Retrofit final drive vent?

[G5RJO]

I have yet to see a new vented final drive, how is it vented? I saw something in MCN showing a black tube on top of the drive next to the disc. How is this installed? I assume that it connects to the hub via the refill hole, is this correct?

I would like to perhaps 'upgrade' my existing 08 final drive to the vented version as a preventative measure, is it possible to fit the vent to an existing drive? Any advice appreciated.

Roger.

 

[xjrjason]

I was thinking the very same thing.

Mate of mine has an '08 GSA, which had it's FD replaced under warranty (sparkly new type, with vent).

It would appear to be the inside flange/casing that is different (black part), whether it can be changed I don't know, but it looks very similar in every way otherwise.

Anyone in the know?

 

[velofelo29]

Is there not a vent path through the speedo sensor, seems to run in my mind that I saw this when doing an FD oil change.

 

[Stretchamus]

I presume the vent is there to prevent an oil leak, apart from that, does it give any mechanical longevity to the final drive.

 

[TeaPig]

I presume the vent is there to prevent an oil leak, apart from that, does it give any mechanical longevity to the final drive.

Unless they have actually changed the internals in this latest modification, a breather alone isn't likley to help longevity. I've not seen any sign of a breathing system inside older drives, moreover, sometimes when the filler plug is removed there is often a hiss or a pop as pressure equalises. I suspect the main purpose is to reduce internal air pressure in the drive and hence also on the large oil seals which may thus reduce lip wear and so the chances of an oil leak.

Without a close inspection its hard to speculate if the new system can be retrofitted. Although all that is required is a simple hole to the outside world, the trick is to let gas in and out but retain oil and keep out water. If the 'only' purpose is to breathe then given the relatively low incidence of seal failure it doesn't seem worth worring about.

No doubt all will become clear once someone starts taking the new FD's apart. It woul be wonderful if the internals are also new but the mechanical issues have been there and unresolved since the 11xx so I'm not hopeful

 

[xjrjason]

I would speculate that the reason for the breather is to allow more oil in the FD housing.

Oil gets hot, expands, and doesn't pop the seal! Major improvement. More oil, less heat, oil works for longer at higher temps = FD doesn't explode.

 

[Kremmen]

I would speculate that the reason for the breather is to allow more oil in the FD housing.

The oil capacity is exactly the same as the unit removed..180ml

 

[Stretchamus]

Unless they have actually changed the internals in this latest modification, a breather alone isn't likley to help longevity. I've not seen any sign of a breathing system inside older drives, moreover, sometimes when the filler plug is removed there is often a hiss or a pop as pressure equalises. I suspect the main purpose is to reduce internal air pressure in the drive and hence also on the large oil seals which may thus reduce lip wear and so the chances of an oil leak.

Without a close inspection its hard to speculate if the new system can be retrofitted. Although all that is required is a simple hole to the outside world, the trick is to let gas in and out but retain oil and keep out water. If the 'only' purpose is to breathe then given the relatively low incidence of seal failure it doesn't seem worth worring about.

No doubt all will become clear once someone starts taking the new FD's apart. It woul be wonderful if the internals are also new but the mechanical issues have been there and unresolved since the 11xx so I'm not hopeful

What I thought, thanks TeaPig
So unless someone knows what's inside thats different its still

 

[MattW]

I would speculate that the reason for the breather is to allow more oil in the FD housing.

Oil gets hot, expands, and doesn't pop the seal! Major improvement. More oil, less heat, oil works for longer at higher temps = FD doesn't explode.

Breathers deal with air expansion due to temperature and atmospheric pressure changes. This will help to control pressure difference across seals and may increase seal life.

FD's fail due to pretty crap design and poor assembly tolerances, not the amount of oil they contain.

 

[rudiemoto]

hi matt

FD's fail due to pretty crap design and poor assembly tolerances and its a bmw
but we still ride them
and me getting a 12
good job i can rebuild my f,d

 

[MattW]

and its a bmw
but we still ride them

Yup

and me getting a 12

So you're going to the dark side?

good job i can rebuild my f,d

Good job I know a man in Swinton who can rebuild mine (not that I've got a 12...)