Can I turn my rotors?
Thread Starter
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Junior Member
Joined: May 2012
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Can I turn my rotors?
Hey all my front rotors are warped on my 98 900w and I was looking on ebay for a new set, first I'm wondering if I can turn or resurface my rotors? Anyone ever done this? Second, will all Blade rotors work or just 98/99? Thanks
Rick
Rick
Retired Super Moderator - At large E=MC2
Joined: Feb 2011
Posts: 2,299
Likes: 4
From: Tulsa,OK
To answer your question on turning, yes it's possible.
The trick is finding out what yourrun-out is (how warped the rotor(s) are),
and then seeing if you can still have useful spec when you are done turning them.
You'll need a dial-mic and a base for it. I attach mine to the fork,
add a slight compression to the tip past touching the rotor,
then rotate the rotor, observing the maximum and minimum readings.
Subtract the minimum from the maximum and you will have your run-out.
Then take a micrometer and measure the thickness of the rotor. Subtract the run-out
from the current thickness. This is what your rotors will be when finished turning.
If that still meets the spec for minimum thickness on your rotors,
it can be turned to true.
Personally, you should add (imo) .2mm to .3mm to that to allow for future wear,
when making the call.
As an example, my F3 manual shows 4.8 to 5.2 as stock thickness.
The minimum is 4.0mm.
The maximum tolerance for run-out is .30mm.
If the current run-out is .70mm, I have to shave .40 (usually .20 per side)
to get back to the maximum tolerance.
I would shoot for .15 to .20 (again for future wear) meaning, I actually need to take
off .55 to .60mm (or .275 to .30 per side).
If the disc is currently 5.0mm thick, that means I'll end with 4.35 to 4.4mm of meat.
That works and I still have a decent margin.
If the disc was less than 4.75mm? Then, NO I would not pay to turn, I would replace.
At that point, you will be less than my (admittedly, arbitrary) minimum for extended/useful life.
Hope this helps you in your decision process, Ern
The trick is finding out what yourrun-out is (how warped the rotor(s) are),
and then seeing if you can still have useful spec when you are done turning them.
You'll need a dial-mic and a base for it. I attach mine to the fork,
add a slight compression to the tip past touching the rotor,
then rotate the rotor, observing the maximum and minimum readings.
Subtract the minimum from the maximum and you will have your run-out.
Then take a micrometer and measure the thickness of the rotor. Subtract the run-out
from the current thickness. This is what your rotors will be when finished turning.
If that still meets the spec for minimum thickness on your rotors,
it can be turned to true.
Personally, you should add (imo) .2mm to .3mm to that to allow for future wear,
when making the call.
As an example, my F3 manual shows 4.8 to 5.2 as stock thickness.
The minimum is 4.0mm.
The maximum tolerance for run-out is .30mm.
If the current run-out is .70mm, I have to shave .40 (usually .20 per side)
to get back to the maximum tolerance.
I would shoot for .15 to .20 (again for future wear) meaning, I actually need to take
off .55 to .60mm (or .275 to .30 per side).
If the disc is currently 5.0mm thick, that means I'll end with 4.35 to 4.4mm of meat.
That works and I still have a decent margin.
If the disc was less than 4.75mm? Then, NO I would not pay to turn, I would replace.
At that point, you will be less than my (admittedly, arbitrary) minimum for extended/useful life.
Hope this helps you in your decision process, Ern
To answer your question on turning, yes it's possible.
The trick is finding out what yourrun-out is (how warped the rotor(s) are),
and then seeing if you can still have useful spec when you are done turning them.
You'll need a dial-mic and a base for it. I attach mine to the fork,
add a slight compression to the tip past touching the rotor,
then rotate the rotor, observing the maximum and minimum readings.
Subtract the minimum from the maximum and you will have your run-out.
Then take a micrometer and measure the thickness of the rotor. Subtract the run-out
from the current thickness. This is what your rotors will be when finished turning.
If that still meets the spec for minimum thickness on your rotors,
it can be turned to true.
Personally, you should add (imo) .2mm to .3mm to that to allow for future wear,
when making the call.
As an example, my F3 manual shows 4.8 to 5.2 as stock thickness.
The minimum is 4.0mm.
The maximum tolerance for run-out is .30mm.
If the current run-out is .70mm, I have to shave .40 (usually .20 per side)
to get back to the maximum tolerance.
I would shoot for .15 to .20 (again for future wear) meaning, I actually need to take
off .55 to .60mm (or .275 to .30 per side).
If the disc is currently 5.0mm thick, that means I'll end with 4.35 to 4.4mm of meat.
That works and I still have a decent margin.
If the disc was less than 4.75mm? Then, NO I would not pay to turn, I would replace.
At that point, you will be less than my (admittedly, arbitrary) minimum for extended/useful life.
Hope this helps you in your decision process, Ern
The trick is finding out what yourrun-out is (how warped the rotor(s) are),
and then seeing if you can still have useful spec when you are done turning them.
You'll need a dial-mic and a base for it. I attach mine to the fork,
add a slight compression to the tip past touching the rotor,
then rotate the rotor, observing the maximum and minimum readings.
Subtract the minimum from the maximum and you will have your run-out.
Then take a micrometer and measure the thickness of the rotor. Subtract the run-out
from the current thickness. This is what your rotors will be when finished turning.
If that still meets the spec for minimum thickness on your rotors,
it can be turned to true.
Personally, you should add (imo) .2mm to .3mm to that to allow for future wear,
when making the call.
As an example, my F3 manual shows 4.8 to 5.2 as stock thickness.
The minimum is 4.0mm.
The maximum tolerance for run-out is .30mm.
If the current run-out is .70mm, I have to shave .40 (usually .20 per side)
to get back to the maximum tolerance.
I would shoot for .15 to .20 (again for future wear) meaning, I actually need to take
off .55 to .60mm (or .275 to .30 per side).
If the disc is currently 5.0mm thick, that means I'll end with 4.35 to 4.4mm of meat.
That works and I still have a decent margin.
If the disc was less than 4.75mm? Then, NO I would not pay to turn, I would replace.
At that point, you will be less than my (admittedly, arbitrary) minimum for extended/useful life.
Hope this helps you in your decision process, Ern
Thread Starter
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Junior Member
Joined: May 2012
Posts: 8
Likes: 0
Thanks I haven't checked the runout of the rotors yet. If they are un turnable has anyone used the Chinese rotors from ebay? I ride only street, not really a super aggressive rider. I do plan to have this bike for a while though...
Rick
Rick
Party Animal, ROTM June 2014
Joined: Oct 2008
Posts: 671
Likes: 0
Brakes are very important to your survival.... is this a part you really want to go the cheap route with? If it were me, I would stick to either stock parts or reputable aftermarket.
Just my opinion tho.
Just my opinion tho.
March 2013 ROTM
Joined: Dec 2011
Posts: 84
Likes: 1
From: Columbia City, IN
Nick
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