Stroke lengths, TP sizes and SCR for various springers...

[Shed tuner]

Weihrauch HW90 Gas Ram - 30 , 106 , 75.

that's the fac version, UK stroke is ~80mm

[TonyL]

Cheers JB.

[TonyL]

The HW50 piston weighs 186 gm, the HW55 163 gm. The HW55 piston head is aluminium, and extends back into the piston, giving available length for the compressed mainspring of 95.6mm in the 55, against 108mm in the 50.

I suspect that if Venom used the HW50 piston in their 55, it was as much for the extra spring room as the mass.

It appears that the HW99 piston is 156mm long and not 146mm as I'd expected, after further reading it turns out that ONLY the external dimensions of the HW99 action are the same as an Old School HW50 action.

When Weihrauch changed from the Old School 50 to the HW99 they increased the cylinder bore from 25mm to 26mm, they increased the piston stroke from 65mm to 71mm, but more importantly to my search for a suitable piston Weihrauch shortened the transfer port from 26mm to 16mm --- a full 10mm.
This explains why the HW99 piston is a full 10mm longer than I expected as the internal length of the cylinder is 10mm longer than the Old HW50.

All the best Mick

Some excellent information applicable to the "old school" HW50, newer type HW50/99 and HW55 from another thread of Mick's.

[Shed tuner]

measured my HW90 port at 3.0mm x 11mm
(it's now 3.2, which is conservative, but gasrams have more preload)

[robs5230]

Has anyone listed the specs for the HW99S? Or have I just missed it?

Does anyone know whether any changes have been made between the early and later (new) 99's?
Thanks Rob

[T 20]

Has anyone listed the specs for the HW99S? Or have I just missed it?

Does anyone know whether any changes have been made between the early and later (new) 99's?
Thanks Rob

You missed it Rob --- it's in the first post.

-----------bore-stroke-cc----TP--------TP volume---scr--------piston weight

HW99s ---26----71---37.7--3x17?------0.120-----314:1------235 - 225 - 225g piston with seal and no
liner. Add 10g if you leave the weight inside
the piston


I'm pretty sure that the transfer port would be nearer to 16mm in length --- My findings are a couple of posts up.





All the best Mick

[TonyL]

As per Mick's findings:-

"Old school" HW50, later variant (but NOT the HW50/99) with the synthetic seal:-

Bore 25mm, Stroke 65mm. Transfer port 3mm X 25mm. Piston weight 200 - 202 grams.

Thanks, Mick.