Nr-4 Service

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Hi,
I'm stuck on my NR-4 now, I thought it would be a good time to service it after doing my rear brake.
I can't figure out how to remove the piston, I've dismantled the piggyback oil reservior and removed some pretty nasty oil.  But what now?
Has anyone ever done this before?

I've downloaded the NR-2 service sheet from the files section but it's only got me this far.

Any pointers would be great
Cheers,
Luke

PS- yes I know this was a silly thing to do, but sometimes my tool arm is quicker than my brain [smiley=disbelief.gif]

[rapiddescent]

oh dear.
the shock is nitrogen charged so unless you have the noleen equipment - then you're going to have to send the parts to a noleen service agent to fix it up.

Also, please be careful because the damping pin is held under pressure.  There is a good story where a proflex sponsored UK rider shot a damping pi through the car roof in the carpark at a race.

the only noleen servicers i know of are CVI in the UK and NoleenUSA

callum

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I have a noleen filler kit, and I was carefull to bleed off all the pressure in the dampener before dismantling it.
I also have a complete new set of o rings and seals to install.
All I need to do is figure out how to remove the piston to put them on.
Then I can reassemble and recharge the shock with the filler kit.

But the piston is prooving very hard to remove- what am I missing  

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  wahooo! I have the piston out and disassembled.  I looked up a page on how to service motorcross shocks, and everything on the NR-4 is sooooo similar just a lot smaller.  I'll write a little how to on this when I get a minute.


But now for the bad news....... my seal and bushing kit is the for the wrong shock!!!!!  It's a noleen nb-1000 kit, which looks like it may be for an older noleen shock with an 8mm shaft.
I might just have to source some new o-rings and leave the bushes be. [smiley=upset.gif]
Oh well, the kit probably fits the shock on my 955 in NZ anyway

[Ionit]

Do you have any pictures of the NR-4 disassembled. I bought the nitrogen filler with the intention to do the same thing but without proper instruction I am too intimidated to start. Is this the filler you have?

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Sorry, I was too covered in shock oil to go messing around with my digital, but here's a cut-away pic I found on the internet


I've also uploaded the motorcross shock service instructions I used.  The NR-4 is basically the same construction, just smaller and lighter.  The only real differences are that there is no air bladder in the NR-4, instead it has a air compartment formed between the two moving seals in the piggyback reservior.

When reassembling the shock you WILL get oil everywhere- be prepared

Yes your refill kit looks the same as mine, but beware, the seal and bushing kit that was included appears to be for a shock with a smaller shaft diameter, maybe a NR-2 or ODS?
Anyway I ended up not replacing any of the bushings or seals, just giving everything a darn good clean and she's functioning pretty well again.

Note- the motorcross manual says one must recharge the shock with nitrogen.  This is not to keep your oil in pristine condition but to avoid the danger of over-pressurization when the shock heats up.  it air and nitrogen have different expansion rates.   [smiley=coolfrown.gif]  Well call me gung-ho but I can't see my little shock getting hot enough to explode on me  if I filled it with air, so I did just that.

I'm also planning a modification to it to let me use a normal shock pump.  I may drill out the rubber needle valve and fit a high pressure shock valve in it instead.
The end result being a valve on the bottom of the piggyback reservior.
This would let me use a standard shock pump and stop me fiddling around with filler kits, fitz and pumps/nitrogen tanks.
Could be a bit risky though- what do you guys think?? [smiley=groucho.gif]

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oops, the pic didn't post for some reason, here's a link to my gallery.  Some of the seals/bumpers in my shock were a different colour but all in the same spots

ftp://http://idriders.com/proflex/galleries/loaded/noleen.bmp

[shovelon]

I am sure that the majority of air is nitrogen. I too am not a big believer in nitrogen. The reason that nitrogen was introduced was to keep the foaming tendency down. I do believe that nitrogen creates more heat when compressed, and can transfer that heat to the oil. But that much heat?

Terry

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Yeah, that was my thinking too Terry
I can imagine a motorcross shock being put under a lot more stress, (more weight,  bigger hits, faster speeds, tighter dampening valves etc) and heating up a bit, but as for a mountain bike shock I think air will do fine.  

Unless I'm going to be riding in an active volcano I can't see expansion through heat causing any problems at all.

What do you think about putting a valve in the piggyback chamber of the NR-4?  possible??
Cheers,
Luke

[p1973rsr911]

Does anyone have a recommendation for shock oil?   Synthetic vs. conventional, manufacturer, viscosity (cSt).    I am actually rebuilding a NR-1 for a ProFlex 856 rear.

[Blackjoy]

Just call Noleen.  They are still in business.  I had my NR-4 and NR-2 serviced by them about four years ago.