[TR] TR3 Leaf Springs?

[Randall]

> If I took my old ones to a spring -

> maker here in the Portland (Maine) area, what data would I need to

> provide to them, along with my old springs? It's obviously possible to

> make them look right but still be too stiff...

 

The drawing in the workshop manual should be enough.  Page 203 here

https://drive.google.com/open?id=0B2H2NJt34OffYWZiN2VlZGMtNTkxMi00NGUzLWE4Nz
MtMGRkODRkYzU3MDU1

 

The ones I got from TRF appeared to have two problems:

1) The leaves were not tapered in thickness as shown in the drawing.

 

2) (More importantly, I think) The leaves were just a bit thicker than given
in the drawing.  Not by much, but apparently it doesn't take much.  I found
an on-line site that would calculate leaf spring stiffness (sorry, I've lost
the link).  When I put in the measured thickness of the new spring leaves
(along with all the other data), it came up with a spring rate very similar
to what I had measured.  When I put in the numbers from the workshop manual,
the result was much closer to the rate in the manual.

 

In case anyone is interested, here's a photo of my lashup to measure spring
rate.

http://s258.photobucket.com/user/TR3driver/media/Tools/DSCF0008.jpg.html

 

Two needle valves (one is hidden in the photo) allow adjusting the amount of
air in the cylinder.  The resulting force can be calculated from the air
pressure displayed (times the area of the cylinder piston), and the
deflection measured with a ruler (not shown).  Cost for the whole
contraption was only about $50 (the used air cylinder was $25 with shipping
from ebay).

 

As it happened, I got given a pair of original springs, so I kind of lost
interest in the quest for new ones.  Unfortunately, they seem to be sagging
pretty badly, so I need to be working on this topic again soon.

 

 

-- Randall 

56 TR3 TS13571L daily driver

71 Stag LE1473 - awaiting engine rebuild

71-2-3 Stag - awaiting gearbox rebuild

 

 

 

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