Clutch conversion

[tony.mon]

I have been trying for some time to try to eradicate the clutch grab problem some Storms have.
It seems to be unrelated to the clutch itself, because I and others have tried to replace plates, bearings, baskets, etc, etc, without success.
Some things seem to work, but not consistently, you try it on a different engine, and no improvement.
For myself I play around occasionally on the drag strip, and it really ruins the launch, frankly it's too risky dialling in a full handful of revs and slipping the clutch; if it grabs it looks likely to throw you off the back.

But talking last year to some of the guys who race these in the Thunderbikes series, and they have found that converting the clutch actuating mechanism to a cable-type actuation sorts the problem.

The Varadero clutch cover fits on with three out of four mounting holes lining up, and that's enough, and then all you need is a cable=type lever and lever mount, and of course a cable.
You also need a shorter clutch pushrod.

So I started to get all of the bits together, and then found something on EBay that looked like it was worth a try.
Basically it's a hydraulic master cylinder and lever, which just replaces the standard one. It uses a braided line, to move fluid, and at the lower end it has a small cylinder.
The cylinder moves a thin rod, and on the end of the rod is a barrel nipple, which acts exactly like a cable and lever does.
It's meant to be used as a hydraulic conversion from a cable clutch, and according to the makers (Chinese) it's for MX bikes.

I couldn't find it again on EBay, but this is similar (however lots more expensive, the one I found was about £30 including delivery:-)
http://www.superbike.co.uk/viewers/view ... ersion+kit
So this enabled me to use hydraulics as normal, but fitted onto a Varadero cable-type clutch cover.

It's taken a bit of playing around, but I got it up and running today.
Here's some pics:
Firstly the Vara clutch cover in situ-


The lever, and master cylinder end of things-


And a couple of the slave cylinder, with the rod and barrel nipple end-



I haven't yet tried a dragstrip full-on start, will do tomorrow.

But it seems to work ok.

There's just a tiny bit of drag when the clutch lever is pulled in; there's a span adjuster on the MC/lever assembly which fouls the switchgear; I'll grind a bit off that tomorrow or bode something so that I get full lever movement and action. Just makes it slightly awkward to get into neutral from first or second, and would probably be worse in cold weather, or when the engine oil isn't up to full temp.

I have got a lever, mount and cable set from a ZX6R which I was going to use if I couldn't get the hydraulic set up working properly, but haven't needed to use it.

The only odd thing is that the hydraulic item has smaller banjo bolts than normally fitted to the Storm, and there's no bleed nipple, so all you can do is fill with fluid and wait until the bubbles come up into the reservoir.
Easiest thing would be to find a banjo of the correct thread size and length with a bleed nipple installed, but couldn't find anything when i tried to find one.

Oh, by the way, you also need a holder for the lower cylinder, I just bought a Vara one, which fits onto two bolts on the alternator cover.

[AMCQ46]

Interested to see how the drag start works out tomorrow.

[lloydie]

why not just use the storms master cylinder ?

[tony.mon]

I was going to; the other hydraulics came as a set, so I thought I'd give them a go before mixing and matching.
The piston size looks smaller on the new one, but the main reason is that the new lower cylinder and braided lines are fitted with smaller banjos.
I'd need to get a line made up to suit.

I may do this, though, because the new mc weeps around the reservoir seal very slightly, and I could still use my flash dogleg lever, matching the brake side.

[sirch345]

Very impressive Tony although I am suprised you went for a semi-hydraulic system, I thought you would have gone for a complete cable operated clutch seeing as you took the trouble to convert it. Obviously you have your reasons, I'm assuming you think the lock-up problem is clutch slave cylinder related, or at least you're hopefully going to find out if it is

Good luck with it, I'll be interested to hear what you think.

Chris.

[tony.mon]

Actually, if the cable conversion suggested by the racing boys works, then my money's on the master cylinder.

As far as I can tell, when the clutch grabs, it feels exactly as though your fingers have slipped off the lever, and it's pinged fully home.

For that reason I wouldn't be surprised to find that it's the master cylinder, or possibly the slave, because when you feed the clutch lever out ( or at least, the way I do it) is that the movement to the bite point is quick, and sudden, and then the feed into and through the bite point is slower.
I think what may be happening is that the piston in one or the other cylinder acts in a damped manner, and can't react as fast as it's asked to.
That means that your fingers stop at the bite point, but then the piston continues to move after your fingers have stopped.

That feeds in more clutch; just as you dial in more throttle, and then the clutch locks and there's a graunchy noise as the clutch tries to deal with the torque overload.

All of this is just my opinion; I tried a couple of launches today but as the bike's been off the road for more than two months I'll need to get myself back up to using it in full before dialling in big handfuls.
So far, seems ok, but when I tried to slip the clutch in seconds with full throttle, about 3-4K, it grabbed.

More playing about needed before I know for sure.

Oh, and I could have just used a cable and lever; bought a spare one to have on standby, but I like adding a bit of difficulty, and it's all bling, showing off a bit, and something no-one else has yet. Shallow, yes, but fun.

[benny hedges]

but why does it only do it when the engine is hot????
im wondering if its the pushrod heats up the clutch fluid so it expands and fks up the pressure somehow.... like when you have the clutch pulled in on a hot engine, it increases the pressure in the slave cylinder, holding it off the bite... then when you release the lever (and release the pressure in the hose & slave) the increased hydraulic pressure surges back & unexpectedly lets the clutch go.

not sure about the master cylinder theory as it's done the same on mine with 3 different mcs - 2 oem storm mcs and the cbx thats on it now.

im wondering if for an experiment, it would be worth putting a nylon insulating spacer between the slave pushrod and the actuating pushrod... or to replace it altogether with nylon.
the engineering plastics ive got are as strong as steel so cant see it doing any harm - but they dont conduct heat.

it does the same on the sp1 btw, when it's hot & mistreated at launch

interesting your thought on hydraulic overload.... maybe a solution, or experimental bodge, would be to restrict the return hole in the mc.... when it grabs it acts as though the hydraulic pressure is lost too quick, in an uncontrolled way, as if you hand slipped off the lever as you say, or as though the hose burst... the only place for it to go is back into the res through the return hole.
restricting the return should result in a more controlled release

[Diabolus]

Do you think Honda would have discovered this issue when the firestorm was designed and just brushed it under the carpet If your not expecting it, it could easily have you off I,ve come close to dropping it when leaving a junction at full lock and pillion on the back. not good

I find that if I put it in neutral as soon as pulling up at lights ect it the grab doesnt happen very often, but its always there as one day I thought it had gone after doing loads of pulling away and then out of the blue it grabbed

Ill have too ask my step brother if he gets this on his storm, it didnt do it when i rode his and i was giving it a hand full every where but one difference between his storm and mine is I try and maintain mine (he never cleans his bike, the fluids are black and dirty ,ccts are standard and its got loads of miles on it, it starts first time thats all he cares about think he would just get another bike if it gave up, some people are like that i guess) the clutch is easy to pull in on mine but his is stiff and harder to pull the lever.

[tony.mon]

the clutch is easy to pull in on mine but his is stiff and harder to pull the lever.

That's just a dirty slave cylinder and pushrod, behind the sprocket cover area.
Dirty fluid won't affect the feel of the clutch at all.

[KarlosVTR]

my old one done it once or twice and about split my ballbag in half once.

i hope this cures it

[sirch345]

Actually, if the cable conversion suggested by the racing boys works, then my money's on the master cylinder.

As far as I can tell, when the clutch grabs, it feels exactly as though your fingers have slipped off the lever, and it's pinged fully home.

For that reason I wouldn't be surprised to find that it's the master cylinder, or possibly the slave, because when you feed the clutch lever out ( or at least, the way I do it) is that the movement to the bite point is quick, and sudden, and then the feed into and through the bite point is slower.
I think what may be happening is that the piston in one or the other cylinder acts in a damped manner, and can't react as fast as it's asked to.
That means that your fingers stop at the bite point, but then the piston continues to move after your fingers have stopped.

That feeds in more clutch; just as you dial in more throttle, and then the clutch locks and there's a graunchy noise as the clutch tries to deal with the torque overload.

All of this is just my opinion; I tried a couple of launches today but as the bike's been off the road for more than two months I'll need to get myself back up to using it in full before dialling in big handfuls.
So far, seems ok, but when I tried to slip the clutch in seconds with full throttle, about 3-4K, it grabbed.

More playing about needed before I know for sure.

Oh, and I could have just used a cable and lever; bought a spare one to have on standby, but I like adding a bit of difficulty, and it's all bling, showing off a bit, and something no-one else has yet. Shallow, yes, but fun.

Tony, I see where you're coming from on this conversion, it'll be interesting to see which way it goes. I hope for your sake after all the work put into this that you get a satisfactory result Keep us posted bud,

Chris.

[benny hedges]

Still reckon its heat in the slave cyl and/or pushrod

[tony.mon]

Still reckon its heat in the slave cyl and/or pushrod

Boiling the fluid?
Or just jamming it up as it's expanded due to heat soak forom the casings? Can't see how the pushrod will get very hot, really.
It's just at engine temp, same as the rest of the components.

Any more clues?

[benny hedges]

yeh m8 i think its expanding the fluid and raising the pressure so as soon as you release the lever (and open the return valve) the pressure drops quicker than expected and it lurches off....
just another theory as ive had 3 different master cylinders on mine and it does the same thing - when it's hot....

but then again, it only does it when you give it welly.... like fast launch from the lights

will be interesting to see your semi cable mod against a full cable clutch.... i think doing away with the engine mounted slave cylinder will do the trick

[tony.mon]

Ah, right, get your drift.
Well, the MC I now have on is completely non-standard, so it should rule that out, or in, if it's cured.

Here's one for you, any idea of any other clutches that will fit?

It's the splined shaft dimensions that are critical; if it means modifying the clutch case itself that's not much work, you could easily lose the water pump, for instance.

Wonder if the Blackbird one fits, and if so, whether their owner's forum have ever had the same issues?