Re: [doc] Front springs

["essexdick" <tny1964@xxxxxxx>]

   Cor blimey guv! i only wanted one of them horses with a sring 
underneath to play on in my garden...... me and my big mouth eh tony

--- In doc-uk@xxxxxxxxxxxxxxx, Martin Gutkowski - DMC Ltd 
<martin@...> wrote:
>
> Hi All (esp Mark)
> 
> I've driven a lot of DeLoreans now, and more than one with old 
front 
> springs on the rear. I also have moderately lowered rear suspsnsion 
on 
> my own car, by about an inch with Grady's (former) shock setup.
> 
> 1) Front springs on the rear make the rear too low IMO, in fact 
> sometimes lower than the front. Anything lower than where the 
control 
> arms are level is a bad idea IMO.
> 2) On my own car I've eaten 2 sets of back tyres in 10,000 miles 
thanks 
> to the lower setup (toe-in is correct and although I'm a fan of 
> wheelspinning, so is Chris H and he's done more miles on one set :-
) 
> I've got adjustable lower links on my other car and the wheels sit 
> noticably straiter at the back.
> 3) A softer ride on the rear makes an unbelievable difference to 
the 
> ability to lose the back end, in a similar, but more predictable 
way as 
> loose trailing arm bolts do. I've recently had two cars in at the 
same 
> time - one Stage 1 and one Stage 2. The Stage 1 car (less powerful) 
was 
> far too tail-happy. The difference was front springs on the rear, 
and I 
> can vouch for the rest of the suspension on both cars, and both had 
the 
> same set of pirellis.
> 4) In playing with the adjustable suspension we do, you can make 
the car 
> thoroughly dangerous (but a great drift machine, if you're into 
that!) 
> by stiffening up the front and softening up the rear. It's quite 
surprising.
> 
> "
> 
> The rear suspension uses the 'Second Order Lever' It has its 
fulcrum and effort(spring) in opposite ends and the load in the 
middle, just like a wheel barrow set up.
> 
> The front suspension uses the 'Third Order Lever'  The fulcrum and 
load are at opposite ends this time with the effort(spring) is in the 
middle, such as a shovel.
> 
> "
> I'm not entirely sure how you can apply lever principles to the 
rear 
> suspension because as I see it, there isn't one. The weight of the 
car 
> is passed directly to the hub carrier at one end of the lever. The 
other 
> is just a pivot. There's no multiplication involved unless you look 
at 
> the angle of the spring/shock which in this case is only non-
vertical to 
> get it out the way of the tyre, hence needing a slightly stiffer 
spring 
> than if it were vertical, at a ratio exactly proportional to the 
angle 
> of the spring/damper compared to the vertical (at a guess, but it's 
> probably as near to no difference as makes no odds). That's "moment 
of 
> forces" stuff and Newtonian physics, IIRC, but it's a while since I 
did 
> my A-level Maths and Physics!).
> 
> The front suspension is a second order lever, although dealing with 
a 
> multiplication of effort rather than a division of it.
> 
> You're absolutely correct that all other things being equal, the 
rear 
> spring can be weaker for the same effort, given the geometry. 
> Unfortiunately all other things aren't equal because someone had 
the 
> bright idea of plonking the engine over the back wheels :-)
> 
> 
http://www.tiscali.co.uk/reference/encyclopaedia/hutchinson/m0017416.h
tml
> 
> Martin
> 
> 
> 
> Nick Tomlinson wrote:
> 
> > 
> >  I personally tried the front springs on the rear trick, but this 
resulted in too wallawy, too soft a ride for my liking. Just a basic 
test like pressing down on the bodywork showed this.
> >
>







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