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Discussion Starter #1
I can't really afford a fancy rear shock. Hell, I can barely afford a new spring for the stock shock. Anyways...

Is there any way to get the old rear shock oil OUT and new oil IN?

I have access to a large garage, lots of tools, so that isn't the problem. Lathe, band saw, MIG welder, table saw, you name it.

I know somebody here (FOG, dad, I'm looking at you guys....) has tried this at some point, what were your findings?
 

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You could drill a hole in it, it's gas charged but thats not a big deal. then you'll need to weld on a boss to be able to reseal it, and of course re- presurize it with nitrogen.

Y?

FOG
 

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isn't it nitrogen already in the stock form ?


Mulcibre : did you check for the spring swap dad already described in a different thread ?
 

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Discussion Starter #4
I didn't realize it was a gas shock in stock form, no kidding....

I've read dad's post on the hypercoil spring in detail, the issue that dad brings up is that the damping rate of the shock is just woefully inadequate, and results in tire tearing at track speeds. The cost in tires alone would eventually add up to the cost of a penske or works shock, so I was hoping there was a way to side-step the tearing issue with dad's spring mod.

I do ride fast enough that I think it would be a problem.

My initial guess is that adding more pressure would create a stiffer shock. The shock body is made of steel right? In which case, welding it wouldn't be so bad.

Seems to me, that welding an air line to the shock, which goes to a remote fill point with a gauge attachment is the way to go here. I wonder how much the fittings/gauge cost though... if the cost comes close to $100, then it just isn't worth the effort.
 

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Fitting an air line will only be like a stiffer spring, and allow sag adjustment. The rebound will only get worse as you add air pressure. The nitrogen is in there to retard oil foaming. you would need to increase the visvosity of the oil to improve the rebound . but then the Bounce is afected too.

FOG
 

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Keep in mind that the pressure is only working against the area of the damper rod, where it goes through the shock body. Not a lot of surface area there. Everywhere else in the shock has the pressure working against both side.

Putting a heavier oil in and a heavier spring might just be the ticket though.
 

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FazerDude said:
Keep in mind that the pressure is only working against the area of the damper rod, where it goes through the shock body. Not a lot of surface area there. Everywhere else in the shock has the pressure working against both side.
The extending force on that shock from the piston effect of the shaft is about 54# calculated using the charge pressure. Those items are detailed in one of my posts on the subject and include the details. Pressure was about 245# if my memory is correct but it's a spec that's in the factory service manual.

I wouldn't bother with taking that shock apart unless you were a suspension expert with all of the tools handy. To pay somebody for that service would be well into the direction of a new and proper shock. If you have specific issues with one like leaks or bent, search a used one for about $35 and be done with it. OR buy a Penske. 8)
 

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Dad's absolutely right, I went along with the thread just to see where it would go. Also I'm always ac used of being negative.

On being negative; it comes from the fact that there almost ain't much you can do that will actually be an improvement to a EX. Other than tailoring the suspension to suit how you ride, almost everything else beside decoration is going backwards, and I fine it necessary to tell you (it's my job)

FOG
 

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Discussion Starter #9
no problem guys, at least we had a mature discussion on why it's completely unreasonable. My most important mod for the bike... getting a job... is almost complete, then I'll be able to hook it up with a penske or works shock. Thanks all!
 

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Let me just add that the tire tearing will only be a problem on the track. Even the most ideal street twisty riding will not be hard enough on the tire to cause the severe tire problem that only a pretty fast rider will have on the track. If this is to be a street bike I wouldn't worry about the tire thing. On the other hand, if you're severely balling up the rubber on your street rides, you'll have the tearing problem on the re-sprung stock EX shock. I would find it hard to believe that any street riding is balling rubber like the track and if so, if you've survived another week of that, :eek: would highly advise against such riding on the street. ;) ;D

These opinions are based on extensive experience with both track and intense street twisties, and a reasonable amount of both specifically on a re-sprung EX.
 

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While we are talking shocks, anybody know a ballpark PSI for a nitrogen Fox Shox? I can't seem to remember ???
 

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Prolly on the order of 300 PSI.

FOG
 

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Discussion Starter #13
the bike is gonna be a do-everything, track, performance street, commuter, and touring. When I go back home again, I'll be riding against my girlfriend's brother and uncle on a pair of zx6r's at the track, so I have a feeling the 500 will have to give 110% just to keep up :-\
 

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Mulcibre said:
the bike is gonna be a do-everything, track, performance street, commuter, and touring. When I go back home again, I'll be riding against my girlfriend's brother and uncle on a pair of zx6r's at the track, so I have a feeling the 500 will have to give 110% just to keep up :-\
That'll do it. ;D If you're going to track it that much go all of the way to a Penske, skipping over the Works shock.

And don't get overanxious and think you might do well to wind it tighter. Top performance will be using a redline in the range of 10,000 to 10,200 with a 10,500 being absolute tops. Frequent excursions higher than that are fruitless and take a real toll on the bottom end. Also, stock main jet is the best up top. It will run with one larger but will not pull as strong, being slightly too rich. Fog can add more first hand info to that. Good luck. :)
 
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