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Join Date: Dec 2001
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This might help:
Helper springs are designed to completely compress at normal ride height, and used to maintain load on the main spring at full travel. Once the helper spring is closed it is inactive.

Tender springs are part of a dual rate spring system. The tender spring is open at normal load, and therefore it is still active, and closes at a predetermined load.

and:
Helper and tender springs are both made from a flat wire spring that are designed to completely compress. In Whiteline's view, the difference is mainly in the application of the spring and at what point they close in the chosen application. This is obviously dependent on spring load, where a helper spring is generally known to close BEFORE normal load is applied, and a tender spring is generally known to close AFTER normal load is applied.

Here's a link to the Paragon site showing coil over spring rate vs effective rate, and torsion bar spring rate vs effective rate. https://www.*****************.com/kb_results.asp?ID=58

If I understand this correctly, and not saying I do. A 28mm torsion bar has a 254 lb/in effective rate which is the same as a 450 lb coil over which has an effective rate of 253 lb/in.

By adding a 500 lb spring to a 28mm torsion bar is the same as using a 950 lb spring?

It seems an ideal set up would be a main/tender spring (or torsion bar/tender spring) set up. The main spring or torsion bar deals with the normal load, i.e. a good ride and handling, and the tender spring deals with the turbo squat.

Maybe some knowledgeable suspension person will pipe in and shed some light on this.
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Harold
'79 930/DP935
'68 VW 3.3 Turbo Crewcab
Old 06-02-2013, 08:09 AM
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