Front Brake Problems

Hi all,

I`ve noticed my front brake doesn`t feel right recently .Its very spongy and will pull back to within less than 1/2" of the grip.It will slow the bike down but I think it should have a more positive feel. I`ve bled out the system ,the pads are ok,and there are no leaks.Do I need new master cylinder seals ? Is replacing the seals a good idea or should I change the complete master cylinder?Any advice appreciated ,

thanks, Jim.

Are you absolutely sure there are no air bubbles in teh line or cylinder.

If you are sure you bled out the system good and still don't have a good feel at the lever then it is probably time to do the master cylinder rebuild. The kit is cheap. I think it was less than $10. I had to do this to my '01 one of the seals had a tear in it.

Invest in a CR routing kit, I came off the Hondas and nothing I have done on the YZ makes it feel or stop like the Hondas, except the CR line routing. I never used more than one finger to stop my CR's but on the thumper, I hit the anchors with all my might just to slow down!!

My 02 bike stops great - one finger! Sometimes too good and washes out! :) Nothing wrong with the stock system here! :D Maybe there are some differences in the model year, rotor, master cylinder, pads, etc...

I have compared the CR front brake to my own YZ and the Honda certainly feels better,so what is a CR routing kit,and where can I get one?

The easiest way to blead your front brake is to fill a squeeze bottle with brake fluid. Remove the master cylinder lid, attache the squeeze bottle to the bleeder on the caliper. Open up the bleeder and force fluid up from the calipper to the master cylinder. Do this till you hear no more air bubbles entering the master cylinder. Watch out for fluid overflow from the master cylinder resvior. Close the bleader screw at the caliper. Attach a hose to the bleader screw draining into a container. Then bleed the brakes in the conventional manner by pumping the brake and holding it while cracking the bleder screw. Close the bleder screw, relase the brake. And repeat this process. The first procedure with the squeeze bottle will make the whole process very easy and fast.

The "CR routing kit" can be acquired from Fastline or DSP and it allows one to route the front brake the same way as the Honda. This gives you a shorter route for the fluid better feel on the lever less spungy feel.

This must be an 01 thing, does anyone with an 02 have "spongy" front brakes? Mine are really strong, I don't have to squeeze very hard at all. I rode my friend's 01 YZ426F and also noticed the front brakes' feel is different. Did they do brake upgrades between 01 and 02? My 02 has 245mm up front and 240mm in back IIRC, do the 01 have the same rotor sizes? Did they change the assembly/piston, make the pads larger, what's the difference?

Has anyone ridden both the 01 & 02 years and noticed this difference? Hmmmm... :)

Mine is a 2002 and it doesn't have feel and stopping power, I have to really come on it hard and the lever almost comes to the bar. I have bled it and it's better right after the bleeding then gradually gets worse.

Has it always been this way? You might have a warped rotor or bad pads. If you have to squeeze that hard, you might also have a leaky bad master cylinder or pistons (any leakage down by the pistons?) - you should not have to squeeze that hard to get the pads to squeeze the rotor. If you are sure that you have no air in your system, then something mechanical has gone wrong. Have your system checked to make sure the caliper/pistons and master cylinder is properly working - I suspect that you may have a leaky seal in the master cylinder - you can somewhat check that just by bleeding the brakes (i.e. the fluid should squirt out when you sqeeze) but you can't really tell if it's holding the proper pressure to stop the front wheel.

I have checked all that you describe above and all is okay; however, I shall try going to a different brand of brake pads, thanks AV!!

Jscott-

Are you leaking brake fluid? Does the level stay good, or do you get low pretty fast? I found on my brand new '03 YZ that the hex bolt that holds the hose to the master cylinder was torqued to 11 ft. lbs. It requires 22 ft lbs! I was losing fluid fast and the front brake was very spongy.

good luck!

-Fiddler

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