Disc Brakes: new legislation/WOF checks

[LB]

If this subject has already been talked about, can someone please point me in the right direction to find the thread?

I have just found out, via a workmate, about this.

He has just moved over here from the UK, and shipped his bike out. When getting a VIN for the bike, they measured the thickness of his discs and he was told they were too thin. He asked me about it, and I thought they were having him on. However, talking with two mechanics at a bike shop, they tell me that in February legislation came in saying that the thickness of discs must be measured, and once they get to the minimum thickness (as specified by the manufacturers, sometimes punched on the discs near where they bolt onto the axle) they must be replaced.

Holy shit, at the rate I clock up kms I'll be in for a new set of discs every 18 months or so. That's big money.

FYI my workmate's bike is a ZXR600 (I think that's the model, I haven't seen it yet) and it's done 26,000 miles.

Anyone else know anything about this?

[Lou Girardin]

As far as I know, it's true. Having said that, I've never seen them measure discs for a WOF. They do for compliance though.
Lou

[Motu]

Well,yeah it's true - but it's another of thoses things that is in the book but not done in real life.Rules are car biased of course.Disc rotors are to be failed if they are below minimum thickness - but how do we test this in a visual inspection? it's not possible in a car inspection,we are not allowed to pull wheels off - but on a bike,yeah,they are right out there,easy to test - but remember...if he thinks they are below minimum and doesn't have the specs on hand - you will have to find and supply the data.

That said,it is something that is picked up in a VIN inspection,as is this case,would be rare in a WoF test.

[Kwaka-Kid]

really?! hasnt this law been out for like millions of years?! my dad said its always been around and they could fail you, and why not? if your discs and past the thin mark they might shatter under hard braking oneday (it doesnt take a while, but its happend alot) anyways it takes forever to wear discs? my bikes dont 30,000km and still no reasonable edge to the discs... maybe its soft pads i run? dunno.

[Andrew]

This scares me each time I go to get a new WOF.

[Kwaka-Kid]

gotta lvoe not being scared when it comes ot WOF's relaaaaxed

[Motu]

Yep,it's been a rule for a long time.

[Coldkiwi]

the min thickness is usually stencilled on the rotor holding the disc isn't it? hardly takes rocket science to read it then work out the thickness off vernier calipers!

[F5 Dave]

Having just had the discs skimmed on my new (old) touring barge they are close to min thickness. Someone there told me that in Tauranga some of the cops were carrying around mics & measuring bike discs. Hell we skim & wear them down a lot thinner in racing & I have never see a modern disc shatter. Old Iron ones were thick for a reason.

Notice how cops like to pick on people who look like they can afford the fines? Criminals never do & they are harder to catch + they might get a bop on the nose.

But back to my discs which I will probably have to replace eventually, I got them skimmed as they were so warped the bike jumped like a kango when the brakes were applied. It was seriously dangerous on the test ride & I didn’t ride it again until fixed. The bike wore a new WOF which was issued by a testing station. Before they were skimmed they passed the measure test, they obviously didn’t ride the bike that’s for real.

Safety? Nah - LTSA & Police wouldn’t know about it if it toppled off a ladder & bonked them on the head.

[White trash]

Kawasaki owners beware!

We probably fail one Kawasaki a week for rear disc below min thickness.

Sorry.

[Motu]

the min thickness is usually stencilled on the rotor holding the disc isn't it? hardly takes rocket science to read it then work out the thickness off vernier calipers!

I've just had a look at all the bikes in my shop - only the Ninja has min thickness stamped on it...it may be on the others,but could take some finding.Remember,the cost of your WoF is based on the time it takes to do the test - waste the inspectors time and he has the right to charge you for it.

[Kwaka-Kid]

ok F5 dave, maybe ur right but i have heard of 2 people in Formula 3 to have had a disc Shatter, aswell as my old man telling me hes had it happen/heard of it with mates.

[Posh Tourer :P]

If this subject has already been talked about, can someone please point me in the right direction to find the thread?

I have just found out, via a workmate, about this.

He has just moved over here from the UK, and shipped his bike out. When getting a VIN for the bike, they measured the thickness of his discs and he was told they were too thin. He asked me about it, and I thought they were having him on. However, talking with two mechanics at a bike shop, they tell me that in February legislation came in saying that the thickness of discs must be measured, and once they get to the minimum thickness (as specified by the manufacturers, sometimes punched on the discs near where they bolt onto the axle) they must be replaced.

Holy shit, at the rate I clock up kms I'll be in for a new set of discs every 18 months or so. That's big money.

FYI my workmate's bike is a ZXR600 (I think that's the model, I haven't seen it yet) and it's done 26,000 miles.

Anyone else know anything about this?

First hand, straight from the horse's mouth....
Got the VIN for the BM, new registration after a complete rebuild. Had to fill out a brake certification check sheet, detailing what work had been done on the brakes, and specifying actual and min thicknesses for all components (pad and disc as well as drum and shoes), and runout vertical and horizontal (as it were). Also certify condition of all hydraulic hoses and components, and that the brake fluid had been drained and replaced (complete rebuild duh...). This all had to be signed by a mechanic. Ass covering if ever I saw it, but was deemed necesary. The rule may have been around forever, but a directive to actually pay attention to it may be the cause of any new attention. Eg Onehunga Vehicle Testing Station have just recently (last yr) started brake testing bikes, where they havent for the last 20yrs.
In the sphere of cages, yes disc thickness is sometimes checked, normally by the garages who stand to gain from offering to replace it themselves (experience of friends).

[Motu]

If they removed a wheel to check rotor thickness ask them why,they are not allowd to do that - it's a VISUAL inspection only,no invasive tactics allowd.

From my case book - once did a car WoF and as we had a wheel off to do some suspension work I noticed it had a cracked rotor,so failed it on that,I can do that even though I didn't fail it on the original inspection.A rotor for a 73 Galaxy was not available so the owner took it away.A few months later he brings it back - now I know it still has a cracked rotor,but I can't see it,I can't use prior knowledge...so 4 years later I am still issuing WoFs to this vehicle.If I fail it on a tyre and pull the wheel off,then I've got him again...until then,it's out there....somewhere.....?

There are many sound engineering reasons to fail an undersized rotor,but only one is relavent - it's out of manufacturers specifications,end of story.

[Andrew]

the min thickness is usually stencilled on the rotor holding the disc isn't it? hardly takes rocket science to read it then work out the thickness off vernier calipers!

A fine example of a paper engineer and not a practical engineer! Using Vernies wouldn't you be measuring the thickness of the lip? Isn't a micrometer a better instrument to use?