Removing left fork oil: suceess

[Oldnick]

If anyone feels angry about my continued trials, then close this page now!

OK. Enough people had said iut could be done that I bought some semi-rigid 1/8" OD air/vacuum line, the stuff they use for  air pressure meters etc. It was the thinnest I could get. I could not gert it into the top of the leg beyond about 1/4". So I grabbed a zip-tie and tried with that and I could get it well into the oil, although it is fiddly. EncouraGed, I flattened the air line with pliers (it is rigid enough to hold its shape) and it worked.

The extraction was not as smooth as it could be.I did not have a syringe that fitted the line so I made "adaptors"; different sizes of pipe and electrical tape. The seal was so-so and needs to be perfect. Trying to suck viscous oil out through a squashed 2mm tube takes some serious and held vacuum. But about 8-10 mins work I guess. I had another syringe, large end open and small end sealed, and I just kept on taking oil and adding it to the second syringe until I had my 23cc, then blew out the tubing back into the fork leg. I did that a few times as oil ran off the tube walls and pooled.

Now I have the tool for the job (well, when I get the seal sorted out) I would say 2 minutes to extract oil, and the rest of 10-15 mins to do the mech work

[WintrSol]

At least, now we know it CAN be done! Interesting that the clearance is that small, but not entirely surprising.

Now you need to ride, to see if that 23cc is what you needed.

[Oldnick]

Yep. I stuck with it because it annoyed me that the _theory_ was out there but no description. I hope somewhere my description helps somebody.

I forgot to carry the info over from the other thread. Get the front wheel just off the ground. Loosen the top leg tube clamp allen bolt, loosen fork tube top seal nut from tube: very slowly lower the front wheel until the nut comes free from the tube. Undo the little lock nut under the tube cap. Remove tube cap. Remove lock nut. Lower the front wheel to push out the damper rod and suspension top end; that makes it easier to get at the little rubber bung down in the tube. It's just a drop in fit. Take well-sealed tube setup, flattened for maybe 8" at the end, and work it down next to the damper rod.

One way to tell if you have struck oil is to blow using the syringe. If you hear bubbling you are in the oil. The further into the oil the less frothy the bubbling sounds.

Because you have to force the issue, and because the tube has to retain iuts flattened state, semi rigid nylon is the only way to go. Most motor or hydraulics places will sell it.

Not the day for testing cornering performance today...raining most of the day  I think if I tried some hard cornering I would have mnore troubles than how much oil I had in the forks!

Anyway, I appreciate your chiming in and giving a hint on how to proceed.

The rubber stopper does just slide up; the threaded but is reduced in size. The damper rod is firmly held in place and does not move, except a little side to side.

[Oldnick]

OK. So today I tried the trike on some sharp corners, under accelerqation, with both forks down 23cc. Much better. I hit one corner I had not done before, gunned it in, and hit a lot of washboard where cars have been turning, off a 65mph highway onto a side road, faster, often braking. There was a bit of shuddering and I was caught by surprise and backed off, but not the same need tgo overstreer I was getting. For all I know that's the way it is!

Also did a road I had not ridden before that is a combination of straights and really tight curves, with lots of rough bits.A lot more comfy and without that floaty feeling of my hands on the bars.

I am going to have another go, to remove 23cc more each leg and see what happens. It may end up that I have to use lighter oil, but it's worth a try to have another go. As I say maybe I am just pushing the limits anyway. But having found a quick way to experiment, I am happy to trial.

[WintrSol]

Great! When it starts to dive on moderate braking, I think you've gone far enough.

[Oldnick]

Yeah!

Well I can sit on the trike and actually pump the forks a bit now.....

I have to assume that when I first rode it, the forks were very low on oil, the way they were leaking. But back then I was not riding as hard, and had no idea how the thing _should_ behave.

[Oldnick]

So today I tested dive under braking. It seemed to be not too slow, in that dive was pretty immediate. Under the max load I could apply to the forks (on a trike that means lean on the _back_ brakes to throw weight fwd then  apply front brake to _really_ stop) I had I reckon 2" of travel left in the fork, and that's where it  stayed. That was washing off speed pretty damn fast. I _may_stop harder if I am not staring at my front wheel! My bike days still make me want to watch the road when braking. 

Sound OK guys?

[The emperor has no clothes]

So today I tested dive under braking. It seemed to be not too slow, in that dive was pretty immediate. Under the max load I could apply to the forks (on a trike that means lean on the _back_ brakes to throw weight fwd then  apply front brake to _really_ stop) I had I reckon 2" of travel left in the fork, and that's where it  stayed. That was washing off speed pretty damn fast. I _may_stop harder if I am not staring at my front wheel! My bike days still make me want to watch the road when braking.  

Sound OK guys?

Sounds about right for 2 wheels but I've never done 3. For me the most telling sign of good fork action is how it does in washboard stuff and if it maintains contact with the road.

[WintrSol]

Yep, you're balancing spring rate against damping. Too soft a spring, and you loose grip on rough pavement when the wheel is bouncing, but, too hard a spring, and you lose grip because the handlebars are bouncing. Of course, if you don't ride much on that kind of road, and like a Rolls Royce ride, soften away.

Some years ago, I found a discussion on how to evaluate suspensions when balancing spring rate against damping, but I can't find it now. Of course, the author could adjust both, and was a racer; a little different when compared to a cruiser, as I recall.

[mark81]

Glad to hear you're making progress and getting it all sorted out. Thank you for not stopping until you figured out how to get the oil out, and most important sharing the info with all of us.

[Oldnick]

Sounds about right for 2 wheels but I've never done 3. For me the most telling sign of good fork action is how it does in washboard stuff and if it maintains contact with the road.

Yeah well that's certainly a lot better now.

With careful breaking technique, I can exercise the front wheel about the same on 3 wheels as on two. You have to really haul on the back brake, getting weight forward, then squeeze in the front. If you don't transfer weight with the back brake the front just skids...luckily, on a trike all that means is a flat spot!

[Oldnick]

Yep, you're balancing spring rate against damping. Too soft a spring, and you loose grip on rough pavement when the wheel is bouncing, but, too hard a spring, and you lose grip because the handlebars are bouncing. Of course, if you don't ride much on that kind of road, and like a Rolls Royce ride, soften away.

Some years ago, I found a discussion on how to evaluate suspensions when balancing spring rate against damping, but I can't find it now. Of course, the author could adjust both, and was a racer; a little different when compared to a cruiser, as I recall.

I tend to ride as hard as I dare in any circumstance, so I do not want too soft a ride. A lot of my riding is on country back roads that are sometimes a bit lumpy and I want my tyre on the road! But it was way too hard before. I am surprised by how much difference 23cc made, given that the springs hold...600-700cc?         

Another thing. I was checking the fork oil capacity on this forum and found a thread where a lot of guys were satying they ended up with ~1 oz less than reccommended.       

[Oldnick]

Glad to hear you're making progress and getting it all sorted out. Thank you for not stopping until you figured out how to get the oil out, and most important sharing the info with all of us.

HAH! The not stopping had become sheer bloody-mindedness!  But yeah having had a win I reckoned the best thing was to share what did it for me. If it saves somebody else a lot of hassle then my bloody-mindedness was not wasted.

[larswlvs]

This has got me to thinking. why could you not just drill, tap and plug the bottom of the fork tube like older forks have done for years ? I sure there is a reason or someone would have done this.

[Oldnick]

Waiting,, with interest..

[WintrSol]

This has got me to thinking. why could you not just drill, tap and plug the bottom of the fork tube like older forks have done for years ? I sure there is a reason or someone would have done this.

They probably stopped doing that because the lawyers told them to. Can you imagine what would happen if they were over-tightened, and the threads blew out? Sure wouldn't be fun, 'cause you know, only one would fail. I've got them on my CB450, and am very careful when I put them back in.

[Fazer]

This has got me to thinking. why could you not just drill, tap and plug the bottom of the fork tube like older forks have done for years ? I sure there is a reason or someone would have done this.
They probably stopped doing that because the lawyers told them to. Can you imagine what would happen if they were over-tightened, and the threads blew out? Sure wouldn't be fun, 'cause you know, only one would fail. I've got them on my CB450, and am very careful when I put them back in.
Posted on: Yesterday at 03:02:49 PM Posted by: Oldnick
Insert Quote
Waiting,, with interest..
Posted on: Yesterday at 11:52:38 AM Posted by: larswlvs
Insert Quote
This has got me to thinking. why could you not just drill, tap and plug the bottom of the fork tube like older forks have done for years ? I sure there is a reason or someone would have done this.
Posted on: February 01, 2016, 06:52:22 PM Posted by: Oldnick

This topic was just covered in the January 2016 issue of Rider magazine.  The author, Mathew Wiley who answers technical questions dealing with bike mechanics stated that a thickened "boss" with a flat spot to seal the steel screw would be desired, but if there were enough aluminum material to support the harder steel screw threads and you would also need to make a flat spot for the screw to seal, that it could be done. 

[Oldnick]

Yeah IIRC the older Hondas had just such a thickening and flat spot. YUou could probably seal the screw but I doubt there is enough Al there for a strong thread.

[Fazer]

My 89 Shadow had a screw at the bottom of each fork to drain the oil.  I changed it out in about 10 minutes.  Not nearly as complicated as these Valks--but not near the bike either.

[indybobm]

There is a screw in bottom of the Valk forks also. The screw has a seal on it. You have to remove the axle and lower fork caps to get to it. Not there to drain oil but would it?

[Houdini]

There is a screw in bottom of the Valk forks also. The screw has a seal on it. You have to remove the axle and lower fork caps to get to it. Not there to drain oil but would it?

Only on the right fork, not the left one.

[Oldnick]

HAH! If I have removed the wheel and axle, it's a couple of minutes more to remove the forks and upend them! ...and _then_ it's the left fork that's the problem....