Bultaco Sherpa Forks

[hightown]

What is the main difference between the Ossa mar 35mm forks compare to the Bultaco Sherpa forks. Is it the size of the holes in the damper.

Thanks

Hightown

[swooshdave]

Are you including the triple clamps in the discussion?

The other difference you have to worry about is the spindle offset.

[woody]

Assuming it's just the internals you're talking about.

The actual damper rods are the same on both bikes, the holes drilled into the damper rod are identical but on the earlier Bultaco forks (around mid 70s models) the holes in the piston are different. The Sherpa has slots wheras the Ossa has holes and it looks to me as though the Sherpa arragement allows more oil flow. The 340 Sherpa has the same damper rods with the same holes but the piston is completely different from the Ossa and earlier Sherpas. It is just a solid square with round edges and I assume the oil just moves past the gaps at the sides of the piston.

I never have managed to suss out exactly how the damping in front forks actually works. However, my thoughts on the Sherpa letting more oil through on the compression and rebound are consistent with the behaviour of both types. The Sherpa forks don't damp as well as the Ossa (subjective, my opinion) on compression or rebound for the same oil quantity/viscosity. I tried 5 - 30 weight in the Sherpa and nothing got them as good as the Ossa. Too soft on compression and too quick to rebound. Even with too much 30W oil in so that they hydraulic locked on compression, they still topped out on rebound (several forks on different model Sherpas, not just one set)

After much messing with the forks on my 340 Sherpa I still couldn't get them right, gave up and fitted Ossa damper rod assemblies instead. Forks work as I want them now. About 180cc of 10 weight.