New drive shaft lubing issue - v11 Sport

[guzzi323]

I was lubing the driveshaft (off the bike) during a tire change and I noticed a pinhole at the back of the mid-shaft which allowed grease to come squirting out as I pumped it in. It's inside the yoke where it connects to the shaft. I thought it might have come from when I was greasing the rear fitting but I cleaned it off and re-greased the center section. I could hear it oozing out the pinhole. I think it's not a big issue as I can manually smear grease on the splines of the half shafts but it's one more thing to keep an eye on.

[Scud]

I've lubed a few of these, and each one allows grease to escape in the same area. I think it's by design. If you put too much grease and it can't escape then you are changing the alignment of the whole drive system.

[coreytrevor]

I would think the hole serves the same purpose as the cap some shafts have there that will pop out if you over-grease it.

 

If there was too much grease and the shaft hydro?locked and couldn't compress when it needed to I imagine there could be spectacular and instantaneous destruction to the transmission and/or final gearcase.

[guzzi323]

I'd think if it was a 'pressure relief' it would be not right near the nipple. I can't imagine much grease gets down the length of the shaft splines before the grease comes out the end. No matter for me. I'll just manually grease the shaft splines whenever I change the tire.

[MartyNZ]

As Scud says, there is an escape hole in the grease cavity on every driveshaft. Normally the drive shaft length extends and compresses a little during suspension travel. This is the reason that the sliding spline exists, and it needs lubrication.

I can think of two reasons why you need that little hole.

1. If the grease cavity was full of grease without an escape path, then it is possible to get a "hydraulic lock", which would make something bend or break at the next bump on the road. (at a guess, I'd say the gearbox top mount).

2. Grease is mostly oil mixed with a thickener, so as the oil seeps away, the remaining thickener needs to be flushed away by fresh grease. That little hole allows that flushing to happen.