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Discussion Starter #1
I know.. I know.. you're thinking not another spongy brake thread...
but read, I read the other ones before posting a new one.

This is on a 2007 1000.
Last fall, the front brakes were spongy. I tried bleeding every which way that's been recommended.
Top, left, right, top, ....
I tried the "tie the brake lever over night".
Next day, I see brake fluid on the floor, below the left caliper.
I order all the parts, seals, bolts, etc. etc. and rebuild the calipers. the pistons looked fine.

Assemble everything, bleed the hell out of it. probably 1/2 quart through the whole system.
still spongy...

order more parts and rebuilt the master caliper piston. Assemble the whole thing, bleed and bleed.
still spongy!

I tried the "tie the brake lever over night" again. next morning, checked around the system and found no leaks and lever was still in the same position that I had tied it.

still spongy.

Cracked the banjo bolt on the master and bled through there for a bit... still spongy.

Just to clarify.. I know how to bleed breaks. been doing it on cars and other bikes for long time.
Use my brake bleeder (vacuum system) to do the initial work. and finish the job by: Squeeze the lever, open the bleed screw, let some fluid come out, close the screw, and try again.

The strange thing is, when I bleed the master cylinder through the bleed screw, I see some microscopic bubbles come out. this happens after bleeding another quart of DOT4 through it.

what else could it be?
the master cylinder housing is bad, letting air by ? if so, why isn't leaking fluid?
 

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Not sure if you do this, but I was turned onto a little secret about vacuum bleeding years ago.

The bleed screw is probably letting air in (the stream of little bubbles) and so you are never actually fully bleeding.

Using a turn or 2 of plumbers teflon tape on the bleed screw threads may be the final solution. (i do this to all the bleed screws in my systems)

Just throwing ideas out there. :)
 

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Discussion Starter #3
Thanks for taking a stab at this problem. You are absolutely correct about Teflon tape. If using vacuum bleeder, air will be sucked in and Teflon tape is needed.

This is from Honda's service manual: "If air is entering the bleeder from around the bleed valve threads, seal the threads with teflon tape. "

In my case, I see those tiny bubbles when using the brake lever for creating pressure and then opening the bleeder screw.
 

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Had this happen on my 06 a couple years ago. If your not seeing fluid leaking out of anywhere, then yes your master cylinder is bad. I bought the parts brand new OEM and did it my self for around 50$ if I can remember.
Heads up. The snap ring is a bitch to get seated while holding the spring down at the same time. Had to get my girl to have another set of hands.
 

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Did you grease the caliper seals? I know on all Brembo calipers they come with a little packet of grease for the seals assembly. OEM says to use brake fluid on inner and grease on outer dust seals. If there is excessive friction between the piston and seal that will increase the threshold for piston sliding past seal as you apply brakes vs. piston/seals deforming as you apply brakes. This will result in increased slack in pad to disc engagement and make the brakes feel spongy.
 

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Don't know if this is helpful or not., but my 2013 was always spongy. Bled quarts through it, tapped everywhere to knock bubbles off, still spongy. Bike only had a few hundred miles and was like new when I got it. Replaced the MC with a Brembo MC and it was night and day, couldn't be happier.
 

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Discussion Starter #7
Today, I found a tiny showing of "wetness" around the tube that come out of the MC, connecting to the hose to the reservoir.
the "wetness" become more apparent when I push down on the dust cover.
Looking at the parts diagram, there is an O-RING (91212-422-006 ) that is suppose to seal the "connector" (45503-KV3-006).

Here goes another ~$30 since there should be no leak there. However i don't think this will solve the issue as this is the low pressure side of the MC.



We'll see....
 

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Discussion Starter #8
Did you grease the caliper seals? I know on all Brembo calipers they come with a little packet of grease for the seals assembly. OEM says to use brake fluid on inner and grease on outer dust seals. If there is excessive friction between the piston and seal that will increase the threshold for piston sliding past seal as you apply brakes vs. piston/seals deforming as you apply brakes. This will result in increased slack in pad to disc engagement and make the brakes feel spongy.
Good point!
If I remember correctly, the service manual calls for using silicon grease when the seals are put in and that's what I did.
 

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Discussion Starter #9
Don't know if this is helpful or not., but my 2013 was always spongy. Bled quarts through it, tapped everywhere to knock bubbles off, still spongy. Bike only had a few hundred miles and was like new when I got it. Replaced the MC with a Brembo MC and it was night and day, couldn't be happier.
it is helpful as it is another reference point.
When this saga started, I went to some dealer tried the brakes on a few different bikes. They all felt solid.
Even on my bike the rear is super solid. Move about 1" and then hits a wall.
 

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If you don't mind spending the money I would suggest a Brembo MC and stainless lines if you don't already have them.

Or if you want a new OEM MC I have one off a 2015. Took off with 1100 miles on the bike. Also have the OEM brake lines if needed.
 

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If you don't mind spending the money I would suggest a Brembo MC and stainless lines if you don't already have them.

Or if you want a new OEM MC I have one off a 2015. Took off with 1100 miles on the bike. Also have the OEM brake lines if needed.
And if you want a spongy OEM MC, I have a nearly-new one off my 2013 😄
 

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Discussion Starter #12
Had this happen on my 06 a couple years ago. If your not seeing fluid leaking out of anywhere, then yes your master cylinder is bad. I bought the parts brand new OEM and did it my self for around 50$ if I can remember.
Heads up. The snap ring is a bitch to get seated while holding the spring down at the same time. Had to get my girl to have another set of hands.
For reference, the service manual specifies a Honda tool for reaching in there and removing the snap ring.

I found a similar one on Amazon, for ~$15.
Has some bad reviews but, I figured it should be good for my uses.
It worked very well.

Here's a picture of it.

 

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Maybe a dumb question, but how much wear / mileage on your pads? On my '07, I've been average 20K on the front pads, and right now my brakes are a little spongy, and the front pads look like they still have 2-3mm of pad material, but last time this happened, I swapped to new pads and the brakes were back to solid. As the pads wear, the volume behind all eight pistons will keep increasing, and that could easily be 2-4x more volume that in the lines, hence relatively "more" spongy even without air bubbles in the lines.
 

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I know.. I know.. you're thinking not another spongy brake thread...
but read, I read the other ones before posting a new one.

This is on a 2007 1000.
Last fall, the front brakes were spongy. I tried bleeding every which way that's been recommended.
Top, left, right, top, ....
I tried the "tie the brake lever over night".
Next day, I see brake fluid on the floor, below the left caliper.
I order all the parts, seals, bolts, etc. etc. and rebuild the calipers. the pistons looked fine.

Assemble everything, bleed the hell out of it. probably 1/2 quart through the whole system.
still spongy...

order more parts and rebuilt the master caliper piston. Assemble the whole thing, bleed and bleed.
still spongy!

I tried the "tie the brake lever over night" again. next morning, checked around the system and found no leaks and lever was still in the same position that I had tied it.

still spongy.

Cracked the banjo bolt on the master and bled through there for a bit... still spongy.

Just to clarify.. I know how to bleed breaks. been doing it on cars and other bikes for long time.
Use my brake bleeder (vacuum system) to do the initial work. and finish the job by: Squeeze the lever, open the bleed screw, let some fluid come out, close the screw, and try again.

The strange thing is, when I bleed the master cylinder through the bleed screw, I see some microscopic bubbles come out. this happens after bleeding another quart of DOT4 through it.

what else could it be?
the master cylinder housing is bad, letting air by ? if so, why isn't leaking fluid?
Hi,
i had the same issue on my 2012 1000
first, I changed the MC service kit, the sponginess reduced, but still there
secondly, changed the Brake lines to HEL on race setup, got a bit better, but that sponginess still there
finally, upgraded to Brembo RCS 19 MC, the sponginess was gone, but since i was using oem brake pads, the brake effectiveness was not there
then some one on the 1000rr forum recommended Carbon Lorraine C60 Brake Pads, I couldnt find C60, but got hold of XBK5
Also used Teflon tape on Bleeder nipples,
the sponginess has long gone,
 

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Maybe a dumb question, but how much wear / mileage on your pads? On my '07, I've been average 20K on the front pads, and right now my brakes are a little spongy, and the front pads look like they still have 2-3mm of pad material, but last time this happened, I swapped to new pads and the brakes were back to solid. As the pads wear, the volume behind all eight pistons will keep increasing, and that could easily be 2-4x more volume that in the lines, hence relatively "more" spongy even without air bubbles in the lines.
Hi,
is it sponginess or MC lever travel, i faced this issue, there was high lever travel till the hardness point, i mean, usually there should be hair width gap between the brakepads and disc, sometimes due to vaccumm when the lever is released, the caliper pistons travel a bit far back, when u press the lever it travels a far distance creating sponginess effect.

i tried lot of ideas to make the Pistons not to travel far back

thanks
 

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Discussion Starter #16
Hi,
is it sponginess or MC lever travel, i faced this issue, there was high lever travel till the hardness point, i mean, usually there should be hair width gap between the brakepads and disc, sometimes due to vaccumm when the lever is released, the caliper pistons travel a bit far back, when u press the lever it travels a far distance creating sponginess effect.

i tried lot of ideas to make the Pistons not to travel far back

thanks
Excellent question and thanks for asking. hope it clarifies the situation.

I've only been working on this thing and haven't ridden it yet. So my definition of spongy is about lever travel and lever feel.

The new bikes, while sitting in the show room that I have tried had a very small lever travel before they stopped moving.
My rear brake pedal is the same way. moves a bit and stops, as if it hit a hard stop.

The front lever travels a long way and it feels like I could sqeeze more and more, hence my description of spongy.
Also, if I pump it quickly, the travel lessons. Symptom of air in the line.

If I were to graph hardness vs. travel, I would describe my feel of new bike brakes as
hardness = travel ^ 2

I would describe my front lever's hardness as
hardness = travel as in linear
 

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Discussion Starter #17
Maybe a dumb question, but how much wear / mileage on your pads? On my '07, I've been average 20K on the front pads, and right now my brakes are a little spongy, and the front pads look like they still have 2-3mm of pad material, but last time this happened, I swapped to new pads and the brakes were back to solid. As the pads wear, the volume behind all eight pistons will keep increasing, and that could easily be 2-4x more volume that in the lines, hence relatively "more" spongy even without air bubbles in the lines.
please see below, I mention that my spongy feel is with the bike being stationary.
The brake pads seem to be OK, they seem to have a lot of meat on them.
 

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Might wanna ride the bike first and use the brakes while actually moving before you spend time and money correcting a problem you may or may not have. What you are describing happens on my bike as well while just sitting in the garage. I have stainless lines and a Brembo MC.
 

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I agree ride the bike first, I believe we have mostly been replying in the context of a brake system under way where the pads are subject to heat, friction and pistons are subject to pad kickback and fluid behaviors is affect by everything.
 

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Excellent question and thanks for asking. hope it clarifies the situation.

I've only been working on this thing and haven't ridden it yet. So my definition of spongy is about lever travel and lever feel.

The new bikes, while sitting in the show room that I have tried had a very small lever travel before they stopped moving.
My rear brake pedal is the same way. moves a bit and stops, as if it hit a hard stop.

The front lever travels a long way and it feels like I could sqeeze more and more, hence my description of spongy.
Also, if I pump it quickly, the travel lessons. Symptom of air in the line.

If I were to graph hardness vs. travel, I would describe my feel of new bike brakes as
hardness = travel ^ 2

I would describe my front lever's hardness as
hardness = travel as in linear
Hi,
the oem MC has issues, even after changing the service kit there is sponginess, the Brembo RCS 19 has a different feel, i pressume there is some point in the oem MC where the bubbles do not come out, i tried to remove the oem MC and calipers from the bike and put a spacer between the brake pads, and move it around and then bleed it, it does help

another issue i see here is that Honda never made a service kit fully assembled, they give u with seals removed, u have to literally squeeze, pull push the seals in, i think that would damage or put micro cracks on the seals, causing sponginess, just like a piston loosing compression in cylinder bore
 
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