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(At this point my front brake is strong, could do endos) So my front tire pops, I take the wheel off. Take it to a shop, they fix it, I bring it back, put it on the bike, disc slides in without issues, but now my front brake is so weak, and it comes to the handle bar quite easily. So I try to bleed them out, but can’t get them any better than what they were already at when I put the wheel back on. But they were perfect before? So why? It can’t be my pads, this is pissing me off.

06 rmz450

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They probably used wd-40 or some oil to get tire on the rim.  Probably got sprayed all over the rotor. Clean it with brake cleaner

 

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Try reverse bleeding the system. If that fails the master cylinder might be bypassing and will either need the dirt cleaned out or new seals. Easy job.

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14 hours ago, William1 said:

Dirty rotors

Sticking slider pins

Sticking pads

Sticking caliper piston

What are the slider pins?

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What are the slider pins?

Slider pins are what hold the pads in the calipers.,

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16 minutes ago, DSD840 said:


Slider pins are what hold the pads in the calipers.,

Okay so I looked over everything, I press the brake until everything is firm against each other. But the pistons just have no strength to push really hard. I bled the system yesterday a lot. But yeah the pistons just arnt getting pressure?

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Okay so I looked over everything, I press the brake until everything is firm against each other. But the pistons just have no strength to push really hard. I bled the system yesterday a lot. But yeah the pistons just arnt getting pressure?

It’s unclear to me how air would be introduced into a closed system when all you did was change a tire. However, the way I have always gotten air out of a system is like this. I remove the front wheel, place a flathead screwdriver between the brake pads and have some one hold it there. Manipulate the front brake lever till the pads are out as far as they can go without the pistons falling out of the calipers. Then remover the front brake master cylinder from the handlebar and hold it straight up above the bike with the banjo fitting at the lowest part. Then have the person with the screw drive compress the pads back into the calipers. This may need to be repeated a few times, but I have never had it not work out the stubborn pockets of air. The bubbles want to rise to the top so you just need to give them the straightest possible route. Good luck.
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11 minutes ago, DSD840 said:


It’s unclear to me how air would be introduced into a closed system when all you did was change a tire. However, the way I have always gotten air out of a system is like this. I remove the front wheel, place a flathead screwdriver between the brake pads and have some one hold it there. Manipulate the front brake lever till the pads are out as far as they can go without the pistons falling out of the calipers. Then remover the front brake master cylinder from the handlebar and hold it straight up above the bike with the banjo fitting at the lowest part. Then have the person with the screw drive compress the pads back into the calipers. This may need to be repeated a few times, but I have never had it not work out the stubborn pockets of air. The bubbles want to rise to the top so you just need to give them the straightest possible route. Good luck.

What do you mean compress the pads back into the caliper? Do I take them out? And you say put the screw driver in between the pads, I did this....

image.jpg

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If the sliders are rusted, the caliper flexes instead of sliding. Lubricate them. Read your owners/service manual.

Also, those pads look pretty thin and probably should be replaced with OEM ones.

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^^^Yup, good advice here. Pads look worn out, they may be glazed. Clean your rotor with brake cleaner thoroughly, replace your pads with OEM (none of the aftermarket ones are nearly as good!) and replace the pins if they are corroded or have any grooves worn into them. They should be smoothly polished and no grooves for the pads to get hung up on.

You can use Honda OEM pads, which are typically quite a bit cheaper than buying them from Suzuki.

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2 hours ago, Ethan Owens said:

What are the slider pins?

This is a pic of a slider pin and they usually come in sets of 2 (front/back).

IMO the pads in your last pic need to be replaced and while you are at it, look at your rear pads and replace pads as needed and the slider pin(s)

I check slider pins every time I replace the pads and usually replace the pins every 2 to 3 pads cus they can get corroded, bent, grooved and effect how the brakes work.

hqdefault.jpg

Otherwise when I change a tire I usually GENTLY use a big screw drive to open/compress the piston a bit so its easier to put the  wheel back on and NEVER have to bleed the brakes. Only times I bleed is when I either change brake fluid (about every 2 years MAX) or actually take the calipers off the bike.

IMO and obviously you need to sort out what the issue is with the brake before you ride and be methodical in the process.

I good manual helps and good luck.

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Lots of good info here, but one thing that hasn't been mentioned is rebuilding the brake caliper and master cylinder. I'm not saying this is for sure the issue, but if the bike is a little older and it's never been done, the brake system would probably benefit from a rebuild.

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What do you mean compress the pads back into the caliper? Do I take them out? And you say put the screw driver in between the pads, I did this....
image.thumb.jpg.cec1ded40ddb91daa2970311ea2c019c.jpg

That is fine. If you twist or pry the screwdriver side to side it will force the pistons back into the caliper. That forces the fluid in the caliper back up into the master cylinder and it will push any air bubbles with it.

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Let's look at the timing, worked before, don't work after? What may have happened is during the change your disks were contaminated with something (grease or oil) then your pads as you re-installed. The first thing I'd do is clean the rotor with brake cleaner than grind a thin layer off of the pads and see if that gets better. If better buy new pads and clean rotor again and your done. If not than look deeper into the hydralic system.

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Spin the front wheel and make sure the rotor isn't bent. Had a rear wheel fall off the trailer and land just right while replacing a tube once. Pumped the brake back up and everything seemed fine for about 10 feet. Got it "straight enough" for the day with an adjustable wrench. Ended up running it a couple more months.

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I work on bikes for a living and when i have bikes in the shop for tires I usually wipe the rotors with a rag sprayed with brake clean. While this cleans off any dirty finger prints or soap used to mount the tire, it also removes all the brake bust on the rotor that actually helps the pads grip. Braking is not so good at first on a test ride, but returns to normal after the the 2 miles of moderate braking, essentially performing the bed in process again as with installing new pads. That is one theory and hopefully with some mileage after cleaning them they will return to normal. I also see you said its an 06. Most manufacturers recommend replacing rubber components in the braking system every 4 years. Though no one ever does until there is a problem. So my second theory is one I see too often on older bikes. The rubber piston in the master cylinder gets hard and brittle over time and typically does not move much through its potential travel so it stays sealed to the same area of the cylinder until agitated. I have seen these pistons crack when pads are spread in the caliper and force the fluid backwards through the piston. Also when bikes come in for brake flushes and the piston is put through it complete range of travel they either get stuck in the cylinder or loose their seal all together. If this is the case a master cylinder rebuild is required. Luckily for most Jap bike and especially dirt bikes, as long as the parts are available, they are usually cheap for a rebuild kit and are very easy to replace. 

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Thanks all! I was able to fix my issue enough to get the bike out on the track again today. I adjusted this little screw on my unbreakable brake lever, causing the lever to be further away from the bars, thus giving me more leverage to pull the brakes tighter! So it’s pretty normal now, just still confused on how all of this happened in the first place just by taking the wheel off

1ED089DE-DA42-4E20-832B-4530C0471EB1.jpeg

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