Brake rotor question

[gisleDK]

Here in Denmark we have to bring in our motorbikes for a govermental checkup once in a while, and they told me that my front brake rotors were worn down. So I bought new EBC brake rotors, but they don't appear thicker at all?
Can any of you guys explain?
I'm sure I got the model right, EBC cataloque is pretty straight forward (MD2024 for my XS1100 S).

[Geezer]

Some burocratic fool that couldn’t find his ass with both hands and a bloodhound is telling you to replace parts that he knows nothing about.

I’d check the thickness of the pads while I had it apart but it’s probably fine.

Geezer

[strom]

Well... you got some eager fresh jerk. Check for XSive grooving of the rotors, run your fingers from the center out. If they are way thicker at the outer couple of milimeters, they are worn. If you check the new ones, they have no grooves. Take the new ones back to the guy that said they were bad, show him for comparison and if he says the old ones are OK, make him pay the bill. BTW: Have a few friends with mallots handy.

LP

[Bud Manley]

I've found here in the U.S. that if recieve an answer different from what you want or feels makes sence just go to someone else. You can go to the Bureau of Motor vehicles with a question and recieve 6 different answers from 6 different people.

[gisleDK]

Thanks for the posts, I will try to get a hold of that pinhead that probably made me throw way too much money out the window.
To be continued....

[Jerry]

rotor specs

From the manual...

Minimum Disk Thickness: 6.5mm (.026 in)
Maximum deflection: 0.15mm (.006 in)

To prove the official wrong you will need these numbers, your old rotors, a good micrometer (to measure thickness) and a dial indicator to measure runout.

I think it is unhighly likely anyone could view rotors and declare them out of spec, unless they have obvious damage or are *deeply* grooved.

[Jerry]

correction

Sorry, fingers not working t well this AM.

Maximum Disk Thickness: 6.5mm (.26 inches), not .026 inches as in previous post.

[nashville_bill]

Jerry,

You do mean "Minimum" disk thickness? Right?

[Jerry]

Minimum it is!

In any event, don't know how any official could look at a rotor and say it is worn out without knowing stock spec. Most owners don't know, and the information is in an odd place in the manual, in the section that discusses rebuilding the master cylinders. (At least that is where it is in the XJ manual.) Sounds to me like gisleDK got a bike-unfriendly officer at his inspection.

[gisleDK]

I just measured my new EBC brake rotors, and it seems they aren't even 6mm!
ARGH!!!

[strom]

U sure bout that 6,5mm? Thats fat as hell and IMHO original thickness when new. I wouldnt worry bout it till 5mm or so.

LP

[Jerry]

Here is a screen shot of part of page 5-14 in the XJ service manual with the rotor spec:



Far as I know these are the same specs for XS rotors.

[MartyA]

Yeah, Clymers says the same for the 78-81.

[rockyr74]

The xs rotors are sooooo lame; I don't think they are any thicker than the minimum spec when new.

I might speculate that an aftermarket rotor might have slightly different specs depending on the material. .24" (6mm) isn't outside the realm of reason - What matters is smooth operation without pulsation or grabbieness and no fade after they heat up.

I don't know if I would worry if I had thin rotors that worked well, but I might just give them a few real good hard stops to see if they faded.

My experience has proved on the other hand that thin OEM rotors tend to warp and pulsate. My cheap self has tried turning them with very poor results.

[gisleDK]

EBC brake rotors are useless!!!

Just got a reply from the authorities here in Denmark, and they told me directly that my brand new EBC brake discs are ready for just one thing...a garbage can.
Murphys law in working action.