Front Brake Spongy - Honda Motorcycles - FireBlades.org
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post #1 of 20 Old 03-29-2006, 7:23 AM Thread Starter
 
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Front Brake Spongy

Sound simple – air in the pipes/splitter/callipers.

When I bought the bike last year the brakes were a little spongy and so they were bled and where great, for about a week max, and were like they were again. A change in fluid put them right and in about a week they were spongy again.


The bike’s been stood all winter and the lever comes back to the bars, bled and better but spongy. Fluid change/bleed and wow! Amazing again, another week on and guess what…back to the bars again! wtf?

There is no loss of fluid, when they work there great, even though they as spongy they work, just not very well!.

Any thoughts?

I’ve had it suggested it could be the master cylinder so I have a loaner on its way, but why would air leak in and fluid not leak out, especially with the pressure in the system under breaking?
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post #2 of 20 Old 03-29-2006, 7:47 AM
 
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Re: Front Brake Spongy

I have the same problem... I am intrested to hear a fix...
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post #3 of 20 Old 03-29-2006, 7:51 AM
 
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Re: Front Brake Spongy

Using the search tool you would have found this post:

Quote:
Originally Posted by sl954
I have not recieved them yet, maybe I'll wait until they come in.
Abtech, is there a link to your "wordy" discription on bleeding brakes? I would be interested in reading it.

Thanks



Here is one of them:

Quote:
Quote:
Originally Posted by Venom
One little trick that i was told about a year ago, Is when you think you have just about all the air out. But you still just a little mush when you first start to squeze the lever.

Take a piece of velcro, Squeze the lever pretty hard, Wrap the velcro around the lever. So that the velcro keeps presure on the lever. And let it sit over night. Wile it sits over night the last little bit of air get adsorbed in to the fluid. In the morning grab the lever , Take the velcro off,( or what ever you used to tye the lever back) And relesase the lever slowly.


I know it sounds like a load of B/S. And i thought the same thing till i tryed it. And sure enought that little last bit was/is gone. I frist tryed that my self when i put SS brake lines one my 12. Getting that last bit of air out of the banjo bolt was driveing me nuts. So i thought i would give it a try and sleep on it. Need less to say i was a verry happy camper the next day.



This is really just a bandaid, as the air and fluid will seperate in a short period of time leaving the brakes just like they were before.

Here is the way we do it and it works period.

First, if you have a MityVac, find the box it came in, place it back inside along with the instructions and return it to the place you purchased it. With less than half of that money in your pocket, order a bleeder banjo bolt for the master cyclinder and install it before you begin.

Put the bike on a race stand, so it's relatively level (side to side).

I suggest buying a set of Speedbleeders to make this simple job even easier. If you don't have the Speedbleeders, then just get an 8 mm open end wrench, about 2 to 2.5 feet of clear plastic hose and an empty coffee can.

Pull off the rubber caps on the bleeders (doing one side at a time) and place the clear hose over the nipple and the other end into the can.

Remove the top of the reservoir and top it off with fresh Motul 600 DOT 4 racing fluid.

Pump the lever a few times until you get some serious resistance and then while applying pressure on the lever, open the nipple with the 8 mm wrench about 1/4 turn and as the lever begins to move, tighten it back up.

Repeat this last step until you no longer see any air bubbles in the clear tubing. Note you will have to keep an eye on the reservoir level to make certain you ALWAYS have plenty of fluid.

Once you no longer see any bubbles, move to the other caliper and repeat.

Let the brakes sit for about 5 minutes and then repeat the bleeding operation.

Now take the handle of a large screwdriver and start tapping on the brake line (again one side at a time) beginning at the caliper and slowly moving upward toward the master cylinder. If you have the stock lines, then make certain you carefully tap both sides of the junction and then follow it up to the master cylinder.

Again let the brakes sit for about 5 minutes and then move your clear plastic tubing to the bleeder bolt at the master cylinder and using the same technique, bleed this nipple until there are no air bubbles in the tubing.

This last step is the most important, as the air bubbles always travel up to the top of the lines (as well as get stuck in the T junction on stock systems). I have heard so many people tell me they have bled the brakes 10 or more times and the brakes are still squishy and then they go out and buy a MityVac and go through a couple of quarts of brake fluid and still have crap for brakes. Everyone that says they have "totally" bled the brakes (but didn't do the master cylinder) has always had a ton of air in the top of the lines and are amazed when they see even more bubbles come out of their supposedly "airless" system.
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post #4 of 20 Old 03-29-2006, 7:56 AM
 
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Re: Front Brake Spongy

where do you buy a master cyl bleeder bolt?
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post #5 of 20 Old 03-29-2006, 8:02 AM Thread Starter
 
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Re: Front Brake Spongy

I found those threads but mine's not the same - they are perfect when first bled - there is no residual sponginess to them, that why I do not think air is being left in the system after bleeding.
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post #6 of 20 Old 03-29-2006, 8:11 AM
 
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Re: Front Brake Spongy

Quote:
Originally Posted by machinehead
I found those threads but mine's not the same - they are perfect when first bled - there is no residual sponginess to them, that why I do not think air is being left in the system after bleeding.
Unfortunately, that is EXACTLY what is happening. The air blends with the fluid when you bleed them and once you get a firm lever, it seems great. Over time, the air seperates and becomes trapped in the junction or at the Master Cylinder and compresses when you use the brakes.

I have won quite a few bets after a rider with your exact problem bets me that there isn't ANY air in the lines. I then do the above procedure and bleed out a ton of tiny air bubbles from their lines.

This procedure doesn't indemnify you from good brake maintenance, as I always take the brakes down at least once a year and clean out the calipers (I even remove the pistons and drop all the parts in a dip tank to get them completely clean). Stainless Steel lines will help, especially if your stock hoses are a couple of years old. Eliminating the junction (which is a favorite hiding place for trapped air) is reason enough to go with Stainless lines. Check your pad thickness on both sides and make certain they are within service limits.

BUY a Banjo bleeder bolt (Street & Competition carries them) and a set of SpeedBleeders and maintaining your brakes becomes very easy.

Also, when you say you replaced the fluid, did you entirely drain the system and make certain all of the old fluid was replaced? If not, you just pollute the new fluid with your old water soaked stuff which will prevent the system from ever working properly. You must always use fluid from a new unopened container due to the hygroscopic properties of brake fluid where the fluid absorbs moisture and the moisture then breaks down to it's component parts (one of which is Oxygen).

Last edited by abtech; 03-29-2006 at 8:21 AM.
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post #7 of 20 Old 03-29-2006, 9:52 AM
 
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Re: Front Brake Spongy

One other possibility is the crush washers were reused and no longer getting a good seal. This can seep small amounts of air over time, though usually the failure is more obvious. Though this is less likely that what Abtech describes.

Must obey the sheep dog
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post #8 of 20 Old 03-29-2006, 10:40 AM Thread Starter
 
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Re: Front Brake Spongy

OK I'll try bleeding the bleeding things again!
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post #9 of 20 Old 03-29-2006, 10:53 AM
 
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Re: Front Brake Spongy

Looks like another garage visit to my friends, just in case..

Thanks for the tips, Abtech..
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post #10 of 20 Old 03-29-2006, 11:00 AM
 
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Re: Front Brake Spongy

I wouldn't get carried away with a mityvac or special brake bleeding tools. Just tap the lines and fittings with a screwdriver to dislodge the bubbles to the top and bleed them out there. You may be able to see some of those tiny guys escape. Have plenty of fresh fluid from a NEW container. DOT4 loves to absorb water, which absorbs air, which absorbs sponginess, wich absorbs your time.
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post #11 of 20 Old 03-29-2006, 11:36 AM
 
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Re: Front Brake Spongy

Quote:
Originally Posted by dattaway
I wouldn't get carried away with a mityvac or special brake bleeding tools. Just tap the lines and fittings with a screwdriver to dislodge the bubbles to the top and bleed them out there. You may be able to see some of those tiny guys escape. Have plenty of fresh fluid from a NEW container. DOT4 loves to absorb water, which absorbs air, which absorbs sponginess, wich absorbs your time.
Is there an echo in here? I recommend buying a bleeder banjo bolt or bleeding up top gets pretty messy. I only recommend the SpeedBleeders as a matter of convenience. If you race or do a lot of trackdays, bleeding your brakes should be a regular routine, as you will be wearing the pads a lot more than on the street.

BTW, water consists of AIR (just in different concentrations), it doesn't need to absorb it.
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post #12 of 20 Old 03-29-2006, 12:52 PM
 
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Re: Front Brake Spongy

If I already have SS lines on w/ SB's but I didn't buy the Banjo bleeder (going to right now ). Will I have to drain whole system free from fluid or can I be "careful" and swap em out and bleed the system?
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post #13 of 20 Old 03-29-2006, 1:12 PM
 
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Re: Front Brake Spongy

You can just swap the banjo and bleed, but it will be messy.
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post #14 of 20 Old 03-29-2006, 1:27 PM
 
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Re: Front Brake Spongy

I've got an ebay bid on a mityvac... I bled by hand when I put the galfer lines on, but I didn't have any clear tubing so I used black automotive brake hose. Did the job but it ain't perfect.

And then there's this asshole...
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post #15 of 20 Old 03-29-2006, 2:25 PM
 
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Re: Front Brake Spongy

Quote:
Originally Posted by phobiaphobe
I've got an ebay bid on a mityvac... I bled by hand when I put the galfer lines on, but I didn't have any clear tubing so I used black automotive brake hose. Did the job but it ain't perfect.
You can't see when the bubbles stop with opaque hose dummy!
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