The dreaded pulsing brakes

[slofox]

Interesting take on "warped" brake discs here. http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths#


Dude seems to be saying that the disc doesn't warp but the pad material adheres to the rotor unevenly and so the thickness of the rotor then varies.

Make sense anyone?

Coz if this is indeed the case, removal of that pad material ought to cure the pulsing brake oughtn't it? How hard is it to remove the adhering material I wonder...

(Don't want to have to shell out for new rotors just now since my income will drop to zero very soon...).

[sinfull]

Dude seems to be saying that the disc doesn't warp but the pad material adheres to the rotor unevenly and so the thickness of the rotor then varies.

.
Think you're reading it wrong, what i read just from what you quoted is that the pads are grinding the rotors unevenly, not leaving material on the rotor ?
You could perhaps get them turned down to just above min requirements for revinning check !

But have to say, i've never seen anyone mic. my rotors during a warrant check, just during the revin process !

Edit : no just read the article and he does appear to be saying that the pad material adheres to the rotor lol tell ya what there aint no material stuck on my front disc, it's shiny as but she has a slight surge going on, i say it's bent lol

[iYRe]

brakleen worked for me..

http://crcindustries.com/auto/crc-brakleen-brake-parts-cleaner

[FJRider]

Most capable engineering workshops should be able to re-face the rotors. Not as simple a job as you may first think. Discuss with the workshops in your area as to expected cost .... and as to charge out time rates ... for the operation.

The end result thickness, may not warrant any more removal ... and replacement second hand rotors may be a better option.

[carburator]

Most capable engineering workshops should be able to re-face the rotors. Not as simple a job as you may first think. Discuss with the workshops in your area as to expected cost .... and as to charge out time rates ... for the operation.

The end result thickness, may not warrant any more removal ... and replacement second hand rotors may be a better option.

buy new rotor's I would'nt bother trying to skim grind the rotors first you have to derivet them from the bells
( ok you can turn them in to full floaters but thats another thread )
some of the older style ( yea the fark thats chunky heavy bugger ) you can skim

pull the pads and look for uneven wear, check that all the pistons are working
( had a stuck piston in a warbird once gave the same effect )

DTI's are cheap as chips these days or even just con your local engineering shop
into doing a runout cheak on the discs on the bike for a dozen..

[caspernz]

Brake shudder not caused by rotors warping? Ah ok, so why does that exact problem go away when I get rotors skimmed on the car?

Can't say I've ever had a problem with warped rotors on a roadbike. Yeah ok, maybe I ride like a nana...could that be why...

[Motu]

Pad material transference has been a controversial theory in the trade for a few years, now it looks like it's hit mainstream. When you see the outline of a pad on a cast iron rotor, it's not a rust mark, but caused by a hot stop with the foot kept on the pedal, but mostly it's not visible. Of course the cure is a skim of the rotor....so the controversy of warped or pad transference will continue for some time yet.

[bogan]

DTI's are cheap as chips these days or even just con your local engineering shop
into doing a runout cheak on the discs on the bike for a dozen..

Are they what! I just got a mitogo (no typo) for 35bucks to my door, and it came with a magnetic stand.

I've heard skimming is often only a very temporary fix, as new metal is exposed to different heat/forces so it just warps again. The PO of my bros said he had the disc skimmed, but there is a bit of runout come back which knocks the pads back ever so slightly, more noticeable since I put HH pads in cos they have better feel. I wonder if getting it stress relieved first is a good plan?

[Ocean1]

I've heard skimming is often only a very temporary fix, as new metal is exposed to different heat/forces so it just warps again.

It's a sometime Buell problem, that big inside out disk runs much higher surface speeds than usual. The XB12X developed a pulse, 2 per rev.

Thought I'd sort that fucker out, so I de-glazed the surface with a sandblaster, (wallnut). Problem reappeared within 5 min. De-glazed disk again and changed pads. Lasted 10 min. Changed the disk mount bolts. No change. Machined disk, during which I noticed a couple of hard spots. Seemed to clean up well within spec' so put it back on and tried it. Problem reappeared in 20 min.

OK, there's a barely measurable variation in thickness, probably from deflection of the disk in the lathe over those hard spots. Right. Made a bit of tooling, mounted disk on a purpose-built mandrel and cup ground the sucker. Surface perfect, thickness minimum but perfectly even. Refit the disk with yet another set of pads. Built the heat cycles gradually, thought I'd cracked it this time, for almost an hour.

I gave up. Pete organised a new disk under warantee. Which he didn't have to. Problem solved. Reckon it's slight flaws in the disk material, either from new or from some heat related local abuse. Either way once it's there is seems you're stuck with it.

[ajturbo]

same problem with the CR... new disc.. problem solved.... for a while, next time, i just sanded it by hand ... hasn't been a problem for over 10,000ks now...

[carburator]

Are they what! I just got a mitogo (no typo) for 35bucks to my door, and it came with a magnetic stand.

I've heard skimming is often only a very temporary fix, as new metal is exposed to different heat/forces so it just warps again. The PO of my bros said he had the disc skimmed, but there is a bit of runout come back which knocks the pads back ever so slightly, more noticeable since I put HH pads in cos they have better feel. I wonder if getting it stress relieved first is a good plan?

Disc's are a comsumable item, along with pads ( ok a set for the front of the R1 feels like someone has ripped me a new one )

we set the race cars up to less than 0.1mm runout, having a bit of runout does knock the pads back off the rotor
and in rallying this is a good thing.

since bike disc's ( modern ones ) are that thin once they warp thats it forget it your chasing your tail.
however some discs do develope hard spots ( more from heat soakage ) and can give the same feel and effect
of haing a warped disc is use.

[yachtie10]

Good thread

ill add my 2 cents in case it helps or a expert can explain it better

Bandnew bandit 1250 ABS
brakes worked well until 18000k
changed pads and soom after developed a pulse
took back to dealer who fitted them they took pads out and did some work on them problem a bit better but soon returned
wasnt really bad so decided to live with it for a while as money was tight.

when i next replaced the pads issue went away and hasnt returned

[Sharry]

Thanks slofox, I was going to start this thread today.

I bought my 1998 Hornet 600 at 27,000kms with its original brake disks.

At 72,000kms I had had enough of the juddering at low speed braking with the front brake and put two new pretty disks on the front. I think it was the left disk that was warped.. Problem was solved...

Untill I again had enough of the worsening juddering on the front at low speed braking and had all three disks and brake pads replaced at 89,500kms. It was the left disk and problem was solved again.

This lasted untill a couple of weeks ago so I took her to Cycletreads again today, at 74,000kms, who discovered the left rotor was the problem again replaced it with the spare right hand front rotor and the used brake pads. She was braking smoothly all the way home.

The brake pads that were removed at 89,000 have 5cm and 4cm left on each pair, indicating even wear.
As an dindication of my riding style I replaced my rear tyre one week ago at 93,500kms, it was put on at 87,000kms.
Cycletreads are non the wiser as to the cause , the only thing I do is I dont want to replace the front disk every 4,000 kms.

I will buy some CRC Brakleen and see if it fixes it.
If any one has any other bright ides they would be welcomed .

[spanner spinner]

Thanks slofox, I was going to start this thread today.

I bought my 1998 Hornet 600 at 27,000kms with its original brake disks.

At 72,000kms I had had enough of the juddering at low speed braking with the front brake and put two new pretty disks on the front. I think it was the left disk that was warped.. Problem was solved...

Untill I again had enough of the worsening juddering on the front at low speed braking and had all three disks and brake pads replaced at 89,500kms. It was the left disk and problem was solved again.

This lasted untill a couple of weeks ago so I took her to Cycletreads again today, at 74,000kms, who discovered the left rotor was the problem again replaced it with the spare right hand front rotor and the used brake pads. She was braking smoothly all the way home.

The brake pads that were removed at 89,000 have 5cm and 4cm left on each pair, indicating even wear.
As an dindication of my riding style I replaced my rear tyre one week ago at 93,500kms, it was put on at 87,000kms.
Cycletreads are non the wiser as to the cause , the only thing I do is I dont want to replace the front disk every 4,000 kms.

I will buy some CRC Brakleen and see if it fixes it.
If any one has any other bright ides they would be welcomed .

Sounds like the left hand caliper is dragging or pulling the disk to one side or overheating it, pull your left hand brake caliper off and check for stuck pistions etc. If my memory is working right these bikes use a sliding 2 pistion calpier, the rubbers that the brakes slide on wear out and cause the caliper to twist in use. Buy some new ones (there cheep) pull the caliper slider to pieces clean pins and fit new rubbers lube with a rubber grease hope this is of some help.

[actungbaby]

Hi thanks for the link

But the cause might be but the efect is easy to see was on my bike anyways

Mind you whoulditn it be even heating and cooling thats what bikes have so called floating discs

I ended up replacing both brake rotors and calibers but brakes still lack bite and left side doesint grip as well

seems be getting better but will try removing the left side pistons and using brake grease on the seals and

bit clean around them



Interesting take on "warped" brake discs here. http://www.stoptech.com/technical-support/technical-white-papers/-warped-brake-disc-and-other-myths#


Dude seems to be saying that the disc doesn't warp but the pad material adheres to the rotor unevenly and so the thickness of the rotor then varies.

Make sense anyone?

Coz if this is indeed the case, removal of that pad material ought to cure the pulsing brake oughtn't it? How hard is it to remove the adhering material I wonder...

(Don't want to have to shell out for new rotors just now since my income will drop to zero very soon...).

[actungbaby]

Sounds like the left hand caliper is dragging or pulling the disk to one side or overheating it, pull your left hand brake caliper off and check for stuck pistions etc. If my memory is working right these bikes use a sliding 2 pistion calpier, the rubbers that the brakes slide on wear out and cause the caliper to twist in use. Buy some new ones (there cheep) pull the caliper slider to pieces clean pins and fit new rubbers lube with a rubber grease hope this is of some help.

Thanks for that info didnt relize they twist like that i sperated them by taking them out wrong so will order new set

rubber grease is good too

when went for warrent guy said brakes felt bit soft but they probley get better with wear athough they second hand pads

I got with seconad hand calibers might be disc to pad bead in thing , I adjusted the brake lever as vfr has this and did few hard stops

and rotors where bloody hot nearly burnt me hand hehe left was still slighty cooler but say its that slighty sticking pistons

I went for ride on kawaski ex 250 j my dads selling and brakes on that machine had way more bite

[Sharry]

Sounds like the left hand caliper is dragging or pulling the disk to one side or overheating it, pull your left hand brake caliper off and check for stuck pistions etc. If my memory is working right these bikes use a sliding 2 pistion calpier, the rubbers that the brakes slide on wear out and cause the caliper to twist in use. Buy some new ones (there cheep) pull the caliper slider to pieces clean pins and fit new rubbers lube with a rubber grease hope this is of some help.

Thank you for that, I will enlist the help of someone who is more fmiliar than myself at taking brakes apart and reinstalling.

[scumdog]

Both the front discs on my T-Sort ended up badly warped, buggered if I know how, nearly blurred my vision under light braking, anyway I replaced them with new floating discs and new pads.

Now sweet-as.

It's your BRAKES people, don't shag about with them - or it will very likely bite you in the arse. (And I don't mean a 'fail' at WOF time)