Front brakes - some questions

[Plymothian]

Sorry for another brake thread, but I have a couple of questions.

I've just done the winter maintenance on my 2004 FZ6. OEM pads still had 3/4 left so i put them back in. I cleaned pistons, and scraped some crud from the side of the pads (didn't touch the surface though). My holder plates are facing in the right direction, and I used Copper grease on the bolt shanks, and on the backs of the pads and they have stopped squeaking (yay).

However, they are still binding very slightly - I can get just over 1 spin of the wheel. They also seem quite spongy (i.e not as sharp as other bikes i have ridden).

My questions are:

Would my first step be to replace the piston seals?
Will braided lines increase braking performance?
Are braided lines generic, or do I need FZ6-specific ones?
Is there any value in upgrading front calipers to 4 pots (not keen on this idea due to expense)?

Cheers guys

 

[trepetti]

I love good brakes, but I respect them as well. So when I work on a problem, I want to make sure I didn't just mask the symptom

So for your problem, stay focused on the probable causes:

1- improper assembly. Make sure the pads are seated correctly and are not binding in the caliper bracket.

2- properly installed wheel and wheel bearings. Remove the calipers and spin the wheel to see how different it is without the brakes.

3- caliper seals.

Do the easy stuff first but most importantly find the root cause before fixing and replacing parts.

To your other questions, stainless lines are great and while not fz6 specific they need to be the correct length. I used the Galfer but any good quality lines will be fine and will offer an fz6 kit.

Lastly, the 4 pot calipers require a fork change, so while they are better, they are a bigger project than just brakes.

Good luck

 

[Plymothian]

Good advice there, thanks. Yes they are all seated correctly, there was no problem getting them in and out, and everything was clean and not corroded.

The wheel bearings seem fine from an untrained eye, wheel spins nice and free with the brakes off. I'm guessing that the pistons are the weak point so far - I could push them back with my fingers but they aren't as free as I thought they'd be. When I pumped the brake, one of them came out easily but the other didn't. The wear on all 4 pads was exactly even so I don't think any piston is doing more work than the other, but the piston retraction (or lack of) makes me think this is what's causing the slight binding.

So another two questions then:

Can anything be done to the pistons apart from cleaning with soapy water? I didn't touch them with grease as I thought it could contaminate the brake fluid? Or can you grease the outer (exposed) section of the pistons?

Can I safely remove the pistons without bleeding the fluid, or should I bleed forst to prevent it coming out?

 

[TownsendsFJR1300]

Yamaha recommends seal replacement every TWO YEARS. I've found in real life you can get 4-5 years out of them. Did my FZ and my old FJR (same calipers). Tried cleaning(AFTER full disassembly), helped some but within a year was dragging again..

If you've cleaned them best you can without disassembly, its time for new seals (and cleaning).

The seals simply harden up, aren't as soft and don't retract the pistons as new. New seals make a world of difference..

I would NOT put brake grease on the visable part of the pistons (trying to help the seals). It'll just attract grit and won't fix old, hardened seals..

Your bike is a bit easier to do with 2 piston pots vs 4 pistons.. Its been about 3 years since I did mine and I still get 4-4.5 "free spins".

Re the braided lines, yes you need ones specific to the bike. You can get the same set up as stock(loop over the front fender) OR TWO separate lines running direct from the calipers to the master cylinder. The last is a little easier to bleed IME..

 

[Pplater]

I'm waiting for the caliper's O ring seals and piston from the local dealer. 10 years and they haven't been changed. Way overdue but i haven't rode much the past 5 years.

As for the question on whether steel braided brake hose improves stopping power, i asked Mr Venhill himself of Venhill Brake Hose some years back at a local bikers' meet. He told me only the tyres and brake pads affect stopping power. Steel braided hoses improves the ease u apply max braking force, but 2 fingers on OEM hoses gets me max braking force too, so, i'm replacing stock hoses with the overdue O ring seals and pistons at my regular shop next week

 

[Plymothian]

Thanks everyone - good job I asked about greasing the pistons.

In that case I will order some new seals and see how that goes, I'd guess they haven't been done for a while anyway. If that doesn't improve things (with fresh brake fluid as well) then at least i know the system is well maintained and safe. I will then have to decide whether I want to fork out for braided lines. Possibly changing bike next year so don't want to spend too much on aftermarket stuff!

 

[FinalImpact]

As i read that, did you actually bleed the brakes? If not, it accounts for:
- spongy lever
- poor rotation count

Trapped air makes a soft lever. It also does not help in the hydraulic sense to retract the pistons once the lever is released. In addition, once the temperature comes up, air expands creating more pressure thus increasing the drag.

Take a look at post 7 here for a couple of tips to firm up that lever... BRAKE BLEEDING, CALIPER AND PAD INSPECTION

 

[TownsendsFJR1300]

As for the question on whether steel braided brake hose improves stopping power, i asked Mr Venhill himself of Venhill Brake Hose some years back at a local bikers' meet. He told me only the tyres and brake pads affect stopping power. Steel braided hoses improves the ease u apply max braking force, but 2 fingers on OEM hoses gets me max braking force too, so, i'm replacing stock hoses with the overdue O ring seals and pistons at my regular shop next week

Just to clarify, with the OEM rubber hoses vs SS braided, the OEM's are going to expand(especially under hard braking) and the braided won't. The performance, IME, is considerably better with MUCH more feel to the lever and somewhat less travel (again, the rubber brake lines expand, waste effort, etc).

Re not using the bike for a long period of time. That really won't make a difference. Rubber seals, with time, (like tires), tends to not flex, brakes drag, etc... My FJR didn't have 7,000 miles on them when they needed replacement...

You'll see a significant difference replacing those 10 year old seals (drag wise, not likely stopping power-UNLESS they were leaking-NOT likely)...Taht is with everything else being equal, no air in system, etc..

 

[FIZZER6]

My brake caliper seals are original with 25,000 miles on them (2006 model) and I just cleaned them for the year and I can spin my front wheel with brakes installed 4-5 revolutions and only normal contact drag with the pads. It's not really that difficult to rebuild the calipers at any time so I'm just waiting until I suspect a problem. I tend to put my hand on the calipers every so often after a ride and feel if one caliper is warmer than the other which would indicate dragging pads.

Change your brake fluid ever season.

 

[FinalImpact]

...... as I thought it could contaminate the brake fluid? Or can you grease the outer (exposed) section of the pistons?

Can I safely remove the pistons without bleeding the fluid, or should I bleed first to prevent it coming out?

Although SS lines are nice and they don't balloon like rubber lines, you still have to bleed them properly to obtain proper operation.

FWIW: The OEM brake fluid is glycol ether base and it absorbs moisture. It's suggested to be flushed and bled annually. Many will use a suction device (MightyVac etc) and thats OK for evacuating empty lines.
- For best results, pressure bled all systems to remove trapped air. Pressure will condense trapped air molecules into larger bubbles that can exit via the bleeder. While vacuum bleeding can quickly fill an empty line set, it can also take small bubbles and spread them throughout the system leaving the operation spongy which defeats the purpose.
- That said, once the bulk of the lines are filled and the system provides clamping action to the rotor, proceed to pressure bleeding as suggested in the link above.

EDIT: Also confirm the floating pins allow the caliper to move. If its not floating properly, that can also lead to spongy feeling.
X - Never use petroleum products on ANY brake rubber component. It damages it and it must be replaced.

 

[TownsendsFJR1300]

My brake caliper seals are original with 25,000 miles on them (2006 model) and I just cleaned them for the year and I can spin my front wheel with brakes installed 4-5 revolutions and only normal contact drag with the pads. It's not really that difficult to rebuild the calipers at any time so I'm just waiting until I suspect a problem. I tend to put my hand on the calipers every so often after a ride and feel if one caliper is warmer than the other which would indicate dragging pads.

Change your brake fluid ever season.

Just a side note to add.

Being you have the S1, your bike obviously only has 2 pistons per pot (and floats to center itself). Although the S2 with 4 pistons will give better performance there's also TWICE as many pistons to "goo up/drag", etc...

And lastly, CAREFULLY touching the rotor or using a lazer temp gun (right after a ride) will be MUCH more an indicator (vs calipers) of excessive heat/dragging/air in system, etc.. :thumbup:

 

[Plymothian]

Thanks for the replies - I need to bleed the system soon so while I'm at it I will probably fit new seals and SS lines. It's interesting to hear people's methods of brake bleeding, as there seem to be lots of ways to do it. MCN released a video of how to do this, but it attracted lots of criticism because the guy sucked out the old fluid from the top reservoir with a turkey baster until it was empty (thus introducing air into the system first).

Another British chap (search "Delboys garage - front brake rebuild" on youtube) simply attached hose to the bleeder, squeezed the lever to build up pressure, released the banjo and caught all the old fluid in a bottle, then closed off the banjo. Repeat as necessary and topped up the Res. with new fluid before it go low enough to take in air. Seems a lot easier to me, but I'm sure other people would prefer a different method.

 

[FinalImpact]

FWIW: on a full system you can bleed both ends in 20 minutes if you remove the old fluid first. If you continuously add new fluid, it will take much longer as you're simply making more contaminated fluid to pump out. I prefer syringe as it offers very good control. On a cage with larger volumes, I use a turkey baster.

It DOES NOT introduce air into the system from emptying the MC unless you actuate the lever. IF YOU pull/push the lever with it empty, YES, air will be introduced into the lines. DON'T PUMP THE LEVER WHEN EMPTY!


You can also use the syringe as a catch can.


For the cost of a new can of fluid you can have it fixed and install the lines at will. A proper caliper refresh will take a bit longer.

 

[nitroheadz28]

By any chance, does anyone know the PN for the caliper seals and if they're the same from S1 to S2?

 

[petergreko]

Front Seals:

2005: 4HC-25803-50-00

2007: 3MA-25803-10-00

Rear Seals:

2005: 5SL-25803-00-00

2007: 5SL-25803-00-00

As you can see rears are the same, front are different.

 

[nitroheadz28]

Much appreciated :thumbup: