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Shock absorber resistance
#1
I am refurbishing a front shock absorber, with all parts off the car, and intend to make a trial fit/check for stiffness before re-fitting to the car (which is a 1934 4 Seat Tourer). It would find it useful to have some idea of the stiffness I should expect, or perhaps I should say the range of stiffness obtained, as the adjusting nut is wound in.
All the articles I have seen simply offer the idea of making adjustments to suit the ride, which is a bit bland. I prefer to talk numbers, so  with the centre support bracket clamped in the vise  I am hoping to learn what sort of load can be resisted when pulling on the end of either arm. Can anybody help? Is it all documented somewhere, 'cos I can't find it!!
I should add that the two outermost arms were found to be slightly concave; but this was enough to allow contact with the friction disc only at its outermost part, to show a ring of blinded disc some 3mm wide - the rest had never been in contact! Nipping a disc against an outer arm with finger and thumb a allows a feeler gauge to be inserted from the centre towards the periphery to explore this concavity. After some effort with a belt sander, the arms are now much improved.
Ron Hayhurst
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#2
I find 20 lb to start the arm moving is a good starting point.  A luggage scale with a "tell-tale" pointer is useful.
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#3
Many thanks for the response John. I now have good contact across nearly all the face of the discs and have set the centre support bracket up in the vise for some tests, these have been using a spring balance attached at the end where the bolt passes through. With the adjusting nut wound a good way up, and with one arm held from rotating, the pull to initiate movement on the other arm is currently 10lb. 
I just need to check that you are suggesting that with this set-up I should be looking for 20lb on each arm. I am a long way up the thread and thought a check was in order before busting either of the star springs.
Comments from any others would be really welcomed.
Ron
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#4
Not an Austin specific answer but the only numbers I have come across:

For the simpler Hartford shock absorbers (as opposed to the multi disc version) the suggested poundage for vehicles up to 20cwt is 19lbs. Perhaps this gives a clue.
I would think in the case of the Austin front s/a the poundage would be per arm.

I think I set mine to about 15. This is the reading as the arm is moving as opposed to the higher reading as one overcomes initial "stiction".

Hope this gives a clue,
Regards,
Stuart
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#5
Many thanks for your comments John and Stuart. The rebuild will include new star springs front and back and employ a new centre bolt. These offer more resilience than the old ones which may have lost their tension. The new bolt is needed because the old one is either braised or riveted to the star spring and cannot be used with the new star.
I will set the load at 15lbs on each arm and make a close measurement of how far the tensioning nut has been wound up the bolt. After stripping I will fit it to the car, taking it up to this same setting, and then see if adjustment is needed when tried out on the road.
A final thought: I may take load readings against position of tensioning nut (measured with a depth gauge) and stick it on a graph! Might give some indication of where the final load is after road testing and making further adjustments - anyway....it's a thought!!
Ron
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#6
I cheat, once the correct tension is found using what ever method you like then I checked the centre bolt tension with a torque wrench so now when I service the car it is a 2 minute job to bring them back up to where they were.
Cheers

Mark
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#7
Good thinking Mark! I'll take some readings with a torque wrench when checking the load on the arm(s) when set up on the bench. These will be used when back on the car, as you suggest. All grist for the mill and many thanks for adding to this thread.
Ron
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