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I don't know about some but I test my springs every time I go in. Maybe I have an advantage since the Doo race manual lists specs but I keep an eye on things that way...at least once a season or more. I calculate the in/lb spec from the installed ht force listed and set up a jig to hold the spring and at a set ht I weigh it down to that spec. If all's well I put it back in, if not it's out. I test the driven by the "fish scale" technique in the book as well. If it pulls to spec I'm happy with it, if not it's out. There's also a free length listed that is expected to "sag" a small percentage as it finds a set value. They specify more than a 1/4" replace but I'd think that's a bit much.

So how do we doo this? Here's my example...

Pink/Pink drive spring

137.4mm or 5.4" free length

230/350-230# @ 2.9"

in/lb spec is 92 (5.4-2.9=2.5...230/2.5=92)

Using a suitable tube as a fixture at a length of 4.9" (1/2" short), carefully set 46# of wt on the spring and it should just touch the tube. I use pre-weighed steel machining blocks.

If it crushes real easy and has no support at all the spring is junked. If the weight feels "light" on the spring it's fine.

I have used a valve spring tester on some shorter springs for easier results.

Does this make sense to any of you or do just toss em out as a matter of course? I hope this is helpful.
 

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Get a clutch spring tester & test your new springs prior to installation because the specs aren't always close. You will find that some are off by as much as 40 lbs.
 
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