Please help!!! Fork springs don't work

[Zhenya13]

Well today I finaly got to installing the progressie fork springs I bought a month ago. Now I did it using Pablo's method. I cut the original spacers to make new ones for the progressive springs. PVC tubing that I got was just a tad to thick to go in to the tube.
The only problem was, as to how much of the new oil to fill in. I used a vacuum sucktion oil gun,at my local car mechanic,  to get the oil out. However I did not know How much of new oil to fill in. I think I overfilled it cause when I put everything back together the oil was coming out of the forks.
Now one other thing to mention is that I put the springs in with the tighter coil in the bottom of the spring, hope thats right.

Now to the problem! As soon as I got on the bike I almost killed my self. It was like the bike has no shocks what so ever. With every smallest bump it was like my hands are being hit with a hammer. But  the worst part was breaking. When I started to brake I could not controll the bike, the stearing was shaking and the will was woubling from side to side, I almost fell.

What did I do wrong please help!!!

[Ed89]

Sounds like you have overfilled and the fork is not compressing at all.  There should be instruction as to how high to fill the oil to.  Remove the spring and spacer, compress the fork all the way, measure the distance from the top of the oil to the top of the fork.  The instruction will tell you what that distance should be, if not, just search the forum.  Then only you put the spring, washer and spacer in (after extending the fork, of course).

HTH.

[scratch]

Either that and/or too much spacer/preload. The tire was squirming under the pressure of braking! Now, I've stated 350ml/cc's when I changed to Progessives, but now that I've gone to 5wt I can really feel how stiff the spring is for me (I'ma 125lbs/57kgs) and that's with only 3/8th inch of preload.

I thought the fluid level was supposed to be 140mm from the top of the fork tube, with the tube fully compressed inside the slider (lower fork leg), without springs: http://gstwins.com/forum/viewtopic.php?t=17726&highlight=140mm

[cay]

The local dealer said 372 ml per leg -- alternatively, you could measure the height as described in the documention provided with the springs.  That's what I did.

[scratch]

372cc's with the stock springs. He has the Progressives which displace more oil; you would encounter hydrolock at the end of fork travel and 'bottom out' causing your front tire to 'squish' and deform to compensate, the tire then becomes the suspension and can become overwhelmed by both traction forces and load and wash out.

[raylarrabee]

I straightened out a coathanger, then measured out the oil depth stipulated in the directions.  Put a piece of masking tape on at the right place.

Used this to measure.

[Blueknyt]

funny, most folks ive talked to and a few sites ive seen say( concerning stock forks)

: with the tube compressed and the spring installed, pour in the oil intill its about 6" from the top of the tube, then extend, put in your spacer (if required) install the cap and tighten to spec.    


this is how i do it and dont have any problems.

useing the suction tube methode isnt the greatest. your better off removing the front wheel, and pulling the bolt in the bottom of the fork and let it all drain out the bottom.

[Ed89]

funny, most folks ive talked to and a few sites ive seen say( concerning stock forks)

: with the tube compressed and the spring installed, pour in the oil intill its about 6" from the top of the tube, then extend, put in your spacer (if required) install the cap and tighten to spec.    

Measure oil height with the spring installed?  I suppose I am wrong about that then.  My bad.  Sigh.  Senility setting in.

Cheers,
e.

[Blueknyt]

i dont know if its right or wrong, but the 3 bikes ive done this to all seem to work well.  i suppose if the tube (chrome part) is really long like on some choppers you would have to be more precise. but even my parts guy who still races said it the same way nearly word for word.

the forks use a combination of AIR trapped in the tube and valved oil passages.  oil doesnt compress but air does, when the fork compresses it pushes on oil which squirts through holes in the valves,making its way from the Lower leg into the tube. this oil flowing slows the tube travel, as the oil fills the tube its trying to take up the space that the air occupies raising the pressure, this pressure fights against the oil coming, further softening the compression. Air forks can add preload to a fork (think Air ride) but as air is less dense then oil, it can leak past seals easier and should never have more than 10 psi in each fork.   the more oil and less air the harder it will be as the oil will have less area to go.