My spongy front brake story

[greeneb]

I have an 03 250E and I am having problems with the front brake lever traveling too far before engagement. I searched around and it seemed to be an all too common problem and well as a spongy feel. Well, this was news to me because my 99 250E never had, nor to this day has a problem with the front brake.

So, upon suggestions I back bled (from the article "Don't Curse the Bremos") and forward bled for quite a while. Hung the MC up so the air bubbles could rise, etc. The feel and engagment got much better, even felt good. So I considered it fixed. Rode about 25 miles this weekend, got home, same darn free play in the lever before engagement!! :debil:

So, upon other suggestions of removing the caliper and using the lever, push the pucks out, then force them back. Did this several times... along with hanging the MC up and tapping the brake line like crazy... and the brake lever feels better than it ever has, and engages quickly. I forward bled them just for good measure.

My question is.... what is the success rate for pushing pucks back or back bleeding or forward bleeding??? Has anyone somewhat permanantly fixed their front brakes with these procedures?

Wonder how long the good feel will last this time?

Thanks, (sorry for the long story)
EG

BTW, I have no visible leaks...

 

[Katoum]

In case you have not already done so, you might want to check the rotor runout, if it is warped a little it push the piston back into the caliper, my old YZ use to warp when it got really hot from fire roading, then full late breaking into corner causing some blue disk, next application of break would require two full pumps on the lever. Also check for air trapped in the banjo bolt, tip the bar up and tap the bolt with wrench and look for any bubbles that rise from bottom of reservor.

 

[r1lew999]

I have got a new 02 300exc and also suffered with spongy front brakes that did not engage until the lever was nearly back to the bar.
I attempted to remove the front caliper to back bleed them but managed to nearly round the soft alloy caliper bolt heads (lesson for me: NEVER use 12 point sockets on these soft nuts. always use 6 point flat grip sockets).
So i just pushed the pistons back into the caliper without removing anything then pump them back out with the lever. I did this about 5 times and the brakes were massively better.
I also took some of the collar off the black plastic adjuster knob to give a bit more adjustment. now the brakes are perfect.

I could not believe the difference this has made. Previously I bled the brakes with about 0.5 litre fluid using the conventional top down method without any success.

So far this mod has lasted for 3 rides with no sign of sponginess. I can only assume that the master cylinder had a pocket of air which was shifted by forcing some fluid back through it.

Thanks for all the tips.

Paul (300EXC, UK)

 

[jeb]

Originally posted by r1lew999
I attempted to remove the front caliper to back bleed them but managed to nearly round the soft alloy caliper bolt heads (lesson for me: NEVER use 12 point sockets on these soft nuts. always use 6 point flat grip sockets).

I'm about 100% sure those caliper bolts are steel, not a soft alloy. Good idea to use a 6 point socket whenever you can, though.

 

[marcusgunby]

I find most bikes benefit from moving the pistons across once in a while-i rode a 03 KX the other day and my CR brakes felt only average-i havnt touched them all season-im going to move the pistons across and see how it works out.

 

[KTM-Lew]

Mine went soft once in a year of owning it. I did the push the pistons in and bleeding it and it has been fine since. The one thing I allways do is park the bike with the bars turned to the left so the MC is at the highest point.

Seems to have worked. My bike was last ridden early in July(back & knee trouble) and the lever is still solid. :yeehaw:

 

[Chouca]

So i just pushed the pistons back into the caliper without removing anything then pump them back out with the lever. I did this about 5 times and the brakes were massively better. I also took some of the collar off the black plastic adjuster knob to give a bit more adjustment. now the brakes are perfect.

What a simple and efficient miracle-cure, I took about 2 - 3 mm off the plastic and now I can adjust the front brake to the right position, gives me way better frontbrake control!!!

. :thumb: