Hydraulic clutch problems

[Gary Slahor]

Just soliciting some thoughts and opinions on a problem I've been having with the hydraulic clutch on the VanDiemen w/ 08GSRX1000.

Before the addition of the Flat Shifter, which required cutting back the sprocket cover (lost 1 retaining bolt at the top) to provide clearance for the shift solinoid, the hydraulic clutch was flawless...... never required any attention, worked every time for 3 years.... just perfect. Now with no change other than slight cutting of the sprocket cover......EVERY time the car goes out on the track, it comes back with no clutch, and fluid spilled all over the nose, under the clutch master cylinder. So far I have: rebuilt the existing master cylinder (no change).......replaced the master cylinder with a brand new unit from Pegasus (no change)....... rebuilt the slave cylinder with new seals from Suzuki(no change)...... replaced the slave cyl/sprocket cover with new Suzuki unit (but also had to cut it back to clear the solinoid - no change) and replaced the braided stainless hose and all fittings (no change).

So I've replaced every component in the system with no improvement, and the only thing different is the modification to the sprocket cover.... So as strange as it seems, it must be related. I even tried going back to my cable operated shifter in case the solinoid was causing some problem, but again no improvement.

Any thoughts ?

Does anyone have a recommendation for an aftermarket bracket to hold the clutch slave cylinder, so I can do away with the cut down sprocket cover ? I'll try anything at this point.

TIA..............Gary

[brownslane]

How about throwing all the hydraulics out and converting to cable? It is lighter, easier to set up and (other than heat) is impervious to much of the hydraulic problems. I have converted both my R-1 powered sports racers into cable and have been pleased with the results. I saved over a pound in weight as well

The only question in my mind is how to make the change to GSXR. Is the slave cylinder pushing or pulling? If pulling, then it is a simple change.

Sorry if this a bit off topic. Back to the hydraulic problem...it would seem that there is something compressing the slave cylinder and pushing fluid back into the master...and it would appear this is related to the removal of part of the cover. I would be looking at attenuation (harmonic vibration) that is moving the slave. Can you mount the slave differently, in such a way that it is supported better?

Also, another question; how to you remedy the problem before the next session? Is it as simple as bleeding the system again, or is the slave affected in other ways (over-extended piston as example)?

For me, the conversion to a cable resolved a whole number of challenges including a difficult bleeding process and I saved weight as well.

Good luck, this sounds like a royal pain!!
T

[ghickman]

Gary
Fairly certain I know what the problem is. On the inside of that cast slave cylinder cover is a steel plate which has a specific mass attached to it. This is a harmonic deadening device which keeps the piston from getting kicked back and vibrating. Did you happen to remove this or anything around it?

If you have my cell number I'll be in the machine shop all day long and you are welcome to give me a ring.

[brownslane]

Gary
Fairly certain I know what the problem is. On the inside of that cast slave cylinder cover is a steel plate which has a specific mass attached to it. This is a harmonic deadening device which keeps the piston from getting kicked back and vibrating. Did you happen to remove this or anything around it?

If you have my cell number I'll be in the machine shop all day long and you are welcome to give me a ring.

Kinda what I thought. With these high revving "buzzy"motors, vibration is a big challenge. Found all that out years ago in F4 with the two-strokes.

Best, T

[glenn cooper]

What I ended up doing was to put a piece of fuel cell foam in the clutch master reservoir.
Not sure what cutting the sprocket cover had to do with it, but in my case it seemed to be the fluid getting aerated in the clutch master cyl reservoir.

My RFR has never done this, btw, so I think it may be chassis related.

Either way hydraulic clutch systems to me are a solution to a problem that never existed(!) and I am totally behind converting the 07/08 to the earlier (03/04 or maybe 05/06 also) cable operated system.

It's relatively easy to do the sawp w/ parts off the earlier year engine, but you'll need to shorten the 07/08 clutch outer pushrod (the one poking out of the left side crankcase) to approx 101 mm. This is due to the fact that the inner clutch release pushrod (the aluminum tube looking deal loacted behind the clutch assembly and requiring clutch assy removal to get to it) is longer on the earlier gen engines.

[RobLav]

Concur with mechanical clutch cable... simple, light, effective.

[formulasuper]

Concur with mechanical clutch cable... simple, light, effective.

Same here, had the same scenario with my Busa, ended up with mech cable. Has worked flawlessly for the last 7 yrs.

[Gary Slahor]

Thanks for the replies. I would like to convert to mechanical cable, but it would have to be a custom design, as the part I need to cut off the sprocket cover to clear the shift solinoid is where the factory clutch cable attaches.
The fuel cell foam in the M/C resevoir is a good suggestion and easy to try.
I'm also thinking about copying Jay Novaks custom fabricated slave cylinder bracket that doesn"t flex as much (made out of 3/8 Al plate).
It's curious that the problem remains with 2 different sprocket covers, each cut slightly different amounts, with and without the inner rubber and stiffener. The fact that the factory felt it necessary to add the rubber and stiffner plate kinda indicates that they knew there was a problem.
Thanks again.................Gary

[Brett Lane]

This sounds kinda stupid, and I apologize. But did you replace the crush washers on the banjo fitting? I had the same problem. The crush washers lost their seal.

[Gary Slahor]

Thanks Brett...... not stupid.... a valid comment. I did get new crush washers with the new line and fittings, so I think I got that covered.

[glenn cooper]

I'm almost certain the factory damper that attaches to the inside of the sprocket cover is mainly for quieting down that area. It might even be EPA related for noise emissions...

[10rmotor]

I had a similar clutch problem with my kawasaki. I have an external slave cylinder that worked great for years, then all of a sudden it would lose fluid. Checked all the lines, rebuilt the master, changed the slave cylinder, no change. Finally swapped out the lockheed MC for a tilton and it seems to be fine.

[JakeL]

Hi Gary -

I am having the exact same problem on my car, as it turns out. I was curious if you've sorted out a resolution just yet?

I too have removed that inner plate, if I am remembering the one, since the shift cable bolts to that slave cylinder bracket on my car.

I'll try the foam-in-the-reservoir trick that His Coopness mentioned.

Thanks for any pointers...

-Jake

[Gary Slahor]

Jake,

I've learned a bit more about my problem, and I'm convinced that the problem occures because I cut part of the sprocket cover away to provide clearance for my power shifter solinoid. Clutch worked flawlessly for 3 years untill I cut the cover back.

The first cover I cut back, I cut it pretty severly and had to eliminat the inner stiffner and rubber insert. Even with the foam in the resevoir and an external stiffner bracing the sprocker cover to the frame, I still lost the clutch every time I went out on the track.

The second cover that I cut back, I was carefull to cut it only enought to just clear the solinoid and I was able to retain most of the internal stiffener and rubber insert. I still had the same problem, untill I added the resevoir foam and the external brace, that braced the cover back to the frame to keep the cover from flexing. This past weekend at Summit Point it almost fixed the problem. The clutch was still working at the end of a 23 lap race........although it was pretty spongy. I still had to bleed it after every session.

I'm still going to convert to a cable operated clutch. It is a much simpler system
Hope that helps,

Gary

[JakeL]

Gary -

Thanks for the reply. I never had any issues in 3+ years with my Stohr DSR, and that clutch cover was severely cut *except* I never got rid of the damper stuff. Seems likely related.

I also have a Flatshifter, and the load cell is mounted at that end, which is why I've modified the clutch cover.

Would be interested to see what you do in terms of modifying the system for the cable clutch - interested to see the pedal end and the slave end. I understand the 05-06's used cable actuation, so the cover bolts right on with the above-mentioned shortening of the clutch rod.

Good luck!

-Jake

[Revs2-12k]

Gary,

Sorry you still have clutch issues, hope you get them cleared up by Atlanta.

How about a different location for the Flatshifter force sensor?

I noticed Charles Dempsey's Stohr FB located the load cell/force sensor behind his steering wheel paddles, vs. down by the engine. (I never got around to asking him exactly why.) Seems logical for such an electronic device, since there would be less vibration and it's much cooler than the engine bay.

Force-is-Force, so mount it in the cockpit. That way you can go back to a stock GSXR sprocket cover.

[JakeL]

Richard -

The FlatShifter instructions call for mounting the load cell at the engine end if using a cable. Interesting that Doc's works OK with it mounted by the paddles. May have to give Senor Critter a call.

-J

[Revs2-12k]

Yep, I also follow directions and mounted it down on the sprocket cover. It took some extending of the Stohr supplied cable bracket to keep the overall cable length correct.

In retrospect, up behind the paddles may be a better place for such a relatively delicate device.

I'm sure our man Critter will be in Atlanta (not sure about Dr. Charles's FB). I'll ask him to shed some light on the subject.

[Gary Slahor]

Jake/Richard,

Are we talking about the same part ? I had to cut my sprocket cover to provide clearance for the big heavy 12v chrome plated solinoid that pushes and pulls directly on the shift arm to shift the gears. I can't imagine mounting that remotely and having it push/pull a cable. That thing is huge and draws upwards of 30 amps every time you shift. Did someone actually (sucessfully) mount that up near the steering wheel ?

Gary

[Revs2-12k]

No, sorry different Flatshifter system, you did'nt specify which

Here is the Flatshifter Expert that Jake & I have. I'm referring to the Black load sensor w/ Rod End on the right of photo 1.

Photo 2 is another version of the load sensor Flatshifter used (red one) mounted in a Kart, that is the application I'm referring too for our Stohr application.

[formulasuper]

I'm almost certain the factory damper that attaches to the inside of the sprocket cover is mainly for quieting down that area. It might even be EPA related for noise emissions...

Ah, I guess that explains the purpose of the thick rubber pad under the right side outer clutch cover on my F1.3

[JakeL]

Gary, Coop,

What brand of master cylinder are/were you using?

Some of the DSR guys reported solving the problem by switching to Tilton MC's from Wilwood or AP:

http://dsrforum.yuku.com/topic/9734

I had Tiltons on the DSR. This car has Wilwoods. Maybe I'll try a Tilton...

Curious to know what you guys have though...?

Jake

[proutyc]

Hey Jake do you have a stop on the clutch pedal so it doesnt over extend?

[S Lathrop]

I ran into this problem, of aerating the hydraulic fluid, in the master cylinders when I first started building FCs with the Pinto motors. It affected all the cylinders. So if you are seeing this in the clutch only, you can bet that you will see it in the brakes if you make some other change. It is a harmonics problem and the stiffer the chassis, the more likely the problem.

The quick solution was a condom placed over the opening to the master cylinder and make sure you got all the air out.

The final solution was to remote mount the reservoirs for the master cylinders and not use metal reservoirs. AP makes a great dual or 3 port reservoir that has a bellows in the top to keep air away from the fluid. The reservoir is segmented so that a leak in one cylinder will not drain all the fluid from the other cylinders and you can see the fluid level through the reservoir's sides.

[glenn cooper]

I believe the clutch master was a Girling on my last car, not sure but Mike B might know as it's probably in his spares crate.

[formulasuper]

I ran into this problem, of aerating the hydraulic fluid, in the master cylinders when I first started building FCs with the Pinto motors. It affected all the cylinders. So if you are seeing this in the clutch only, you can bet that you will see it in the brakes if you make some other change. It is a harmonics problem and the stiffer the chassis, the more likely the problem.

The quick solution was a condom placed over the opening to the master cylinder and make sure you got all the air out.

The final solution was to remote mount the reservoirs for the master cylinders and not use metal reservoirs. AP makes a great dual or 3 port reservoir that has a bellows in the top to keep air away from the fluid. The reservoir is segmented so that a leak in one cylinder will not drain all the fluid from the other cylinders and you can see the fluid level through the reservoir's sides.

Steve, the aeration problem I had with my RT5 was definitely in the slave cylinder since it never happened until I converted over to the Hayabusa engine. I would bleed it & by the time I got to the grid it was already full of air. Even tried a couple of brand new slave cylinders & after a few laps the air was back in again. Finally made a simple lever actuated system with a push/pull cable that works perfect.

[S Lathrop]

Steve, the aeration problem I had with my RT5 was definitely in the slave cylinder since it never happened until I converted over to the Hayabusa engine. I would bleed it & by the time I got to the grid it was already full of air. Even tried a couple of brand new slave cylinders & after a few laps the air was back in again. Finally made a simple lever actuated system with a push/pull cable that works perfect.

I assume that when you bleed the clutch, the clutch will work until you turn the engine on?

If that is the case, air has to be getting into the system some place. The only other option I can think of, is that the air is be drawn past the seals which is very possible. The problem is harmonics, with enough vibration at the right frequency strange things are possible. The solution would be to isolate the slave cylinder from the vibration.

The FB I am working on now has a cable clutch because that is what the engine has.

[Gary Slahor]

My Master cylinder is a Girling, and I never had an ounce of problem with it with either the Pinto engine (FC) or the Suzuki GSXR (FB) (with unmodified sprocket cover). It was only when I cut back part of the sprocket cover and lost one of the mounting bolts, that I started having my problems.
My opinion is that by cutting back the sprocket cover, it is now flexing due to engine vibrations and the flexing is pumping fluid back up into the master cylinder..... because I find it spilled on the floor of the nose under the clutch master cylinder.

[Mike B]

I believe the clutch master was a Girling on my last car, not sure but Mike B might know as it's probably in his spares crate.

Was and still is.

[JakeL]

Thought I'd report back.

Changed to a Tilton master cylinder for the clutch, and my problem is gone. Has worked 100% ever since switching, and have not had to re-bleed every time I disconnect the slave cylinder bracket, which I had to do previously on this car.

Behavior now matches what it was like on my DSR (which also had Tilton masters), which is that it would seem I basically don't need to bleed the clutch unless I open the system.

-Jake