Brake Shudder

[cruelcheffy]

I noticed a few weeks ago some vibrations coming through under braking. I since had it serviced, and the shop (MackI) made me aware of it. I decided not to have them look at it as things got a bit tight (wife lost job etc), bill was already $800 for the 25K service.
So today again on the way home it made me focus on it again. Once at home I touched the disks and noticed that the right disk is a lot warmer then the left. I am assuming that it must be warped, but it doesn't seem to show when spinning the wheel and looking at it with the naked eye.
Could it be something else, perhaps in the caliper??

Would appreciate some advice.

Cheers

[druu]

Could be the brake pistons not retracting or could even be something to do with your head stem, possibly loose?

First thing I would do is take off the calipers and clean the pistons up as much as you can without removing them, then bleeding the system good and proper. See how you go after that.

[polonY]

90% probably warped brake disc. very rarely visible to naked eye, even during rotation. its not a difficult part to replace, if you can source it yourself then you'll save alot of cash. thats where my knowledge ends

now im guessing when i say the cooler of the two discs would be the warped one as the brake pad isn't making continual contact with the disc to create friction and heat.

[Sprint]

My approach would be:

(1) Elevate your front end and check the headstem for both lateral play and any notchiness when the steering is pivoted from side to side.

(2) Check the discs with a runout dial - will show which is warped, if at all. Someone here should have such a tool so you can set up to do this simple check.

If the above two steps don't identify the problem, then by all means strip down your brakes and rebuild them.

GL.

S.

[smeghead]

PM Sean'o, he just got some disk truing done over east. Didn't take long and didn't break the bank. If you do this install new pads & bed them in properly.

Personally, I like good brakes & would not hesitate to strip & rebuild the calipers to be sure all is good. Also check for any hose issues such as kinks or crimps.

Make sure the caliper bolts are torqued correctly.

Loosen the top triple clamp bolts & the axle pinch bolts (NOT the lower triple clamp bolts) & bounce the front end a few times to 'true' the wheel in the forks. Retorque from the top down.

[XSorXpire]

My approach would be:

(1) Elevate your front end and check the headstem for both lateral play and any notchiness when the steering is pivoted from side to side.

(2) Check the discs with a runout dial - will show which is warped, if at all. Someone here should have such a tool so you can set up to do this simple check.

If the above two steps don't identify the problem, then by all means strip down your brakes and rebuild them.

GL.

S.

If you dont have a dial gauge get something flat like a steel ruler or something that you can hold securely against your forks or calipers at 90 degrees to your disks and spin your wheel while the ruler (or whatever) lightly touches your disk. You may notice the warp that way, it will appear as light between the two surfaces.

[cruelcheffy]

Thanks for the advice and tips so far.
I am off to work now, so the weekend will be set aside to track that probllem.

Cheers

CC

[cruelcheffy]

OK, found the problem.
The right hand disk is warped by about 1 mm, and the pads are worn 50% more then the on the left!
Now what?
Do I need to replace it, or does it have to come off and need to be machined?
I assume it will be one or the other.
If machining is needed, any advice on where to go?

[druu]

I think only place in Australia that does machining is over east? I'd replace it..

[thro]

^^ replacement discs aren't cheap.


if you do find somewhere that can machine them i'd be keen to hear about it.

Obviously if you take meat off the disc its more likely to warp the next time (due to less metal to dissipate the heat), but warped discs are more likely caused by braking real hard, getting them hot and then parking the bike before cooling the pads down....

[cruelcheffy]

^^ replacement discs aren't cheap.


but warped disc's are more likely caused by braking real hard, getting them hot and then parking the bike before cooling the pads down....

That's what I though.....spending extra money is not what I need right now.
I am not one that works the breaks real hard, so I am surprised about that.
I have just read on an US RX site that it has happened to a few people over there.
Sucks!
A club mate of mine had his Z 900 disc machined, maybe he can point me in the right direction.

[druu]

I'd buy a second hand replacement in good condition, either locally or from eBay/overseas. But if you do want to get it machined, contact Planet Disc (Planet Disc Pty Ltd - Motor Cycles--Parts & Accessories--W'salers & Mfrs in Wantirna South, VIC - yellow.com.au).

[reddog]

What bikes share the same discs? I'd be looking to source a s/hand wheel off a wreck or similar. Apatheticend may be able to help you out if it shares discs with a race style bike.

[BigTim]

Motorbike discs are reasonably difficult to machine, compared to car rotors, because there's simply not enough meat there to take any warping out, plus a lot of bike rotors are "floating" (with the contact area not directly fixed to the section bolted to the wheel).
It won't be the cheapest, but your best option is to find another pair of rotors that are in decent nick.

Also, the pads worn more on the right caliper than the left could very well mean your pistons are gummed up, and are sticking. Consider having a look through Rocket's thread here, and have a crack at rebuilding your calipers. It's not overly difficult, and makes a noticeable difference. It also could have cause the warping in the first place, when one caliper was constantly applying more pressure than the other.

[Scaramouche]

Motorbike discs are reasonably difficult to machine, compared to car rotors, because there's simply not enough meat there to take any warping out, plus a lot of bike rotors are "floating" (with the contact area not directly fixed to the section bolted to the wheel).
It won't be the cheapest, but your best option is to find another pair of rotors that are in decent nick.

Also, the pads worn more on the right caliper than the left could very well mean your pistons are gummed up, and are sticking. Consider having a look through Rocket's thread here, and have a crack at rebuilding your calipers. It's not overly difficult, and makes a noticeable difference. It also could have cause the warping in the first place, when one caliper was constantly applying more pressure than the other.

Seemed to have come in to this a bit late.. Sounds to me like the cart is before the horse here guys. You appear to have a seized caliper, which has causd overheating to the disc rotor in question hence 50% greater wear to the pads on that caliper. Resulting in warped disc. SOLUTION is clearly to rebuild BOTH calipers, changed warped disc and fit new pads. How you go about this is dependant solely on costs effectiveness. You never rebuild one caliper only to the front - can be hazardous to handling...........my 2c worth.....TC

[BigTim]

I did say calipers, homeslice

[Scaramouche]

I did say calipers, homeslice

I know Tim, and I apologise to you if you took offence buddy...as I said, came in abit late on this one.................No harm no foul...........

[cruelcheffy]

I did check the calipers today, nothing sticks. Given that the bike is not even two years old, and was checked at the 24k service 3 weeks ago I am a bit at a loss as to why the disc is warped. I don't ride very hard, break even with front and back and generally look after it.
A new rotor is $300, so if a repair is not substantially cheaper, then this is what I have to get.
I spoke with Gav from GD Engineeriing, he will have a look at it next week.

[cruelcheffy]

Little follow up report on my Break Shudder problem.

I took the bike down to G.D Engineering, and Gav was very helpful. Left it with him for a day and he did a great job straightening the disk as much as possible.
He knows his stuff, and I look forward to have him help me getting my old Z 1000 back into shape.
A Kwaka man through and through, as one can see by some of the old beauties in his workshop!

Thanks Mate, I'll be back

[lee]

How exactly did you test all 2/4/8 pistons weren't sticking in your front calipers?