Me and my friend are having a dispute.

he says its a bad idea to machine the rotors when im putting on new pads, i should just buy new ones, especially because i drive quite hard, and i might crack a rotor.

I say machining a rotor is fine and that he should go fly a kite.

whos right?

 

As long as you're not turning them below their minimum thickness, turning the rotors is a good idea.

 

weather should be nice out soon, ill go make sure hes flying a kite somewhere nice

 

Some of the OE's at some point in time (including one I worked for) were recommending not surfacing rotors when doing pad replacements if the runout was ok and there was not a lot of surface problems. I dont know if this has changed, it might have.
When you cut a rotor on 99% of the machines out there, it leaves it like a record. In other words, there are valleys and ridges left by the machining process. Some places will take a grinder with a medium grit sanding disc and knock off some of that. Its helpful. This was also in service procedures where I worked the same time the recommendation for not surfacing rotors came out, although I had been taking a grinder to rotors for 8 years by that point in time.

 

spend the couple extra bucks and put fresh rotors on if you are worried... safety first.
POZ

 

Those cheap rotors are more dangerous than a worn set of OE's.

 

I am sure there are bad machining jobs around. I have had many sets turned and have all been nice and smooth.

Turning the rotors will give extra bite compared to not turning them, I have done this both ways. Unless you will be below minimum thickness clearly stated on the rotor/hub area just turn them down. About 7.00 a piece to turn around here and new ones are what 30-50 ? since they have the hub included.

 

If ya have the money...New ROTORS, but if the old ones are in good shape, go for turning...depends on the thickness, and what you are wanting to do...

 

NEW ROTORS will NOT in any way be an upgrade in stopping power over a properly turned rotor.

 

Well it depends on the rotors, if your talking stock you are right, but if you are talking aftermarket they "Could" be a upgrade.

 

i cant imagine that slotted or cross drilled rotors with stock calipers are going to make much of any difference with the crappy stock calipers.

All im looking to do is put some high quality brake pads on my car for some minor road race type duty.

When i can afford bigger wheels ill step up to a larger disc and better calipers.

 

the bottom line is, whats your front bumper and hood worth to you?

 

We are talking apples to apples here, right. I just knew someone would do this. Machined factory rotors will stop
just as good as a new standard aftermarket one will. OK

Drilled and slotted rotors are not going to help much if anything at all on the street. If you autocross they will help dissipate heat better since you are using the brakes very aggressively repeatedly. Slotted and drilled rotors for the street are for show.

Larger rotor and caliper would be the best way to go. Hope this was thorough enough.

 

it will see some track duty, hoping to do solo 1 which is timed racing on tracks like shannonville, and cayugas road course, mosport etc

new rotors would be nice but ive already dumped sooo much money into suspension and other things that all i have cash for is buying some quality brake pads
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i also have to think an OE place would reccomend this because they make more money off selling new rotors.

 

That wasnt the intent. Surfacing was only recommended if necessary after inspection of the rotors.

Aftermarket rotors will only help if there's something different about them to help dissipate heat. Slots arent going to do that. Holes might, but then again you've reduced the swept area. I'm still running a home crossdrilled rotor on one side and non-crossdrilled on the other and I can tell you that the car pulls slightly (less braking power on the crossdrilled side) and that the crossdrilled rotor runs significantly cooler. I'm sure there is some tradeoff inbetween, between braking power and temperature reduction that would result in less brake fade I'm sure. There was also weight reduction, but it was fairly minimal. There's a lot more to braking than just increasing mass like some think, or drilling holes like its the solution to all your problems. Its about heat transfer and that requires taking everything into account.

Anyway if you havent already, put on the new pads, machine the rotors (hopefully they're above minimum thickness) and go have fun at the track.

 

im a mechanic and basically you can turn rotors but lately a lot of cars have needed new rotors because the old ones arent worth using because theyre in such bad shape. some rotors can be saved and cut on a machine which do come out nicely and all. but like said above you need to make sure it doesnt go below the minimum thickness. are rotors are a little more expensive because yes we have the hub and all and you may need new seals and or bearings depending on condition. but if theyre warped really bad id say buy a new set and if you do make sure to wipe them down with brake cleaner before putting them on since they come covered in an oil to keep them from rusting.