2010 FREE PISTON BROKE?

[walent215]

next to the oring on the free piston is what looks to be a Teflon or nylon washer with a "crack" in it...kind of like a lock washer...not sure if that is the design or it is broke? also the piston has 2 holes drilled in it...is this stock or has someone drilled it? thanks in advance.

Edited June 21, 2014 by walent215

[slammedmind]

next to the oring on the free piston is what looks to be a Teflon or nylon washer with a "crack" in it...kind of like a lock washer...not sure if that is the design or it is broke? also the piston has 2 holes drilled in it...is this stock or has someone drilled it? thanks in advance.

Im not sure on the piston, but the nylon washer is fine, thats how it comes.

[walent215]

Im not sure on the piston, but the nylon washer is fine, thats how it comes.

awesome...thanks a lot....

[sploon]

Really common for them to crack. Altho i dont think thats a crack its like a guide to locate the oring.

Look at upgrading to a alloy piston. i went through 2 plastic pistons before i had a plastic one smash and cost me 1 fork cartridge >.< $$$

2011 yz250.

 

I dont know where in the states you can buy them because Norm Cobb from suspension tech in New Zealand had them made.

[Hans Schmid]

Someone drilled the piston....

DaveJ with Smart Performance will sell you aluminum pistons for about $70 a piece...

[walent215]

so these pistons break often and destroy cartridges? really? wow.....so if we don't upgrade to aluminum we run the risk of catastrophic failure...not good...

[grayracer513]

Who said anything gets destroyed?  All the OEM parts of that piston are plastic.  The most most catastrophic thing that's apt to happen is you'll get a bit of it stuck in something like the bleed port and have to do more than the normal amount of disassembly.  

 

Once they're drilled, they aren't likely to fail in any case.

 

The "washer" is a high pressure seal.  The "crack" is the "scarf-cut" on the ends that eliminates end gap while allowing the seal to expand.  Oil gets behind these and blows them out against the bore walls, forming a better seal at high pressure than the O-ring can. 

[walent215]

Who said anything gets destroyed?  All the OEM parts of that piston are plastic.  The most most catastrophic thing that's apt to happen is you'll get a bit of it stuck in something like the bleed port and have to do more than the normal amount of disassembly.  

 

Once they're drilled, they aren't likely to fail in any case.

 

The "washer" is a high pressure seal.  The "crack" is the "scarf-cut" on the ends that eliminates end gap while allowing the seal to expand.  Oil gets behind these and blows them out against the bore walls, forming a better seal at high pressure than the O-ring can. 

sploon...a few posts up from yours....

 

thanks for the info on the piston and "washer" ....good to know....I feel much better knowing that....

Edited June 22, 2014 by walent215

[sploon]

sploon...a few posts up from yours....

 

thanks for the info on the piston and "washer" ....good to know....I feel much better knowing that....

..... i said you should look at replacing it...... esp since its allready apart. it doesnt happen to everyone but i just had a bad run with them and the only explanation i could get out of it was it was caused by lack of finess overjumping etc. Dont jump to conclusions but the alloy piston is what i put in all my bikes from now on.

[walent215]

Not jumping to conclusions, just wondering what the story is with them? Thanks everyone for the education....feeling much better about them now....I put new seals and bushings and new fluid in ....can't wait to try them out....