BSA Owners' Club Workshop Discussions

The BSA Workshop => Singles => Topic started by: phill on 07 Jun, 2018, 12:40

Title: Clonk
Post by: phill on 07 Jun, 2018, 12:40
Hi,
        I have restored a 1960 C15 but have a small problem that I hope someone can help me with. When pressing the front forks vigorously up and down there is a loud clonk when at the limit of the upward travel. Looks like I will have to revisit the front forks but has anybody an idea what might be wrong?

Many thanks,
Phil
Title: Re: Clonk
Post by: JulianS on 07 Jun, 2018, 19:09
Probably the spacer sleeve and bushes coming into contact with each other on full extension, due to poor damping, a design fault.
Title: Re: Clonk
Post by: ducati2242 on 07 Jun, 2018, 20:17
I made my own Eddie Dow type damper rods for my B44 they work quit well but I would try a thicker viscosity oil first .
Title: Re: Clonk
Post by: phill on 08 Jun, 2018, 10:38
Hi, thanks for that. I have drained out the fork oil which was 20 grade as per manual and replaced with 40 grade (also upped the amount slightly). This has made a big improvement so maybe I won't have to strip down the forks again.

All the best,
Phil
Title: Re: Clonk
Post by: JulianS on 08 Jun, 2018, 14:42
With the weight of a rider when in use they will not clonk as much, they will not get to full extension as easily as when unloaded.