[DeTomaso] Resetting Ride Height With Stiffer Coils

Tue Aug 24 11:22:00 EDT 2010

The shock is mounted at an angle so the mass acting upon it is not purely the weight of that corner of the car. As an approximation I would measure the compressed length of the current spring whilst still on the car and under load, then as the weight rating of a spring is the mass required to compress it 1 inch you can work out the 'effective' mass acting on the spring and then transpose that from a 350# spring to a 450# as David has done. This of course assumes you have linear rate springs and that the exisitng springs have not sagged over the years. You can check the latter once the springs are removed and see if they are still a full 10" uncompressed.

What you should be doing is corner weighting the car on scales because simply setting the perch lengths equal is unlikely to result in an ideal weight distribution. But then your putting those Aldan's back on so you'll probably have plenty of opportunity to do this exercise again in the near future...... :>)

Good luck,
Julian

> To: detomaso at realbig.com
> Date: Tue, 24 Aug 2010 01:40:04 -0400
> From: pantdino at aol.com
> Subject: Re: [DeTomaso] Resetting Ride Height With Stiffer Coils
> 
> 
> It will be interesting to see if that is the case.
> Goran sent me some information regarding suspension systems once that was over my head, but I do remember that the force felt by the spring is not the same as the weight on the wheel. Therefore the change in spring compression may not be 0.4"
> 
> 
> Jim
> 
> 
> -----Original Message-----
> From: David & Marilyn Bell <davidabell at worldnet.att.net>
> To: Mike Thomas <mbefthomas at comcast.net>; 'Tony DiGiovanna' <tonydigi at optonline.net>; detomaso at realbig.com
> Sent: Mon, Aug 23, 2010 10:23 pm
> Subject: Re: [DeTomaso] Resetting Ride Height With Stiffer Coils
> 
> 
> Mike,
> If your car weighs roughly 3200 lb and the weight distribution is roughly
> 0/60 front to rear, then the weight on the front is 1280 lb so each front
> pring must support 640 lb. A 350 lb/inch spring will deflect 1.8" under
> han load while a 450 lb/inch spring will deflect only 1.4". So you need to
> rop your front spring perches by approximately 0.4" to maintain the same
> ide height.
> Dave Bell
> 
> ----Original Message-----
> rom: detomaso-bounces at realbig.com
> mailto:detomaso-bounces at realbig.com]On Behalf Of Mike Thomas
> ent: Monday, August 23, 2010 7:44 PM
> o: 'Tony DiGiovanna'; detomaso at realbig.com
> ubject: Re: [DeTomaso] Resetting Ride Height With Stiffer Coils
> 
> hanks. Should have added that both new and old springs are 10" Aldan
> oils, so the free height is the same on both rates.
> Mike
> -----Original Message-----
> rom: Tony DiGiovanna [mailto:tonydigi at optonline.net]
> ent: Monday, August 23, 2010 5:23 PM
> o: 'Mike Thomas'; detomaso at realbig.com
> ubject: RE: [DeTomaso] Resetting Ride Height With Stiffer Coils
> Don't assume the new springs will have the same free height.
> hink you are best served to measure the ride height of the car relative to
> he ground with the old springs, then change springs and adjust back to
> hose settings.
> -----Original Message-----
> rom: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] On
> ehalf Of Mike Thomas
> ent: Monday, August 23, 2010 8:11 PM
> o: detomaso at realbig.com
> ubject: [DeTomaso] Resetting Ride Height With Stiffer Coils
> OK, time for the math wizards to have a head shed . . .
> I'm swapping out my front springs from 350 lbs to 450 lbs, and want to
> chieve the same ride height. Since I won't (I assume) get as much spring
> ompression with the 450's, I'll need to revise the spring perches on my
> ldan shocks. I'm guessing I'll need to compress them slightly more on the
> hock (the collar height up the shock body) since the springs won't drop as
> uch when I let the car back down and the springs settle in. My car is
> tock up front with the addition of an aluminum radiator, so probably close
> o stock weight on the front wheels.
> Any thought on how much more to compress, or notes form someone whose been
> here, would be helpful. Pulling and readjusting or trying to adjust the
> ront on the car are both a much bigger PITA than the rears. I'd like to
> ave to do it as few times as possible.
> Thanks in advance for your sage advice.
> Mike Thomas
> ellow '74 L #6328
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