Testing shock absorbers

Richard Tool · Oct 22, 2024

Does anyone know of a method for testing shock absorbers off the bike ?
I am beginning to restore my 1956 Dominator basket case . I have the original Armstrong rear shock absorbers and I presume they are no longer fully functional. Internet searches have not produced a source for rebuilding them .
Some say they can be disassembled and drilled , tapped and plugged for oil replacement but how much oil and how to seal them is one issue.
Thanks in advance for any help.
RT

Triton Thrasher · Oct 22, 2024

The test is take the springs off, then pull and push the dampers.

If you can’t find out the correct quantity of oil, keep adding oil until you feel damping effect through the whole stroke of the rod.

marshg246 · Oct 22, 2024

Richard Tool said:
Does anyone know of a method for testing shock absorbers off the bike ?
I am beginning to restore my 1956 Dominator basket case . I have the original Armstrong rear shock absorbers and I presume they are no longer fully functional. Internet searches have not produced a source for rebuilding them .
Some say they can be disassembled and drilled , tapped and plugged for oil replacement but how much oil and how to seal them is one issue.
Thanks in advance for any help.
RT

With the springs off, push down - should be easy. Pull up, should be much harder and the faster you pull the harder it gets. If either test fails, then changing the oil might fix it but doubtful as it's more likely the seals.

You might want to reread through this: https://www.accessnorton.com/NortonCommando/original-armstrong-shock-rebuild.33403/

Grandad · Oct 25, 2024

I was taught ( too many decades ago ) to " prime " the dampers / pump them up and down full stroke a few times and them keep them standing upright until installed.
Trouble is I can't remember if it applied to bikes or cars, still it cannot hurt to do so.

Testing shock absorbers

Richard Tool

Triton Thrasher

marshg246

Grandad

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