I know this isn't related to OEM application, but noise doesn't necessarily correlate to something wrong with your brakes.

 

Thanks for the input SouthFl I guess your right! I am at work already i just have to wait till the brake shops opens today so he can correct the shimming problem. Hopefully that will that. You live in South Fl huh? What part and what track do you go to?

 

Tracks I've driven at:
Sebring, Homestead, Palm Beach Int' Raceway aka PBIR (formerly Moroso), and the Daytona 24hr circuit.

See:
www.chinmotorsports.com
www.pbocflorida.com
www.drivenasafl.com

All of the above have instructor and classroom curriculum for HPDE (High Performance Driving Event/Education) track days.

 

Sweet, I have only been the the track in homestead but i did not go with my 8 =(....anyways...So i took the car back today, told the dude what had happened and he said that he would fix it. Shaved some material off the rotors and bam now the car is breaking better than ever

 

What school did you go to?

Break =/= Brakes.

 

Well, if they installed some 'breaks' into your car, well there's your problem.

 

umm... obvious question.... did you bleed the brake system correctly? How are your fluid levels?

 

Brake rotors rarely if ever warp. They don't need to be cut every pad replacement either. It isn't even necessary to sand the rotor face with new pads either. There's been some good advice, and some not so good in this post.

People who think rotors warp usually are dealing with UNEVEN pad deposits on their rotor face due to overdriving (overheating) whatever brake pad they have on the car. Uneven pad deposits can be removed by an agressive bedding procedure as was described above. If you can't get rid of them by rebedding or are unwilling to try, cutting the rotors will remove the uneven pad deposits. If you have uneven pad deposits you should rethink your pad selection or rethink your driving (braking) style.

If you don't have uneven pad deposits a simple rebedding of the new installed pads is all that is required to get maximum performance from them. Cutting rotors as a matter of course following brake pad replacement is uneccesary but many mechanics do it because someone told them to, they don't want to listen to complaints about pulsating pedals, or they want to add on a little to the bill.

Squealing from pads, particularly performance pads and track pads, is not uncommon. Wear indicators squeal to notify worn pads, but new pads may squeal also from vibrations between the caliper piston and the pad back. Many OEM manufacturers put shims on the back side of the pad between the piston and the pad to reduce or eliminate squeal. Some mechanics forget to replace the shims which leads to squeal. Synthetic brake grease applied to the backs of the pads (for God's sake not the front) and to the shims will help reduce squealing. I was in a hurry and I didn't use the shims or grease on my track pads last week at Sebring and I swear I could carry a tune driving around the pits with the squealing. Those same pads were absolutely silent with the factory shims and some grease in previous events.

 

Thanks for the input Justjim, yea I noticed what you said about the shimming. My problem was that when i had my rotor hubs and calipers painted, they painted on the actual rotor itself. Because the old pads were so worn they did not grip the entire rotor. However when the new pads were installed the part that was painted on the rotor now was making contact with the new pads. So i had about 1/16th of the rotor significantly higher than the rest of the rotor, im not to sure but after it was cut the squeal when away, i am assuming this is what was causing the squealing. I did replace with OEM pads as well which was a mistake as to seeing how you can get High-Performance hawks for a little bit more.

 

Yeah, I got the ceramic hawk pads and was very pleased with them.

 

For the most part, cutting rotors are a thing of the past. You either replace them or leave them as-is.

The only reason you would want to cut them is if they were still in spec but had deep grooves in them from running the prior pads to the rivets. Deep grooves will cause the brakes to shutter. Otherwise, I'd say you are fine.