Fix for rusty shaft ? Discuss

Rememo said:
I just finished undercoating my truck with Woolwax, which is a lanolin product. It's similar to Fluidfilm, but a bit thicker and has less odor.

I'm a big fan of ACF50, but when I finally get around to cracking open my drive shaft housing, I'll be coating the inside with Woolwax, since it's more viscous than ACF50. Plus the undercoating wand will make it really easy to coat the entire housing. ;)
Click to expand...

Cheers for the heads up, all interesting and good info, is that Woolwax heat resistant also.
 
Smogbob said:
Yep we agree on that same as the original video, was just thinking of making the swingarm more solid around the hole, as once a hole has been drilled, it might crack around the hole, maybe jbweld could avoid that, maybe overthinking.
Click to expand...

I don't believe it will crack as the hole is round. you stop drill the end of a crack to prevent it cracking further on aircraft skins. that's a beefy hunk of metal and putting a 4mm hole through that circle wont cause any cracking to the best of my knowledge.
32 yrs aircraft technician
 
I think BMW are over optimistic if they think they can keep a shaft drive casing, with two rubber sections to allow articulation, totally watertight long term. However they have made no provision so far for draining out any water that does manage to get it in, hence the corrosion problems. I would say this is a design failing, and the potential drilling location may be something put there by BMW in case they decide to do something about this in future, as it would not then require any expensive changes to the casting/tooling for the casing.

The main problem I see with this is that to be most effective it needs to be open all the time, and not rely on periodic draining by removing a bung, but in this case by allowing air in at any time, it could promote the formation of fresh condensation inside the casing every time the bike cools down. There is also the issue of water ingress for off-road types when fording reasonably deep water, though I guess it would fairly quickly drain back out.

If I was sufficiently concerned about this to drill and tap the casing (which I am not) I would probably fit something like one of these to allow the option of it to be either plugged, or open with a short plastic drain tube:

https://uk.rs-online.com/web/p/pneumatic-straight-fittings/7715068/
https://uk.rs-online.com/web/p/pneumatic-straight-fittings/0867336/

A selection with M5 or M6 threads:
https://uk.rs-online.com/web/c/pneu...063&sort-by=P_breakPrice1&sort-order=asc&pn=2
 
The very best fix for ‘rusty shafts’ is to stop worrying about it - how many failed shafts has there been compared to the total sales?

Just get your bike serviced as the schedule and sleep easy :)
 
fred_jb said:
with two rubber sections to allow articulation,
Click to expand...

Fred, I'm trying to understand how much movement there is from the bevel box to the swing arm during the suspension travel. I'm probably misunderstanding something in that it looks to me to be a small amount at the rear of the bike?

Clearly the paralever brace doesn't compress or stretch, just a small amount in the bushes.. Therefore as the axle and the brace to frame mounts aren't in the same place (about 11cm apart) it must mean that as the suspension moves up and down the position of the bevel box relative to the swing arm changes - trouble is I'm not clever enough to work out the potential distance over the full 200mm of wheel travel - any idea how to calculate it?
 
Mr Bean said:
Fred, I'm trying to understand how much movement there is from the bevel box to the swing arm during the suspension travel. I'm probably misunderstanding something in that it looks to me to be a small amount at the rear of the bike?

Clearly the paralever brace doesn't compress or stretch, just a small amount in the bushes.. Therefore as the axle and the brace to frame mounts aren't in the same place (about 11cm apart) it must mean that as the suspension moves up and down the position of the bevel box relative to the swing arm changes - trouble is I'm not clever enough to work out the potential distance over the full 200mm of wheel travel - any idea how to calculate it?
Click to expand...

Sorry - I'm not clever enough either! However lots of info online if you ask Mr Google, for example this interesting article:

http://largiader.com/paralever/
 
gazkitchen said:
I don't believe it will crack as the hole is round. you stop drill the end of a crack to prevent it cracking further on aircraft skins. that's a beefy hunk of metal and putting a 4mm hole through that circle wont cause any cracking to the best of my knowledge.
32 yrs aircraft technician
Click to expand...

Will certainly take your word for it with that experience in drilling in aircraft, no mistakes allowed for sure. :thumb2
 
fred_jb said:
I think BMW are over optimistic if they think they can keep a shaft drive casing, with two rubber sections to allow articulation, totally watertight long term. However they have made no provision so far for draining out any water that does manage to get it in, hence the corrosion problems. I would say this is a design failing, and the potential drilling location may be something put there by BMW in case they decide to do something about this in future, as it would not then require any expensive changes to the casting/tooling for the casing.

The main problem I see with this is that to be most effective it needs to be open all the time, and not rely on periodic draining by removing a bung, but in this case by allowing air in at any time, it could promote the formation of fresh condensation inside the casing every time the bike cools down. There is also the issue of water ingress for off-road types when fording reasonably deep water, though I guess it would fairly quickly drain back out.

If I was sufficiently concerned about this to drill and tap the casing (which I am not) I would probably fit something like one of these to allow the option of it to be either plugged, or open with a short plastic drain tube:

https://uk.rs-online.com/web/p/pneumatic-straight-fittings/7715068/
https://uk.rs-online.com/web/p/pneumatic-straight-fittings/0867336/

A selection with M5 or M6 threads:
https://uk.rs-online.com/web/c/pneu...063&sort-by=P_breakPrice1&sort-order=asc&pn=2
Click to expand...

Certainly liking the idea more and more at the moment.
 
take the rear shock off its lower mount, remove the wheel and push the arm up and down from its lower point up 200mm or what ever the travel is... you'll soon see how much they move ;)
 
It moves enough to stress the uj,s if it siezes.If it's left like that too long you might get a premature view of the shaft through the broken casing.
 
Mr Bean said:
So you don't know either... ;)
Click to expand...

no.... :) but the two arms are about the same length... so as the rear arm comes up, the paralever actualy will push the bevel box down.. so it kind of maintains the ride hight a bit....
 
beaver said:
no.... :) but the two arms are about the same length... so as the rear arm comes up, the paralever actualy will push the bevel box down.. so it kind of maintains the ride hight a bit....
Click to expand...

Agreed, but what change does it make to the space that the gaiter fills?
 
beaver said:
no.... :) but the two arms are about the same length... so as the rear arm comes up, the paralever actualy will push the bevel box down.. so it kind of maintains the ride hight a bit....
Click to expand...

Yes, I think the idea of this arrangement is to limit the change in angle of the bevel box which would otherwise happen and which would affect the suspension, either extending or compressing it depending on which direction the torque is being applied, when accelerating or decelerating.
 
the gaiter will open up... by about 12-14mm max according to my measurements
 
Nippy Normans supply Touratech, Wunderlich, Desert Fox and many other makes of accessories.
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