Got a line on a F3 rear shock that looks like it's never been mounted for <$30. Problem is that the reservoir has been removed. It's included with the sale, but of course, the nitrogen is all gone. Thing is, I'm looking at pics online and I do not see how the shock gets filled again. My own bike is an F2 and I was hoping to upgrade to the F3 shock, but:

1. Where is the nitrogen put back into the assembly? Was expecting to see a Schrader valve somewhere, but...?
2. Who can do it? SM says 142psi, but who can accurately supply nitrogen at the needed pressure?

Thanks!

 

So...no one with an F3 has ever had to put gas in the rear shock?

 

There are specialists who rebuild shocks, I would think they can do it.

If it will bolt straight in or not I suppose anything can work with enough fiddling.

 

Im guessing you dont have the 94 F2 shock, which is essentially the same as F3 shocks. If you have to go through the trouble of having a factory shock filled with nitrogen then you may as well have it completely rebuilt for your weight & type of riding. But replacing a OEM shock with a different OEM shock even if you do have it rebuilt really isnt much of an upgrade. Or the better option would be the aftermarket Fox shock or and Ohlins, and have those rebuilt for your weight & type of riding.

 

Yeah, well, I'm not keen on spending that kind of money. Fox no longer makes a shock for the F2 or F3, and while I might be able to monitor eBay for the next 10 months to find a used one, that's a less than appealing option.

The Ohlins...well, that shock cost about 1/2 of what the whole bike is worth. That's from sellers that have what they claim is a shock that fits my bike, even through Ohlins shows nothing for the F2 or F3 on their website except fork springs.

Anyway, I've done a few track laps on the F3, (some years ago) and I liked the suspension a lot better than what's on my F2 (the guy I swapped bikes with agreed that the F3 was a noticeable improvement). Eventually, I'd like to find some F3 front forks to go along with the F3 rear shock, but ATM it's only the shock that I have a line on.

As far as my original question, I found the answer myself. The stock F3 shock (and 1994 F2 shock) has NO provision for recharging with nitrogen. Race Tech has a replacement reservoir bladder cap with a schrader valve that must be installed if the shock has lost pressure. Race Tech will rebuild the shock and add their bladder cap for about $200. I could live with that.

 

You dont need F3 forks, only if you want upgraded braking. Find a set of 94 F2 forks, they're the same as F3 forks except the brakes and wheel. That way you can still use the original wheel and brakes thats on your bike now. F3 fork, now you got to get the F3 wheel, and F3 brake rotors and calipers, that IS "spending that kind of money".

 

On a side note, how the heck did they get the nitrogen in the shock in the first place if there is no schrader valve. The air we breath is around 79% nitrogen anyhow.

 

True...mostly. But the F3 forks are much more common, AND, the F3 tube and inner workings will fit fine in the F2 bottoms, so I can keep my wheels and speedo. But I would love the F3 brakes (however, not at the cost of losing the speedo).

The other thing is that a lot of sellers are fairly clueless as to what the parts actually came off of to begin with, so while they might advertise that it's an F2 part, they may have only a vague idea of the year. Thus that one year where the F2 got the cartridge forks might be a bit elusive.

Valid Q.
Yeah, but if you've ever been to Houston in the summer, you know that that last 20% of oxygen can carry a buttload of moisture. Plus, oxygen under pressure is just not the safest thing going (re: check the thickness of welding tanks).

 

F3 uppers & internals with F2 lowers, makes sense. You definitely have to look at what your buying when buying from eBay. I got all excited one time and bought what was said to be a Ohlins F2 shock on eBay at a awesome price. After a day or so I was looking to see where it was on the shipping route, and looked at the picture of the shock again and BOOM, I realized it was not a F2 shock. But it was a shock for some kind of honda. I ended up sending a message to Ohlins FB page with all the numbers. They responded withing a day and said the shock was for a 87 to 90 Hurricane 600. I ended up selling the shock, got my money back with shipping cost and all, even made a couple dollars.

 

If you're ever in the market for a Fox shock, I got one I'd sell. It would need rebuilt for your weight and it looks like it but theres no use in buying one unless you were gonna get it rebuilt.