GB Gearbox Oil Leak

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robin.parker
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GB Gearbox Oil Leak

Postby robin.parker » Fri Mar 07, 2014 9:48 am

Can anyone please tell me, what is the current thinking on how to prevent gearbox oil escaping via the speedo drive and cable? The patient is a 1957VH with a GB gearbox.
Thanks,
Robin.

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robjameson
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Postby robjameson » Fri Mar 07, 2014 12:39 pm

My current thinking is that I have stopped trying!
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1956 Ariel KH (LARGE project!)
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robin.parker
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Postby robin.parker » Fri Mar 07, 2014 4:04 pm

Well OK Rob, but I know full well that they didn't leak when they were new, or even nearly new.

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Postby robjameson » Fri Mar 07, 2014 4:23 pm

I've used o rings, big, little, medium. Nothing seems to work for me, it seems to depend on what day it is and how the bike feels, sometimes I'll get months without a drop, other times it decides to drop most of it out. I'm at a loss, so I gave up!
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1957 Ariel VH
1956 Ariel KH (LARGE project!)
2016 Honda CBR600RR

robin.parker
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Postby robin.parker » Fri Mar 07, 2014 6:17 pm

I did improve things by using about a 12" length of heat-shrink sleeve along the cable and over the ferrule, but I have been warned that this might cause oil to work it's way up to the speedo head, which would not do it any good!
Drags suggest using a little fibre washer (2096.53) I'll order one of those when I next need some other spares.
Robin.

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marcus whatling
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Postby marcus whatling » Fri Mar 07, 2014 10:51 pm

Gearbox with oil in it . I think an oil seal would be a good modification on the gearbox side of the cable outlet
As the speedo drive gets old and worn oil leaks past a worn bush the oil seal might help keep the oil in (maybe a change to an oillite bush due to lack of lube)
As our bikes are ridden at a different pace to the old Days this might help ?
The older type boxes with a speedo cable upwards were better .
But just leaked (grease) from somewhere else !

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Postby pete.collings » Fri Mar 07, 2014 11:17 pm

I believe the speedo drive spindle is grooved to allow oil to run down for lubrication of the bush. I have never seen a spindle/bush assembly that was appreciably worn, I guess that if a major loss of gearbox oil occurred, the rest of the box would sieze up through lack of oil before the speedo drive could be damaged.
The bronze bush has an O ring on the outside as a seal, and a little oil running through onto the cable inner is no bad thing, it's only when the oil reaches the speedo head that problems start. I would make sure the inner cable had a reasonable (but not excessive) amount of grease applied, and then wipe off the grease from last few inches before it enters the speedo head.
I think overtighening of the alloy bottom nut on the speedo cable (to try to stop a leak) will only make the leak worse. possibly using silicone gasket goo on the inside of the nut, with shrinkwrap tube on the outside may help to eliminate any leaks?

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Re: GB Gearbox Oil Leak

Postby jj.palmer » Tue Mar 11, 2014 11:17 pm

[attachment=0]Scan1.pdf[/attachment)
Hi
Having recently reassembled the gear box I came to the conclusion that the spiral (helical) groove on the speedometer drive spindle was there to stop the oil leaking by pumping the oil back to the gear box as per a "Archimedes screw", but the thrust washer could possibly restrict that flow so I therefore bypassed the thrust washer by drilling a small hole, as per the sketch. The additional hole also assists in rotating the spindle bearing to align the retaining screw.
I may have it all wrong, it may leak even more, but time will tell when I have it out on the road.

Regards
John Palmer.
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Scan1.pdf
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robin.parker
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Postby robin.parker » Wed Mar 12, 2014 5:56 pm

Thanks chaps,
I'm trying the fibre-washer idea at the moment, I'm doubtful but I'll give it a go. Otherwise, I'll be trying your suggestions.
regards,
Robin.

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Re: GB Gearbox Oil Leak

Postby jj.palmer » Fri Jun 27, 2014 2:17 pm

Hi
Now back on the road but still a small oil leak from the speedo drive, I have now made and fitted at the lowest point of the cable an "oil soak pad", result no oil on the garage floor, the fitting is quite unobtrusive. Obviously the cloth pad will require changing periodically, see photos.

Regards
John Palmer.
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