Initial lever travel?

[racefactory]

06 Zx6r... floating rotors with dual radial-mounted, opposed 4 piston, 4 pad calipers. Pads got plenty of lining.

Awesome brakes, solid feel- but I'd personally like the initial lever travel to be much shorter before the brakes bite and take effect.

Maybe it's the floating disc or 4 pad caliper design but I'm much used to a short travel before it bites

How is this adjusted or modified?

Thanks.

[Deano]

Have you got braided lines ?
Have you bled all of the air out of the lines and cylinder ?
Some degree of lever tavel is good for feel IMO. Progressive biting on the discs.

[imdying]

If they're rubber hoses, get some line clamps and clamp off the hoses. What does that do to the lever?

[racefactory]

Please read the post guys.

I have got a solid bite, rigid feel with lots of power. No need to bleed air. 2 fingers will send the rear wheel up in the air with ease.

It's the initial lever travel that doesn't do anything which I would like to lessen.

Let me explain that again- when you pull any brake lever at first, there is no resistance at all. After a short travel it will bite and the brakes will have an effect. This biting point is very solid and powerful on my bike but it's that initial no-resistance bit that seems long to me. As if you have to pull quite a way just to arrive at the 'brakes take effect point'. It doesn't feel like a degradation of parts or anything, just the way it works. Feels like it could be calibrated or set better.

No idea how to do this though. Maybe something to do with master cylinder.

[OutForADuck]

As the post above said...

There are a number of reasons for initial travel, pads, lines, air, master cylinder rate.

The obvious place to start is the lines, it takes a little pressure for pad bite and if you have rubber lines and especially ones that are not fixed down the initial effort will go into bending/expanding them and then start to put pressure onto pads.

The next thing is PADS themselves. Some pads have initial bite some don't, compound on the pads makes a huge difference.

These are the first places to start and then if you still are not happy look at an adjustable ramp rate master cylinder like Brembo make for racing or such like, but given the cost of these you are a lot better off to try the other options first.

BTW, brake pads work by forcing a frictional material against the disc. That frictional material is held together using a resin or bonding compound, this vapours under braking and moderates the friction (i.e. stops it just getting more as the heat builds). Its this that gives you the ability to have "feel"and control over your braking so changing to pads with more intial bite may trade off your "feel"and control at the lever. Get online and listen to those that have tried different brakes and compounds because they all trade one area of performance for another.

[imdying]

Whatever, sort it yourself then. If you knew even the initial steps for diagnosing this, you wouldn't be asking on here in the first place.

[DEATH_INC.]

If the operation of the brakes is otherwise correct, then;
Pop the reserviour fitting out of the master cylinder so you can see the feed/ bleed holes, then shine a torch in there and see how far the lever travels before the small bleed hole is closed by the seal. You can then shim the m/c to reduce this if it seems excessive, but it is CRITICAL that the bleed hole is uncovered when the lever is released. You'll need enough mechanical know-how to be able to disassemble the m/c and rebuild it.

[Deano]

Whatever, sort it yourself then. If you knew even the initial steps for diagnosing this, you wouldn't be asking on here in the first place.

Ditto - you try to be helpful and get told to suck eggs !!

[bogan]

If the operation of the brakes is otherwise correct, then;
Pop the reserviour fitting out of the master cylinder so you can see the feed/ bleed holes, then shine a torch in there and see how far the lever travels before the small bleed hole is closed by the seal. You can then shim the m/c to reduce this if it seems excessive, but it is CRITICAL that the bleed hole is uncovered when the lever is released. You'll need enough mechanical know-how to be able to disassemble the m/c and rebuild it.

what he said, or you could possibly shim the lever return (again leaving the bleed hole uncovered is critical!) somehow so it doesn't go back as far. Either way remember to ensure the brake light switch still operates correctly.

[onearmedbandit]

Thread fail lol.

[Sensei]

I found using cooking oil was excellent replacement for brake fluid as when it heats up you can cook stuff like fish & chips in your brake reservoir ready for when you stop at the end of yor ride or race ...... May help with you lever trouble too !!

[steve_t]

Whatever, sort it yourself then. If you knew even the initial steps for diagnosing this, you wouldn't be asking on here in the first place.

How else is he supposed to get his post count up? :msn-wink:

[racefactory]

If the operation of the brakes is otherwise correct, then;
Pop the reserviour fitting out of the master cylinder so you can see the feed/ bleed holes, then shine a torch in there and see how far the lever travels before the small bleed hole is closed by the seal. You can then shim the m/c to reduce this if it seems excessive, but it is CRITICAL that the bleed hole is uncovered when the lever is released. You'll need enough mechanical know-how to be able to disassemble the m/c and rebuild it.


bogan

what he said, or you could possibly shim the lever return (again leaving the bleed hole uncovered is critical!) somehow so it doesn't go back as far. Either way remember to ensure the brake light switch still operates correctly.



= the only proper answers in this thread. Can't the others read?

Good stuff, does sound a little messy but it's always better once you get stuck in eh.

[Deano]

= the only proper answers in this thread. Can't the others read?



Two words. Get fucked.
Can you read that clearly enough ?

[racefactory]

He only asked how to decrease the free take up travel, not how to improve bite, feel, or braking power of any kind you fuckwit! You only have yourself to blame mate, no need to start this rant.

You need to go to your garage right now and press your front brake, it's not rocket science. just roll your bike forward and press the brake lightly, it will have zero effect for a short section of travel and then only start to provide that brake friction. whether or not your brake is spongy or hard after that point has zero relevance to what this guy is asking. braided lines or not, most bikes have this sort of deadzone. Do some reading comprehension practice you moron.

btw I don't know the answer to this but my bet is it must involve some sort of shimming at the lever end like those chaps mentioned

[Owl]

Awesome brakes, solid feel- but I'd personally like the initial lever travel to be much shorter before the brakes bite and take effect.

How is this adjusted or modified?

I get the same deal with my S3, though I stay on top of it. Try cleaning and freeing up the caliper pistons to get them working evenly. I do mine about every 5000-7000km to improve lever travel. Used to be about 3000km when my calipers contained the original un-coated pistons.

[Deano]

Free travel could be reduced by making sure the brakes are well bled. And seeing as you don't know the answer either, who the hell are you to poke your nose in. Are you his mate ?

In any case, telling people to 'go back and read the post' when they are offering a genuine suggestion is not doing yourselves any favours IMO.

[racefactory]

Keep on digging my friend, keep on doing that digging!

It's not air softening that squeeze, it's free lever travel. The amount of spring back you get when you release the lever. Some bikes have heaps, others have next to nothing. You probably don't have any on your bike or have not ridden enough bikes to realize this difference and I apologize for my tone but you clearly don't know what the issue at hand is here. When you bleed brakes successfully in my experience you make that grabbing of the brakes much more solid but you still have to press the lever some way to even initiate the slightest of that grabbing.

Again, my apologies Deano.

[bogan]

I get the same deal with my S3, though I stay on top of it. Try cleaning and freeing up the caliper pistons to get them working evenly. I do mine about every 5000-7000km to improve lever travel. Used to be about 3000km when my calipers contained the original un-coated pistons.

what coating and where do you get em from?

[Deano]

Keep on digging my friend, keep on doing that digging!

It's not air, it's free lever travel. The amount of spring back you get when you release the lever. Some bikes have heaps, others have next to nothing. You probably don't have any on your bike and I apologize for my tone but you clearly don't know what the issue at hand is here. When you bleed brakes successfully in my experience you make that grabbing of the brakes much more solid but you still have to press the lever to even initiate that.

Again, my apologies Deano.

I'm no mechanic - I simply made a friendly suggestion that was rebuked. Maybe he should have stated how much free travel was there to clarify his query.

Whether it is incorrect or not, it deserves a better response than was given.

Have a nice day.

[racefactory]

I agree but there's no need to start the whole get fucked thing in the first place.

I wish you a nice day too.

Back to topic: I remember the only other thing that has changed this for me in the past was when I got a new master cylinder for an old CBR250RR. I don't mind some initial travel at all as long as the grabbing is solid but each to their own.

[Juzz976]

Try a Master cylinder off another bike with same or close piston diameter,
its not the amount of fluid or pressure thats the problem its the lever geometry.

Taken as a ratio of lever angular movement to piston displacement:
some levers will move the piston quicker initially then progressivly slow down some the other way around (the latter is my preference, however I will not be judging you at this point).

You need to have a look at where the pivot points are to see how relative travel speed is at flection and extension.

Good luck

Edit: also a combination of how far past the feed/air relief hole the piston returns to as DEATH_INC said.
Some bikes have adjusters for this EG FZR250 and others just wear and get worse.
This could be the case for you, mine has a pin on a swivel, therefore no adjustment just replace when worn.

[Owl]

what coating and where do you get em from?

No idea what the coating is and the pistons were from a later model (07) S3.

[imdying]

Meh, I've a massive box of master cylinder shims of all sizes, but fucked if I'm going to give those to anybody without figuring out what the actual problem is first... that's just asking for hurt. Mind you...