Front Fork Seals/Prog Springs

EasTexRIII said:
Thanks for input guys - I'm baffled that I feel like I drained the forks thoroughly including the dampers by pumping them until they had no pressure and continuing to pump several more strokes afterward (no jokes plz). When I put in the 667cc's I then pumped up the damper thoroughly and after waiting for it to level out it was overfilled, so had to pour a little out and fall back on the level measurement method. With the damper rod up, it sits approx 10mm lower than with the rod down (compressed) - I think the picture is misleading n the rod should be down for the measurement. Anyone know if that's correct?
Click to expand...
What's the best way to get all the old fork oil out in order to replace it with the new 7 weight?
 
Here's the thing Clint , I experienced exactly the same thing a few weeks back . On filling the fork , the damper rod should be pumped at least 15 to 20 times to displace the air and fill the cartridge . You know when this is done coz you feel the damper rod "damp " fully during the up and the down stroke with no sudden give ! Then you walk away and kiss the mrs whilst the damper rod and oil settle . On returning from kissing the mrs, or having a beer depending on the mrs mood , you then measure the air gap which should be 89mm according to the specs ! Now then ! Why doesn't the 89mm correspond to 667cc ? After much head scratching , it occurred to me that the progressive springs displace more oil , around 100cc less oil per leg in fact to obtain the 89mm air gap with my hyperpro springs . On completion , I put a zip tie around the stantion against the oil seal cover and took the bike for a good old thrashing. . The zip ties indicated that I had been using all but around 1third or so of the available fork travel , thus leaving a bit extra for when the little lady is perched on pillion ! The handling is transformed and the fork seals still intact so happy days ! :) :)
To answer the initial question though, air gap should always be measured with the fork fully compressed and the damper rod down ! :thumbsup:
 
vocaldog said:
What's the best way to get all the old fork oil out in order to replace it with the new 7 weight?
Click to expand...
Best way to get the old oil out , is to remove forks from bike , undo the fork top cap , compress the spring via the aluminium bush which exposes the fork cap locknut at the top of the damper rod . Loosen the locknut and unscrew the fork top caps from the rod . Remove the aluminium bush , remove the spring and whilst holding the top and bottom of the Forks together , pour the oil out of the fork leg . With the fork tubes compressed together you can just about grab the top of the damper rod , pull this upwards and then pump the rod full strokes up and down until the cartridge too is empty of oil ! It should take about 15 to20 full strokes to do this and you will feel when it's empty . It's best to then leave the whole fork upside down in a receptacle for a while to let the remainder of the oil run out . Return the fork back to upright , make sure the tubes are fully compressed and refill with the correct amount of oil ! After removing the top caps , if you are not replacing the seals make sure you hold the top and bottom of the fork together at all times when turning the fork upside down or the 2 halves will separate !
Hope this helps :thumbsup:
 
Nat67 said:
Here's the thing Clint , I experienced exactly the same thing a few weeks back . On filling the fork , the damper rod should be pumped at least 15 to 20 times to displace the air and fill the cartridge . You know when this is done coz you feel the damper rod "damp " fully during the up and the down stroke with no sudden give ! Then you walk away and kiss the mrs whilst the damper rod and oil settle . On returning from kissing the mrs, or having a beer depending on the mrs mood , you then measure the air gap which should be 89mm according to the specs ! Now then ! Why doesn't the 89mm correspond to 667cc ? After much head scratching , it occurred to me that the progressive springs displace more oil , around 100cc less oil per leg in fact to obtain the 89mm air gap with my hyperpro springs . On completion , I put a zip tie around the stantion against the oil seal cover and took the bike for a good old thrashing. . The zip ties indicated that I had been using all but around 1third or so of the available fork travel , thus leaving a bit extra for when the little lady is perched on pillion ! The handling is transformed and the fork seals still intact so happy days ! :) :)
To answer the initial question though, air gap should always be measured with the fork fully compressed and the damper rod down ! :thumbsup:
Click to expand...


You're zackly right. I figured those things out as I went along with the same results as you........ great minds stink alike! :D
 
EasTexRIII said:
You're zackly right. I figured those things out as I went along with the same results as you........ great minds stink alike! :D
Click to expand...
:rolleyes: :rolleyes: I don't suppose you measured the oil that came out of each leg did you ? I had a little under 150cc less oil in the left leg as I did the right one ! That is a heck of a difference . :thumbsdown: :) :)
 
Nat67 said:
Best way to get the old oil out , is to remove forks from bike , undo the fork top cap , compress the spring via the aluminium bush which exposes the fork cap locknut at the top of the damper rod . Loosen the locknut and unscrew the fork top caps from the rod . Remove the aluminium bush , remove the spring and whilst holding the top and bottom of the Forks together , pour the oil out of the fork leg . With the fork tubes compressed together you can just about grab the top of the damper rod , pull this upwards and then pump the rod full strokes up and down until the cartridge too is empty of oil ! It should take about 15 to20 full strokes to do this and you will feel when it's empty . It's best to then leave the whole fork upside down in a receptacle for a while to let the remainder of the oil run out . Return the fork back to upright , make sure the tubes are fully compressed and refill with the correct amount of oil ! After removing the top caps , if you are not replacing the seals make sure you hold the top and bottom of the fork together at all times when turning the fork upside down or the 2 halves will separate !
Hope this helps :thumbsup:
Click to expand...
Thank you so much for that excellent step by step, but Jeez..... that makes me want to just open the caps, put in the new springs, and leave in the old 5W oil.
 
vocaldog said:
Thank you so much for that excellent step by step, but Jeez..... that makes me want to just open the caps, put in the new springs, and leave in the old 5W oil.
Click to expand...
Unfortunately , you can't change the springs without removing the fork caps ! It sounds much worse than it is to be fair . The hardest part is compressing the spring via the aluminium bush to get at the cap lock nut . I am lucky enough to have a fork spring compressing tool which makes life easy but I think @EasTexRIII used workshop innovation to do his ?
20170211_140511.jpg
 
I have a little gizmo that Nolton left in my shop when we did his forks. It is a graduated steel tube about 1/8" in diameter that has a stop ring on it amnd a syringe attached to one end. Fill the fork tube as noted above with a little more oil than necessary, set the stop ring on 89, compress the fork tube and draw off oil to the proper depth...simple
 

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