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Re: Vixen front spring free lengths and rate? 2222222

To: Russell Talbot <russell@hockerley.freeserve.co.uk>
Subject: Re: Vixen front spring free lengths and rate? 2222222
From: Dr John Upham <webmaster@ukmotorsport.com>
Date: Thu, 04 Jan 2001 00:39:23 +0000
Russell Talbot wrote:
> 
> John
> 
> I'd use the scientific method as the other Russell suggests to work it out.
> Do I recall you saying you'd had some trouble with the shape of the top
> mounts?  They might therefore be a little different to others.
>
  True. I don't think that the bolt position is different relative to
  the chassis tubes but they appeard to have been "borrowed" from an
  M type chassis.

 
> At risk of stating the obvious:
> 
> Adjustments to free length are preferable as they should not affect the
> handling unless they become so long you risk the coils binding.  Shortening
> springs makes them stiffer.
>
  true.
 
> Russell's scientific method could give you weights larger than the weight of
> the car owing to the mechanical disadvantage of the spring.  For the same
> reason you really need to measure the compressed length to work out the load
> on the spring and the desired compressed length to calculate the spring
> rates - eg take the spring off - replace the damper and measure the spring
> length at your desired ride height (although I'd guess the answer won't be
> much different to Russell's).
> 
> If it's any help the ride height of my car - measured to the bottom of the
> chassis outrigger corners is 170mm at the front and about 180mm at the rear
> (I only measured one side though!).  The front spring/shock measures 340mm
> from eye centre to eye centre at this height
>
  Thanks for that. I will post the measurements. I could also measure
  the other S3 that is probably a lot more "shagged" than the yellow
  car.

  Regards,
  JU
 
> Russell
> 
> ----- Original Message -----
> From: "Dr John Upham" <webmaster@ukmotorsport.com>
> To: <russell.towns@kvaerner.com>
> Cc: <mtowns@westsussex.gov.uk>; <russell@hockerley.freeserve.co.uk>;
> <tvr@autox.team.net>; <tvrdude@netzero.net>
> Sent: Wednesday, January 03, 2001 10:36 AM
> Subject: Re: Vixen front spring free lengths and rate? 2222222
> 
> > Russell,
> >    Thanks. If you get a chance can you measure the distance between
> >    the lower bolt eye on the damper unit and the top of the lower
> >    spring platform. I can then compare that with the Koni unit.
> >
> >    Regards,
> >
> >    JU
> >
> > russell.towns@kvaerner.com wrote:
> > >
> > > John
> > >
> > > I believe that both Matt and I use 130 lb/inch with 14" free length on
> > > Monroe shocks at the front. The back is either 130 or 2 x 65 as with
> > > yours..
> > >
> > > Have you tried the scientific method to calculate your ratings?
> > > Assuming your springs are 13" and 185 if they are compressing by 3" then
> > > the weight at the front is 6 x 185 = 1110.
> > > If you want them to compress by 4" then divide 1110 by 8 = 139
> > >
> > > I would have thought the difference between 130 and 185 would make about
> > > 1 - 1.5" difference. So with a shorter length you should not have been
> > > far off. What size are the collets that hold the spring on the shock?
> > >
> > > All guess work though. Good Luck!
> > >
> > > Russell
> > >
> > > -----Original Message-----
> > > From: tvrdude@netzero.net [mailto:tvrdude@netzero.net]
> > > Sent: Wednesday 3 January 2001 02:45
> > > To: webmaster@ukmotorsport.com
> > > Cc: tvrdude@netzero.net; tvr@autox.team.net; Towns, Russell
> > > /JBEC-Portsmouth,IT; russell@hockerley.freeserve.co.uk;
> > > mtowns@westsussex.gov.uk
> > > Subject: Re: Vixen front spring free lengths and rate? 2222222
> > >
> > > John,
> > >  Sorry, just thought of other things. where are you measuring the extra
> > > 1-2"? If at the bumper in front, this would be greater measurement than
> > > at the wheel. Raising the rear would drop the "front bumper" more if
> > > that
> > > is your desired outcome.
> > >   Bill
> > >
> > > Dr John Upham wrote:
> > > >
> > > > Dear All,
> > > >      The front of my Vixen S3 is sitting too high. The rear seems
> > > >      about right on
> > > >
> > > >      4 x 65 lb/inch (measured on a spring compressor
> > > >      at Reading University) of 14" free length
> > > >
> > > >      The fronts are 185 lb/inch and 13" free length (I think
> > > >      but not sure).
> > > >
> > > >      Bearing in mind I'm using a 1600 Kent Crossflow engine with
> > > >      an alloy bellhousing, can anyone recommend some front
> > > >      spring spec figures please?
> > > >
> > > >      I reckon the car is nose up by around 1-2 inches too much.
> > > >
> > > >      Best Regards,
> > > >
> > > >      John
> > > >
> > > >
> > > >
> > > > --
> > > > Dr John Upham, The UKMotorSport Index,
> > > > http://www.ukmotorsport.com/, webmaster@ukmotorsport.com,
> > > > Voice: +44 (0) 976 634 053 (W), Voice: +44 (0) 125 287 2551 (H),
> > > > Voice: +44 (0) 976 634 053 (M)
> > > > Registered address: Reid House, Mill Hall, Cuckfield, West Sussex RH17
> > > > 5HX
> > > > Registered number: 3445711
> > >
> > > Shop Safely Online Without a Credit Card
> > > http://www.rocketcash.com
> >
> > --
> > Dr John Upham, The UKMotorSport Index,
> > http://www.ukmotorsport.com/, webmaster@ukmotorsport.com,
> > Voice: +44 (0) 976 634 053 (W), Voice: +44 (0) 125 287 2551 (H),
> > Voice: +44 (0) 976 634 053 (M)
> > Registered address: Reid House, Mill Hall, Cuckfield, West Sussex RH17
> > 5HX
> > Registered number: 3445711
> >
> >

-- 
Dr John Upham, The UKMotorSport Index,
http://www.ukmotorsport.com/, webmaster@ukmotorsport.com,
Voice: +44 (0) 976 634 053 (W), Voice: +44 (0) 125 287 2551 (H),
Voice: +44 (0) 976 634 053 (M)
Registered address: Reid House, Mill Hall, Cuckfield, West Sussex RH17
5HX
Registered number: 3445711

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