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Working on a Shock: 46 mm kyb 08 yz125

Want to minimize friction of the piston band seems a bit tight.

I have seen mention of clearancing the band...someone mentioned just the top & bottom (leave the center higher,)....what is the preferred method, rotate and sand?

Also, mostly mentioned with the 50mm pistons , but where and what diameter hole is drilled (to equalize pressure behind the band).

Thanks I searched and could not find details on this.

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Working on a Shock: 46 mm kyb 08 yz125

Want to minimize friction of the piston band seems a bit tight.

are you sure it'S tight?

The KYB bands usually are running quite good (at least my experience)

just those of a Showa (esp. 50mm) often seem to be pretty tight

Did you repace the piston band? In this case it has to be compressed to fit.

See this thread here:

https://thumpertalk.com/forum/showthread.php?t=757378

There's also a pic of the drilled band

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Yeah, mormally the 46mm kyb fit just right.

On the showa's we use a levigated (spelling???) hone to hone the shock body.

This would probably work on he kyb as well -- if needed.

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it's not a new band , i was revalving the shock and just analysed the existing band. there is a couple of lbs of stiction, I didn't put a spring scale on it, but I could. My intutition says it would be better if there was less stiction.

so in you experience how much stiction is there normally? I am testing by hand with lubed band & inner wall but not fulll of fluid (mostly dissasembled)

thanks for the advice so far

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I just measured the stiction (force to overcome static friction...i.e get the damn thing in motion lol).

There is 12.5 lbf of static friction...seems like a lot to me...but maybe this is common?

This is with the piston band/cylinderwall/shaft & seals well lubed

FYI the forces from the seals/wiper bushing are negligeable, there was no measurable difference in force without the wiper/guide/seal assembly

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the kyb has almost no stiction normally and work well due it , take some off till it's smooth in the bore

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thanks mog,

should i chuck it in the lathe and hold sand paper on it...is that the best way?

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the kyb has almost no stiction normally and work well due it , take some off till it's smooth in the bore

:smashpc:

yes, the 46mm KYB ,but not the newer 50mm.(CRF09-KXF10).

i think the best way would be softer O-Rings on the Piston(less 70 Shore) and stock new Piston Bands.

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yes use sandpaper , just measure it and go in small steps, on the showa i find 50.2mm is about right(50.3 std)

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