Has anyone investigated having their rotors turned, rather than replaced? I have grooved rotors and I am going to be taking care of the problem shortly. The question is whether I should get them turned or just replace them. I'm on a pretty tight budget.

Thanks in advance.

Joe

 

depending on how bad they are, u should be able to bring the rotors into a machine shop and have them turned. Even if you install new rotors they need to be turned.

 

Not true. No need to turn a brand new rotor. They all go thru a quality check which includes a run-out check.

 

I agree Scott - if you feel you have to turn a new rotor, you need a new rotor supplier...

Lil Dvl - BMW, er, MINI recommends new rotors, but having seen the rotors (they don't appear to be unique in any way) I would think they could be turned. Check to make sure they don't fall below the minimum thickness after they're turned.

 

I think the main reason for the rotor replacement recommendation is because the stock rotors wear fairly quickly. I read a post a few days ago (can't remember where now) about someone who replaced his pads and rotors with aftermarket ones and his wifes pads with aftermarket pads. He noticed a few days later that there was a lot more brake dust on the wifes car than on his. The pads were the same ones, only difference was the stock vs aftermarket rotors. He found out from a MINI SA that the stock rotors are fairly soft and wear quickly.

 

The minimun thickness spec on the rotor is for using them again. If they are within spec, then go for it. No need to turn them, but the brake peddle will feel a little soft until the new pads bed in.

 

hmmm, most of the rotors i have installed in my day say on the box. Please turn new rotors because tolerances of manfacturing practices differ slightly

 

Runout on new rotors should be within spec. If anything I hit them with some brakekleen and scuff em up with some gritty sandpaper.
If they are within min tolerance, most rotors can only be turned once. I have no experience with MINI rotors, but tons with other cars. Yrs ago you could turn them mugs like 3 or 4 times. Back when I was in College one of my instructors told me, if your budget is limited and you have grooved rotors, as long as they arent warped, there is no need to turn the grooves out. The pads will wear right into the groove. We used to have 3 choices in aftermarket pads, organic, metallic and semi-metallic. I believe they stopped making the organic only pads. They were a lot softer and would easily wear out before wearing the rotor out. Now you have a choice between aftermarket lifetime pads and lifetime rotors. If you put lifetime pads on stocks rotors, you know whats going to happen. If you put lifetime pads with lifetime rotors, which will wear out first? If you can deal with the squeaks I mean!

 

I always go for which one is cheaper and easier to replace :P Usually it comes down to putting pads that are a tad softer than the metal rotors

 

i think going with upgraded aftermarket rotors might work for you.. powerslot makes slotted rotors that will last you longer than OEM rotors. the cryogenic version rotors are extemley tough and super solid.. i have them on friends' honda. they are flawless and still dont need to turned after second set of pads..(they show some wear but, nothing like hondas OEM)

go to the tirerack.com or webbmotorsports.com for more details.. (btw, you do not have to turn these new rotors at all.. these are good from the factory)

 

I'm not a fan of turning rotors. My experience has been that when you turn a rotor it becomes more prone to warping. I'd guess it's because when metal is removed the rotor becomes less able to handle the heat without warping.

Chuck

 

A couple of comments:

1. Turning the rotors. Depending on how much thickness would remain after the rotor was turned, it may be an option. However, if the depth of the grooves/scores is such that there will be very little usable rotor thickness remaining, turning is a false economy - how much are you going to pay for the turning versus just replacing with new rotors?

2. Cryogenic treatment of replacement rotors. If you plan on keeping the car for a while, cryogenic treatment is a great way to extend the life of the replacement rotors. As BMDoubleU notes, the cryogenic rotors are much tougher/more solid.

3. Pads. If the car is not going to be tracked, ceramic pads are the best combination for stopping distance improvement and reduction of brake dusting. In fact, one might argue for two sets of pads if the car is going to be tracked - one set of ceramic pads for non-track driving and a set of metallic composite for tracking. If tracking is in the picture, then cryogenic treated rotors is even more compelling.

4. Turning new rotors to get them true. I agree with Eric (Eric Rowland) and Scott (ScottinBend) - if you have to turn new rotors, you need to get rotors from a different supplier. The new rotors should have zero runout. Buying the cheapest rotors and then turning them may also be a false economy, because you have turned potentially 1/4 of the life of the rotor off to get it true plus there is the cost of turning the rotor.

 

I turned a used set of Power Slot rotors, cost $36, before changing the front pads to Ferodo 2500's. I have 2 track days and several k street miles without a problem so far. The rotors will be replaced when the front pads wear out.

Pretty good economy (new Power Slots = $240).

 

Maybe, but when new blanks can be had for around $33, it's hard to justify the money to turn them.

 

$240? must be for front and rear..

 

$240 was for the fronts only, plated and slotted.

 

Hmmm, there is a little bit more to the false economy calculation:

1. How much did you pay to have the rotors turned? If it was for free, that is good for you, but not necessarily predictive for others - they can't plan on getting their used rotors turned for free....

2. How much life is left on the rotors after turning. Replacing the rotors when the pads wear out is not the decision criteria - it is when the rotors reach minimum thickness. If you run the rotors beyond minimum thickness, you run the risk of ejecting the piston that presses the pad against the rotor - bad news. Actually, very bad news.

Lets try the false economy calculation with the above points in mind:

Scenario A (Recycled PowerSlot rotors)

Cost of used rotors..............$36
Cost to turn.......................$50
Remaining rotor life...............50%
Cost of replacement pads.....$90
Cost to install used rotors....$100

Scenario B (New PowerSlot rotors)

Cost of new rotors.............$250
Cost of replacemnt pads......$90
Cost to install new rotors.....$100

Effective cost of used rotors ($36+$50+$90+$100)x2 (50% remaining life)=$552 versus replacing with new PowerSlots ($250+$90+$100)=$440

There are ways to reduce the costs if you are mechanically skilled, but for the average MINI driver, who may not be mechanically skilled, the above calculation is relevent. Also, as JeffS mentions, new non-PowerSlot rotors can be had for $33; that makes the argument for turned rotors even harder to justify.

 

The powerslots were already on the car. The cost to resurface the rotors was $36. The new rotors are on the shelf waiting for their turn (so to speak).

The rotors measured out ok to resurface, the dimension is cast into the rotor hat so it's easy for the machine shop to check.

Cost 1.
Resurface rotors $36
Pads $120
Install $0 DIY
Total $156

Cost 2.
New rotors (PS) $240
Pads $120
Install $0 DIY
Total $260

Savings of $106.

I will change out the rotors with the next pads, more due to the fact that it will be the start of the track season than due to wear. The thinner rotors might not hold up to the heat as will as new. I might also try a different pad material then. Or possibly go to a BBK.

 

thats kind of steep.. mine cost only $80 for slotted and nickel plated.. the cryogenic rotors cost $40 buck more... are your cryogenicaly treated?

 

where did you get slotted & plated for $80?

What about OEM replacements for $33??? Man I haven't seen these prices.


I spoke with my local service guy (who has been pretty trust worthy) and he confirmed what is mentioned above, the OEM rotors are very soft and his experience suggests when the pads are gone the rotors will be at, or beyond, spec; therefore making them unturnable (at least safely).

I think the issue with turning them beyond the spec is the ability of the rotor to retain its shape strength under heat. I have been told stories of rotors coming apart on the road due to being under spec. This sounds like a day I would not like to experience.

-azminied

 

I haven't investigated mu brakes much recently, but I put those fancy cryo-treated rotors on my Cooper towards the middle of the last track season. They worked great... until the winter came. Now, I've got some steering wheel shudder under braking. I tried bringing the brakes up to temperture one day, just to see if re-bedding the pads would make it go away. Of course, I couldn't get the brakes up to temperture. I did a whole bunch of 60-20 stops and never got the brakes to get warm. I guess that's part of the problem with upgrading pads.

I bought the cryo-treated rotors in hopes of having less problems with them, but it doesn't seem to be working out.

But, like I said, I haven't looked too closely at my rotors and pads in a few months. They're behind steel wheels / snow tires, so it's hard to see what's going on in there, and taking a wheel off when the ground is covered in snow isn't fun.

Perhaps I'm just getting close to the end of the brake pads and that's making things strange? I'm a brake newbie, so any advice would be helpful.

The steering wheel shudder under braking didn't develop when I was doing track days, so I don't think it is heat related pad deposits - unless it took a while for the symptoms to show up.

 

yep, $70 for the rears and $80 fronts.. (not exact price, but pretty clost)

at www.ajusa.com

 

hmm, thats weird.. i have had no issues with warping or anything remotely close to those symptoms. what kind of pads are you using?

 

Based on the symptoms (steering wheel shudder), rotor warping would be my guess as to what is occurring. The only sure-fire way that I know to confirm if rotor warpage is the problem, is to remove the front wheels and measure the run-out with a dial micrometer. Any run-out is a warped rotor.

The primary reason for switching to cryo-treated rotors is to have increased resistance to heat stress and the resultant cracking and having to discard the rotor before it is worn down to the minimum thickness. A side benefit of the cryogenic treatment is greater resistance to rotor wear. I haven't read anything about cryo-treated rotors being more resistant to rotor warping. Lets face it, tracking the car is an extreme duty application. If you are going to play, it is only reasonable that you should be prepared for things needing to be replaced due to the tracking activity.

Unfortunately, I don't know of any other way to check rotor run-out other than to remove a wheel - you need unobstructed access to the rotor.

Possible (brake pads being the source of the shudder), but highly doubtful.

Rotor warpage generally doesn't immediately present itself; rather it occurs over a period of time. There is an initial tiny amount of warpage, followed by increased warpage as the brakes are applied again and again.

 

warpage might also be attributed to having the lug bolts attached in a circular fashion and over torqueing (sp) them. I have not heard of anyone else having this problem with the frozen rotors. Were they the slotted or stock type?