Fork bleeding

[docc]

I can appreciate the proper method to change fork oil is to remove them. I have done it that way, but it's a PIA especially on the early Sport where the absolutely everything up front mounts to the triple clamps.

 

So, I thought I would be creative while the front wheel is off for a tire and open the forks on the bike, siphon out the fluid, cycle the cartridge and give it some fresh juice. I knew I wouldn't get all the fluid out this way (or sediment in the very bottom), but I figured it's better than no fluid change at all and thought if I do it more frequently, it's going to add up.

 

I was disappointed that the refill to 100mm air gap was only about 200ml. After doing the compression side I measured the recovery volume and see more like 300 ml . . .

 

So, first, I'm afraid the oil level is going to drop as the forks cycle (?)

 

And, second, instead of using a tube inserted in the upper housing (about a foot/ 310 mm), can fluid be siphoned out through the cartridge rod thereby getting nearer the very bottom of the reservoir?

[gstallons]

With the front axle removed , you can remove the socket head (Allen) capscrew at the bottom of the fork to remove all of the fluid. There is a tiny set screw that holds this bolt tight , so look for it. You can extract the internals out of the fork tube and observe the fork fluid as it goes all over the shop floor! There is an index at the bottom ( double-d or hex ) to keep the internals from spinning as you tighten the bottom screw..

[docc]

So, no clever shortcut . . .

 

Traxxion Dynamics sells a Fork Bleed Tool that looks like it screws on to the cartridge activating rod. Seems like a guy could just fit a tube to it and suck the fluid out from the bottom. I couldn't get down past the spring base by inserting a tube from the top (about 2/3  of the way down).

[emry]

You will still leave about 50mm worth of fluid in the fork (that is a guess not a measurement), the compression rod stops short of the rebound assembly. I have just pulled the cartridge bolt on forks that use it as previously mentioned if you really want to change the fluid. Normally if I am putting new fluid in it gets new seals also so it is a fork off job anyways.

 

Docc, that photo with the pump is too funny!!! No insult meant of course. 

[docc]

HA - no insult taken.    I realized from the start that this was a bit of a bodge. I suppose I'll let it circulate for a while and pull the lower bolt (now that we all know about the SET SCREW that's not in any of the diagrams).

 

I'm thinking I should probably change the fork oil every other front tire (about 14,000 miles). It still looks like it could be siphoned out of the actuating rod.

[emry]

If you are changing the front that often are you changing the rear also? It goes over the same bumps and gets worked even harder.    Personally I think you are going for overkill.    But it definitely wont hurt if you have time and the oil. 

[docc]

I feel like I let it go too long this time: about 25,000 miles after my spring change/sideways-fork-rebuild in 2008. If I can suck it out from the bottom (where the action is) I think this might be an OK expedient. Otherwise, I don't think I've changed much just changing the oil around the spring.

 

Maybe it'll mix itself around, but looks like better method to remove the bottom bolt and drain it all. At least that can still be done without releasing all the kit from the triple trees.

[andy york]