cleaning front brake disc bobbins / rivets?

[Bretty]

My front brake has a slight pulse at low speeds. The surface has no high spots (measured with a vernier while rotating the front wheel). As I've read that the disc is semi-floating, I thought I might be able to remedy the problem by cleaning the disc bobbins/rivets to allow the disc to float. At the moment everything is solid and I'm assuming the disc has a wobble.

I've seen videos on youtube of people cleaning the bobbins by putting a nut and bolt through the hole and using a socket to rotate them while giving a good application of brake cleaner. But mine don't have a hole in the middle?!

Has anyone done any cleaning of the rivets? Is there another way to rotate them or is it a spray and toothbrush job?

Wot you reckon?

[darrsi]

Personally from experience, it won't make the slightest bit of difference at all.

[darrsi]

As a starting point I would be looking more towards making sure the pistons are moving okay and not seized up anywhere.

[joebloggs]

As a starting point I would be looking more towards making sure the pistons are moving okay and not seized up anywhere.

+1 on the calipers

No runout on the disc so look at them 1st

[stevierst]

Cleaning the bobbins should make a bit of difference, it has done on a couple of mine in the past when I had pulsing brakes. Cleaning the calipers is always recommended, but sticky pistons are not a cause of pulsing at low speed.

You can tell if they need it if the disk is solid and doesn't move at all, or if there is a grating noise with minimal lateral movement of the disk.

Nut and bolt through the bobbin with loads of brake cleaner when you start turning. Keep going until the bobbin is free, but don't be tempted to use a drill like I've seen in the past.

Patience and cleaner is the key!

[darrsi]

Hotspots on a disc can cause a grabbing effect at low speed, which won't really show up with a vernier.
Normally caused by holding a brake on at traffic lights with a hot disc so it leaves a pad deposit on the disc.
Some are very obvious to the eye but not all of them.

What brake lines do you have on the bike, are they the original type, or new braided?
Old style lines can get tired then have bulges in the line causing juddering sensation.

I was unfortunate enough to have faulty braided lines which cost me a lot of time, money and patience, before discovering what was wrong by default, because the brake lines were the only thing I hadn't changed on the whole front end of my bike.

Was the same feeling as a warped disc, but because they were braided I never suspected them whatsoever and in hindsight i stupidly overlooked them. 

[joebloggs]

Have you tried oiling your pads, that should take care of any pulsing at low speeds, be sure to give a real good tug on the lever next time you want to stop 

[Timbollew]

Please for the love of sweet baby Jesus ignore joebloggs's comment!

[darrsi]

Have you tried oiling your pads, that should take care of any pulsing at low speeds, be sure to give a real good tug on the lever next time you want to stop 

Why would you say that? 

[Val]

My front brake has a slight pulse at low speeds. The surface has no high spots (measured with a vernier while rotating the front wheel). As I've read that the disc is semi-floating, I thought I might be able to remedy the problem by cleaning the disc bobbins/rivets to allow the disc to float. At the moment everything is solid and I'm assuming the disc has a wobble.

I've seen videos on youtube of people cleaning the bobbins by putting a nut and bolt through the hole and using a socket to rotate them while giving a good application of brake cleaner. But mine don't have a hole in the middle?!

Do not beleive everything you see on the internet 

As you have stated your disc is semi-floating and the bobbins does not have a gap and does not need cleaning by design.

The problem is somewhere else like the disc or the lines...

Have you tried oiling your pads, that should take care of any pulsing at low speeds, be sure to give a real good tug on the lever next time you want to stop 

That was supposed to be a joke...but its not funny related to brakes, someone may take it seriously. Just to be clear do not do that 

[Bretty]

Oil the discs, haha! 

Well I have 2 cans of brake cleaner and the plan is:
1. Clean pistons and pads with toothbrush and brake cleaner.
2. Brillopad / wirewool disc with brake cleaner
3. Toothbrush and brake cleaner on rivets.

I don't understand why the brake lines would create a pulse. Mine are all standard.

Everything actually runs freely and the pads do retract and don't drag. But a clean won't hurt. With a fixed caliper you have to have some movement somewhere to allow for the slight warp of a hot disc.

Anyway, it needs sorting because a couple of times I've locked the front wheel under heavy braking when it shouldn't have.

I'll let you know how I get on....

[midden]

Ive started getting the same once the bike has slowed to a near stop. 

[darrsi]

Oil the discs, haha! 

Well I have 2 cans of brake cleaner and the plan is:
1. Clean pistons and pads with toothbrush and brake cleaner.
2. Brillopad / wirewool disc with brake cleaner
3. Toothbrush and brake cleaner on rivets.

I don't understand why the brake lines would create a pulse. Mine are all standard.

Everything actually runs freely and the pads do retract and don't drag. But a clean won't hurt. With a fixed caliper you have to have some movement somewhere to allow for the slight warp of a hot disc.

Anyway, it needs sorting because a couple of times I've locked the front wheel under heavy braking when it shouldn't have.

I'll let you know how I get on....

Brake lines can break down with age and get weak spots, so when you brake the pressure can cause a bulge in the line. It will then give a pulsing/throbbing feeling when braking, which can be mistaken for a warped disc.


You wanna buy yourself a small pot of Red Rubber Grease to put on the exposed parts of your cleaned pistons, it will help keep the crap and rust at bay.
And get the wire wool on the pad pins, and make sure there's no indents on them either, stopping the pads from moving freely sideways.




As for the "oil the discs" comment, yes i realise that's a (bad) joke, but you have to remember these posts stay on here for a long time, or get found in a search, and it only takes a complete newbie to only read that part and believe it then.....well, you can only imagine the rest.
Saw it on another forum years back and some youngster listened to some joker and cleaned all his brakes with WD40 on advice. That didn't end well.

[darrsi]

Ive started getting the same once the bike has slowed to a near stop.

I thought yours was caused more by leaving the disc lock on?     

[joebloggs]

Disclaimer........
If your dumb enough to oil/wd40 your brakes them please don't come crying to me.................

[bigsteve]

this might be worth checking out for bobbins

[Bretty]

this might be worth checking out for bobbins

http://www.youtube.com/watch?v=1qoPqN2GBdw

That's where I got my inspiration! BUT my bobbins don't have holes through them!! They are like rivets!!
Isn't everyone's Fazer like that?

[Val]

this might be worth checking out for bobbins

http://www.youtube.com/watch?v=1qoPqN2GBdw

Delboy has the best garage videos and I watch him a lot. IMO he is wrong on that one.

Floating discs are the only ones that should be cleaned, semi-floating by design does not need cleaning.

Do you think Yamaha would have missed such important brake maintainance procedure if it was required?

The point is rivets has high pressure by design and they are not meant to be rotated, consider yourself lucky there are not holes there 

See this discussion with Delboy here:

http://www.bikerforum.co.uk/topic/30502-cleaning-brake-discs/page__st__20

[darrsi]

this might be worth checking out for bobbins

http://www.youtube.com/watch?v=1qoPqN2GBdw

Delboy has the best garage videos and I watch him a lot. IMO he is wrong on that one.

Floating discs are the only ones that should be cleaned, semi-floating by design does not need cleaning.

Do you think Yamaha would have missed such important brake maintainance procedure if it was required?

The point is rivets has high pressure by design and they are not meant to be rotated, consider yourself lucky there are not holes there 

See this discussion with Delboy here:

http://www.bikerforum.co.uk/topic/30502-cleaning-brake-discs/page__st__20

Gotta agree with you on this one, plus I tried it myself before and it did nothing!

[Bretty]

Well I don't know what qualifications any of these people have (I read that long discussion on the other forum)... 

But anyway the calliper is gonna get a right good cleaning... and the discs - just a non-vigorous toothbrush clean of the rivets and a scrub of the braking surface. 

[darrsi]

Well I don't know what qualifications any of these people have (I read that long discussion on the other forum)... 

But anyway the calliper is gonna get a right good cleaning... and the discs - just a non-vigorous toothbrush clean of the rivets and a scrub of the braking surface. 

Give the pad surface a bit of a going over with emery paper, or whatever weapon of choice you have to hand, to take any glazing off them, then after you've cleaned the caliper up i would suggest deliberately putting the pads back on in the wrong order, meaning put the left pad on the right side and the right on the left.
This will upset the natural grain of the pads against the disc and will need a day or two to bed in again, but in the process will clean the discs for you.
If you do have any hotspots on the disc then "giving them a scrub" won't do sod all as they are literally baked on (been there, done that too).
You'd be better off getting the bike up to speed a few times in succession and doing some hard but controlled front braking.


This is another reason why i'm not a fan of softer compound brake pads. It's each to their own, but i prefer a grabbier response when braking, and with less brake dust to cause these types of problems.


Here's a bad example for instance, with some iffy WD40 advice too.


http://badweatherbikers.com/buell/messages/32777/637340.html?1308075343

[midden]

Sorted mine by changing the pads which were down to the metal.  So silly question time Brett,  have you checked your pads by physically removing them?

[darrsi]

Avoid soft pads up front, go for sintered.


Been using these for years now, and even though i'm not a hard braker, they just don't wear out, and don't wear the discs either.


Highly recommended. 


http://www.ebay.co.uk/itm/Galfer-HH-Sintered-G1370-Front-Brake-Pads-Yamaha-FZS-600-1000-FZ6-FZ8-FZ1-/141532460947?hash=item20f3fdf793:g:pmAAAOSwg3FUq9j2