How to change fork oil without removing fork legs ?

[Nyme]

I am sure I have read somewhere that a simple way to remove old fork oil and change(as I don't want to do anything else to them at this point) is to :

Undo top nut on each fork leg and remove - with forks uncompressed and bike on center  stand  with front wheel lifted by a jack under engine.

Use a large Syringe with long clear hose attached (and I am sure I read, tied to a long thin plastic rod so it reaches straight to bottom of fork leg) to suck out old oil,

Then simply pour in correct amount of new oil to get correct level from top and do the top fork leg nut back up ?.

However, I think I also saw that you need to compress forks to check oil height (unless I can just go by volume poured in).
I think yet again this can be done with a syringe with correct length of tube attached, inserted to fork leg and just extract oil until no more comes out - so at correct height.

I have seen postings on difference with Progressive springs (I have gold valve kit fitted with the springs), the oil weights and heights from top of leg, but would be grateful if someone could just confirm this is how I can do this, and preferably that they have used this approach,  before I start to try it ? Any advice welcome.

Many Thanks

[Gryphon Rider]

The method of measuring from the top of the fork down to fluid level to ensure the right amount of fluid is done with the springs removed.  The other method is to ensure the forks are completely drained, then add the carefully measured proper volume of fluid.  The volume is different left vs right and Standard/Tourer vs Interstate.  All this information is found in the service manual.  The tolerance for the volume of fluid required by the manual (± 2.5mL [±0.08 US oz]) is tight enough to require a graduated cylinder to measure it.  If you are confident that you have the proper volume of old fluid in it now, I suppose you could carefully measure the amount you take out of each leg, then replace it with exactly the same amount.

If the forks are working fine, I wouldn't bother changing fluid, no matter how old, until fork seals start leaking.

[Nyme]

Thanks for response, and I had overlooked the springs out bit.

The measure what you take out and refill same volume makes some sense and keeps it simple although not sure what grade is in there now, or even if shop put correct volumes in - but they did have fork legs out and instructions from Progressive,  so I ought to be able to assume they put correct amount in as per those instructions.


I am only really considering doing this as I have always suffered a really nasty 'chattering' or harsh 'clunk' from front end over even minor road imperfections and never been able to resolve it. Makes anything other than really nice smooth tarmac a noisy and uncomfortable embarrassment.

Ii was like it when I got it 7 years ago and the fitting of a progressive gold valve and springs kit didn't resolve it. Not sure how much or what oil bike shop put in and I am not at all certain they did the job as per instructions.

So either way I still have the annoying issues.

Head & wheel bearings fine, forks tight in clamps, screens/cobra's/fender guards etc all tight on but still got this horrible front end clattering away (no better or worse than before progressive stuff fitted so at least they didn't cause this).

had been thinking about getting a Traxxion AK20 kit fitted, but a horribly expensive job and I thought I would just try and change oil to get volume about right and maybe try a different weight Oil.

Any views on what weight ? I know what manual says, but at 12stone riding 50% solo (and missus is 10 stone when two up) I am not sure whether to go heavy or light oil to see what difference it may make.

[Bighead]

If you have a clunk in the front end you may have worn bushings in the forks but the only way to tell is take them off and take the forks apart. Personally I don't think oil alone will be your fix.

[olddog1946]

I can feel your pain. I also have a clunk in the front end, tried progressive springs, all new innards (3 times), 5-10-15 weight oils and nothing has made a difference. My first two tries were done by a local shop (with a copy of the honda instructions). The third and actually 4th try were done by the closest Honda shop, with a tech that has 41 yrs experience. He put in the progressives and new bushings/seals and I installed the forks...sounded like the front end was gonna break apart when I hit the entry into a driveway or parking lot.  Took em back...he pulled the progressives, put the OEM springs back in and re-assembled. He stated he'd just put them together the way they came apart the first time and then noticed it was not assembled correctly on the second go around. Came out better but still clunks, I've since replaced the steering head bearings, and still no luck. So, I'm just living with it til it has to come apart for new seals again. I'll do it myself next time, that way I don't have to pay some "tech" to screw it up for me. I've since accumulated the necessary tools to do this.

[valknomad]

Olddog1946.... That really sucks! (and frustrates the hell outta ya). 

Nyme... I just installed Progressive springs a week ago (with forks still on the bike).
agreed!!!   Must be measure with SPRINGS REMOVED and COMPRESSED.  I used a syringe to remove the oil. 
Was able to get all but approx 2oz out from each leg.  But simply reinstalling the "same amount that came out is not a good method".   I did not get as precise as +/- 2.5mL,  but did measure 5.3" (right) and 5.6" (left)   (measured 3 times).

[Led]

I have owned MANY different bikes in my time. They all "clunked" in the fork area, when you hit something sharper, other than a rolling highway. That is just the sound the fluid makes when being forced through the fork super fast. The fork wishes to travel faster than the fluid can.  It is sort of like "hydro-lock".......but doesn't hurt anything. 

Heck.......even my Honda dirt bikes would make that clunking noise on occasion. Nothing wrong, just the way it has always been.......

But clean fluid never hurts at all!!     

[rugguy]

Gryphon: I thought the "volume" measurement had to be done with the springs out, but the "distance" measurement could be done with the springs in? Am I mistaken? I am in the middle of fork seal replacements and would like to be sure.

Thanks

The method of measuring from the top of the fork down to fluid level to ensure the right amount of fluid is done with the springs removed.  The other method is to ensure the forks are completely drained, then add the carefully measured proper volume of fluid.  The volume is different left vs right and Standard/Tourer vs Interstate.  All this information is found in the service manual.  The tolerance for the volume of fluid required by the manual (± 2.5mL [±0.08 US oz]) is tight enough to require a graduated cylinder to measure it.  If you are confident that you have the proper volume of old fluid in it now, I suppose you could carefully measure the amount you take out of each leg, then replace it with exactly the same amount.

If the forks are working fine, I wouldn't bother changing fluid, no matter how old, until fork seals start leaking.

[Gryphon Rider]

Gryphon: I thought the "volume" measurement had to be done with the springs out, but the "distance" measurement could be done with the springs in? Am I mistaken? I am in the middle of fork seal replacements and would like to be sure.

Thanks

On pages 13-24 and 13-32 of the service manual, it definitely tells you to insert the springs AFTER measuring the fluid level.

[pancho]

There are some plastic damper/protector plates glued to the inside the front fender,, check to make sure one has not broken loose and rattling when you hit a bump.

[rugguy]

Gryphon.....I saw your post too late. And I apparently can't (won't/didn't read) the manual correctly. I put new seals in but added the fork fluid with the $%#@! springs in and uncompressed. I love the new feel of the stiffer front end below 60mph....but at 70+ the front end shimmys, shakes and wobbles like it's going to come apart. And when I get into a big truck's slipstream.....I hold on for dear life! I can only imagine that the reason is the excess fluid essentially negates the spring action and makes my front end a hard front (as opposed to hard tail). I'm positive that the extra ounce I added of 15w to each side isn't helping at all either.

Gryphon...I also read one of your posts where you said the following:

You're fine.  The way I measured mine was to snag an 8" long 'zip tie' off the work bench and use it as a dipstick.  It is thin enough to fit down the vent holes and the spring and such.  The ridges on the back also are handy for reading the oil level.  I put in just shy of the recommended amount and then checked with the dipstick.  Then added until it was right. 

Did you measure this with the spring and components in or out? Compressed or not? I know this should be clear tome but I am sometimes easily confused.

I am certain I already might know the answer to this, but is there anyway for me to pull the forks, drain the fluid and replace the fluid with the springs IN? Or, do I need to tear it all down again, buy the Honda tool for the spring cap on the right fork, remove the springs and do it that way.

I am open to doing whatever I have to do to get it right....but am also open to cool shortcuts that work.....unlike mine that did not.


Answers to a couple of questions in advance:

No, the front end did not wobble of shake before seal replacement. Seals were replaced due to a leak and "mushy" ride
Yes, axle bolt, pinch bolts and fork cap bolts all tight and torqued to spec
No, new seals are not leaking
No, there is no front end play between wheel, axle and forks
No, there is no cupping or uneven tire wear on relatively new Avon Cobra
No, there is no "wheel hop" like you would expect if I threw a balancing weight

As always, any help is greatly appreciated....

[Gryphon Rider]

I'm pretty sure the quote about using a zip-tie as a dipstick wasn't from me, as I never did this.  There is a "Gryphon" on this board, but I am "Gryphon Rider".  Might it have been him?  What I did was thoroughly drain the old oil and add a carefully measured quantity of new oil.  I went out and bought a 250 mL graduated cylinder specifically for this.  I can't remember off the top of my head how far one would have to take the forks apart in order to thoroughly drain them, but I know for certain that I did NOT remove the springs.  What I do remember is turning the forks upside down and pumping them and letting them drain over night, which might have been overkill, but I had the time.

[rugguy]

Gryphon Ryder.....thanks. I apologize for incorrectly attributing that post to you. I just read the manual again and they say to fill and measure with the springs out. If I do it with the springs in, what would the correct volume or measurement be for each leg with the stock spring in?

[Gryphon Rider]

The volume of fluid doesn't change.  It's the method of measuring down from the top of the fork tube to the surface of the fluid that requires the springs to be out.

[rugguy]

That makes perfect sense. The volume wouldn't change either way. So all I am going to do is remove the extra 2 ounces of fluid I put in and see the difference that makes. It's hard to imagine that 2 ounces would make that much difference but it is an increase of 8% of the volume.

Thanks again for your help.....