Disk Rotor Service Limit

Guys, explain this if you can please.
I took my twin front rotors off and miked them, 4.43mm and 4.46mm. Service limit is 4.5mm.[So says the factory manual], So are they both scrap? The reason I ask is because when I look at potential replacements which are marked for my bike[they are the correct diameter and have the correct bolt number/spacing], they're ALL brand new, and ALL 4.5mm thick.[like me youre thinking:blink: ].How can a new rotor be on the service limit? Is there something I don't know here?:dry: :blink:
Thanks in advance people.Incidently, the rotors are 27 years old and started life 6mm thick.:S

Post edited by: tellietubbie, at: 2007/04/17 21:50

The rotors on my 26 year old bike now measure 4.80 mm and the 24 year old bike measures 5.10 mm. It sounds like somebody butchered yours on a brake lathe. Best to refinish them by grinding out the scoring and hard spots, thus removing very little material.

Hey tellietubbie - Here is my experience with brake disks.

I just had the 3 disks on my "77 Kz650 Custom done at a local machine shop. They had scoring on them like an old old LP album. The machinist has been doing these types of jobs for over 45 years and he does them by hand with a grinding disk. No computerization in this old shop.

He said the disk was 7 m.m. thick from the factory stamping on the disk hub and after he was done they measured 6.79 m.m. The service limit on mine were 6 m.m.

Given that the bike has been in my family for nearly 25 years I don't believe they were ever turned by a machine shop before.


Cheers-Colin Firth-Ontario Canada

Oldcoldankles,good advice,thanks a lot.Like your bike,never seen one of them.If you feel you're getting on a bit feel free to crate it up,I'll look after it for yer
Reborn650:very interesting,wish I could find an older machinist,I just can't convince myself that it's a good idea to leave what for me are valuable artifacts with spotty teenagers with wide staring eyes from night before:dry: A typical price for my disks would run me the equivalant of $900 American dollars:ohmy: [3 disks].I need a decent machinist.Thanks a lot,your comments are appreciatedB)