BSA Owners' Club Workshop Discussions

The BSA Workshop => Twins => Topic started by: Pippinz on 26 Jul, 2018, 18:13

Title: Fork Plastic sleeve next to the shuttle valve
Post by: Pippinz on 26 Jul, 2018, 18:13
Like most things after taking the forks apart and inspecting the condition I decided to replace one of the plastic sleeves next to the shuttle valve because the bottom edge was quite distorted and not as it should be. I took great care removing it and putting a new one on. The sleeve has two thicknesses. The one I took off had the wider part next to the shuttle valve. This does make sense to me but I have just read an article that states the opposite.

Which is correct and can anyone explain the function.

Thank you
Title: Re: Fork Plastic sleeve next to the shuttle valve
Post by: Charles R on 30 Jul, 2018, 11:48
Hi Pippinz

I can't explain the function of the sleeve well enough to work out which way round it should be.  However, the workshop manual for my model shows the thicker end at the lower end of the stanchion.

I've attached a diagram from the workshop manual (00-5707) and a photo of my forks partially stripped down.

I shall fit my sleeves with the thick end in the lower position.

Cheers, Charles
Title: Re: Fork Plastic sleeve next to the shuttle valve
Post by: Bess on 30 Jul, 2018, 15:29
Hi Pippinz,
                The sleeve acts as a well. When the damping is working it lifts oil to lubricate the fork stanchion.

Best wishes...
Title: Re: Fork Plastic sleeve next to the shuttle valve
Post by: Charles R on 03 Aug, 2018, 11:11
Hi Bess

I hadn't thought about it being used to provide lubrication for the stanchion.  Wouldn't the part of the stanchion that is enclosed inside the outer member be bathing in oil all the time?

Cheers, Charles
Title: Re: Fork Plastic sleeve next to the shuttle valve
Post by: Bess on 03 Aug, 2018, 13:01
Hi Charles,
                When the fork is fully extended oil migrates back to the bottom of the slider. When you use the bike the stanchion lower end dips into the oil and dampens your ride picking up oil to lub the upper bearing.

Best wishes...