heres my latest mad cap idea-single sub tank.

[marcusgunby]

So here is it, it uses only 3 parts in total, the bars are capped at each end, the volume is about 150cc which i think is about right, i havnt tested it yet but have shown it for discussion, IMO the idea of using one leg only will help on the adjustment side, ive heard a enzo type setup has a course adjuster that does nothing most of the time, then over less than half a turn it goes to almost fully closed?

 

[elf]

Nice Idea Marcus. There is a guy selling a kit called "air bar" over on ktm talk. which is like yours but plumbs both forks into the bar.
On the enzos I have found that you can ajust one side at a time to fine tune them.
So what about oil level? do you just raise the level in one side? I wonder if it would be enough?
I went from 100mm air gap to 70mm in my forks, less than 70 and the forks wont bottom.

 

[marcusgunby]

I went with std airgap for now-i can easily add some so i started low.I did think of doing the both legs into one setup, but after thinking about it, i decided the fork is now speed sensitive so whats to be gained? more parts to go wrong?

this setup seems to be simple and hopefully relaible and you only have to play with the air gap on one leg, we will see if it works? also i wanted a different valve, the one i wanted was a screw type set into a banjo-i hoping that will screw straight into the bleed hole without the need for the adapter, they didnt have one in stock so i will order it and test that as well.

with the bar pad on, the hose and 90m degree swival is well covered and hopefully well protected.

 

[MXSparx]

Have you ridden with it yet? Or just getting it all put together? Seems pretty slick :cool:

 

[bclapham]

we will see if it works?

LOL :rotfl: i wish i could be there to see it!!! :yikes: :coocoo: :)

 

[steve125]

It is a neat idea! My main concern is the pressure differences between the forks at the last 4 inches of travel. I would think raising the oil level in the "air bar fork" to the proper level, would be very important, to maintain a close balance in the high pressure range near bottom. Also an additional schrader valve is needed to vent to atmosphere. Then you will have the oil drain back "in" part,,, handled. :cool:

Ok Marcus, start doing the math. :)

 

[steve125]

LOL :rotfl: i wish i could be there to see it!!! :yikes: :)

I just had a thought, I hope those bar end caps are on tight. :yikes:

Or the next time he bottoms,, his grips will blow off. :rotfl:

 

[bclapham]

I just had a thought, I hope those bar end caps are on tight. :yikes:

Or the next time he bottoms,, his grips will blow off. :rotfl:

:rotfl: :laugh: :coocoo:

 

[NO HAND]

Wow, I'm glad to see that. That's a neat setup you got, it looks clean too. How do you like it? I still got some plumbing lying somewhere to try but I was just too lazy to put it on. :cool:

 

[marcusgunby]

Steve im thinking the forks can work in any combination you want, eg all compression one side and all reb on the other, so i deduce that having unequal airgaps shouldnt be a problem? on the fitting the far bars are actually made of a really strong alloy , i was expecting the drill bit to eat into them it didnt at all, in fact it started to walk along the bar even when the hole was a few mm deep, also the tap didnt eat into the bar that easy-hard stuff.

I tried to blow the bar ends out with a compressor but they didnt budge, for venting you can pull out on side of the tubing as its a push fit system-under pressure it seals harder.

 

[Danger]

Interesting idea using only one fork for the air bar. I'm on the verge of making one myself but using both forks. I would think you are negating the benefits by only using one fork. The other fork will still have the characteristics of a fork with out a sub tank, and so the whole setup would be less effective in my view.
But no harm in thinking outside the square and giving it a go.

 

[steve125]

I tried to blow the bar ends out with a compressor but they didnt budge, for venting you can pull out on side of the tubing as its a push fit system-under pressure it seals harder.

Does anyone know what the air pressure in a fork with the oil level around 100mm and bottomed out, in PSI is??

The charts I have say anywhere from 500 to 2000 depending on the oil level. But the charts don't say if its PSI or not.

example: 98mm air gap = 700
40mm=2000

I assume it's PSI ?? :yikes:

Also Marcus,, I understand the hose coupler system, but you want the oil in the bars to drain back into the fork. So you need to vent up stream at some point.

 

[BradFrost]

I just hope you get a few hours otta it before you drop the bike and have to take the whole front end back to the lab.

 

[Rcannon]

I think the idea will work. I love the idea of not adding an external tank. There is no decent spot for the tanks in the other systems. besides, it looks easy to convert the Marcustank to dual sided operation if necessary.

I worry about the hole in the handlebars. My reason? A few months back I was ill. I was watching the history channel. The special that day was "avaiation disasters" (A welcome break from their 24 hour Nazi coverage)

The airplane profiled was the british Comet. It was a great plane, but had a nasty habit of blowing up. After 1 hour and 59 minutes of crashes, they finally disclosed the problem in their design. There was a small round hole or window in the center of the plane. Over time cracks wouldl form from the center of the window. The idea appeared to be somethign about aluminum not liking to have round holes in it. I was fairly wasted on pain medication at the time, but it still appeared serious.

Do you see any long term problems from drilling the bars?

Having said that, if yours hold up, I am drilling mine. I have the too tech subtank. I love the performance. The tank location blows. It does not leave much room for the cables and lines.

 

[BradFrost]

Oh it'll work. Until it blows the tube and fiitings off the bar, covers ya in greasy muck and gives you a permanent nose ring :laugh: Nah, maybe not but it could make an otherwise 'no problem' get off's a real bummer.

 

[elf]

I.

Do you see any long term problems from drilling the bars?

.

I don't see any problems, The center section of the bar is supported on both sides by the bar clamps. Most of the stress on the bars is on the outside of the bar clamps.

 

[marcusgunby]

The bars are super strong i think and also the aftermarket clamps i have ,clamp over a even bigger area than std, i would trust these bars more than twinwalls-ive seen these fail without drilling or even crashing:(

On the setup-i do think the way i have done it will make it less effective than a twin setup, but i guess it means i close down the valve a little more to compensate and then its similar? it maybe a twin setup is the way forwards and its very easy to convert it-takes a few minutes is all.I like the idea of less tubes and fittings as these a weak points IMO.

Steve ive heards the max pressure is only about 150psi but i dont know this to be true.I superglues the ends in place and i dont think they will go anywhere at all.

I did look at the setup and it does look a little like its too level(ie not down hill) i need to get a adapter for the forks that doesnt place the valve so high, the bango setup i hope to try next will do this i hope, this is only a testing mule at present-i hope to refine it as i go. :cool:

Also i think i should have drilled the hole at the very bottom of the bar but i was worried it would not have room to fit the connector, i can place ascrew in that hole and redrill i guess :ohmy:

 

[Rcannon]

Seriously, keep us updated on this idea. I can see that it woudl be possible for me to turn my too tech bottle into this bottleless design.

If you really think about it having one leg controlled is no big deal. The force issue? Well, if this was a problem we woudl all be screwed. Look at the brake caliper. It is only on one fork leg. Imagine the twisting force this must add to the front end in a panic stop situation.


Maybe it is this extremem force that is stoppign me from passing RC in the woops????

 

[marcusgunby]

On supermoto bikes they have the rims really offset to get them in the swingarm(ie front and rear tyres out of line), now that does have a effect but most are happy with the compromise.

 

[mop]

Marcus:
I believe that 150cc of secondary chamber volume is alot: Enzo tanks are about 80cc volume. What oil level did you raise your fork to? I've never tried it, but I think that you may encounter some weirdness of handling with the system affecting only one side....but again, I've never tried it, so give it a shot! Also, what is the I.D. of the hose you used? It looks smaller than the flow restriction of enzo tanks. Good luck with this experiment!

 

[Robin13]

Marcus:
I believe that 150cc of secondary chamber volume is alot: Enzo tanks are about 80cc volume. What oil level did you raise your fork to? I've never tried it, but I think that you may encounter some weirdness of handling with the system affecting only one side....but again, I've never tried it, so give it a shot! Also, what is the I.D. of the hose you used? It looks smaller than the flow restriction of enzo tanks. Good luck with this experiment!

The volume of the tank you need probably depends on the oil level you are running. If you are running a lower oil level you will probably need a smaller tank. And about the one leg thing. Didn't marzochi have forks with rebound in one fork and compression in the other? So it will probably not matter much. And the hole in the bar won't weaken it at all, that part of the bar will probaly only have to deal with some twisting forces.

 

[JTT]

I just had a thought, I hope those bar end caps are on tight. :yikes:

Or the next time he bottoms,, his grips will blow off. :rotfl:

:) Better make sure those liability insurance premiums are paid up. I wonder if even the CSI guys could figure out how a trackside spectator got shot :yikes:

 

[mop]

Robin13:
The handling "weirdness" I was talking about was from experience I've had in the past when one side oil seal blew a great deal of oil out of the leg, and also another time when the spring in one leg actually broke. It was hard to put my finger on exactly what it was, but it was something noticeable especially when braking hard. These situations as well as the subtank project we are discussing are "SPRING ELEMENT" related. The Marzocchi REBOUND/COMPRESSION separate leg set up is "DAMPING ELEMENT" related. Personally, I never tested the Marz. fork with this system, so I cannot comment on it, but I would think it would be weird too, but they had success with it, so maybe I'm talking out of my ass(?).
The oil level in the FORK is important for what happens then the fork compresses quickly, whether it will feel like a high oil level or not. The volume of the secondary chamber (in this case, the handlebar) is important for what happens when the fork is compressing slowly, how soft it feels like a low oil level. So if the oil level is set pretty high, it will feel ALOT stiffer in one leg when the fork is compressed quickly, and that is the situation where the "weirdness" MAY happen. That is just my opinion, cuz I've never tried this, so I'd like to know how it goes.

 

[marcusgunby]

interesting points, on the weirdness -well with a broken spring i think it would react wierd:) but in this case IMO the thing you will feel will be a speed dependant airgap like a enzo but to a smaller effect.Mazzo forks feel like normal forks and you cant tell the difference,in fact the new 50mm shiver is meant to be a top performing fork.

I am a little worried the tubing is too small i/d, its 2.5mm , the airgpap isnt a problem as i can add so easy.The enzo im sure has much bigger tubing but from what i have read you have to crank the adjuster right down so maybe i can afford to go smaller than that setup, on proirity was to use std caps so it will have to be a small tube as the hole through the air hole is about 2.5mm.

the enzo uses 2 chambers of 80cc so mines about right at 150cc?

 

[mop]

Marcus:
The enzo set up is 80cc per tank per leg. Is your system utilizing both legs or only one? What oil level are you running in the leg which the tank is used on? I was wondering about the I.D. of the hose you used? Enzo tanks can be run at 2 turn open from closed, but it is pretty restrictive. Adjustments of a 1/2 turn are noticeable, even from 4 turns out to 5 turns (minimum). This leads me to believe that maybe there is more flow to be had if the hose I.D. were larger(?).
Marzocchi "SHIVER" forks are SHOWA twin chamber design, and don't have separate legs for rebound and compression as far as I know. The forks that did have that feature were from the late 80's, early 90's, and were not a high performance fork. But I don't think they had the weird feeling that I am thinking about...
The connecting hose used on the Enzo set up is a #3 US braided steel line (which is all inch size), which has an I.D. of about 3.5mm I think. They use a fitting which requires drilling out the standard air bleed hole to accept an 8mm x 1 thread. The hole in that fitting is around 3mm. Max on the tank adjuster is shut, max at 5 turns is pretty much wide open 3mm hole I think.
But enough of this techno-BS, go try your set up and then we can see how they work! It will be easy to reverse-engineer them once you test them! Good luck!