Can't get pressure on front brakes

[Steinrawr]

Hey fellow riders, I have a problem I can't figure out.

My front brakes wont pressurize. I've bled a lot of brakes during my time, and have never had problems with this before.

This is what I did:
- removed both calipers (they were working perfectly before)
- dismantled everyting, keeping track of where it goes
- cleaned them thoroughly, removed any dirt
- painted them gold
- refitted everything
- put them on the bike with new pads, and connected the hoses

I've run at least 1,5 litres of brake fluid through them, and spent hours getting them working, with no luck. When painting I got a little paint around the hole for the brake hose bolts, i carefully scraped it off with a knife. All copper-rings are new.

There's absolutely no pressure at all. Whatever I do, I can't get any resistance in the lever. nothing at all. When I pump hard and quickly for a long time it just spews out fluid from the "container".

All fluid coming out from the calipers looks good, and has no traces of air in them.

 

[trepetti]

Odd. I don't think this is it, but let's start getting ides on the table. I will make an assumption that other than out the bleeder, there is no other place all this fluid is going.

The only time I had a situation where bleeding was taking too long sand using too much fluid, was the time I had the bleeder open a little too much. Each time I released the brake lever at the end of a bleed, it was sucking air in around the threads of the bleeder.

Another possibility.... when you said you 'dismantled everything', do you mean you removed the pistons? If you did, make sure you reinserted them with the hollow side out, toward the brake pad.

Good luck and keep us informed.

 

[Steinrawr]

Thanks for your reply.

Yep, the pistons are the correct way: With the hollow part out.

I don't think the bleeders are at fault as I open and close them every time I pull the lever.

This is what I do to bleed:
1: pull the lever all the way in, 5 times and hold it in
2: open the bleeder valve
3: close the bleeder valve
4: release the lever

I've repeated theese steps so many times I can't even count: at least two hours of non-stop following above instructions.

I'll take the brake calipers of and inspect them again, but there are no apparent leaks I can find..

How smooth must the mating surfaces of the brake line copper-rings be? I have tiny scratches on mine. perhaps that's enough to allow air to flow back in?

 

[FinalImpact]

Your process should work.
Options depending on resources....
A syringe and pliable tubing to the right side, open the bleeder and suck it through. Did you mess with the upper lever at all? Because you moved fluid I'll say the port at the reservoir is open and the lever is seating as it should. You just have a huge bubble in the line....

Get a syringe and suck the fluid and air out. Seal the bleeder and continue.... Also read the sticky at the top of this thread...

 

[TownsendsFJR1300]

I would UN-BOLT the RIGHT caliper and bring it to the other side (all STILL hooked up). Get the caliper slightly higher or even with the LEFT ONE AND THEN BLEED.

I suspect you probably have a bubble in the "over the fender loop" which isn't moving. Making it easier to push that bubble out should work.

Start bleeding with the one FARTHEST from the master Cylinder.

AND PUT A SPACER in the caliper so you don't spit out the pistons...

If you can borrow a Mity Vac or similar brake bleeder, it would be considerably faster and more effective.
I use the MV for initial bleeding, then follow up with "standard", by hand bleeding..

 

[Steinrawr]

I''ll definitely use a Mity Vac next time.

I figured it out. took everything apart again, and cleaned all surfaces to a perfect smoot surface, and removed a blob of hard paint from the underside of a bolt. The blob might be the reason I couldn't get pressure.

A little awkward, but now it feels more right. Would love to have it even more harder as the innermost level on my lever does not gain full braking power.

Thanks for the help

 

[TownsendsFJR1300]

You should have full lock at half the travel of the lever.

 

[Ohendo]

Pretty simple but overlooked thought...make sure the calipers are on the correct sides of the bike, bleeders at the high point. Probably not your case, but check anyway.
They can be installed backwards, and it's been done by members here.

 

[Ben sIII]

I found this bike a bit of a pain to bleed, not sure f the aftermarket SS hoses are a larger diameter or what but with the near vertical drop air wouldn't always come out.

In the end last time i left the bike on its side stand with the bars locked to the left. then i used a tie down strap to hold the brake lever against the bar. i just left it over night, you could vibrate the lines to help make the air move up or just run the engine to vibrate it to help as well, but for me this got all the air to the master cylinder and then just topped it up. Note, i also rotated the MC on the bars to get a better angle

 

[TownsendsFJR1300]

+1 ^^^. This does, indeed work

Do this and you WILL see improvement. Overnight, several days should do it.

 

[FinalImpact]

From the Sticky - top of Tech Section..... Read the part about tapping the caliper.....

***********************************
BRAKE BLEEDING, CALIPER AND PAD INSPECTION
***********************************

First off; bleed your brakes annually! Why? The OEM DOT 4 fluid is an ether glycol product which absorbs moisture at nearly twice the rate as DOT3 fluid. These fluids are hygroscopic and absorb moisture which breaks down the hardware as it converts into acids. In addition, moisture in the system reduces the boiling point (may boil over) and can induce brake drag as the pistons do not retract as effectively when there's moisture or air in the system. Granted, new synthetic fluids withstand this better than old ether - glycol based fluids, it just makes good sense to inspect the entire system and bleed the brakes annually.


The process I use to bleed brakes:
Tip number one - buy a syringe and some soft tubing. Preferred is silicone as it can stretch to any size fitting you might encounter and it very pliable. When it comes time to do a brake flush, simply suck out the old fluid, clean out the reservoir and dump in the new DOT 4 fluid. Note: A turkey baster will work to remove old fluid too. Our goal here is to NOT MIX old and new as its more fluid to pump out.

• NOTE: Always use Fluid from a NEW UNOPENED CONTAINER!!!
  The reason being, once the seal on the container is broken, the fluid begins absorbing moisture. Also, If it possible, perform brake repairs/bleeding on low humidity days!
  PROCESS:
• Crack the bleeders to insure they can be loosened and then snug them down FIRM. Fit a long section of hose to the bleeder and into drain pan.
• Clean MC lid, remove it, remove old fluid (clean inside and seal if dirty). DO NOT PUMP lever when fluid is removed....
• Fill MC w/FRESH FLUID, install cap/lid.
• Pump lever/pedal and hold lever down with pressure.
• Crack the bleeder and continue applying pressure to lever. When the lever bottoms, seal the bleeder promptly.
• Repeat above steps until clean fluid is coming out. WATCH THE FLUID LEVEL! Don't allow the level to get low or it will force air into the lines!
• Do both sides if applicable.
• On the final bleed (both sides), seal the bleeder before the lever reaches bottom. This prevents air from entering the system.
• Fill MC to correct level, install lid and clean everything spotless!
• Repeat once a year using NEW DOT 4 fluid!

NEW LINE INSTALL:
If you've installed new lines and have allot of air in the system, use the syringe and open a bleeder. Connect the syringe and pull back on the plunger to pull fluid through from the reservoir.
- BEGIN AT BULLET SECTION above to obtain a firm lever!

Use a syringe to remove old fluid! It's way better than pumping it through!

If you have a long hose, run it straight into a pan or bottle. Here I was in pinch and just let it fill up the syringe.

• Do not get brake fluid on anything as it eats paint and will/can dull powder coated items too.
• ** DO NOT LET THE MC reservoir go empty and suck air or your brakes will be all mushy and you'll have to start the bleeding process over!! **

***********************************

Additional tips:
IMO Vacuum bleeding never gives a solid feel. Pressure bleeding forces the trapped air under pressure to condense into larger bubbles. As the bubbles increase in size, they often move to the top where the bleeder is and can be removed.
To assist the trapped air bubbles in making their way out of the brake system, use a dead blow hammer or a firm block of wood and tap on the caliper striking towards the ground. DO NOT TAP INLINE WITH THE CALIPERS PISTONS ESPECIALLY on FLOATING CALIPERS! If you choose to tap that way, do so gently you can damaged the disc and induce air into the system. This small shock (hammer tap) can remove trapped air bubbles. The momentary shock helps them condense and make their way out of the caliper. Don't leave marks or damage anything. Your tapping too hard if this occurs!

Note: The rear of both S1 and S2 FZ6's are floating calipers. The front of the S2 models are fixed 4 piston calipers. S1 front calipers are floating calipers.

***********************************
Brake Pad Replacement:
As brake pads wear, the pad backing and calipers piston move towards the rotor. With the piston out of the caliper it attracts and retains brake dust.
BEFORE SHOVING THE PISTON BACK INTO THE CALIPER and TRAPPING the ABRASIVE BRAKE DUST IN THE SEAL, CLEAN THE PISTON(S)!!!
The dust seal can only stop so much from getting past it! To extend its life and reduce wear use an old paint brush and rag & brake cleaner to clean the pistons. To get behind the piston on the S2 front caliper, use the brake lever to extend the piston. Use a shoe lace to scrub the back of the piston! When they are clean and free of debris, push them in and move on to the next one. Mine all push with my thumb. No tools were needed to force them inward. You do need to STOP fluid movement tho (Lock the Pistons).


Locking the Pistons out:
First, pull the lever a bit and get a couple pistons out. Then tie the lever down so it seals the bleed port. Now when you push in a piston, one or more will pop out because the fluid can not return to the MC!


Wipe the brake dust off. A horse hair paint brush, cotton towel, and shoe string work great for this:

No you don't have to use your feet! lol :
Hold the Shoe String against the piston on one side (while holding the caliper in same hand) and pull on the string with the other hand. WALLA! That narrow crack covering the piston is now clean. If you must, saturate the string with brake cleaner and give it tug! It works great!

When done cleaning:
- Crack the bleeder and push all four pistons in.
- Seal the bleeder and release the brake lever.
- Install pads and insert pins. Pump lever to build pressure and hold the pads in place.

Remove the pin and drop in in the anti-rattle clip. Insert the pin & keepers and its on to brake bleeding.

For Rear and Front S1 calipers, the sliding caliper pins should be cleaned and inspected for wear. The slides need greased before new pads are installed.​

ALSO: Seals do wear out / get hard.
OEM Suggested Replacement interval:
Brake Pads: If necessary
Piston Seals: Every two years
Brake Hoses: Every four years
Brake Fluid: Every Year

NOTE: Anti-rattle clips points forward!

FRONT:
Brake pad lining thickness inner & outer pad: 4.5 mm (0.18 in)
Discard Limit: 0.5 mm (0.02 in)
S2 Caliper Bolt Tq: 29ft/lbs, 40Nm
Banjo Bolt: 22 Ft/lbs, 30Nm
Bleeder Tq: 4.3 in/lbs, 6Nm

Disc Thickness:
Disc Discard limit: 4.5 mm (0.18 in)
Brake disc deflection limit: 0.10 mm (0.0039 in)

***********************************
Checking Rotor Defection:
***********************************
I'm not going to go into detail on this but if the wheel leaves my sight I inspect it. Its MY LIFE AT STAKE and I trust very few with my life!

Hint: Wheel was off and out of my sight for tire replacement so I thought it worthwhile to check rotor trueness upon installation just to confirm nothing happened that I was not aware of.

Brake disc deflection limit:
0.10 mm (0.0039 in)

Measured
Inner - Outer radius:
RS = 0.0002 - 0.0004" Less than 1/2 distance between marks.
LS = 0.0008 - 0.0013"

Each mark is 0.001" so its within spec! Steel Quick Clamp in combination with the axle bolt made the Magnetic Base on the dial stay put! :thumbup:

Needless to say the sun was evil and with a white dial, didn't stand a chance of getting a clear photo of the setup and read the dial.
LS outer....

In short, you need the proper tools for the job. In this case, I improvised creating a base and getting the needle square to the rotor so the inner and outer edge could be checked for trueness.

***********************************

Edits:
2016-02-27 restored pictures