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How to make back brake more sensitive?

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How would you make your back brake more touchy so i just do a little pressure and it will be close to locking up. I really have to press hard on mine for it to lock up and i'd prefer to have it more sensitive... Thanks.

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Pressurize the system. Take a large syringe with brake fluid in it and connect it to the caliper bleeder nipple. Remove air bubbles from the line and then crack open the bleeder nipple. Force fluid from the syringe into the system. You should be able to see the pistons/pads move some as you force the fluid into the system. As the piston/pads get closer to the rotor as you are pressurizing the system, close the bleeder nipple. There is a bit of trial and error to get the desired sensitivity you want from the lever feel.

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Pressurizing the system would seem to me to be a dangerous proposition, but I am not an expert in hydraulics.  The reason the diaphragm is in the MC is to allow the system to be at atmospheric pressure.  If any contaminants find their way into the fluid (water?) and that fluid heats up, it would seem the expansion could cause a sudden lock up at the worst possible time.  You have probably already tried raising the brake lever a bit to give you more leverage, and you have probably bled the system to improve its feel.  For more stopping power, you could deglaze the rotor and the pads with sandpaper to see if that helps.  The other alternative is a new rotor if yours is too thin or premium brake pads designed to give you maximum bite.  We're trying the Braking CM46 which are supposed to have a strong bite.  So far, so good.

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Pressurizing the system would seem to me to be a dangerous proposition, but I am not an expert in hydraulics.  The reason the diaphragm is in the MC is to allow the system to be at atmospheric pressure.  If any contaminants find their way into the fluid (water?) and that fluid heats up, it would seem the expansion could cause a sudden lock up at the worst possible time.  You have probably already tried raising the brake lever a bit to give you more leverage, and you have probably bled the system to improve its feel.  For more stopping power, you could deglaze the rotor and the pads with sandpaper to see if that helps.  The other alternative is a new rotor if yours is too thin or premium brake pads designed to give you maximum bite.  We're trying the Braking CM46 which are supposed to have a strong bite.  So far, so good.

 

All I can say is that I have never had a issue with doing this. Done it on my moto's and on my Enduro/DH mtn bikes. The only Draw back I've come across is when I go to put new pads on I'll have to crack open the bleeder to purge a bit of fluid so the pistons can be pushed all the way back in to allow enough clearance for the new pads to go in.

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lol not sure what spaceboy thinks he is accomplishing, You either need to bleed the brake lines or need new/different pads, a new rotor will help if yours is worn.

It reduces the free play in the lever/pedal making the brakes much more sensitive. Of course that assumes the rest of your system isn't worn out. i.e. fresh fluid, brake pads and a rotor that is still in spec.

Edited by spaceboy

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all that does is push some fluid in to your reservoir. might knock a couple air bubbles out if your lucky. Ithe only way you could pressurize it would be if your master cylinder isn't extended properly and you will easily develop a heat locking brake.

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Pressurizing the system would seem to me to be a dangerous proposition, but I am not an expert in hydraulics.  The reason the diaphragm is in the MC is to allow the system to be at atmospheric pressure.  If any contaminants find their way into the fluid (water?) and that fluid heats up, it would seem the expansion could cause a sudden lock up at the worst possible time.  You have probably already tried raising the brake lever a bit to give you more leverage, and you have probably bled the system to improve its feel.  For more stopping power, you could deglaze the rotor and the pads with sandpaper to see if that helps.  The other alternative is a new rotor if yours is too thin or premium brake pads designed to give you maximum bite.  We're trying the Braking CM46 which are supposed to have a strong bite.  So far, so good.

 

 

lol not sure what spaceboy thinks he is accomplishing, You either need to bleed the brake lines or need new/different pads, a new rotor will help if yours is worn.

 

What Spaceboy is describing is simply the "Reverse Bleed" method of bleeding brakes.  He's not talking about pressurizing to high pressures.  He is only suggesting a positive pressure as high as what can be imparted with a plastic syringe before the syringe tube blows itself off the bleeder nipple, which is only slightly above atmospheric...  What he is accomplishing is a more effective method of bleeding by "pushing" the air out of the system in the direction it naturally wants to go, as opposed to trying to "suck" the air out in the direction it naturally does not want to go.

 

This is the preferred method of top notch mechanics and is hands down more effective than vacuum bleeding in most situations.  It is the method of bleeding suggested by most good service manuals.  What Spaceboy is saying is 100% correct :thumbsup:

 

The right way:

 

P4170414_zps2fed6bb0.jpg

Edited by Fattonz

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You shouldn't have to press hard at all, just the dead weight of your foot should lock the back up. Something is wrong, likely air in the system, or could be a stuck piston, or the master could need a rebuild.

Pressurizing wont do anything except take a little slack out of the lever and cause the brakes to drag. It wont change your ratios so you'll have to press just as hard as before to get the same power. It cant make up for bad brakes.

Reverse bleeding is not pressurizing. Pressurizing is forcing excess fluid into a closed system. Reverse bleeding should be done with the cap off or loose to allow trapped air and excess fluid to escape.

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You shouldn't have to press hard at all, just the dead weight of your foot should lock the back up. Something is wrong, likely air in the system, or could be a stuck piston, or the master could need a rebuild.

Pressurizing wont do anything except take a little slack out of the lever and cause the brakes to drag. It wont change your ratios so you'll have to press just as hard as before to get the same power. It cant make up for bad brakes.

Reverse bleeding is not pressurizing. Pressurizing is forcing excess fluid into a closed system. Reverse bleeding should be done with the cap off or loose to allow trapped air and excess fluid to escape.

 

Yeah doing it without the cap off the MC doesn't make a whole lot of sense to me, and upon rereading it looks like that is what he was meaning eh?

 

In any regard, I've bought used bikes that you had to damn near squeeze the lever white knuckled to get the brakes to grab, then gave them a good reverse bleed (essentially a fluid change) and they felt like different brakes after...sensitive, and grab like brand new ;)

 

Check out the fluid on my son's cr before and after....lol.  Previous owner was a tad neglectful :facepalm:

 

P4180457_zpsb39111f7.jpg

 

P4180465_zps8cea6eec.jpg

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What Spaceboy is describing is simply the "Reverse Bleed" method of bleeding brakes.  He's not talking about pressurizing to high pressures.  He is only suggesting a positive pressure as high as what can be imparted with a plastic syringe before the syringe tube blows itself off the bleeder nipple, which is only slightly above atmospheric...  What he is accomplishing is a more effective method of bleeding by "pushing" the air out of the system in the direction it naturally wants to go, as opposed to trying to "suck" the air out in the direction it naturally does not want to go.

 

This is the preferred method of top notch mechanics and is hands down more effective than vacuum bleeding in most situations.  It is the method of bleeding suggested by most good service manuals.  What Spaceboy is saying is 100% correct :thumbsup:

 

The right way:

 

P4170414_zps2fed6bb0.jpg

 

I totally agree with the reverse bleeding method you describe.  It is far less wasteful of fluid and time.  My concern was doing this with the MC sealed, because I thought it would collapse the diaphragm and put too much fluid in the system.  You are saying you would do this with the MC cap on?  

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I totally agree with the reverse bleeding method you describe.  It is far less wasteful of fluid and time.  My concern was doing this with the MC sealed, because I thought it would collapse the diaphragm and put too much fluid in the system.  You are saying you would do this with the MC cap on?  

 

No, absolutely not.  I would do it with the cap off.  If you read back a couple of posts you'll see where I explained kind of misreading Spaceboy's post.  I have a habit of sometimes pulling the trigger before thoroughly reading what I am replying to :blush:

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All I can say is that I have never had a issue with doing this. Done it on my moto's and on my Enduro/DH mtn bikes. The only Draw back I've come across is when I go to put new pads on I'll have to crack open the bleeder to purge a bit of fluid so the pistons can be pushed all the way back in to allow enough clearance for the new pads to go in.

 

It's all good, that's what discussions are for.  I didn't say you were wrong, only that I have serious concerns about the approach as I read it.  If my concerns are not warranted, I will be the first to acknowledge my error.  As for my interest in brakes, it is mostly because my dumb self did something unwittingly stupid recently that ended up being very expensive and time consuming from a healthcare perspective.  I put a brake lever on a bike that pushed the MC plunger in by about a mm at rest, no more, and that was enough to lock the brakes and put me on the ground in a way that was quite surprising.  I would rather make noise about something like this and be proven wrong than say nothing at all.  The good people here will tell me I am wrong, if I am, and they will tell you, too.  I think if you are not taking the cap off the MC as you are forcing fluid in, it is potentially dangerous.  I have been wrong before, though.  I will research further, because it is important.

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No, absolutely not.  I would do it with the cap off.  If you read back a couple of posts you'll see where I explained kind of misreading Spaceboy's post.  I have a habit of sometimes pulling the trigger before thoroughly reading what I am replying to :blush:

 

You posted as I was writing.  This is a constructive discussion and I appreciate your clarification very much.

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Nothing wrong at all with a little extra pressure in the system, but I would use a residual valve instead of the method described. In a whole bunch of auto apps the residual valve is built in, and a lot of people will add one when doing a rear disc swap. Usually 2psi is enough to keep everything tight and removes quite a bit of take-up out of the pedal.

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All I can say is that I have never had a issue with doing this. Done it on my moto's and on my Enduro/DH mtn bikes. The only Draw back I've come across is when I go to put new pads on I'll have to crack open the bleeder to purge a bit of fluid so the pistons can be pushed all the way back in to allow enough clearance for the new pads to go in.

The problem I foresee is that the extra pressure will heat up the fluid a lot easier.

My KTM's Brembo brakes are great. Never had problems. But I bleed the line til there's clean fluid coming out the bleed valve every 15 hrs of riding. That's just to keep things fresh.

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How would you make your back brake more touchy so i just do a little pressure and it will be close to locking up. I really have to press hard on mine for it to lock up and i'd prefer to have it more sensitive... Thanks.

My rear brake is adjusted pretty tightly, so all I gotta do is barely push down the pedal and the brakes are engaging. Other slow riders like RickyCarmichael prefer brakes that are squishy and soggy, but still work well when he pulled the brake lever all the way to the handlebar. Wut did he know?? Lol

Bleed the system thoroughly as a start. If you need help with that, search the forums bc plenty of threads exist for bleeding brakes.

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The problem I foresee is that the extra pressure will heat up the fluid a lot easier.

My KTM's Brembo brakes are great. Never had problems. But I bleed the line til there's clean fluid coming out the bleed valve every 15 hrs of riding. That's just to keep things fresh.

 

Brembo brakes are freaking amazing.  I don't know if it's the caliper that makes the difference or the MC.  I haven't taken apart a Brembo system yet to see the difference, but it's pretty clear there is one.

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