Clonk

[phill]

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

[JulianS]

Probably the spacer sleeve and bushes coming into contact with each other on full extension, due to poor damping, a design fault.

[ducati2242]

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 .

[phill]

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

[JulianS]

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.