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

Fri Sep 24 20:01:38 EDT 2010

And as I recall, Ted is a -real- engineer.  Perfect! :)

Asa Jay

Quoting Ken Green <kenn_green at yahoo.com>:

> Asa,
>  
>     There is detailed suspension info on the Ted Mitchel web site,   
> really impressive. 
>  
> Ken
>
> --- On Fri, 9/24/10, Asa Jay Laughton <asajay at asajay.com> wrote:
>
>
> From: Asa Jay Laughton <asajay at asajay.com>
> Subject: Re: [DeTomaso] Resetting Ride Height With Stiffer Coils - the sequel
> To: detomaso at realbig.com
> Date: Friday, September 24, 2010, 3:27 PM
>
>
> I'm not an engineer, I only play one on this list.
>
> In simple terms, the new spring are .5" longer, okay, and you lowered 
> them .33, so overall without compression, they are about .2 higher.   
> But that doesn't account for the inch and a quarter.
>
> You replaced 350 lb. springs with 450 lb.  So to me that says you need 
> 150 more pounds.  So, neverminding any super-whamadyne math here for a 
> moment, you need a lot more weight to compress the spring.  I wouldn't 
> be surprised if your car sits 1.25" higher than it used to.
>
> Try lowering the perches some more.  I'm sure someone with a -real- 
> engineering degree will tell you how much.
> :)
>
> Asa Jay
> Pantera Research Institute: Pacific Northwest, Inland Empire Chapter.
>
>
>
> Quoting Mike Thomas <mbefthomas at comcast.net>:
>
>> 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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>
>
> --
> Asa Jay Laughton - sent from somewhere other than home
> ******************************************************
> http://www.racingagainstautism.com
> http://www.teampanteraracing.com
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