dual spring modification

[5thhorsemann]

Has anyone had experience with these?

http://cgi.ebay.com/ebaymotors/Dual-Springs-Coil-overs-Coilovers-DATSUN-240Z-70-74-NEW-_W0QQcmdZViewItemQQhashZitem5adfd9249dQQitemZ390302606493QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccessories

I am told they are better than the ground controll setup for street use, and not as expensive.

[jmortensen]

Coilovers are coilovers for the most part. If you're looking for cheap you can buy generic threaded sleeves and nuts from www.colemanracing.com along with top hats and be done with it and probably come up cheaper than that setup. The only difference between what they sell and what GC sells is that they use a "helper" or "tender" spring. The tender spring has very little spring rate and is only there to prevent the main spring from flopping around at full droop.

Your car won't spend any time at full droop when you're actually driving unless you're doing Dukes of Hazzard style jumps. If Roscoe P Coltrane (and Flash) are in hot pursuit and you think you need to hit that dirt berm and jump the creek and get away, then go ahead and get yourself a helper spring. For the rest of us, it just doesn't matter once you take the car off the jack and put it on the ground.

Edited April 2, 2011 by jmortensen

[jmortensen]

Actually, I just realized I was wrong about the above. You can do a progressive spring setup with coilovers, or you can do a helper spring. More info here: http://e30m3project.com/e30m3performance/tech_articles/susp-tech/springs/index.htm

I do think that what this company is selling is the helper spring which basically keeps the spring from being loose at full droop, so if that is correct it does fit the Dukes of Hazzard example I used previously.

[5thhorsemann]

Once again, I learned my new thing for today. I understood the function of the "tender" spring, but did not know about the helper spring as it affects the rate. Good stuff.

here is the link to the actual item on their site;

http://www.cosmoracing.com/productinfo.asp?cid=259&pid=1340

They advertize up to a 3" drop which is radical for a screw turner kit. Also there is no welding required, the whole giddiup is a slip fit and looks to be held in place by the strut and set screws.

they also offer the single spring kits.

http://www.cosmoracing.com/productinfo.asp?cid=259&pid=1556

But check out those spring rates 280 front & 336 rear, sounds like a real ground pounder! You almost have to install strut tower braces with these kits.

also notice the prices as compared to the ebay prices.

[5thhorsemann]

just want to refresh this post, I did a site search and found some old threads containing info that some of the guys installed these on their S30's, but no follow up was posted. The bottom line is that I need to make a decision soon, and at this point I am leaning towards making my own adjusters per jmortensons suggestion, and buying off the shelf springs at the rates I want. Any input is appriciated.

[riske]

Would also like to hear what people have to say on these! I asked for a set shipped to uk and worked out a LOT cheaper than any other option. seems to ggod to be true.

Whats would i need to fit this kit? just the cosmo single spring and some gas cartridges?

[John Coffey]

There's no advantage to a dual spring setup on a street driven car. Its basically a marketing gimmick. In the racing world dual spring setups are used primarily for aero dependent ride height and pitch control.