Bevel box leak

After the Mistral mapping frenzy in Bungendore a couple of weeks back, I noticed a wee drip of oil on the garage floor under the swingarm. It was dripping from one of the clips that holds the speedo cable and rear brake hose.

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I didn't think much of it and cleaned it up. No more drips over the next few days. So I thought no more of it. After a ride last weekend the drip returned.

Pete was sure it was sure it was either the seal on the bevel box or the output shaft seal on the gearbox. The drillings for the clips go all the way through, so any oil in the void in the swingarm usually drips out through them.


I pulled the bevel box off and sure enough, the seal was wet with oil.

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There was a pool of it just inside the swingarm. The length of the swingarm was dry, so no oil from the gearbox end.

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Fortunately, I had a spare bevel box, courtesy of Roper-San.

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No leaks on this one.

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Reassembled and ready to go!

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Chances are is is just leaking around the boot. If you look at the mating surface of 'Leaky' one you can see the thick glues of fucking silastic that the factory started using around the rectangular 'Compression plate' that holds the front of the boot. This started being done some time around the beginning of 2010 to prevent exactly the sorts of leakage from the clips on the swingarm you've got.

The problem stems from the 'Compression plate' relies on being squeezed tight into the boot recess on the front of the box to prevent oil leaking past the boot edge and into the arm. The problem is it isn't very good at it! The result is oil seeps past the boot and plate and then, because the clip holes go all the way into the void in the swingarm oil will pool and drip out.

By slathering a gallon of silastic around it they can virtually gaurantee the boot won't leak and therefore no drips from the clips. The massive pain in the arse is that the silastic renders the Bevelbox virtually irremovable from the swingarm. You have to use a bottle jack between the bottom of the suspension linkage and the ABS sensor mount to lever the bugger off and then the 'Compression plate' which is retained to the box by two self tapping screws, will tend to bend as it tries to remain attatched to the swingarm! Grrrrr! You have to get in with a screwdriver and lever it off before the box will separate.

I prefer NOT to glue the box on with silastic for this reason. Sometimes they're fine. Sometimes they're not. While it could be the pinion seal I doubt it is but what I'll do is take the compression plate off and then glue up the boot with some Threebond on both sides of the boot lip before re-installing the 'Compression Plate' and then I'll run it on my bike for a week and see if it cures the problem. It usually does. If it doesn't then it is the pinion seal and I'll have to take the box apart to replace it. Only good thing with that is it gives me the opportunity to remove the pinion nut and tab washer and Loctite the buggery out of them like I did mine after the pinion nut dropped its preload. It won't be happening again on my bike!

Pete

I don't wanna silicunt it up neither. I dint look to hard at the boot after pulled it off. I was going to go for a ride to test it out but I ended getting a skin-full of cider instead.

I couldn't find a torque setting for the bolts that hold the box to the arm. I settled on 50Nm. Fairies nuts?

10mmx1.5 I beliee, into alloy? Whatever the book says, I'll look it up. It's not a fitting I use a TW on but it'll have a huge margin on it because it's such a vital mount. If t he bolts shear or the threads pull out the back wheel falls off!

Pete

Thank you for posting and with the pics. It makes hell of a difference! Got a Becker tecnik stand coming looks like a good bit of kit.

Post added to faves for future ref.....

The Becker T is a top bit of kit.

Pete, I looked in the manual but couldn't see anything that I could translate into "bevel gear to swing arm retainer"

50-60Nm is about right for a bolt like that I reckon.

Just went for a spin into the hills. Bevel box didn't fall off or get whiney.