Fork oil questions

[Oldnick]

I will try again instead of burying my question at the end of my thread....

So today I finally got around to removing some oil. I removed 23cc from the right fork. Then I tried the left one. I could not get to the oil. In the right fork I could get a tube down the fork and extract oil with a syringe. In the left, there is no way to the oil. There is a flange that prevents that.

A ride test with many bends and corners and swerving on the straights left me feeling that less oil had made the ride far nicer and secure-feeling on my hands over sharp ruts and bumps, without affecting handling. I also reckon there is less headshake (trike remember)

The oil I extracted was a grey-black fairly opaque liquid that was, IMO, thicker than W10/ATF. The smell was not familiar; not ATF, not engine oil.

So my questions (and I may know the answer to the first):
- how do you get oil from the left fork? (I am wondering if you just remove the suspension bits??....I did not try that because I was fighting with my jack as well and did not think of it)
- does anyone have any idea what the oil is they put in there during servicing the forks?
     - given that the trike now feels better by removing oil I am not  desperate to change it, but it's useful for future reference

Thanks for any advice

Nick

[hubcapsc]

You can probably take the forks off and turn them upside down with the
caps off and wait a day (or whatever) until every drop comes out,
and then put the amount of oil specified in the manual back
into each leg... the amount is different for each leg.

-Mike

[Oldnick]

Thanks for the reply. OK yeah  I could do that, but that sounds like a lot more mucking about than I had assumed from what I had read.

[WintrSol]

To do the same amount of disassembly on the left as on the right, you also have to remove the inner fork bolt, which takes a special tool, as the 'head' is actually like a castle nut. I suppose you could find a proper diameter socket wrench, and grind the end to make a tool to fit.

[Gryphon Rider]

To do the same amount of disassembly on the left as on the right, you also have to remove the inner fork bolt, which takes a special tool, as the 'head' is actually like a castle nut. I suppose you could find a proper diameter socket wrench, and grind the end to make a tool to fit.

You don't need to do that to drain the oil.

[Houdini]

No special tool needed to change oil or seals, only to change springs.  Watch this...

https://www.youtube.com/watch?v=TXZPzQqfAXc

He is working on VTX 1800 forks which are a similar design, jump up to the 3 minute mark.

[Oldnick]

Thanks  for all the replies gfuys. But I hope I do not want to know how to drain forks or remove/rebuild shocks etc.All I want to do is remove 23cc of oil from the left fork.

Can that be done without removing/ dismantling the fork?

[WintrSol]

To do the same amount of disassembly on the left as on the right, you also have to remove the inner fork bolt, which takes a special tool, as the 'head' is actually like a castle nut. I suppose you could find a proper diameter socket wrench, and grind the end to make a tool to fit.

You don't need to do that to drain the oil.

Not to drain the oil, no, you just invert the fork and pour it out. But, to snake a siphon hose in there, I'm pretty sure that's what you have to do.

[Oldnick]

OK WintrSol. thanks. Guess I need to have another go and a dig around. The ride improvement was dramatic and it's worth the effort.

[WintrSol]

The service manual shows that removing the lock nut from the damper on the right fork releases the spring pressure, letting you remove the spring collar to get access to the fluid. Looking at the instructions for the left fork, it appears that removing the inner fork bolt does the same. I haven't done this yet, so can't confirm it is true, but the diagrams imply as much. You might have to lift the spring and rebound rod out to get full access from the top. Good luck, and take care with that spring pressure; even with the front lifted, there is a fair amount of force, which you should know from the right fork.

[Oldnick]

My manual talks of not releasing the springs (they are talking about actual disassembly) until you have a system  of controlled release and replacement of the spring tension.....some sort of screw clamp. That of course means removing the fork, I assume, at which stage I would do what has been said, and simply turn the darn thing upside down and drain it. Seems crfazy if that's what it takes.

Funny thing is, for the right fork I just undid the cap nut with front end jacked, then lowered the jack to compress the fork and push the entire spring assembly upwards and presumably to raise the oil level as the fork collapsed, then just stick a 6mm tube down there and suck out oil. No need to worry about spring tension at all.

Then the LHS was a completely different story.

Jeeze IIRC my old 750 had a drain plug for the fork. Undo the plug, pump the forks, let gravity keep doing its job as you pumped.

[Oldnick]

hmmm....looking at the manual in more detail it would seem the answer to my question is "no" . Even removing the left fork and up-ending it may well not drain oil. You _do_ have to actually start disassembling the darn fork, spring pressure and all,  just to get oil out. Wow.

[hubcapsc]

Here's the special tool I used to defeat the spring pressure...



-Mike

[Gryphon Rider]

hmmm....looking at the manual in more detail it would seem the answer to my question is "no" . Even removing the left fork and up-ending it may well not drain oil. You _do_ have to actually start disassembling the darn fork, spring pressure and all,  just to get oil out. Wow.

When I did my seals, I left my springs in place.  I thoroughly drained my forks and added the carefully measured proper amount of oil to each leg.

[Oldnick]

Here's the special tool I used to defeat the spring pressure...

-Mike

AH.  So it's not that bad at full extension. OK.

[Oldnick]

hmmm....looking at the manual in more detail it would seem the answer to my question is "no" . Even removing the left fork and up-ending it may well not drain oil. You _do_ have to actually start disassembling the darn fork, spring pressure and all,  just to get oil out. Wow.

When I did my seals, I left my springs in place.  I thoroughly drained my forks and added the carefully measured proper amount of oil to each leg.

I get now that I will at least have to take off the fork. Did you need to undo the spring bolt to drain oil? From my view of it and the manual, it holds in the oil.

[Houdini]

<quote>I get now that I will at least have to take off the fork. Did you need to undo the spring bolt to drain oil? From my view of it and the manual, it holds in the oil.</quote>

Nope, loosen the top pinch bolts, loosen the cap, remove the fork from the bike, finish unscrewing the cap and dump out the oil.

Drink beer.

Reverse procedure.

More Beer

[Oldnick]

<quote>I get now that I will at least have to take off the fork. Did you need to undo the spring bolt to drain oil? From my view of it and the manual, it holds in the oil.</quote>

Nope, loosen the top pinch bolts, loosen the cap, remove the fork from the bike, finish unscrewing the cap and dump out the oil.

Drink beer.

Reverse procedure.

More Beer

OK. Thanks. I know I sound a bit of a weeny here, but the trouble is that altering oil level is a "bit at as time" game and may also entail putting some back. SO there may be several tries.So making  it as quick and easy as possible is the go for me. Being a trike, the amount may altyer from a bike for comfortable riding.

[WintrSol]

If you don't have one, you can get a good measuring cup at an auto paint store, guaranteed not to react with the oil. Pour the oil into the cup, and you can decide how much to leave in the cup when you pour it back. Bonus: many come with a cap to seal it, keeping the oil clean until you are ready to throw it out.

[Steve K (IA)]

<quote>I get now that I will at least have to take off the fork. Did you need to undo the spring bolt to drain oil? From my view of it and the manual, it holds in the oil.</quote>

Nope, loosen the top pinch bolts, loosen the cap, remove the fork from the bike, finish unscrewing the cap and dump out the oil.

Drink beer.

Reverse procedure.

More Beer

Yes, this is not a hard thing to do.    I would rather do this than remove a gas tank.   

My wife helped me rebuild the forks on my I/S.  After seeing how easy it was, she said she will do the forks on the STD when the time comes.

[Oldnick]

hmmm..ok I _have_ to disagree about the gas tank. Once I had done it, it was easy, although avoiding kinked lines can be a pain.

The main trouble for me when replacing the forks is keeping the brake pads in place and also forcing them apart to allow putting the disc back in. The other option of course is to remove the brake assembly. IIRC in the end I used a wooden wedge to open the pads up.

Doing it once or maybe twice would not bother me. 4-5 times, just to take out solme oil or put some back, would start to.

[Houdini]

.

Doing it once or maybe twice would not bother me. 4-5 times, just to take out solme oil or put some back, would start to.

Then dump it all out and refill with the recommended amount of fresh oil, or minus out a couple of CC's if you want the ride softer.  Why would you take it all the way down and not change the oil while you were there?  If you didn't put the oil in the last time you have no idea what's in there, maybe the last guy overfilled, or maybe they used tranny fluid instead of fork oil, who knows....

Do it the way it's supposed to be done and be done with it.

[Oldnick]

.

Doing it once or maybe twice would not bother me. 4-5 times, just to take out solme oil or put some back, would start to.

Then dump it all out and refill with the recommended amount of fresh oil, or minus out a couple of CC's if you want the ride softer.  Why would you take it all the way down and not change the oil while you were there?  If you didn't put the oil in the last time you have no idea what's in there, maybe the last guy overfilled, or maybe they used tranny fluid instead of fork oil, who knows....

Do it the way it's supposed to be done and be done with it.

OK. Several things. I was trying NOT to take it all down, henced my questions. They def did not use trannie fluid..as I said it's a grey-black liquid more viscous than trannie fluid. I would say it's fork oil as these guys are not ripoff merchants and  it was a costly "part" in the rebuild. Many guys are telling me to _use_ trannie oil.

But yeah there could be too much oil. Trouble is, what could be right for a bike may be totally different when triked.

I am getting front wheel "hop" when hard cornering  on rough stuff that I am told is "pogo sticking" and that it's caused by too much oil. Maked sense. Oil is there to damp, not help, rebound.

So I am going to remove the forks, empty the oil and try trannie fluid, to the right quantity.

Thanks guys for all the input.

[mark81]

    When I rebuilt the forks on my old cb750 trans fluid was spec fluid, however it was brought to my attention that trans fluid 30 years ago is much different than today. Now there is specific fluid in a range of weights made for forks. I was told atf is 6-10weight depending on brand and additive package. the additives mostly being detergents and friction modifiers are not good for the bushings since they are designed to make the clutches grip not slip

     The weight of the oil used is what determines your level of dampening. The volume of oil in the forks is what determines your spring rate. I have 0 experience with the forks on these Valkyries but found that 20wt fork oil a few ounces over the recommended level gave me the best ride with my setup on my cb750 with the extra weight of the fairing and my fat ass. I did not have a stock setup. I had progressive springs and a lot more weight on the forks than what was factory setup. I had to play with it and test different configurations to get it right.

     I know you paid good money to have your forks done by "professionals" but if they cant stand behind their work or even tell you what fluid they put in your forks I think your best bet is to start from the beginning. drain all the oil out, possibly even fill and drain again to flush unknown fluids. I would start with 10wt fork oil at the recommended level (possibly slightly higher or lower since yours is a trike. not sure of the weight distribution on those. or weight transfer under braking) if your fork travel is too far and your forks are bottoming out or too short and they barely move adjust the fluid level accordingly. If the suspension is too stiff or soft for your liking then change the oil weight accordingly and fill to same level.  You adjust rebound and dampening by changing the fluid weight and overall suspension travel and load capacity by the fluid volume.

I'm not sure about your side of the world but over here fork oil isn't terribly expensive compared to other fluids and readily available.

http://www.peterverdone.com/archive/oilheight.htm

this link was in another post on here I read a while back and thought it was very interesting.  Sorry about being long winded just wanted to make sure you were moving forward and not in a hole on your project

[Oldnick]

OK. Thanks for the great wind!

Sounds like you have looked into this and have a pretty fair idea of what you are talking about.  You are the first one to mention  ATF being no god, and why IIRC.

Just for the record, the shop has not had to defend their work, or tell me which oil, as I have not asked. I am sure what they used was OK in theory, just not so sure about the amount. I have not asked because there are so many opinions about what is right, I had no idea whether their answer would be "right" or not.

One thing about the Valk is that you have to remove and upend one of the forks (the left one) just to get the oil out and I get the sneaking suspicion that you have to open it up to add more. That's what it looked like to me when I had a squiz and nobody has said I am wrong that I remember. Trouble is I saw another thread where a guy said you could just use a syringe and tube on both forks and nobody told him _he_ was wrong either. IIRC the 750s had a drain plug.

Some questions.
- Does spring rate get governed by amount of oil because less oil is more air and that allows air compression and springing? I get the damping bit and viscosity. The stiffer it is the harder to force through small holes.
- Given that one fork is compression and the other rebound, is ikt worth experimenting with different oils in each fork?
- Would redcung oil quantity help with my "pogo stick" problem, by allowing better spring rate? I was told that too much oil would cause the front wheel to hop on washboards. Or is it damping/viscosity causing too slow a response?

That'll do.

[MC Flannel]

hey guys. we have established that the forks are different.  there is one has that damn castellated nut on the top of it that you need the special tool for (not really here is how to make one http://tech.bareasschoppers.com/resources/handy-motorcycle-tools/#forktool), the other doesnt.  you will have to take off the forks to get a true fluid reading.  even a small amount will throw them off.   now to drain the oil on the castellated nut fork you DO NOT have to take off that nut.  The small nut at the top of the dampening rod is the length adjustment for the fork (if when you put the forks back on the front the axle doesnt slide in place perfectly adjust that nut to extend or retract one of the forks).  that small nut WILL fit through the center of the castellated nut, holding washer, and springs.  there was a  post earlier that showed the link https://www.youtube.com/watch?v=TXZPzQqfAXc.  there is a couple of parts to it so watch them all because it is some really good info.  also the question about why taking out a little oil changes things is because oil and air have different compression ratios.  it takes oil more force to compress than air.  I am not tooting my own horn so please don't take it that way, but I am an aircraft mechanic and i know that anything pnuedraulic (air and fluid working together) is meant to run at a certain compression ratio and if not it can damage the orifices in the fork itself so i recommend not doing that.  for a cloud like ride put a lighter viscosity oil in the fork that acts as the shock obsorber but don't change the viscosity in the other because the rebound will suck and when you hit a good bump the fork will not return like you need it to.  i hope this helps and I will gladly help any way i can

[Oldnick]

Hi. Wow. This is serious stuff. Toot the horn all you want mate. Aircraft hydraulics are right up there where you do NOT want errors.

So I was not totqally wrong about different oils in compression and rebound maybe having different oils. However I am interested in how the viscosity would affect the rebound. You say not to change it, because rebound would suck. I can see that if I use even stiffer oil, but what about lighter, to allow faster spring action? I can even see that too much spring from air could force more oil through  the dampers could do damage. I guess guys are looking more for the ride than long term damage.....?

So this little nut that goes through the centre of the castellated nut will come out with no pinging of springs and other hard-to-fix surprises? If so, man you have answered a Valkyrie Maiden's (if there is such a thing ) prayer.

I know I have jumped uyp and down until I am a PITA, but thge last couple of replies seem to be really opening up the topic.

[MC Flannel]

the viscosity of the oils is pretty much how fast the oil will go through the channels in the fork.  the one fork take the initial hit when you hit a bump and that fork determines how stiff it is when the front end compresses.  the other fork determines how fast the front end comes back to meet the road (leave that one alone with the factory amount and viscosity of oil).  and yes if you change the oil viscosity in that one it will change the rate of return, however you arent changing the springs and that rebound is designed for that spring.  its actually a genius design, think about it.  there are not any adjusting valves on the forks for compression and rebound because its all the one fork does!  also don't think of them as separate, when they are tied in via the trees and the axle it acts as one assembly.  like i said freakin genius.  but like all honda products they are very finicky.  make sure you watch those videos on the youtube.  here is another that will show you some different techniques to do the same thing.  its in another language (russian i think) but if you watch the english one first you will know what is going on.  https://www.youtube.com/watch?v=7UVxKuo5ZO8.  also i forgot to mention that this fork design also is on the vtx1800 so if you cant find anything for the valkyrie search for that instead

[mark81]

To answer your questions:-

Does spring rate get governed by amount of oil because less oil is more air and that allows air compression and springing? I get the damping bit and viscosity. The stiffer it is the harder to force through small holes.

yes spring rate is affected by the volume of oil displacing a certain amount of air in the fork tube and therefore leaving less or more air to compress. it assists the coil spring in the forks to absorb impact. it also has the added benefit of being progressive in its ability to do so, meaning the more it compresses the more resistance it has to compress.  most springs have a set rate meaning for example if you put 100 pounds on a spring it will compress 1 inch, 200 pounds will compress 2 inches and so on. Progressive rate springs will become more resistant to compression with more weight. 100 pounds will compress 1 inch 200 pounds will compress an additional 3/4 of an inch. Also do not confuse progressive rate springs with progressive brand springs. I do believe all of progressive brand springs are progressive rate springs but there are springs that are progressive rate that are not progressive brand. ( My 750 also had the ability to pressurize the air to adjust springrate even further (preload) to accommodate different loading situations Same as the adjustable air shocks.)
 
- Given that one fork is compression and the other rebound, is it worth experimenting with different oils in each fork?

Like I said I have 0 experience with Valkyrie forks. What I would do is start with a known baseline of oil level and weight and tinker from there. In my OPINION I would not use different weights of oil in the different forks, however that is based on my limited knowledge and experience in the matter. mc flannel does have very valid information and seems to have a bit more knowledge than I do in this area. I have done a bit of research regarding the 750 forks which are the same on both sides. in that limited research I have never heard of anyone on any bike using different weight oil in each fork. not sure if its because it had not been done or just because of lack of need on a particular fork design.

- Would reducing oil quantity help with my "pogo stick" problem, by allowing better spring rate? I was told that too much oil would cause the front wheel to hop on washboards. Or is it damping/viscosity causing too slow a response?

with regards to the pogo stick problem it depends what is causing the problem. I do know that it is common practice to change the rake on a trike. in some extreme examples of exaggerated rake the forks have little in and out movement due to the angle of force being vertical and the movement of the springs in that situation being almost horizontal therefore the springs do not absorb the load and the valves cannot dampen it. Most likely not the problem but a possibility or a minor factor in the equasion. another situation that could cause this in my mind is that the oil is too thin and going through the valves too fast providing zero dampening, like you mentioned. Also too much oil, not enough air could cause it. if you bounce a basketball that has proper inflation it will bounce properly. add more pressure it will bounce harder and faster. reduce the pressure and it will not bounce as high. the air in your springs acts the same. 

when you say pogo stick what is happening with the travel in your forks?
     Are you using most of the travel?
           if so I would think then it would be an issue with oil weight
   
     Is there no movement at all or only minor movement?
          this would lead me to think there is no room for air and springs to compress or the oil is too thick to flow through the valves quick enough. the way to test this is to use your front brake down a hill and get as much weight transfer as possible over an extended period of time. see how much travel you have in your forks the longer you can keep the weight transferred the less effect the valving and oil weight will have since it will give oil time to pass through the valves. 

my suggestion again, especially since you have a trike with different handling than a bike, is to start with a known baseline and adjust from there.  there is an article in the shop talk section

 http://www.valkyrieriders.com/shoptalk/racetech.htm

 about changing the valves in the forks. Worth a read, there is useful knowledge that can be gained from it. There is also some misinformation on it about one of the forks having only spring and oil in it. There is also the authors email. maybe ask him about specifics of removing oil without removing the forks since he mentioned it

P.S. you are correct the 750 does have a drain that made the trial and error portion of this much more tolerable

[Oldnick]

The pogo stick thing started ...I _think_.... when the forks were resealed and new oil put in. They were leaking and so would have been low on oil. I have a 6deg rake only. It may affect things, but I doubt much, unless the new seals are _very_ tight. It sounds as if this means I now have more oil, maybe too much. As for fork travel, I am not exactly watching, as I am cornering hard at the time. But I get the feeling that the forks are not moving much...so too much oil again and maybe too stiff an oil.  My gut says not too thin an oil, since the forks are very hard and I would imagine that a thin oil would cause a bouncy, softer feeling. That could still cause shudder, but not like this. There is also no way the forks are diving too deep, even under heavy braking! On  a trike, the front wheel is used far less than on a bike for braking, as I have found when locking up the front wheel due to braking form old habit . So it's harder to test for dive. But the forks are very hard.

This whole issue started because I asked what to do to soften the forks a bit after the rebuild. If I can extract oil through this little central plug then obviously I will take some oil and see what happens...that will be a game-changer for me, as I do not have to keep taking forks off to trial.

Thanks for all your input. It gives me somewhere to start and if I can change oil without removing forks I am happy to experiment to get the best I can.

I will check out that thread

[mark81]

if I can change oil without removing forks I am happy to experiment to get the best I can.

if that's all you are after just drill a hole in the side of the fork with a good sharp drill bit to relieve extra oil. plug it up with some bubble gum and top off to desired level

[Oldnick]

HAH! And if I kept the gum moist I could blow bubbles as I went over bumps! And imagine the braking!

Having said that I cannot suss why they did not have drain plugs.

[Oldnick]

BTW I read that article about chngin valves to Racetech etc  and emailed the guy, because he says you _can_ get oil in and out of the forks without removing them...just not how . I have not had a reply as yet.

What riles me is there are posts here that say you just use a syringe and plastic tube. Either I am missing something or they are talking through their hat.

[Oldnick]

Mark81

As I said on my other thread, I tried the brake dive thing and got down to about 2" left of the travel. I do not think the oil is too thick, because the dive was fairly rapid as I applied the brake hard and was not a slow process of compression.

So again, thanks for all your help and support.

[mark81]

 

[JerryCS]

My front suspension was not to my satisfaction so something needed to be done. The seals were not leaking so seal replacement was not essential. If it ain’t broke don’t fix it. I ordered all possible replacement parts if needed now or in the future. The majority rule here on the Valkyrie forum is 10 weight fluid for the forks. Then there is the suggestion of a little less fluid so the forks have more air breathing room. I used both methods.

I ordered the Progressive springs and they are about 0.75” shorter. Then, the initial travel distance on those springs takes very little pressure. It was obvious the bike would be 1” lower in the front. That is not acceptable for me. A spring 0.75” shorter is not progressive in my opinion. My original springs passed inspection so I put them back in and returned the Progressive springs. I can see where the Progressive springs would be OK for some people.

Draining the oil in the right shock revealed 2 ounces too much. I then put in 0.75 ounces less than what the manual calls for. I did likewise with the left fork. The results are better. The Valkyrie does not have the suspension of a lighter weight off-road bike but it is better than before.  I did not want to rely on fluid level. Fluid quantity seems more precise.
Both Fork spring length specs = 13.3” 
Right fork fluid specification is 22.7 US oz for GL1500C/CT. I subtracted 0.75oz.
Left fork fluid specification is 25.2oz. I subtracted 0.75oz.
I am riding at 489 feet elevation and outside temperature of 85 degrees.
I weigh 220 pounds and am 6’5” tall.

The tires used on the bike will most likely have an effect on ride comfort. Formerly I used Dunlop soft rubber tires. The existing tires are Dunlop Elite 3. They seem hard and tough. My rougher ride seemed to get worse when those tires were installed. The fork fluid change still makes a small difference in the right direction. When pressing the front brakes, the bike dips a little more than before. I have a more comfortable ride but a little less stability. I did a fairly tight turn at 80mph on the highway and the bike handles very well.

The right fork spring was removed. Since it passed inspection I did not remove the left fork spring. The left fork inner fork bolt takes a lock nut wrench 44mm, part number 07VMA-MZ0010A for removal. I would not remove that lock nut without the tool. It requires 72 foot pound of torque and there is no way I would put that much pressure on my shocks with a non-symmetrical force. If I develop an oil seal leak, I will order the tool on eBay. The amount of force to compress the forks to install the bolt is not for a fragile person. I used a long clamp tool with soft feet to compress the right fork for retaining washer insertion. At 75 years of age I do not have the strength of you young bucks out there.

Draining and filling was done with the springs installed. Enough pumping and the old oil will come out. I put all the new fork oil in the outer casing area. Then I was very careful to pump the fork as best I could. Then upon riding down the road I stayed on smooth roads and drove slowly to balance the fluid in the inner and outer chambers. With unequal levels I was afraid I might blow a seal on a big bump. After 10 or 20 miles I feel the bike is ready for rough riding.

I also rebuilt all carbs, the hydraulic clutch and all brake calipers. The bike is better than new.

I just finished a 55 mile ride on Texas hill country roads. I am happy with the old springs and the fluid modification. Thanks to this forum and its members for the much-needed advice.

JerryCS