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Gen 6 clutch issues


thet2

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Hi, i just replaced the clutch disks, steels and springs on my VFR 800 vtec abs and have a weird issue

 

Before changing all this i had the clutch slipping, i had cleaned and replaced the clutch oil as had obviously never been changed and was disgusting.

 

I had replaced and bled the system and the clutch feel was much better but still slipping. The steels seemed warped but the clutch in good condition.

 

i replaced the lot as i wanted to start fresh, however not i have this issue:

 

bike on, i put the gear in, leave the clutch out, and it doesnt move, dunno if it's my imagination but if i leave the clutch out very very slowly i feel like it creeps forward but clutch slips.

 

Any ideas what to look at? slave clutch?

One note, when i was tighting the bolts on the pressure plate the plate would spin, i had to put a gear in, is this normal?

 

Thanks for any advise

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Did you zip tie clutch handle before removing slave?  It sound like you need to rebleed.  Try this first zip tie the clutch handle bar overnight and remove screws to oil resovoir for air to move up.

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22 hours ago, VFR750F3 said:

Did you zip tie clutch handle before removing slave?  It sound like you need to rebleed.  Try this first zip tie the clutch handle bar overnight and remove screws to oil resovoir for air to move up.

Hi, thanks for the reply!

i havent taken the slave out yet but i will try your tip first, if not i’ll take the slave out and try and re-bleed

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I also bleed the  banjo.  Wrap a towel around the banjo nut on the master pump loosen retighten quickly it will squirt . this will get that last bit of air out.

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On 5/20/2022 at 1:22 PM, VFR750F3 said:

Did you zip tie clutch handle before removing slave?  It sound like you need to rebleed.  Try this first zip tie the clutch handle bar overnight and remove screws to oil resovoir for air to move up.

As you can see in the drawings the zip tie suggestion doesn't
accomplish much because as you squeeze the lever the piston blocks the
path of bubbles (blue) from reaching the reservoir... but if you leave
the lever at rest the piston retracts enough to uncover the port so
the bubbles (blue) can travel all the way to the reservoir...

 

 


 

BrakeMasterCylinderCutaway.jpg

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On 5/20/2022 at 11:21 AM, thet2 said:

 

Any ideas what to look at? slave clutch?

 

 

If you remove the oil filler cap you can observe if the clutch plates do move and the degree by which they move or not...

ClutchClosed.JPG

ClutchOpen.JPG

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On 5/20/2022 at 11:21 AM, thet2 said:

 

i replaced the lot as i wanted to start fresh, however not i have this issue:

 

bike on, i put the gear in, leave the clutch out, and it doesnt move, dunno if it's my imagination but if i leave the clutch out very very slowly i feel like it creeps forward but clutch slips.

 

 

 

I'm not tracking with how this could be a hydraulic master / slave cylinder  bleed issue.  The default with the clutch lever at rest (out) is for the clutch to be engaged.    Air in the system compresses and prevents the clutch rod from applying force to the clutch stack to dis-engage engage the clutch (slip).  He's saying the clutch is out and the clutch is slipping, so air in the hydraulics cannot be the problem.  If the slave cylinder is maybe partially seized or somehow the master or combination of parts are not allowing the system to release the pressure on the clutch rod, that could be an issue.  Since the fluid was nasty when you changed it maybe there are some corroded parts or plugged passages in that could be the source.  Since your clutch was slipping before it was serviced, that could warrant further investigation.

 

Just to be clear - I think it's a matter of semantics or language translation, you mentioned clutch "oil".  Did you mean hydraulic fluid?  The master / slave system requires the correct fluid, an oil is not specified for that application. 

 

Once the hydraulics are sorted and known good, then it's probably worth going back over the clutch pack installation.  Leaving a disc or steel out of the stack, or getting them out of order could be the problem - I'd be inclined to take it back out and double check your work, comparing to the factory service manual to see that everything is as it should be.  I don't believe you mentioned - did you use OEM parts, or aftermarket?  If the latter, it would be worth measuring them to be sure they match OEM specs for the components. 

 

 

 

 

 

 

 

 

 

 

 

 

 

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I also bleed the  banjo.  Wrap a towel around the banjo nut on the master pump and loosen this will get that last bit of air out.

 

Th zip tie method works.  I do it every year on all my bikes.

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On 5/20/2022 at 8:21 PM, thet2 said:

Any ideas what to look at? slave clutch?

Maybe the clutch pushrod got misaligned when you installed the pressure plate.

 

On 5/22/2022 at 9:00 PM, BusyLittleShop said:

As you can see in the drawings the zip tie suggestion doesn't
accomplish much because as you squeeze the lever the piston blocks the
path of bubbles (blue) from reaching the reservoir... but if you leave
the lever at rest the piston retracts enough to uncover the port so
the bubbles (blue) can travel all the way to the reservoir...

The zip tie method puts the system under pressure making the air bubbles smaller. Smaller air bubbles can travel around tighter corners (inside banjo bolts) and smaller orifices. The bubbles will accumulate just in front of the master cilinder and travel further up to the reservoir as soon as the zip tie is removed. Make sure the steerer is turned to the right

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50 minutes ago, V4 Rosso said:

 

 

The zip tie method puts the system under pressure making the air bubbles smaller.

Under what principal of physics???

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Personally I'd take the clutch slave apart and see if it is seized.

 

4 minutes ago, BusyLittleShop said:

Under what principal of physics???

Boyles law?

Sorry couldn't help myself. I've certainly personally experienced that tying the brake lever back to the bars overnight makes for a significant improvement in lever feel and gets rid of the squishies. Not sure that the same would apply with the clutch as my sense is the actual hydraulic line pressure is much lower. 

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Positive experience matters.   You can tell Sheldon to stick to physics.  I do the same to my clutch.

https://www.apriliaforum.com/forums/showthread.php?179153-zip-tie-your-clutch-lever-instead-of-frequent-bleeding

https://www.superhawkforum.com/forums/technical-discussion-28/zip-tie-brake-lever-after-bleeding-11641/

 

Lets start over

When you changed the clutch did you zip tie the clutch lever yes or no

Is the clutch lever soft or hard does it feel like the brake lever both are 12.7mm masters yes or no

If you did not zip tie you need to keep rebleeding it is a pain in the butt.  I have been there many times when I upgraded to stainless steel lines.

Do not let the reservoir go empty.  Bleed the banjo nut also

https://www.thumpertalk.com/forums/topic/246796-bleeding-brakes-from-banjo-bolts/

 

Did everything work correctly before you replaced the clutch plates?

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On 5/22/2022 at 4:59 PM, VFR750F3 said:

Th zip tie method works.  I do it every year on all my bikes.

Absolutely. My FJ needed this done 1-2 times a year also. Theory was that the bubbles were made small enough to more easily move around/up. Nothing else was done, adn after, they were magic. 

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  • 3 weeks later...

Hi Guys, sorry had been travelling for work for the last 2 weeks and hadn't had time to get back to this, I managed to do some testing this weekend:

 

Slave cylinder removed, i can turn the bike on, push it and put it in gear and it acts normal. 

Reinstalled the clutch slave and it's as if the clutch is fully open at all times.

 

I've rebuilt the clutch slave with a tourmax kit, new seal, pushrod seal and new spring, purged the clutch again and same, i can feel the clutch lever actioning the actual clutch and it feels like the clutch should but again if i pull the clutch, put in to gear and release clutch, it doesn't move and it's as if the clutch is pulled.

 

It's driving me nuts as you can imagine.

 

PS: all is original on my bike apart from clutch kit (TRW complete kit)

 

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On 5/23/2022 at 1:39 AM, VFR750F3 said:

Positive experience matters.   You can tell Sheldon to stick to physics.  I do the same to my clutch.

https://www.apriliaforum.com/forums/showthread.php?179153-zip-tie-your-clutch-lever-instead-of-frequent-bleeding

https://www.superhawkforum.com/forums/technical-discussion-28/zip-tie-brake-lever-after-bleeding-11641/

 

Lets start over

When you changed the clutch did you zip tie the clutch lever yes or no

Is the clutch lever soft or hard does it feel like the brake lever both are 12.7mm masters yes or no

If you did not zip tie you need to keep rebleeding it is a pain in the butt.  I have been there many times when I upgraded to stainless steel lines.

Do not let the reservoir go empty.  Bleed the banjo nut also

https://www.thumpertalk.com/forums/topic/246796-bleeding-brakes-from-banjo-bolts/

 

Did everything work correctly before you replaced the clutch plates?

Yeah everything worked fine just clutch slipping when Vtec kicked in, i didnt zip tie the lever as i replaced the liquid to the clutch system too. i've bled alot of Clutches and brakes in my like and this is the first time i've had this kid of problem.

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You are sure you installed the friction plates in the right order, starting with the one with the larger ID that fits over the friction spring? And the outer friction plate one slot offset to the other friction plates?

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Yep 100%, what i dont understand is without the slave cylinder in it works as intended, i have ordered a new seal, i’m going to take the cover off and recheck everything, in my version of workshop manual there isnt a full diagram, does anyone have a good one i can cross reference to?

 

thanks!

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12 hours ago, V4 Rosso said:

You can find even better diagrams & more in the factory service manual:

 

Thank you, the "service manual" i had was missing all the diagrams, this one is much more in detail. i will try and take it all apart again this weekend and recheck everything.

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HI Guys,

 

I've taken everything apart, the clutch is per the service manual, i think the problem lays with the hydraulic system, i say this as the clutch disk and liners are the same as the old setup, as soon as i push the rod in the lutch has friction, then i can see it push the clutch open slightly (enough for me to be able to push the disks from side to side) it's as if the rod is too long.

Just to recapitulate, this is what i've done so far:

 

Changed friction and steels

flushed the complete clutch liquid

rebuilt slave clutch cylinder

 

I'm at a loss, if anyone has an idea?

 

Thanks

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Most likely suspect (culprit) causing your issue is the “rebuilt” slave cyl, wrong parts/kit, piston in there not the correct dimensions, take it apart & compare to original part(s)? Grasping @ straws, but if everything else is correct...

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The bearing in the pressure plate is not held in, it’s prone to tip and jam, so with actuating rod removed the clutch connects with the gearbox, hydraulics assembly will push the rod out and disconnect the gearbox 

 

I’ve fixed mine in place with Loctite bearing fit

 

You can see if this is happening through the oil filler as the hydraulics are fitted 

 

Tourmax kit is quality 

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