front brakes "pulsing" under hard breaking

the cats pajamas

I used the following product on my brake disks
http://muc-off.com/clean/56-disc-brake-cleaner-5037835913002.html
that was yesterday,
Today i can feel the brake lever pulse under heavy breaking, any ideas on what I did wrong or how to rectify it?
the brakes where fine before i tried to clean them and i thought i wiped any excess off

the cats pajamas

my front brake disks are very very smooth, i cannot feel the slightest imperfection even with my finger nail.
I don't know if this matters but this seems out of the ordinary to me

alias no.9

If the pedal is pulsing, it's the ABS kicking in most likely

Edit, sorry missed the motorbike forum bit, I've no idea if a motorbike will have ABS

Wonda-Boy

Did you actual dis-assemble the calipers or just spray the "general" area? Sounds like one of the discs are warped hence the pulsing. Are you feeling the pulse through the handle bars or the brake levers?

the cats pajamas

it's in the brake lever, not the handle bar.
I just sprayed in the general area.

the cats pajamas

it's in the brake lever, not the handle bar.
I just sprayed in the general area.

Wonda-Boy

Is it pulsing at low speed or do you have to be going fast for you to notice it?

the cats pajamas

have to be doing over 50 mph and have to brake hardish, not mental hard but not soft.
If both conditions aren't met then they seem normal

jameshayes

If i was a guesser, i'd guess warped disk... just a tiny warp..

the cats pajamas

could I warp a disk with normal riding?
I thought it took a serious track thrashing to do that.
is it a replace job if so?

Wonda-Boy

From what you say its sounds like the disc is ever so slightly warped, hence you have to be going fast for it to become noticeable. And you only feelling it through the lever from the warp of the disc the feedback is from the caliper getting pulled when you brake hard at speed from the warp. I seen the bike Andy, them discs could be on that from new. How are the brake pads on the bike.....?

Lad off here had the exact same problem with his old bike and the disc was indeed off by a few mm as tested by M50 honda.

the cats pajamas

the break pads were replaced with the tires after i bought it, so 3000 miles on them probably not even that much.

fleet

ABS?

the cats pajamas

it's a 1999 r6 so no abs here

blu3r0ri0n

Are you sure you thoroughly cleaned the disks after application, if it was warped disk you would have noticed it sooner or that its one hell of a coincidence to happen right after you cleaned them.

It might be that the residue from the break pads have built up over time evenly across the surface and when you cleaned the disks you didn't clean off some of the residue, maybe left them on the side of the disk that is against the wheel as they are hard to reach sometimes? I hope that's it and not a warped disk!

FYI when you are using the front break a lot your break disks will retain the heat for a period of time! So when you come to a full stop at the lights and hold the front break in you are pressing the residue from the break pads against the disks and sort of fusing (probably not the right word to use!) them to the disk , usually its not a problem but if the quality of the break pads aren't great then its more residue to stick to the disks and will need cleaning.

EDIT: It would be worth while to check the pistons in the calliper too while you are at it

Roadcraft

Floating discs on your R6?

You need to clean your disc bobbins, the discs need to be able to move on them.

You could have washed crap into them, get some brake cleaner and spray them they should be able to turn freely.

blu3r0ri0n

Roadcraft wrote: »

Floating discs on your R6?

You need to clean your disc bobbins, the discs need to be able to move on them.

You could have washed crap into them, get some brake cleaner and spray them they should be able to turn freely.

Spot on, I forgot about the bobbins and this is probably the cause!

Good explanation and shows how to clean them here...

Good luck.

the cats pajamas

took the calipers off checked the pistons are all moving, gave them a clean and did all i could.
I have seen that video before where should i go looking for the washer nut yolk ?
thanks for all the help guys

blu3r0ri0n

the cats pajamas wrote: »

took the calipers off checked the pistons are all moving, gave them a clean and did all i could.
I have seen that video before where should i go looking for the washer nut yolk ?
thanks for all the help guys

You might not need them, try Roadcrafts suggestion first and clean it out by hand. If they were free before you cleaned the disks it shouldn't be difficult to loosen them up again.

the cats pajamas

I tried but i cannot move them with hands and cleaner alone.

Keith186

Would bleeding the brake oil be worth a shot?

Trapped air can make them spongy. May need new oil if it's old.

the cats pajamas

Probably would make them spongy but this is a pulsing or even a vibrating in the brake lever.
I think I'll try braking all the bobbins free before anything that drastic.
although the fluid probably could use a change though.

Mr Sheen!

As said by road craft the bobbins are your next thing too check. After that I would say your looking at a warped disc, and to be honest that would be my guess from what you have said.

Did you just ride the bike before cleaning the discs?? Could they have been still hot when you started cleaning them??

Also did you leave the bike sit there after cleaning or did you take a short ride??

the cats pajamas

They could have been hot but i left them dry before i went for a spin.
in fact a may recall a hiss when the water hit it, but I am not 100% about that

blu3r0ri0n

the cats pajamas wrote: »

I tried but i cannot move them with hands and cleaner alone.

Need to try the method in the video next, once you get them all free then you can move on to checking if the disks are warped or not.

the cats pajamas

where should i go looking for a washer bolt?
woodies ? b&q?

Stainless_Steel

the cats pajamas wrote: »

where should i go looking for a washer bolt?
woodies ? b&q?

It doesn't have to be a washer-bolt. Any M5+ bolt with appropriate washer front and back will do.

Max Headroom

Just a thought..are the discs standard or those cheap wavy chinese ones..??

the cats pajamas

On the bike when I bought it they look like the standard ones

raven41

Another low tech (but cheap) idea would be to go over both sides of the brake disc with some sort of light abrasive material. If there is any residue clinging to the surface of the disc this could remove it. If part of the disc is contaminated every time this bit goes throughout the caliper it will cause it to " slip " giving the impression of a warped disc.
I use a kitchen scourer or some very fine grain sand paper
Worth a try....

raven41

Another low tech (but cheap) idea would be to go over both sides of the brake disc with some sort of light abrasive material. If there is any residue clinging to the surface of the disc this could remove it. If part of the disc is contaminated every time this bit goes throughout the caliper it will cause it to " slip " giving the impression of a warped disc.
I use a kitchen scourer or some very fine grain sand paper
Worth a try....