Venting forks

[stu1969]

Hello
I have been told by my local BMW dealer that when a new complete, supplied by the factory readymade for is fitted to a bike it needs to be correctly vented.

I have replaced fork seals and rebuilt many forks on other bikes but have never come across this term before has anybody any idea what this means???????

Regards

Stuart.

 

[duckspeed]

I think the idea is to vent air from the slider to stop air inside becoming compressed and causing unwanted spring effect, also compressed air is likely to push oil passed the seal. Maybe a factory trained old sage may have another suggestion

 

[trainman]

Hello
I have been told by my local BMW dealer that when a new complete, supplied by the factory readymade for is fitted to a bike it needs to be correctly vented.

I have replaced fork seals and rebuilt many forks on other bikes but have never come across this term before has anybody any idea what this means???????

Regards

Stuart.

there were bleed valave on my KTM 950 ADV which you unscrewed at each service, the dealer said it helped prevent blown seals

http://www.youtube.com/watch?v=2FLIP0Pjct8

this implies you do it every ride!! i still dont know how this air becomes a problem unless its down to the heat of the friction causing expansion??

maybe with new forks its to equalise pressure from where they have been stored or delivered from?

 

[skywalker]

I think the idea is to vent air from the slider to stop air inside becoming compressed and causing unwanted spring effect, also compressed air is likely to push oil passed the seal. Maybe a factory trained old sage may have another suggestion

Correct . Open the bleed screw - extend stanchion to length - close screw ,install, simples

 

[stu1969]

Thank you for your replies and for the vid.

I am still a bit bemused where the air would come from and why it hasn’t been an issue on my previous bike

 

[EggChaser]

I am still a bit bemused where the air would come from and why it hasn’t been an issue on my previous bike

Might be something to do with the difference between the spings being inside the forks with oil damping and the BMW telelever design where the shock is not integral with the forks.

 

[Steptoe]

Thank you for your replies and for the vid.

I am still a bit bemused where the air would come from and why it hasn’t been an issue on my previous bike

Think about it..........

You had a large hole in the top of your previous forks, which you used to fill the forks with oil when the forks were in place.

On the GS you insert the "sealed" stanchion into the slider with the oil already in place, So you need to undo the small bleed screw to let the trapped air escape.