I have been toying with the idea of some modifications and would like to pass
some of the potential ideas past the list for opinions. Feel free to
comment, I have my Nomex underwear on!!
1. The GT6's has a spacer under one of the upper spring perches to balance the
stance of the front end. Would adding spacers under both sides
effectively lower the front end? The length of the 3 attaching bolts makes it
possible to put a spacer about 1/2 to 3/4" thick between that and the
shock tower.
2, It would appear that id the bottom shock mount was relocated downward, one
could accomplish the same lowering effect. My thought was to take two
pieces of mild steel bolted into the inside of the two halves of the A frame
(around the trunnion lower attaching point and to where the shock
normally bolts). Then sticking down low enough to bolt the shock lower mount
about 1" lower. Stress on those brackets is my main concern.
Opinions?????
Thanks,
Joe (C)
Mark J Bradakis wrote:
>
> First off, a disclaimer. Don't take any of the following as absolute truth,
> I'm too tired to double check all my references. Chris K. has seen my office,
> he can appreciate the effort required to find a specific bit of information
> piled somewhere in the debris. And I just poured myself a shot of some cheap
> bourbon left over from the Beach Party, maybe I should have gone for the
> Woodford Reserve...
>
> Anyway, I'm somewhat surprised to see Spitfire springs mentioned tonight, as
>an
> hour or so ago I was at the shop staring at the red prod racer, thinking how
> little I actually knew about the car, and considering getting it on the scales
> and checking wheel rates. Speaking of getting it on the scales, I was pleased
> to read the latest "Sportscar" magazine and see that there is a proposal to
> put the D Prepared Spitfire on a diet for next year. Cool.
>
> What Bob B. says about tie wraps on the perch is true. Too bad I don't have a
> photo online of Killer's front springs. Having a spring come off the perch at
> full droop may or may not be an issue. If it has nowhere to go other than
> where it should when it is under load once again, no problem. If there is
>room
> for it to flop about and possibly end up mis-seated then you need to deal with
> it. Depends on your particular shock and perch combination.
>
> Oh oh, I can see this missive may be getting out of hand. I'll try to be
> concise. Yeah, right, Fat Chance.
>
> There are a few critical dimensions related to coil springs. The ones that
> carry the most interest for those of us with the coil-over setup of the small
> chassis Triumph are rate, free length and fitted length. Gee, come to think
> of it those are the most interesting for those of us with the big TRs as well!
>
> But only two of those numbers are independent. These three numbers are in
> themselves easy to understand. Spring rate is simple, defined as the distance
> a spring compresses when subjected to some force. This is usually expressed
> in terms of pounds per inch for those of us using non-metric standards. The
> 425 pound front springs on Killer require 425 pounds of force to compress 1
> inch. Brainless, right?
>
> Free length is also a simple concept. Take the spring, put one end on a flat
> surface, and measure how far the other end is from that surface. If you've
> ever taken apart a Herald/Spit/Gt6 front shock and spring and lived to tell
> about it, you might have noticed that the stock Spit spring is about 14" long
> when not crunched up on the shock. This is from memory, I'm likely off a few
> inches, but the concepts remain the same.
>
> Fitted length is the distance from one end of the spring to the other as it
> sits in place at rest on the vehicle. That stock Spit spring with the 14"
> free length may only be 10 inches long if measured in place on a car.
>
> And there's the rub -
>
> Two springs with the same fitted length could have different free lengths
> and different spring rates.
>
> Two springs with the same free length could have different fitted lengths
> and different spring rates.
>
> Two springs with the same spring rate could have different fitted lengths
> and different free lengths.
>
> I've not gotten into wheel rates versus spring rates. I'll turn off the
> pontificating for now, and work on getting some real numbers for the next
> installment. Those of you who actually know this stuff feel free to chime in.
>
> mjb.
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