Date: Mon, 7 Oct 2002 02:10:03 +0100
Reply-To: Clive Smith <clive.harman-smith@NTLWORLD.COM>
Sender: Vanagon Mailing List <vanagon@gerry.vanagon.com>
From: Clive Smith <clive.harman-smith@NTLWORLD.COM>
Subject: Re: Bigger wheels and Unsprung Weight (nee mass)
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I don't know about Audi 5000 wheels, I've got lovely 15" Audi wheels
Code:
6J x 15 ET45 VWAUDI LWF
437 601 025 5625 072 Germany 8 89
(Audi 200 alloy wheels - same stud pattern as 5 stud Mercedes and
Volkswagen)
Tyres: KUMHO (Korea)
195 R15 1005 Powerguard
I'll weigh them soon, perhaps we can all weigh our spares and maybe then
we'll have some real data to work with.
If you pmail your results to me I'll collate them into a spreadsheet, Lbs or
Kgs no problem, just make sure you all pump them up to say 35 psi and
calibrate your scales with a sack of potatoes first! :-)
However, this will not determine any change to Moment of Inertia, if anyone
is interested in the effect on acceleration and braking distances.
I think we determined that 'worse case' their weight and moment of inertia
might result in a 6-7% deficit (but I certainly haven't done any definitive
calculations). If we wanted to we could either a) Calculate MoI from 1st
principles (an horrendous task) b) Hang a known weight at a known distance
from the centre (front 2WD, no drivetrain drag), trust that everyones
bearings were in brilliant shape, no brake binding and use a stopwatch to
time the acceleration for the 1st 90 degrees of movement (and then try and
estimate a fiddle factor for bearing drag). The comparisons might be half
valid but the absolute value would probably be wildly inaccurate.
Alternately, tyre balancing shop equipment might be used, to accelerate the
wheel and tyre to a know rotational speed, timing it accurately - even then,
you'd have to know the electric motors torque curve to get any idea of
absolute value for MoI. Lets forget it shall we, unless someone out there
has a calibrated rig for just this purpose - I bet theres one within 40
miles of me, since nearly all Formula One and several World Rally
Championship cars are built within that compass of London (except the
current F1 championship winning Ferrari!).
Clive
'88 Syncro Transporter
----- Original Message -----
From: "George Thorburn" <thorgk@ACCESSCOMM.CA>
To: <vanagon@GERRY.VANAGON.COM>
Sent: Monday, October 07, 2002 12:33 AM
Subject: Bigger Wheels and Unsprung Weight
James,
The weight we need to know is the weight of the tire and wheel combined. If
the 15" wheel weighs more and the 15" tire weighs less then every thing may
be even. If the 15" tire weighs more than the 185R14 then the unsprung
weight would increase even more.
Has anybody checked this out. Also does anyone know how much the Audi 5000
15" wheel weighs?
Thanks,
George
'85 Westfalia
>The popular Sunburst SA wheel is listed at 19lbs - only 1lb >more than
stock.
>But the Carat2 wheel, for example, is 23lbs...quick >math...that's 5lbs and
>28% heavier than the stock. And the Rhein style wheel is >24lbs!
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