PUR NRG

Installed Rotora slotted rotors front/rear yesterday and I'm not impressed with their quality control. The rotor casting is sloppy and the vented part is slanted instead of parallel to the rotor surfaces. This results in noticable thickness variation and requires considerable balance grinding.

In the first pic you can see one side is 0.225" thick and the other is 0.370". In the second pic you can see that both sides are equally thick (0.300") and a huge amount was milled out to balance the rotor.

I don't know if the uneven thickness will cause warping or other problems. Time will tell I guess.

Oh, in case 0.07" variation doesn't sound like much, let me put it in context. It's more than 1/16th of an inch and roughly 25% variation in thickness. That's huge. When the overall thickness wears down 0.8" it's time to replace the rotor. The variance in each side is almost that much.
________
MAGIC FLIGHT LAUNCH BOX REVIEW

shelleys_man_06

Do you think it was a fluke? I've never heard of such an unbalanced rotor.

PUR NRG

I don't think it was a fluke. Mill balancing is a manual process so they knew how much they were grinding off to make it balance. This was the worst example but all four rotors had noticable variations in thickness you could see with your eyeball.
________
Lovely Wendie

shelleys_man_06

Why would anyone market such crap-quality rotors in the first place? Perhaps Rotora only looks good on paper?

philodox

I have the Rotora drilled/slotted on my RX-8 which I bought through VividRacing. I did not see this in any of the rotors (front or rear). It may be that the 'batch' that yours were made in were constructed poorly.

PUR NRG

philodox, I don't want to question what you're saying but did you actually look for face thickness variation? It wasn't something I would have noticed except the large milled area made me take a second look. Sorta like how I missing the writing on each box that indicated whether it was for the right or left side until after I installed the rotors. The writing was plain enough to see but I simply hadn't thought to look.
________
Ipad Guides

philodox

I just took another 'once over' look at the rotors, the outer sidewall of it is thicker than the inside, this is the same for all 4. I had a brake specialist put my rotors on since I couldn't get the damn things off (the screw that holds the old rotor to the wheel hub was frozen, had to drill them out). They said they looked just fine and not to worry about it. I just chalked the fact that all 4 are uniform as far as wall thickness up to design and not bad quality control.

PUR NRG

philodox, there's an important distinction I may have miscommunicated. Hopefully bullet points will ease comprehension.

1. Looking from the top down rotors have an inside face of solid metal, a middle area of air vanes, an outside face of solid metal and then the hat.
2. On the front rotors the outside face is thicker than the inside face. That's normal and isn't what I'm talking about.
3. What I am talking about is the inside face varies in thickness. At one end it is 0.225". At the opposite end the inside face is 0.300". The same is true for the outside face, which varies from 0.370" to 0.300".
4. The easiest way to tell is look at the face thickness at 4 equidistant points (12-, 3-, 6- and 9-o'clock). They should be the same.

I've included a crude sketch to illustrate this problem.
________
CHRYSLER 300 HISTORY

Outlaws eXtreme

Makes you wonder if Rotora meant to do that on purpose if it's found on all 4... hmmm... Have you contacted them with this info?

philodox

Nice sketch. That clears things up. Like I said earlier, looking at mine, I don't notice that. Then again, I don't have a set of calipers to measure the width of the inside and outside walls of the rotors like you mentioned. I'll stop by my mechanics shop later today if I get the chance to measure them.

PUR NRG

I emailed Rotora the first two images along with a description of the problem. Haven't heard anything back from them regarding this issue.

I don't think it's intentional--at least I hope it isn't. The vent area should be parallel to the rotor faces. Any grinding done to balance the rotor after casting should be due to small irregularities in the vane area. No way should the amount ground off be anywhere near as much as what you see in the second photo.
________
HAWAII MARIJUANA DISPENSARY

philodox

Great work, please let us know what Rotora says in responce to this. I am getting ceramic pads soon, so that should help with the wear on the rotors themselves to help give some extra longevity to them.

PUR NRG

Here's the response from Rotora:

Thank you for email and our apologies for this rotor that you received.

Here at Rotora, we try to QC all parts during machining and before parts are send out. In this situation a rotor got pass our QC process.

The thickness variation on the inner and outer brake surface is from what we call ?CORE SHIFT? in the core of the rotor during casting. This core shift is usually caused by moisture build up in the core due to humidity before it is used for casing or core box was not properly torque down.

The acceptable thickness variation on the inner and outer brake surface (measurement in your photos) should be 0.1 mm. While our DTV is at 0.0127 mm.

Please return the parts to us and we will you another rotor.

It's nice they acknowledge it's a defect instead of trying to claim it's okay. It would be nicer if they did better QC or paid for return shipping. Oh well.
________
CHEAP YT385 SPRING METAL AIRSOFT PISTOL

Ophitoxaemia

i would expect a shipping refund, plus any machining costs you encountered. they can send you a return tag.

good luck!

james

Outlaws eXtreme

Ooo.. or better, say you placed them on your car, screwed it up, and now they have to replace your entire MS Suspension because of it. :P

Gyro

So...

After a few months with the Rotora Rotors, how have they held up?

PUR NRG

Rotors are rotors pretty much. Except for balancing I can't see how they'd "go bad".
________
PRILOSEC LAWSUIT INFO

Gyro

True....

I am purchasing new rotor/pads for my car and I am going to go with the Rotora slotted or the PowerSlot rotors.

Is there any slight vibration or "hum" under braking with these slotted rotors? I ask because one of the manufacturers said in a disclaimer that it is normal with the slotted design.

Also, Have you heard anything about Axxis pads? I was thinking about going with the Axxis ultimate with my new rotors. I have OEM pads with 90% friction material left, however it just sounds like a good idea to do rotors/pads together. If they are less dusty and quieter will be a bonus as well.