RE: [doc] rear springs.

["Chris Parnham" <secretary@xxxxxxxxxxxxxxx>]

Just a thought John, once you have made your decision on ride height,
and tightened up the clamps, I think you are fully committed to that
height, as it grips very hard on the body of the shocker.  Go get it
right first! 

(who prefers standard rear ride height)  

Best Regards
 
Chris Parnham Hon Sec DOC UK
RHD  vin 12173   "Gully"
1983 vin 20049  "Lefty"
BTTF vin 02631  "Herman"

-----Original Message-----
From: doc-uk@xxxxxxxxxxxxxxx [mailto:doc-uk@xxxxxxxxxxxxxxx] On Behalf
Of John Tien
Sent: 09 March 2006 05:52
To: doc-uk@xxxxxxxxxxxxxxx
Subject: Re: [doc] Front springs

Hey Martin,

So if I want to lower my D's rear using the adjustable
shock option (with stock rear springs)... apart from
setting the adjustable collar on the shocks itself,
are there any adjustment I should do to the suspension
setup on the car so it runs properly?

And what is the minimal height the rear of the D can
take before the wheel starts to hit the wheel arch
when going over bumps?

Cheers!
John

--- Martin Gutkowski - DMC Ltd <martin@xxxxxxxxxxxxxx>
?：

> 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.htm
l
> 
> Martin

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