problem with clutch hydraulics after broken chain

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fatfreddy000
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problem with clutch hydraulics after broken chain

Post by fatfreddy000 »

Got my chain and sprocket kit on today (very nice DID zvm G&B x-ring)
put her back together very happy with myself as id done it all outside in a blizzard.
go to put her in gear and no hydraulic pressure at all on clutch lever.
on investigation there is a small hole on the inside of the sprocket cover where the chain has hit it.
- it's behind the slave cylinder housing but has not caused a leak of fluid.
i fiddled around with it for ages then thought it was worth bleeding it and seeing what happened..
turns out the fluid reservoir was still full but the line had air in it.. took ages to get get it to gravity bleed through via the banjo union bolt.
once all air was out and bled properly through the nipple it worked fine.
will see if it leaks fluid or takes in air over time..
what happened though?
my guess is that the impact of the broken chain against the housing and subsequent holing somehow contacted the slave piston while clutch was in and piston fully protruding thus knocking it out of line enough to allow some air in?..
funny thing.
next i need mend that hole to keep it clean in there- thinking a bit of JB weld or i'll have to take it to get tig welded..
rode home in the snow in first gear riding the clutch for 5 miles with frozen burning fingers.
nearly came off a handful of times, the rear wheal went sideways and tried to overtake me which was unnerving..
sod that, put it away till the thaw!
“If all insects on Earth disappeared, within 50 years all life on Earth would end. If all human beings disappeared from the Earth, within 50 years all forms of life would flourish.” Biologist Jonas Salk
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Wicky
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Re: problem with clutch hydraulics after broken chain

Post by Wicky »

Unless you take precautions taking the sprocket cover off invariably leads to clutch needing bleeding afterwards.

Photo of the damged area? You might still be lucky.

Took me 2 hours to get 5 miles to work early this morning on the bike (most of that time was charging the battery). Worked 1&half hours and come back home.
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sirch345
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Re: problem with clutch hydraulics after broken chain

Post by sirch345 »

Wicky wrote: Fri Mar 02, 2018 7:31 pm Unless you take precautions taking the sprocket cover off invariably leads to clutch needing bleeding afterwards.
As Wicky points out. Next time you remove the front sprocket cover/slave cylinder remove the clutch lever first. Once the slave cylinder and front sprocket cover has been refitted refit the clutch lever.

Good to hear you new chain and sprocket kit was as good as you hoped :thumbup:

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fatfreddy000
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Re: problem with clutch hydraulics after broken chain

Post by fatfreddy000 »

Wicky wrote: Fri Mar 02, 2018 7:31 pm Unless you take precautions taking the sprocket cover off invariably leads to clutch needing bleeding afterwards.

Photo of the damged area? You might still be lucky.

Took me 2 hours to get 5 miles to work early this morning on the bike (most of that time was charging the battery). Worked 1&half hours and come back home.
aah, thats good news..
I've taken it off a couple of times before but hd no issue..
trying to work out how removing it results in getting air in the system?
maybe its just a case of making sure the push rod doesn't pull out.
yep the chain is great- one of the extra heavy duty zvm jobs from DID. very happy with it and for £70 plus sprockets delivered.. bloody bargain NOS
“If all insects on Earth disappeared, within 50 years all life on Earth would end. If all human beings disappeared from the Earth, within 50 years all forms of life would flourish.” Biologist Jonas Salk
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8541Hawk
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Re: problem with clutch hydraulics after broken chain

Post by 8541Hawk »

The issues with pulling air into the clutch system is due to Honda missing a step in the service manual IMHO.

Why the air is pulled in is the easy bit. It happens because the piston in the slave cyl. is large enough that when it moves all the way out (though it will not pop out on its own) it completely empties the reservoir.
Then air gets pulled in and ends up trapped at the banjo fitting. This is the high point of the system and why it can be so hard to bleed the system unless you bleed the banjo fitting also.

Removing the lever helps some but you are still pulling air into the system.

So how do you get it all back together without the air issue?

First, the reason to tie the lever back is to seal the system. When the lever is pulled in there is no way for air to enter.
Which leads to the issues folks have putting the slave cyl. back in place.
With the lever pulled in it can be difficult to install the slave and tighten down the bolts. If done wrong it leads to bent clutch push rods.

This is where I believe the missing step should be added.
All one needs to do is follow the service manual instructions up until you mount the slave cyl.
At that point you place the slave into position and hold it with light pressure.
Then remove the tie holding the lever to the bar.
Then push the slave cyl. home and install the bolts.

Nice and easy with the added benefit of keeping all air out of the system.
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tony.mon
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Re: problem with clutch hydraulics after broken chain

Post by tony.mon »

It's nothing to do with the clutch pushrod.
The slave cylinder has an internal spring.
If you remove the slave cylinder from the sprocket cover, the spring slowly pushes the slave piston out until it is past the seal, allowing air to enter.
On assembly you push it back in again, but air is already in the slave and it takes quite a bit of bleeding to remove it.
About 20 minutes is normal, just keeping and it'll come back.

Even easier than tying the lever back as advised above is to cable tie a socket into the slave to hold it retracted.
That way you can reinstall it without risking bending s pushrod.

Don't get anything welded.

The sprocket cover is magnesium, welding that might be interesting .....
It's not falling off, it's an upgrade opportunity.
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fatfreddy000
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Re: problem with clutch hydraulics after broken chain

Post by fatfreddy000 »

8541Hawk wrote: Fri Mar 02, 2018 10:37 pm The issues with pulling air into the clutch system is due to Honda missing a step in the service manual IMHO.

Why the air is pulled in is the easy bit. It happens because the piston in the slave cyl. is large enough that when it moves all the way out (though it will not pop out on its own) it completely empties the reservoir.
Then air gets pulled in and ends up trapped at the banjo fitting. This is the high point of the system and why it can be so hard to bleed the system unless you bleed the banjo fitting also.

Removing the lever helps some but you are still pulling air into the system.

So how do you get it all back together without the air issue?

First, the reason to tie the lever back is to seal the system. When the lever is pulled in there is no way for air to enter.
Which leads to the issues folks have putting the slave cyl. back in place.
With the lever pulled in it can be difficult to install the slave and tighten down the bolts. If done wrong it leads to bent clutch push rods.

This is where I believe the missing step should be added.
All one needs to do is follow the service manual instructions up until you mount the slave cyl.
At that point you place the slave into position and hold it with light pressure.
Then remove the tie holding the lever to the bar.
Then push the slave cyl. home and install the bolts.

Nice and easy with the added benefit of keeping all air out of the system.
Thanks for that,
Must've jut got lucky the other couple of times I tool that cover off.
It's relief nothing is damaged 'significantly' anyway..
“If all insects on Earth disappeared, within 50 years all life on Earth would end. If all human beings disappeared from the Earth, within 50 years all forms of life would flourish.” Biologist Jonas Salk
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fatfreddy000
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Re: problem with clutch hydraulics after broken chain

Post by fatfreddy000 »

tony.mon wrote: Fri Mar 02, 2018 10:38 pm It's nothing to do with the clutch pushrod.
The slave cylinder has an internal spring.
If you remove the slave cylinder from the sprocket cover, the spring slowly pushes the slave piston out until it is past the seal, allowing air to enter.
On assembly you push it back in again, but air is already in the slave and it takes quite a bit of bleeding to remove it.
About 20 minutes is normal, just keeping and it'll come back.

Even easier than tying the lever back as advised above is to cable tie a socket into the slave to hold it retracted.
That way you can reinstall it without risking bending s pushrod.

Don't get anything welded.

The sprocket cover is magnesium, welding that might be interesting .....
Thanks for tips.
Yep welding attempt could have been disastrous, but entertaining!
“If all insects on Earth disappeared, within 50 years all life on Earth would end. If all human beings disappeared from the Earth, within 50 years all forms of life would flourish.” Biologist Jonas Salk
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