[DeTomaso] Resetting Ride Height With Stiffer Coils - the sequel

Ken Green kenn_green at yahoo.com
Fri Sep 24 18:27:07 EDT 2010


I think there is lateral movement in the suspension when you raise the body with a jack, and when you lower it back to the ground, it resists sitting all the way back down, and can sit a lot higher until you drive it.  I don't think a "good bounce" would do much.
 
How long are the relaxed 350 springs?  If they are a bit shorter, you might have to drop the perches that additional amount.
 
Ken

--- On Fri, 9/24/10, Mike Thomas <mbefthomas at comcast.net> wrote:


From: Mike Thomas <mbefthomas at comcast.net>
Subject: Re: [DeTomaso] Resetting Ride Height With Stiffer Coils - the sequel
To: "'David & Marilyn Bell'" <davidabell at worldnet.att.net>, detomaso at realbig.com
Date: Friday, September 24, 2010, 2:59 PM


As with most sequels, this was not as good as the original . . .

So I finally got the new springs on the car, and I believe Dave Bell wins
the Christmas Turkey (see his last post below).

In our last episode . . .

Ordered new 450lb 10" springs from Aldan.  They were actually closer to
10.5".  Replacing 350s.

When I took the old Aldans off the car, I measured the number of threads
below the collar.  Summing up the various inputs I received from a bunch of
helpful folks, I adjusted the original change in spec from ~.4" to slightly
~.33" lower on the spring perch to compensate for less compression from a
stiffer spring and the angle of the coil/shock assembly when installed on
the car.

.33" converted to ~5 threads on the shock body, so when I installed the new
450 lb springs on the shocks, I reduced the number of threads on each side
by 5, and reinstalled the assemblies.

WTF!!

Where my fender lip was ~25.75" above the ground, now it's ~27"!  Lowering
the spring perch .33", and the .5" longer springs have somehow combined to
raise the car 1.25"!

OK, so I haven't driven it yet (don't really want to look like Jesse James
going down the street), but I've given both fenders a good bounce after
rolling the car back and forth and bouncing it again to settle things as
much as I can in the shop, and no change to the height.  Will take it around
the 'hood to hit the brakes a few times to see if it changes anything.  If
no changes, I'm wondering:

A - send the springs back to Aldan for some really-o truly-o 10" long 10"
springs.
B - go back to he previous thread count and go the other direction.
Both A and B
None of the above
Open a beer and wait for the replies to come pouring in.

. . . Hey, it's Friday, the latter is a given.

Thanks again!
Mike Thomas
Keeping my tips up in Seattle


-----Original Message-----
From: detomaso-bounces at realbig.com [mailto:detomaso-bounces at realbig.com] On
Behalf Of David & Marilyn Bell
Sent: Tuesday, August 24, 2010 9:25 PM
To: David & Marilyn Bell; detomaso at realbig.com
Subject: Re: [DeTomaso] Resetting Ride Height With Stiffer Coils

I guess I either write or think (or both) upside down.  The new springs
should put the tire 1/2 inch further away from the fender, not closer.

Dave Bell

-----Original Message-----
From: detomaso-bounces at realbig.com
[mailto:detomaso-bounces at realbig.com]On Behalf Of David & Marilyn Bell
Sent: Tuesday, August 24, 2010 6:11 PM
To: detomaso at realbig.com
Subject: Re: [DeTomaso] Resetting Ride Height With Stiffer Coils


OK - I purposely mentioned 'roughly' and 'approximately' to indicate this
was a purely bubba type estimate, though probably I shouldn't have used any
decimal places that may have added some artificial precision.

So, I've got 20 bucks that says the top of the front tire will be about 1/2
inch (plus or minus 1/4 inch) closer to the fender lip with the new 450#
springs than with the previous 350# springs (obviously before moving the
spring perches up or down).

Who's in?

Also be sure to drive the car around to settle the suspension before
measuring the fender to tire gap.


Dave Bell (don't need no stinkin corner weights to go around corners fast)


-----Original Message-----
From: detomaso-bounces at realbig.com
[mailto:detomaso-bounces at realbig.com]On Behalf Of Paul - Home
Sent: Tuesday, August 24, 2010 9:47 AM
To: unlisted-recipients:; no To-header on input
Cc: detomaso at realbig.com
Subject: Re: [DeTomaso] Resetting Ride Height With Stiffer Coils


Goran is of course correct and the reason is that springs are not installed
vertically, they are at an angle.

Paul
#9270

Pantdino wrote:
> 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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