FD oil seal problem

[Bear]

Yesterday I changed my FD oil and the outer seal because it was leaking. Dealer who supplied the seal advised me that only the seal was needed. A ten mile ride with new seal looked good so out I went this morning. Thirty miles later its leaking profusely. Before fitting the seal I made sure its housing and the axle it seals to were clean and undamaged. Is it likely that I had a one-off faulty seal or am I looking for something more serious? (including assembly error although I can't see many possible ways to foul it up). The seal lip was oiled before assembly so I wouldn't expect to have torn it when I fitted it.

 

[st247]

Try - put bike on centre stand - grasp wheel at 12 o'clock and 6 o'clock - rock back and forth to see if there's any play in the final drive bearing. BM say 1mm is fine but if you've more that would indicate a problem.

Also - when you changed your oil what was it like, any silver particles in the oil or on the speed sensor, oil black and minging or relativley clean?

 

[Bear]

There is no obvious play in the rear wheel. The old oil was dirty but no worse than I would have expected. No silver particles on either the drain plug or the speed sensor.

 

[pip001]

might be worth trying a new seal before you go any further.if you still have the old seal you could get one from a bearing supplier,just use the old one as a sample.

 

[Bear]

I've actually got a spare genuine BMW seal. As it has BMW embossed on it I suspect its unique to them rather than being available from an engineer's merchant. It's certainly a motorcycle-only part as far as my local car franchise are concerned.

 

[st247]

There is no obvious play in the rear wheel. The old oil was dirty but no worse than I would have expected. No silver particles on either the drain plug or the speed sensor.

Looks like you may have just had a dodgy seal then. I'd fit another one and try again.

 

[Pukmeister]

How much oil did you use? No more than 220ml I hope.

I caused an FD oil leak by adding too much oil (250ml in my case 'cos I misinterpreted the instructions), I also experienced further seal leakage (temporarily) during the heat of an Australian summer whilst living there.

Unlike the previous GS variants, the 1200 models have no breather fitted to the FD as they were meant to be 'sealed for life'. As a result, any overfilling (even slight) results in overpressurisation of the remaining airspace when the FD gets hot with use. This will cause the oil to blow out past the knife edge rubber seals.

When my FD leaked past the outer seal, I simply wiped it dry and continued to use the bike as the leakage was minimal. It effectively fixed itself. I have since done an FD oil change with no further problems, adding only 220ml of castrol SAF-XO oil this time.

 

[Bear]

I measured 220ml reasonably carefully. The level in my 1 litre bottle is just above the 750 ml mark, which suggests I used about the right amount. I'll try another few miles just in case it was a little overfull. The oil used was SAF-XO from a new sealed bottle.

 

[Bear]

A few more miles and it was still leaking so I fitted my spare seal. 20 miles later there's a weep of oil from it. Something I noticed was that there are two grooves round the ciorcumference of the axle. One is to locate the plastic trim covering the seal and the other appears to be where the seal wipes the axle. Is it meant to be there or am I looking at a failed axle at 18000 miles?

 

[Pukmeister]

It's probably a polished area on the shaft where the lip seal sits. I used to see this all the time with machinery seals. If you are lucky the new seal you fitted will bed in and provide a decent seal, though it may take a bit of time and some slight leakage before this happens and the FD becomes oil tight.

 

[Bear]

It looks more like a groove than a polish mark. I'll ride it some more tomorrow morning in the hope that you'r right but I'm not optimistic.