FJR "normal" front rotors rate of wearing?

Maybe has been discussed many times..

Is it normal for a couple of gen1 298mm rotors to wear 0.3 mm of thickness in about 20000 km? ...and I'm very gentle on the lever...

Now I need a new pair (I think)

lele said:

Maybe has been discussed many times..Is it normal for a couple of gen1 298mm rotors to wear 0.3 mm of thickness in about 20000 km? ...and I'm very gentle on the lever...

Now I need a new pair (I think)

Click to expand...

I haven't measured mine (Gen II) but they still look OK after 260,000 km. (They might be a bit thin by now.) If yours are worn significantly by less than a tenth of the distance I have on mine, then I would suggest that something isn't right. (Does 0.3 mm of wear take them below specification?)

With only 20,000 km (in 16 years), the bike has not been ridden very much - less than 1000 miles/year! With that little mileage, I assume the pads are original? If you have had to replace the pads, then calipers must not be retracting fully. If you have used aftermarket pads, what brand?

I think the spec is 450 thousands of an inch. Anything below that the rotors should be replaced.

No the bike has now 140000 km, I replace the rotors and pads with OEM new at 120000km. Today I measure both rotors, they are 4.7mm from an initial thickness of 5mm.The strange thing is that the pads looks new!

lele said:

No the bike has now 140000 km, I replace the rotors and pads with OEM new at 120000km. Today I measure both rotors, they are 4.7mm from an initial thickness of 5mm.The strange thing is that the pads looks new!

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have to ask, did you measure them new also ?? your caliper or micrometer is calibrated ??

guessing something is off on the measurements, and not your rotors in that short of milage.

Yes is strange, if I measure the edge of the disc where the pad doesn't work I got 4.8...I think my micrometer is crap

lele said:

Yes is strange, if I measure the edge of the disc where the pad doesn't work I got 4.8...I think my micrometer is crap

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Sounds like it. If both rotors and pads are OEM, I wouldn't expect measureable wear on the rotor if the pads are still looking fairly new.

Sticky pistons in the calipers could cause a quick wear,but i don't think in about 20000 km...

Infact I realize today both calipers have outers pistons "sticked"..due to lot of dirt and junk and I don't kwon what it is

I have pulled the rear piston out of the caliper and cleaned it up with some WD40 and a fine scotchbrite pad. I never touched the front pistons since they seem to still work fine with 90K on them. I have never measured the rotors though. Wear looks to be normal. I will check it on the next set of pads and take a quick look at it this spring when I bleed all the brakes.

Dave

lele said:

Infact I realize today both calipers have outers pistons "sticked"..due to lot of dirt and junk and I don't kwon what it is

Click to expand...

I think that your calipers will need a service.A good cleaning and new seals..

I just finished cleaning front calipers pistons and seals... someone know a good method to re-filling the circuit with brake fluid without a brake bleeder? (I don't have one)