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Clutch pushrod seal

 
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deuce_7
honda305.com Member


Joined: 18 Mar 2018
Posts: 17
Location: California

PostPosted: Fri May 24, 2019 8:30 pm    Post subject: Clutch pushrod seal Reply with quote

1967 CL77...

Have replaced the clutch pushrod seal several times without much success. It will leak whenever the clutch lever is pulled in, the leak then stops when clutch is released.

The pushrod shows a bit of wear where it passes through the seal, and Iím beginning to think the pushrod is the problem. Any experience out there with this issue? My next step would be to install a new pushrod and seal to stop the leak.

Thanks for any inputs,
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Tim Allman
honda305.com Member


Joined: 02 Dec 2014
Posts: 286
Location: Guelph, Ontario, Canada

PostPosted: Sat May 25, 2019 1:20 pm    Post subject: Reply with quote

The pushrods do indeed wear at the seal, making them undersized and leaky. I've fixed this by installing a new seal, reasoning that there would be wear on the seal as well. Clearly there's a limit to this as the rod wears.

I've often thought that someone with access to a machine shop (G Man?) might be able to fill the groove and repair the rod to its former glory but I have never tried it.
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DJM
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Joined: 09 Oct 2003
Posts: 373
Location: Chesterfield UK

PostPosted: Sat May 25, 2019 3:11 pm    Post subject: Clutch pushrod leak. Reply with quote

A few years ago I came across the same problem and (eventually) found the cause.

The seal and pushrod were both replaced and in perfect condition but the leak persisted.

If you remove the seal you will expose a bronze disc with a hole in the centre which supports the pushrod and holds it central, this hole should only be a few thou bigger than the pushrod itself, just enough clearance for the pushrod the slide through.

In my case the hole was MUCH larger, can't remember the exact size but effectively it meant that the seal was also trying to hold the pushrod centrally, clearly not what is designed to do.

As the clutch was operated the pushrod was, I suspect, moving sideways and the seal was no longer closing round the pushrod, hence the leak.

Fitting a different top gear with the correct sized hole in the disc cured the problem.

I don't think the hole was worn but think it was made that way, it probably always leaked. Since them a friend of mine has found the same problem on one of his bikes.

Removing the seal and checking the hole size is easy, the bronze disc with the hole in the centre is a separate part just driven into place and making a replacement is straightforward.

Unfortunatley removing the old disc means driving it out from the inside so means a bottom end engine stripdown.
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deuce_7
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Joined: 18 Mar 2018
Posts: 17
Location: California

PostPosted: Sun May 26, 2019 9:57 am    Post subject: Reply with quote

Best explanation of the issue/cause of the leaks that I've seen. Thank you for the thorough technical detail.

Been working to dry up oil leaks on the CL77's right side; e.g., crank and countershaft seals, and the leak / dripping situation is much improved other than the pushrod seal. Btw, been using seals (Taiwan) obtained from 4 into 1 and they work well.

Next time it's apart I'll look for any sideways drift in the pushrod where it passes through the bushing.

Probably one of things to live with, if it means tearing down the engine.

Thanks again!
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