HawaiianRS

I'm just curious what peoples opinions are on turning their rotors between every pad change.
I know all shops you will tell you yes, but I think that has more to do with the difference they can charge in labor between a 20 min pad change and taking off the rotors for turning. Plus new pads with an old rotor will make some customers come back complaing of noise during the bedding in process.
The reason I ask is because I always have turned my rotors in the past but now I question the need. After owning my first motorcycle I noticed that aggresive sport bike owners burn through pads almost as fast as their tires, less than 8k miles is not uncommon. I've seen new pads go in a single day at the track. Yet by comparison they keep the same rotors forever. While I know sport bike rotors can't be turned, my point is that they go through multiple pad changes on a rotor without turning or replacing with no negative effect on braking. Same for race cars or street/track cars running one compound for the street and one for the track. Most people I've talked to in this situation run their rotors until they are grooved, or warped (actually it's uneven pad deposit) then bin'em and get a new set. My rotors have negligible wear so I'm just curious what other's thoughts are as I sit here waiting for my new Hawk pads to show up.

TraviZ

iTrader: (2)

i do mine every brake change, its easy to pop off my rotors on my own and i take them into the auto parts store and turn them myself .

RBob

iTrader: (1)

I don't have the rotors turned, used to, not any more. What I do is to scuff/clean them with 240 grit in a circular pattern. Nice and even on both sides and degrease them. Put the new pads on and bed them.

For what it cost to have rotors turned you may be better off just buying new ones. Besides, turning doesn't leave the proper finish on a rotor.

RBob.

TraviZ

iTrader: (2)

proper finish? please elaborate.

DuronClocker

iTrader: (1)

That's kinda what bedding does, no? Gets the pad used to the rotor surface and works the rotors surface to the pad. That machined finish is gone after the break-in period I'd assume.

If I can spend $20/pr to get them turned once or twice in their life, that saves me $100-150 on buying rotors once or more if twice..

TraviZ

iTrader: (2)

exactly, turning rotors is change compared to price of rotors for our vehicles. and turning just resurfaces them to a even surface, like new rotors, its a clean slate.

RBob

iTrader: (1)

One element of a proper finish is that it is to be non-directional. Turning a rotor guarantees a directional finish. Last time I bought rotors for a 3rd gen they were $22 US each. The C4 rotors I bought last December (upgrade) were $32US each. IIRC the C5's are even cheaper. Around here the going rate is more then $20/pair for turning.

Bedding pads has two purposes: first is to deposit an even coating of brake pad material onto the rotor surface. The second is to heat cycle the pad.

Only time I may turn a rotor is if the pad rivets gouged it. Otherwise what is the point? If the rotor still has a decent surface, clean it and put the new pads on. There was a time when rotors where expensive. Then it paid off to turn them.

RBob.

DuronClocker

iTrader: (1)

For my C4HD setup, even just Duralast rotors from Autozone are $91 each. That's $160 savings every time I get them turned instead of buying new rotors. I'm sure I can get GM ones for a bit cheaper, and of course that's the route I'd go (GMPD) but I just got a quick price because I don't have the part number on hand.

HawaiianRS

I think you are missing part of the point. It's not to replace the rotors everytime, only when they are bad enough to require it which should be 2-3-or more sets of pads down the road depending on how hard you are on the brakes. If you turned your rotors that many times you'd be replacing them anyway. Of course if you don't change the pads in time and gouge them, then it would be a call between the price of replacement vs. turning depending on your application. Rbob was right on the money when he mentioned scuffing them with sandpaper to break the glaze and help bed in the new pads. If your rotors aren't warped or gouged why replace or turn them? Just scuff, clean, swap the pads and go.

doc

I only get the rotors turned when they get warped from a track event. I think we should do what Rbob says, just put a good finish on the surface when changing pads. Get them turned if you have a pulsation in the brake pedal, as long as the pulsation is not from the ABS.

DuronClocker

iTrader: (1)

Ah yes I didn't clarify. I wouldn't get them turned every pad change, no no no. Like you said, every 2-3 pad changes or whenever the surface becomes uneven for whatever reason. It is obviously a good idea to scuff with sandpaper between pad changes. Sorry, wasn't thinking along those lines when I had posted earlier. I was only referring to when the rotors need a turning, why replace them if a simple turn would fix them.

HawaiianRS

At least we got it straight now I'm talking about those folks who swear you need to turn the rotors everytime you change pads, I just don't buy it. I've seen people take brand new rotors and turn them before installing them.

RTFC

Cheap pot castings, or even new rotors sitting on a shelf uneven for a while will cause un-trueness. (Just like how you have to store a crankshaft vetical so it does not warp). Rotors should always be "checked" for trueness even when new.

The very best thing to do with NEW out-of-the-box rotors is to install them with a set of very mild (very soft) brake pads to heat cycle the rotors and condition the iron. After about 400 miles (mainly about 10-15 good heatups and cooldowns) pull them back out and then turn them true. At that time they are heat cycled and THEN install the pads of your choice. But always use a soft breakin pad for new rotors

18inchboyds

nope , i never do it on the trans am . I drive like 3k a year , so ill just throw them out after a few years and buy better rotors, like now i have gm drilled and slotted, and they rusted and i never drove it in the rain , but the water got on them and then they sat for the winter, so . i painted the hat part , but in a year or two ill just throw them out and buy drilled and slotted with the black zinc finish. I try to only give my trans am the best . I try to do it right and do it once. But i went cheap on the rotors at the time .

RTFC

My four 2-pc Wilwood rotors alone cost more than many entire cars on this website. Yet eafter heat cycling them I still had to true them on a lath. you want great performance and sweetspot feel of the brakes, you HAVE to true the rotors no matter how much they cost or how new they are. You HAVE to heat cycle them first and condition the iron.

This is not simply MY opinion, this is a fact.

HawaiianRS

RTFC,

I've seen other posts where you've listed your mods and know you are dead serious about your set-up so I have now doubt you have out-lined the best procedure, which IMO could be considered overkill for some. Though it is something I will keep in mind if I upgrade my brakes. For my personal needs my rotors are smooth and I have no pedal kick back from warping or pad deposits so i plan to to just scuff the rotors and replace the pads.