[zach976]

I've got a 2004 gsxr 750 with about 15k miles. I started getting a mushy front brake lever so I took it in to my mechanic. The mechanic put new pads, changed all fluid, and after more problems eventually put a new master on the front. It's been about a month and the front lever will pull all the way to the grip before engaging. I called the mechanic and he said If there is no leaking fluid than he does not know how air is getting in the system. i can bleed at the master and there is a lot of air. Anyone know what the problem is??????
Thanks

 

[Boogieman065]

I'd check the bleed valve on the calipers... and get stainless steel lines regardless of whether the lines are problematic or not.

 

[PacificGSXR1000]

When bleeding it how soon the air apears would give you a clue on if the leak is high or low. But then again presurizing the line would drive air and fluid down then repeated pumping would possibly get the air to go down to the calipers and it would stay there kind of trapped in a corner. Line, o-rings like on the brake pistons or bleed valves can leak air just one way which would be into the system when letting off the brakes. Your air could enter from any where and creep up the line to the master where you are finding it. You could check for a frozen piston or abnormalities in their o-rings where air might come in. You are lucky the newer bike are bleedable at the master unlike older bikes weren't. I'd hate to think what other bills you are going to get to fix the problem. It could just be a case of the crimp for a line isn't sturdy enough to keep air from getting in during retracting the pads and doesn't pass fluid because it isn't a big enough gap. We are talking RCH. Good luck finding the problem with out taking a lot of damage in your wallet.

Oh yah. When bleeding and you are pouring fluid in.... let the fluid sit for a while then with the lid on tap the resevoir. Even if you can't see the bubbles they are there tiny ask heck and they need to be induced into getting to the top of the resevoir. Although it doesn't sound like that is your problem pushing the little bubbles down the line may have them coming right back later on as bigger air pockets. Mityvac makes some great brake bleeding vacumes but you are still going to need to make sure the stuff in the masters resevoir has all the air out. Just pouring fluid in the tank drags little air bubbles into the tank due to the viscosity and surface tension where the two meet suring pouring. Tap tap tap and hope like heck you get a good start.

 

[zach976]

Thanks for your help. My wallet can't handle much more abuse.

 

[ClevelandWheeler]

look for lines and calipers on ebay as it seems that's the only place it could be now.

 

[Magisnyc]

Check for bent rotors too. That could mess with your brake feel as well.

 

[kolberg_1]

My first question would be where is the fluid going to allow the space to be taken up by air...

A leak which you should be able to see, or from the fluid itself, how old was the stuff the mechanic put it? Was it sitting on the shelf in a humid climate for a few months, the fluid will absorb water from the air which will boil and create this air you keep bleeding out. Water can also be absorbed through the brake lines and should be replaced every 4 years or sooner.

How long does it take to lose brake, can you get a good lever? If you cannot get a good lever and air seems to be coming out of nowhere you might want to check the "y" in the line as air will collect at the high spots of each side.

And yes you should replace your brake lines every 4 years or less depending on your climate and how you ride. Soft lines will give you a spongy feel to your brakes as the lines expand to the braking pressure.

 

[zach976]

I'm running the original lines. The mechanic is reputable mechanic so I'm sure the brake fluid is new and fresh. I had a great firm brake for a few weeks. It took about a month or so to go to nothing. I bleed at the master and have some brake but not like when i picked it up from the mechanic. No visible leaks and the resevoirs are full. Thanks for the info.

My first question would be where is the fluid going to allow the space to be taken up by air...

A leak which you should be able to see, or from the fluid itself, how old was the stuff the mechanic put it? Was it sitting on the shelf in a humid climate for a few months, the fluid will absorb water from the air which will boil and create this air you keep bleeding out. Water can also be absorbed through the brake lines and should be replaced every 4 years or sooner.

How long does it take to lose brake, can you get a good lever? If you cannot get a good lever and air seems to be coming out of nowhere you might want to check the "y" in the line as air will collect at the high spots of each side.

And yes you should replace your brake lines every 4 years or less depending on your climate and how you ride. Soft lines will give you a spongy feel to your brakes as the lines expand to the braking pressure.

 

[zach976]

:clap: I installed Galfer stainless lines on the front today and I used a mityvac to bleed with. I did left caliper and right caliper several times and finished with the bleeder on the master. The mityvac was hard to tell if i was getting air with the fluid and I wasted a whole container of brake fluid. (first time screw up i guess) I've got a firm brake lever and it seems to be working fine. If the lever is firm and everything is working properly it shoul be ok right????

 

[samuraidad]

Loss of front brake

Interesting I have been following several of these threads as my son has a GSX R750 (2008) and he to lost his front brake. A visual inspection was made of the brakes and all ,ines with no signs of leakage. I called the dealer and they advised they see this on bikes that are not driven daily. Their fix is to drain the brake fluid remove the bleeder screw and put tefelon tape on the treads before reinstalling it then to fill and flush the lines. They claim air is entering the system via the bleeder screw. This made no sense to me since when you activate the brakes the system become pressurized and if there were even the tinest flaw the fluid would escape. Plus they could not tell me why this does not occur to bikes in the showroon sitting for extended periods of time.

I then called Suzuiki and told them what is going on they claim to have no knowlege of the situation. Interesting very interesting. They did say not to put tefelon tape on the bleeder which I had already come to that conclusion. My next step was to contact the NHTSA and fie a complaint. I hope thoese of you who have an issue will do the same as this is clearly a safety defect whe you have a brake loss.

Not giving up I called the dealer in Ft Lauderdale to get their opnion. I was told they to see the problem and their fix is to replace the rubber lines, that swell with stainless steel braied one and to flush the system and refill with DOT5.1.

Regarding the rotors I would think if the rotor is warped it seems as if you should get a vibration or shutter as you do on car brakes.

I am not yet convinced that there is not a safety defect in the design of the system or parts. It makes me wonder how many if any riders were injuried or killed because of front brake failure and this we may never know

 

[Zippy]

Interesting I have been following several of these threads as my son has a GSX R750 (2008) and he to lost his front brake. A visual inspection was made of the brakes and all ,ines with no signs of leakage. I called the dealer and they advised they see this on bikes that are not driven daily. Their fix is to drain the brake fluid remove the bleeder screw and put tefelon tape on the treads before reinstalling it then to fill and flush the lines. They claim air is entering the system via the bleeder screw. This made no sense to me since when you activate the brakes the system become pressurized and if there were even the tinest flaw the fluid would escape. Plus they could not tell me why this does not occur to bikes in the showroon sitting for extended periods of time.

I then called Suzuiki and told them what is going on they claim to have no knowlege of the situation. Interesting very interesting. They did say not to put tefelon tape on the bleeder which I had already come to that conclusion. My next step was to contact the NHTSA and fie a complaint. I hope thoese of you who have an issue will do the same as this is clearly a safety defect whe you have a brake loss.

Not giving up I called the dealer in Ft Lauderdale to get their opnion. I was told they to see the problem and their fix is to replace the rubber lines, that swell with stainless steel braied one and to flush the system and refill with DOT5.1.

Regarding the rotors I would think if the rotor is warped it seems as if you should get a vibration or shutter as you do on car brakes.

I am not yet convinced that there is not a safety defect in the design of the system or parts. It makes me wonder how many if any riders were injuried or killed because of front brake failure and this we may never know

Rubber lines are not likely to be a problem by themselves in a bike under a decade old. People replace them to get a bit better feel, but not because they are dangerous. Also, I'd be pretty sure there is no design defect. These are parts that very seldom change much if any from year to year, and who's design has been working well for a couple of decades or more. If anything, it is more likely an assembly defect. Reusing a washer, overtightening a connection or overtighting a bleeder screw are more likely.