Hey,

I've got a buddy's shock apart ('10 yz450f) and on my bench, I had the shock apart last fall maybe 30 hours of runtime ago and the wear on the inside of the shock body and on the piston has gotten considerably worse. Which is really no surprise I guess.

Anyone have any experience with this kind of wear ? I'm assuming the fix is a new body and band/seal for the piston ? If I had to guess, I'd say there's an impression on the inside of the body - when you run your finger from non-worn to worn-surface of about 1/64" ? It feels quite significant.

The guy who owns this bike rides MX only at a quick B (intermediate) pace.

What are the effects of this kind of wear going to be (aside from more wear) ? I'd assume fluid will by-pass the ports in the piston and squeeze past the wear in the body/piston ?

I should mention that I had his brother's shock apart last year (fast "A" rider) and the wear on his shock was quite a bit worse. I've had 30 or 40 different shocks apart and have never seen this before.

One option for the shock body would be to have it honed out smooth and round, and then hard anodize it to get the dimension back. That is assuming that you did not have to take off too much material to get it smooth again.

Get a used shock off of Ebay

NastyR1, on 25 April 2012 - 08:19 AM, said:

There's nothing on E-bay that is less than replacing the worn parts (piston/body) with new OEM stuff.

KJ790, on 25 April 2012 - 07:53 AM, said:

Thanks KJ, I hadn't thought of that as being an option. Any idea what shop would do that sort of work ? I'd assume that sorta stuff is pretty specialized ?

crf450319, on 25 April 2012 - 09:45 AM, said:

You would probably need a machine shop to hone it smooth. Search google and see if there is anyone that does hard anodizing in your area. Any good anodizer should be able to handle it, they will have to rig it up with an internal cathode to anodize evenly down in the hole. If the bore needs to be opened up more than .002" or so then you probably won't be able to bring it back into tolerance with hard anodize. In that case I would recommend using something like a low-phos electroless nickel plating to build it back up, but then you are probably talking more money and it may not be worth it over buying a new shock body.

my rider loose the high speed plate nut!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
the thread broke , stock nut , never uncrewed .
the nut ruin the shock body as your and the piston band as your.
check if the nut and thread is stock or changed.

I think you can get nikasil up to about .006" thick.

mxaniac, on 25 April 2012 - 05:44 PM, said:

Thats a thought, but you'd need to hone the inside out first. I wonder how that nikasil would work on the piston seal...oughta b pretty slick. But even after you had it plated it'd still need to be honed back to spec.

Light Honing and Type 2 anodizing is what needs to happen. Have done this before. Make sure you use all new o-rings/band and seal.

Factor E, on 26 April 2012 - 11:07 AM, said:

Not sure why you're advocating type II, it isn't very thick or abraision resistant.  III can be thicker and much more abrasion resistant which seems more applicable but perhaps I'm overlooking something.

Factor E, on 26 April 2012 - 11:07 AM, said:

mxaniac, on 26 April 2012 - 11:50 AM, said:

I agree with mxaniac here. This is the wrong application for type II anodizing and you will never get enough build-up with type II to replace what was honed out. Type II is pretty thin, and it penetrates the surface as well as builds up, so your overall buildup is even smaller. Type III is much tougher and much thicker.

How much material is going to be honed out of a shock in your opinion?

I hone cylinders for a while now using a 3 arm hone from KS tools.
The hone stones of this hone are to weak to get a proper cylinder face, so we use 80 gritpaper on the surface (European 80 gritpaper, US ones have different terms).
Its very very very rough but works best for getting a nice honed surface.
My YZ cylinder is 54 mm stock. I rode 2 pistons on that cylinder and honed it twice as I wrote above and its actuall seize now is 54.003-54.008 mm,
There was no real wear on the cylinder, even with honing a long time with 80 grit paper.

Of course I'm talking about a nicasil coating and no anodizing. But even anodized fork legs are honed in the factory. Look at the outa tubes coating on the inside. You can see the honing near the top cover of the fork.

What I am trying to say is honing doesnt take as much material of a subject as people might think!
If someone measured a tube, honed it and measured it again and can proof that there is significant less material, your welcome!

Vietze, on 27 April 2012 - 03:23 AM, said:

We're not talking about honing a nikasil cylinder, we are talking about honing an aluminum shock body to remove scratches. An aluminum oxide hone is softer than nikasil, so when you hone a nikasil cylinder you do not remove any material. When you hone an aluminum shock body you remove material. You would have to remove enough material to eliminate all of the scratches, which would be a pretty significant increase in diameter from a machinist's point of view.

i wuld find out how much you can get a new shock body for. i think i got one off dave j for around 90 british pounds. just a thought.

Ok, so we have talked about how to fix it.  But what causes it?  Bad anodizing?  Oil?  Piston band?

I've seen it a two times on Showa forks.  Same guy, two different bikes.  Maybe a oil problem?

someone know the price of a new shockbody?

Same on my shock (YZ450 2011). A new shock body here is € 170 plus tax. No too bad imo.
I have had approx 30 hrs on mine when the first service was done. The grooves already have been there then...'don't know where they comes from nor does my mechanic.

Yamaha8378976 or what ever his name is , sayed he got 1 from Davej for £90.

my shock have 100 hours