Front Coil Springs

[canbeam]

I found 3 new sets of Tiger springs in my parts boxes, but I don't recall their rating. The black ones were still in the original shipping box from Dale's and are 10" high that I bought in the mid 90's, the bare metal set in the middle are 10 1/2" high and the bare metal left set is 11 1/2" high. I think I bought those at different times from CAT and/or Sunbeam Specialties. I assume the shorter they are, the stiffer they are, I intend on selling at least one set,, if not two, and keep a spare (s) for my cars, but I'd like to know the rating. Anyone recognize them? I'd estimate the bare metal ones were purchased in the 80's.

 

[HolyCat]

Height does not necessarily correlate to stiffness (spring rate). Spring rate is determined by the material, the diameter of the bar making up the coil (bigger diameter makes it stiffer), and the spacing between the individual coils (more space between individual coils makes it stiffer). If all of these are equal, the different heights would give different ride heights. But it could be that the designers made the springs shorter when they made them stiffer, in order to maintain original ride height. But there is no guarantee that was the case with these three sets. If you have some heavy weights, you can always set some on each spring and measure how much it deflects. You would then get a sense of relative stiffness.

 

[0neoffive]

Back in the racing days we would load a spring with weights until it compressed to a specific ride height. The object was to find identical springs in order to balance the the car for road performance. Compressed to 8" optimum seems to be a reliable Tiger height at 235# just sayin' .
By the way, Admin, I keep getting certificate errors from the Forum web site.

 

[JimsCat]

Years ago, I used a bathroom scale and my drill press to get an approximate rate. I'd precompress the spring about an inch, measure the height at that point and note the reading on the scale. Then I'd compress the spring one inch further and note the new reading on the scale. The difference in the two scale readings would be the rate in pounds per inch. Each spring should be precompressed the same amount. It takes a steady hand to hold the spring compressed at each of the two heights while reading the scale. Spacer blocks with a one-inch height difference could be a useful aid. Perhaps not the most precise method, but multiple tries will aid repeatability and confidence in the results.

 

[canbeam]

Years ago, I used a bathroom scale and my drill press to get an approximate rate. I'd precompress the spring about an inch, measure the height at that point and note the reading on the scale. Then I'd compress the spring one inch further and note the new reading on the scale. The difference in the two scale readings would be the rate in pounds per inch. Each spring should be precompressed the same amount. It takes a steady hand to hold the spring compressed at each of the two heights while reading the scale. Spacer blocks with a one-inch height difference could be a useful aid. Perhaps not the most precise method, but multiple tries will aid repeatability and confidence in the results.

If the black springs are Dales, I'd assume they are at least 450, so I'd need a pretty heavy duty scale to handle the weight. There is a spring shop about an hour away from me, I'll see if they can test them. I don't want to use a set, or sell what I don't need to someone, and not have them be happy afterwards.

 

[canbeam]

Height does not necessarily correlate to stiffness (spring rate). Spring rate is determined by the material, the diameter of the bar making up the coil (bigger diameter makes it stiffer), and the spacing between the individual coils (more space between individual coils makes it stiffer). If all of these are equal, the different heights would give different ride heights. But it could be that the designers made the springs shorter when they made them stiffer, in order to maintain original ride height. But there is no guarantee that was the case with these three sets. If you have some heavy weights, you can always set some on each spring and measure how much it deflects. You would then get a sense of relative stiffness.

I think I'll keep them until I figure out what they are. It's been decades already, so what's another few years.....

 

[canbeam]

Back in the racing days we would load a spring with weights until it compressed to a specific ride height. The object was to find identical springs in order to balance the the car for road performance. Compressed to 8" optimum seems to be a reliable Tiger height at 235# just sayin' .
By the way, Admin, I keep getting certificate errors from the Forum web site.

That's good to know Randy. Thanks.... That's just a little more than I weigh, so just have to try to balance on one coil on one foot and get my wife to measure the height....

 

[JimsCat]

If the black springs are Dales, I'd assume they are at least 450, so I'd need a pretty heavy duty scale to handle the weight. There is a spring shop about an hour away from me, I'll see if they can test them. I don't want to use a set, or sell what I don't need to someone, and not have them be happy afterwards.

Good point. If the spring rate exceeds 300 lbs/in, that eliminates most bathroom scales. Now that I think about it, I was testing formula car springs that are usually much lighter.