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Brake discs - thickness?

MrMogensen

MrMogensen

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I want to change my brake pads and maybe the brake discs, but they don't seem to be particularly worn...

Can't I just measure the thickness of the discs?

What is the recommended lowest thickness, and also what is the measured thickness for brand new discs?
 
According to Haynes Manual:

Front Disc Thickness:
Standard.... 5mm
Service limit ... 4.5mm

Rear Disc Thickness:
Standard.... 5mm
Service limit ... 4.5mm


you can use a caliper or a micrometer to measure it.
 
BTW, mine are originals (as far as i can tell), '04, and have 13k on them - running street brake pads. I don't take it to a track, but I am using brakes quite a bit. Recently, I was installing SS-lines, so I decided to measure the thickness, just for kicks - it was 4.9mm.
 
you can talk to Vegas, he has a lot of miles on his bike. i dont think he has replaced his rotors. you should be fine, unless they are warped from having a stuck caliper.
another thing that could wear your rotors down sooner are those fancy brake pads. i forget what they are called, but they have more metal in them or something....
 
Smersh said:
BTW, mine are originals (as far as i can tell), '04, and have 13k on them - running street brake pads. I don't take it to a track, but I am using brakes quite a bit. Recently, I was installing SS-lines, so I decided to measure the thickness, just for kicks - it was 4.9mm.
Click to expand...

When I bought my bike it had ridden 20.000km... Now it's on 48.000km and I have no idea if previous owner installed new discs - but I doubt it!?

I at my girlfriends house now so I have only got a ruler :D
Will measure the discs/rotors in a day or two at work or home...
 
Norbert said:
you can talk to Vegas, he has a lot of miles on his bike. i dont think he has replaced his rotors. you should be fine, unless they are warped from having a stuck caliper.
another thing that could wear your rotors down sooner are those fancy brake pads. i forget what they are called, but they have more metal in them or something....
Click to expand...

Like "sintermetall" from EBC?... the "non"-organic or whatever they are called?
 
MrMogensen said:
I want to change my brake pads and maybe the brake discs, but they don't seem to be particularly worn...

Can't I just measure the thickness of the discs?

What is the recommended lowest thickness, and also what is the measured thickness for brand new discs?
Click to expand...

From the YAMAHA MANUAL,

Page 4-21:

New pad is: 4.5mm, worn limit is: .5mm (or .020")

From page 4-20:

Front rotor thickness LIMIT is: 4.5mm or .018",
Runout allowance is: .10mm or .0039"

I changed my front pads at about 11,000 miles as I mostly just use my front brake. The rear pads are like new.

BTW, the .020" limit is .020" between the steel backing plate of the pad and the actual braking material sticking out. Yamaha allows them to get pretty thin. Mine was approx .050 when I replaced them... The disc's generally don't wear much, the pads do. Without a micromometer, if the disc's aren't discolored and don't have any deep scratches in them, their likely ok... You need watch the pad thickness themselves more so... Two clips and two pins allow them to be pulled out quickly.. If glazed up, you can scruff them up with some sandpaper or what I do, scruff them lightly on a flat piece of side walk. Brake cleaner after that on both the rotors, pads and if you have an air compressor, gently blow all the remaining brake dust from the caliper assembly (there WILL be a bunch of dust)...

Also, the top anti rattle steel plate (kinda curvy) has a small arrow on it that must face forward, put a little bit of Brake grease on the sliding pins when re-assembling


* The manual does not mention the thickness of a NEW rotor*
 
Last edited:
EDIT: For 04-06 models

Front brake pad wear limit is 0.8MM.
Rear brake pad wear limit is 1.0MM.
Front and rear brake rotor wear limit is 4.5MM.
 
Last edited:
Cali rider said:
Front brake pad wear limit is 0.8MM.
Rear brake pad wear limit is 1.0MM.
Front and rear brake rotor wear limit is 4.5MM.
Click to expand...

In my Yamaha 07-09 shop manual it shows on page 4-21, the FRONT PAD limit to be .5MM, (.020").

Is your manual showing the earlier bikes having different limits (thicker)?
 
Last edited:
TownsendsFJR1300 said:
In my Yamaha 07-09 shop manual it shows on page 4-21, the FRONT PAD limit to be .5MM, (.020").

Is your manual showing the earlier bikes having different limits (thicker)?
Click to expand...

I have the '04-06 service manual, and it does indeed say 0.8/1.0mm for F/R pads.

Either way, with what rotors cost compared to pads, I'm not wearing them down to 1mm or less and risking metal-on-metal and scored rotors! :eek:
 
TownsendsFJR1300 said:
In my Yamaha 07-09 shop manual it shows on page 4-21, the FRONT PAD limit to be .5MM, (.020").

Is your manual showing the earlier bikes having different limits (thicker)?
Click to expand...

Sorry Scott, I overlooked the model year that you have. As the 07-09 have different calipers/pads I'm sure that accounts for the different specs.

My mistake for not paying attention!!!
 
fb40dash5 said:
I have the '04-06 service manual, and it does indeed say 0.8/1.0mm for F/R pads.

Either way, with what rotors cost compared to pads, I'm not wearing them down to 1mm or less and risking metal-on-metal and scored rotors! :eek:
Click to expand...

Cali rider said:
Sorry Scott, I overlooked the model year that you have. As the 07-09 have different calipers/pads I'm sure that accounts for the different specs.

My mistake for not paying attention!!!
Click to expand...

Actually, I saw it was an 04 and figured it would be the same spec's, it obviously isn't.

My assumtion was incorrect, I guess Yamaha lets them get a little thinner with the newer models.. My Boo, Cali rider, NOT yours...

I just checked the rear pad spec's for the 07, those are THE SAME for the earlier models... Hmmm

fb40dash5, +1. I didn't let mine get near that thin, .020 pad thickness is not much and I agree, pads are much cheaper and easier to replace than rotors.


Lesson learned, brake pads spec's for the front are different prior to 07, perhaps just as the front braking system/ forks are slightly different...


BTW, if anyone has a PDF style, early model FZ6 YAMAHA GENUINE shop manual they can send, please PM me. I already have the 07-09 manual.

Thanks, Scott
 
Last edited:
As a point of reference for those who may not have the best measuring equipment, use the UNWORN section of the rotor to get your base line and confirm the OEM spec. Now measure the worn part and subtract.

Unfortunately this may require pulling the rotor in some cases. Just mark it so it goes back on the way it came side and direction.
 
fb40dash5 said:
I have it, you can shoot me your e-mail if you want, though I think I just downloaded it from Boneman's site.
Click to expand...

Got the earlier (06) shop manual, thank you...

The earlier bikes do require the brake pads to replaced slightly sooner as the spec's are indeed different.

This may be due to the difference in the number of piston pots (in each caliber), 2 pistons vs 4 pistons for the 2007 model and up.
 
Would you guys spend time separating those little bits and pieces inside the front/rear master brakecylinder - that is if you were to change the brakehoses anyways? Or just blow out the old brakefluid with an aircompressor?
According to the service manual there are 1 circlip in each master brakecylinder which would need replacement. The other little bits and pieces could be cleaned and reused.

Just got some prices from the local Yamaha dealer (on parts I doubt I can find elsewhere?):

FZ6 (2004-06)

Brakepiston seal kit rear = 8 USD
Brakepiston seal kit front = 180 USD
Rear circlip = 4 USD
Front cirlip = 50 USD (only comes along with complete kit replacing all the little bits in the front cylinder).

* Price for brakepison seal kit front seems crazy?... or?
* Does anyone know if the rear circlip is the same size as the front circlip?

I thought about wheelbearing (front/rear) while I am at it (installing a new chain anyways), but they land on a total of 275 USD for original ones. Dealer said I could save around 70 bucks if I bought unoriginal wheelbearings but that wasn't recommended (of course).
 
bearings are only worth changing if they are broken or damaged, if they are sufficiently lubed then they should be ok

same with the seals, if there's no problem then leave it. it might be worth giving your calipers a clean up with some brake cleaner and a tooth brush, but unless they are sticking or leaking then i'd just leave them
 
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