Warped Rotor

[D_Sp8s]

I've been feeling a slight pulse in the front brake lever. So, I took a dial indicator from work to check the runout on the rotors and the wheel. The front left rotor has a circular runout of .006". The wheel has a circular runout of .008", and the right rotor has a runout of .015".

The service limit in my manual is .3mm which is roughly 12 thou (.012").

Okay, assuming the right rotor is "warped" or beyond it's service limit, what is the next step? Machine the rotor ? BTW, I work at a machine shop so that wouldn't be too hard. :) Has anyone successfully accomplished machining them? Or should I just get new rotors? If so, what should I get?

[Wrider]

You can machine them, but make sure they are within specs after machining for rotor thickness.

[RCStylin']

same thing happened to my RC51 once. I ended up coughing up $500 on ebay for a couple rotors. they are not cheap.

[D_Sp8s]

You can machine them, but make sure they are within specs after machining for rotor thickness.

Right now I have about .450" to work with before they are at the "service limit." I'll see what the guys at my work can do with them.

[D_Sp8s]

same thing happened to my RC51 once. I ended up coughing up $500 on ebay for a couple rotors. they are not cheap.

I was looking online, and I found OEM rotors for 288 ea. and also Galfer Wave rotors for the same price.

[CYCLE_MONKEY]

I've been feeling a slight pulse in the front brake lever. So, I took a dial indicator from work to check the runout on the rotors and the wheel. The front left rotor has a circular runout of .006". The wheel has a circular runout of .008", and the right rotor has a runout of .015".

The service limit in my manual is .3mm which is roughly 12 thou (.012").

Okay, assuming the right rotor is "warped" or beyond it's service limit, what is the next step? Machine the rotor ? BTW, I work at a machine shop so that wouldn't be too hard. :) Has anyone successfully accomplished machining them? Or should I just get new rotors? If so, what should I get?
Um, circular runout has a specific meaning in GD&T, and imply you were measuring the thin outer cylindrical surface of the disk (outside edge not touched by the pads). Do you mean you put the dial indicator on the flat surface that is contacted by the pad and the TOTAL indicator movement was .008" and .015"? I'd say the .008 was probably not too bad but the .012 and certainly the .015 is pretty bad. Sounds like it's time for new rotors. A lot of time any pulsing in the rotors that people THINK is runout really isn't, but you did the right thing to measure it with an indicator, and if it's on a solid base (magnetic, etc.), it doesn't lie. I wouldn't try and machine the rotor, they're really too thin to do that to, unlike the typical car rotor. Try a motorcycle junkyard or e-bay for a used set, or just buy some new rotors.

[D_Sp8s]

Um, circular runout has a specific meaning in GD&T, and imply you were measuring the thin outer cylindrical surface of the disk (outside edge not touched by the pads). Do you mean you put the dial indicator on the flat surface that is contacted by the pad and the TOTAL indicator movement was .008" and .015"? I'd say the .008 was probably not too bad but the .012 and certainly the .015 is pretty bad. Sounds like it's time for new rotors. A lot of time any pulsing in the rotors that people THINK is runout really isn't, but you did the right thing to measure it with an indicator, and if it's on a solid base (magnetic, etc.), it doesn't lie. I wouldn't try and machine the rotor, they're really too thin to do that to, unlike the typical car rotor. Try a motorcycle junkyard or e-bay for a used set, or just buy some new rotors.


Oops! :oops: Yeah you are right about the circular runout!

What are good rotors to go with? BTW I do mostly commuting and the occasional canyon ride.

[CYCLE_MONKEY]

Oops! :oops: Yeah you are right about the circular runout!

What are good rotors to go with? BTW I do mostly commuting and the occasional canyon ride.
I'm an old (REALLY old....) Mechanical Designer, and I guess the GD&T geek in me came out there. :) Are you in metrology, or are you a machinist perhaps? Most peeps here would have no clue what an indicator was or how to use one.

Actually, that I really don't have any experience with. I've never had to replace any, although my rear (and probably my fronts now) are beyond the wear limit. Although, they still stop just fine, don't fade (except under REAL tough conditions), so I'm going to keep running them until I get a job. Best of luck!

[D_Sp8s]

Actually, I'm a Mechanical Engineer. Graduated from the Colorado School of Mines a few years ago. I don't have that much experience with GD&T, however, I should have known better! I am the Quality Manager/Special processes Manager/Test Engineer/all of the above at a foundy/machine shop where we make non-ferrous metal parts for automotive/military/medical/aerospace/etc.

At this point the brakes work pretty well, besides the slight pulsing in the front. So I'll take my time getting to replacing them.

[CYCLE_MONKEY]

Actually, I'm a Mechanical Engineer. Graduated from the Colorado School of Mines a few years ago. I don't have that much experience with GD&T, however, I should have known better! I am the Quality Manager/Special processes Manager/Test Engineer/all of the above at a foundy/machine shop where we make non-ferrous metal parts for automotive/military/medical/aerospace/etc.

At this point the brakes work pretty well, besides the slight pulsing in the front. So I'll take my time getting to replacing them.
......just don't let it happen again! :) Cool man, us few non-IT guys need to stick together! You guys need any good Designers?

[D_Sp8s]

Unfortunately, we only have the need for 1 designer....and we have 1.

[CYCLE_MONKEY]

Unfortunately, we only have the need for 1 designer....and we have 1.
Drat!

[Kim-n-Dean]

... A lot of time any pulsing in the rotors that people THINK is runout really isn't...That is 100% correct. The pulsing is usually glazing in different spots on the rotor.

[rforsythe]

That is 100% correct. The pulsing is usually glazing in different spots on the rotor.

With cars it almost always is. I've seen a lot of bent or warped rotors on bikes though that wasn't just glazing, so it's worth considering.

[Kim-n-Dean]

With cars it almost always is. I've seen a lot of bent or warped rotors on bikes though that wasn't just glazing, so it's worth considering.I'd say he considered it when he pulled out the dial.:D

[CYCLE_MONKEY]

I'd say he considered it when he pulled out the dial.:D
'Scuze me, while ah whip dis out! :D

[CYCLE_MONKEY]

That is 100% correct. The pulsing is usually glazing in different spots on the rotor.
I totally agree. I've read that pad material will get burnt onto the hot disk if the disk is not moving, and know that when running race cars, you try and not use the brakes at all coming in to the pits after a hot lap, and you NEVER use the e-brake when you stop, you use wheel chocks. In fact, if I have to come to a stop in my RAV4 after a long hard stop (i.e. a red light on a freeway or a stop at the bottom of a long mountain hill), I'll put it in park while I sit at the stop.

[Kim-n-Dean]

'Scuze me, while ah whip dis out! :D
The Sheriff's a - DING!!!!!

[CYCLE_MONKEY]

The Sheriff's a - DING!!!!!
He said: "The sheriff is NEAR"! (cheers)


"No, dad-blam it, I said the sheriff was a -DING!"....... :D