Who can check disc warpage?

[The Pastor]

A mate of mine has shuddering brakes, whos a good guy to send the disc's to, to check for warpage.

I know there is F1 in Hamilton, but i think he'd rather have someone in Auckland/north shore he can just drop the disc off and have the guy tell him on the spot sorta thing is the disc is warped or not.


Cheers

Rm

[Scouse]

Take it to the disc warpage shop

[MSTRS]

Check it yourself.
Prop up the front wheel and give it a good spin. Look at the disc edge-on from the front. If the plate moves side-to-side, it's warped. Generally speaking, a warped disc can not be straightened.
It is possible that the carrier has taken a knock, and the disc rotor itself is ok, in which case a bit of gentle levering can improve matters no end.

[The Pastor]

Check it yourself.
Prop up the front wheel and give it a good spin. Look at the disc edge-on from the front. If the plate moves side-to-side, it's warped. Generally speaking, a warped disc can not be straightened.
It is possible that the carrier has taken a knock, and the disc rotor itself is ok, in which case a bit of gentle levering can improve matters no end.
what do you mean carrier?

[MSTRS]

what do you mean carrier?

The centre part, that bolts to the hub. The rotor is the shiny outer ring that the pads contact. Often the carrier is alloy and if a disc gets knocked hard from the side, carrier can get bent. That is straightenable, but if the disc rotor has warped (say from heat) it is f**ked.
This is for a floating disc of course, but your mates VTR has that type

[ManDownUnder]

Put the bike up on blocks so the wheel can spin freely.
Get a pencil and lightly touch the lead to the disk while holding the other end lightly against the swingarm or fork so stop it floating around
Spin the wheel and let the pencil get pushed back if the disk is warped.

Ideally you should have a solid line right around the disk, if not, the (lack of) pencil mark indicates where the warp is

[vifferman]

Older disks didn't have a separate carrier connected to the disk by buttons, but instead had machined flanges. Because of this, they used thin paper shims behind the flanges to compensate for minor manufacturing discrepancies. On these disks, you can straighten minor warpage as follows:
Park the bike so the front tyre is clear of the ground.
Immobilise the front forks (turning the bars to one side will do) so the wheel can't move side to side.
Spin the wheel with a felt marker held against the fork slider so it's adjacent to the disk surface.
Move the marker in, so it just barely touches the disk at a few points when it spins. This will leave marks on the disk, from which you can see which points "wiggle" outwards, and which wiggle inwards.
If the warpage is minor, you can add shims under the low points of the disk, and remove them from point adjacent to where the disk wiggles outwards.
If the warpage is a bit more significant, get a BigArse shifting spanner/ crescent (12" is good), and clamp it onto the disk where it's warped. Lever it in the appropriate direction in or out.
Spin again to check warpage.

Repeat as necessary.

[MSTRS]

Older disks didn't have a separate carrier connected to the disk by buttons, but instead had machined flanges.


If the warpage is a bit more significant, get a BigArse shifting spanner/ crescent (12" is good), and clamp it onto the disk where it's warped. Lever it in the appropriate direction in or out.


This is a late 90s VTR250. It has a floating disc.

Be very careful with this method. The hub where the disc bolts is strong, but not overly so DAMHIK (remember this? http://www.kiwibiker.co.nz/forums/showpost.php?p=1894029&postcount=34 )

[The Pastor]

This is a late 90s VTR250. It has a floating disc.

Be very careful with this method. The hub where the disc bolts is strong, but not overly so DAMHIK (remember this? http://www.kiwibiker.co.nz/forums/showpost.php?p=1894029&postcount=34 )
actually its an 88 cbr250?

[MSTRS]

actually its an 88 cbr250?

Ah, thought it was this one http://www.kiwibiker.co.nz/forums/showthread.php?t=98659
Should still be a floater tho. CBR = 1 disc...CBR-RR = 2?

[The Pastor]

yeah its a floater i think, cbr250 R single disc.

[The Stranger]

I can measure it for you easily enough RM if you bring the bike to me.
I can't do FA with it though if it is buckled - other than remove it and get it to F1 or replace it.
You could always check pricing from Victorian Motorcycle Wreckers. I have purchased several rotors from them in the past. Good place to get low milage GSXR rotors as they are usually written off by about 10,000km.

[The Pastor]

I can measure it for you easily enough RM if you bring the bike to me.
I can't do FA with it though if it is buckled - other than remove it and get it to F1 or replace it.
You could always check pricing from Victorian Motorcycle Wreckers. I have purchased several rotors from them in the past. Good place to get low milage GSXR rotors as they are usually written off by about 10,000km.
how would you measure it?

[Motu]

yeah its a floater i think

Sounds like you are in the poo.....

[SixPackBack]

how would you measure it?

A DTI [dial test indicator] known in the industry as a 'clock' is the accepted method of measuring run out. If Noel does not posses a DTI I can help out.

[Starky307]

how would you measure it?

Use one of these (http://www.sracing.com/Store/Tools/MagDialGauge.jpg).

They have a magnetic base so it gets stuck to a reference datum point that won't move. Set the arms so the dial gauge pointer is on the rotor and slowly turn the wheel. If the rotor is true and straight then the needle won't move, if its bent then the needle will swing back and forth.

I've got one if you wanna come for a ride out to Pukekohe some time, also got a set of bike stands that lift the front by the bottom steering head mount.

[FJRider]

Use one of these (http://www.sracing.com/Store/Tools/MagDialGauge.jpg).

They have a magnetic base so it gets stuck to a reference datum point that won't move. Set the arms so the dial gauge pointer is on the rotor and slowly turn the wheel. If the rotor is true and straight then the needle won't move, if its bent then the needle will swing back and forth.

I've got one if you wanna come for a ride out to Pukekohe some time, also got a set of bike stands that lift the front by the bottom steering head mount.

Often the amount of warp is hard to see with the naked eye. One of the above quoted instruments will tell you how bad the warp is.
Some can be trued by competent engineers with a lathe. Not a job to be taken lightly. But the downside is... usually this operation brings the disc thickness below the reccomended margin.

[The Stranger]

how would you measure it?

As per SPB's post. I think sixpack is closer to you however.

[mulletman]

Maybe the caliper and pads need a clean up ?? Could be a build up of dirt and dust making them shudder,

[FJRider]

Maybe the caliper and pads need a clean up ?? Could be a build up of dirt and dust making them shudder,

The surfaces are .. ummmm ... self cleaning , when brakes are applied.