Turning brake rotors??

I plan to replace all my brake pads on my '82 XJ1100J soon.
I have one front rotor that feels a bit warped as I get that warped feeling when I apply the front brake.
So that brings me the question, do people turn their brake rotors on these bikes? If so, then where do you get them turned? Would a normal brake shop be able to turn them?
Mike

 

Mike,
To my knowledge, turning motorcycle rotors just isn't done. The disks are very thin to begin with and would almost certainly be reduced to unusable dimensions with any machining.
Best thing to do is to save up for a new pair.

 

I had all 3 done oj my XJ1100, cost me 90$ for all 3. They were all in spec when they were done, but they won't survive another turning. I had them done at a local auto machine shop. He said they are just like his race car brakes and that they were no problem. I had to give him a chance since replacement rotors are expensive. He took just enough off to true them up and keep them in spec for thickmess. I have put several thousand miles on it since then with no problems.

 

Turning motorcycle rotors isn't recommended, you need a "non-directional" finish which requires surface grinding (usually.) Yes it CAN be done, but as I said it's not recommended.

Even if you WERE to get them turned I don't think there's enough "meat" to be able to correct a warp the way you sometimes can with car rotors.

chacal carries the EBC full-floating drilled rotors for less than half what a new OE disc runs IF you can even find one.

 

Full floating? Is that different from the stock rotor? What is full floating about a brake rotor? I'm not sure I understand that....

I suspected that the rotors would be too thin to turn reliably...but I had to ask.
But why would I need a "non-directional finish" verses the finish you normally get when you have an automotive brake rotor turned? Why would these be different than the rotors on a car...as far as surface finish is concerned?

Mike

 

I've never been able to find a brake shop that can "turn" or cut these Yamaha rotors....they're made of a hardended material that just chews up the regular stones on the brake machines and rips the rotor surface.

You CAN have them "surface-cut" on a blanchard table (like they use to surface flywheels) and an automotive style machine shop might be able to do that, assuming your rotors are not one of those "deep offset" styles.....then even with a blanchaard table, it becomes a royal pain.

Unless you have a LOT of warpage, there is probably enough material there for one cut.

Floating rotors have a 2-piece system...the center hub is no longer cast as part of the disc itself. Supposedly performs better under high temp conditions, etc. Stock rotors are integral units, although on some models....like on the 1100 rear rotors, if I recall correctly, all 900RK rotors, and the 650 Turbo and 700 model front rotors.....there really isn't a "hub" to the rotor, it's just a flat disc with mounting holes in it, and in those instances, there is no "floating" style rotor available (or necessary).

 

chacal is right, the floating rotor is free to expand at a different rate than the hub plus compensate for minor "runout" that a solid disc can't.

BUT HE FORGOT TO MENTION THEY'RE DOWNRIGHT SEXY:



The hub comes "natural" I painted mine with "Brake Caliper Paint."




The best part is them being a WHOLE LOT cheaper than the now hard or impossible to get OE rotors.

 

I found a shop that turns bike rotors. Most of them you can turn once, but that's it. They don't recommend turning them, but it works ( did for me) I got my rotors turned on my three wheeler and on my four wheeler when I got grooves wore in them from rocks. When they turn rotors that have the vent holes in them, they leave chatter marks sometimes, but they still work alright. I'd give it a try. It may save you some money?

 

Thanks guys!

 

bigfitz what does one of those darn fancy high fluten things cost ya?

 

Varies by bike, chacal has them cheaper than anywhere else I found (I was about to spend $35 too much) most are around $195. Compared to a new Yamaha OE rotor at over $300 (IF you can even find one) I considered it to be a frugal upgrade.

 

cutting disks can be done at a machine shop... they just use carbide bits and go slow(cast iron = low rpm cuts)
machine shops also have grinders which i have no idea how to run yet :/

 

I spoke at length with our engineer/racer. He says that as long as minimums are not exceeded, grinding is the correct method of cleaning up rotors. He recommended GS Grinding in Ventura. He's had them true up rotor carriers he designed and installed on his Suzuki. He said it runs about $50 a rotor.
Now that I'm schooled on this topic (albeit only slightly), I'll be looking into this option.

 

many Shops now have twin face grinders, purpose designed for refacing Bike rotors. Which is THE only way to do it ie: grinding the surface.
Phone around and ask, sooner or later you will find one that has the appropriate equipment.

 

ok i feel the urge to throw in my 2 cents here brake rotors rotors of any kind should NEVER! be ground as such, you must always use a twin carbide tip type lathe to ensure equal amounts of material is machined from each side failling to do this can cause "runout" motorcycle discs are machinable as long as they are still within the manufacturers minimum spec, i would recommend a brake specialist to complete the job a directional swirl is recommended to able the NEW pads to be bed in quicker the same senario is the go for cars aswell new pads should always be fitted with new or machined discs and caliper slides etc should be properly lubed motorcycle discs should be machined at low rpm to ensure there is no vibration or "chatter"marks left as the tip skips over the drilling or slotting. Best bet see chacal get some new stuff but thats just my 2 cents cheers
NZBCSA
(NZ Brake & Clutch specialists assoc)