[s-cars] alignment Q

Thu Jan 15 07:17:08 PST 2009

Does the track have an outer edge that the wheel would
rub against if there is camber?

If it does camber could cause the wheel to rub and slow the car.

--- Vincent Frégeac <s.sikss at gmail.com> wrote:

> If I read the web correctly, derby wheels have a square surface
> contact and
> are hard. In that case, camber will reduce the contact surface and
> the
> contact point will be very close to pinpoint contact, so scrubbing
> from
> camber will be reduced to a minimum. Worth experimenting with at
> least.
> 
> As for toe, 0 toe will minimize the friction but will make the car
> change
> direction at the smallest pebble especially with high camber. A
> slight
> toe-in may be preferable for stability at the expense of little speed
> lost.
> 
> As for the wheel/hub genius idea, if I understand it well, having the
> wheel
> rotating on a fixed hub will increase the contact surface and
> decrease the
> linear speed. This, IMHO, will increase friction. I would rather go
> back to
> the original design, with a slightly viscous lubricant, to create a
> liquid
> bearing. Once more, experimenting will be required to determine which
> viscosity will be enough so the liquid bearing can support the weight
> of the
> car without slowing down the wheels. Since every pebble will kill the
> liquid
> bearing effect, I would go with dry lubricant plus liquid lubricant
> so you
> still have lubrication when the wheel hit the axle when the car goes
> over a
> pebble.
> 
> Of course, this is all theory, so Reality Mileage May Vary.
> 
> 
> Vincent
> 
> 
> 
> -----Message d'origine-----
> De : s-car-list-bounces at audifans.com
> [mailto:s-car-list-bounces at audifans.com] De la part de
> djdawson2 at aol.com
> Envoyé : 14 janvier 2009 17:40
> À : pkrasusky at ups.com; s-car-list at audifans.com
> Objet : Re: [s-cars] alignment Q
> 
> 
>  Toe would cause more scrub than camber.? I think the main goal for
> you is
> to minimize lost energy.? There is an energy loss associated with
> camber...
> look into motorcycle tire design.? High speeds, combined with a lean
> angle
> (essentially camber) generates extreme heat = lost energy.
> 
> Normally, derby car wheels are more like a motorcycle tire than a car
> tire... the contact surface has a radius instead of being flat.
> 
> Think of the pinpoint contact with the road surface.? Only at the
> exact
> point of contact is where the ideal situation exists.? As soon as the
> tire
> moves past that point of contact it is now "scrubbing" perpendicular
> to the
> direction of travel.? It's a little like taking a turn in a vehicle
> with a
> live axle... something has to scrub.
> 
> 0 toe and 0 camber should provide the least energy loss.? I think
> wheels
> wobbling on axles would be a major concern.
> 
> Nice to hear it will be a 930? ;-)
> 
> 
>  
> 
> 
>  
> 
> -----Original Message-----
> From: pkrasusky at ups.com
> To: djdawson2 at aol.com; s-car-list at audifans.com
> Sent: Wed, 14 Jan 2009 2:20 pm
> Subject: RE: [s-cars] alignment Q
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> 
> ?
> 
> 
> I would think toe causes more scrub
> 
> 
> ?
> 
> 
> if camber scrubs... is it better than the full friction of the wheel 
> surface area created by having zero camber?? Just wondering 
> aloud.
> 
> 
> ?
> 
> 
> Thanks Dave - good to hear from you btw...
> 
> 
> ?
> 
> 
> -Paul
> 
> 
> 
> 
>   
> 
>   
> 
> 
>   From: djdawson2 at aol.com 
>   [mailto:djdawson2 at aol.com] 
> Sent: Wednesday, January 14, 2009 4:19 
>   PM
> To: Krasusky Paul (WQQ2PXK); 
>   s-car-list at audifans.com
> Subject: Re: [s-cars] alignment 
>   Q
> 
> 
> 
>   
> 
> 
>   
> I can speak to 
>   camber...
> 
> Zero camber would be best.? Any camber causes a 
>   "scrub."
> 
> 
>   
> 
> 
> 
>   
> 
> 
> -----Original Message-----
> From: pkrasusky at ups.com
> To: 
>   s-car-list at audifans.com
> Sent: Wed, 14 Jan 2009 1:23 pm
> Subject: [s-cars] 
>   alignment Q
> 
> 
>   
> 
> 
> 
> NAC, in fact it's a Porsche.
> 
> 
> 
> So The Boy insisted we make a 930 (of course) for his inaugural
> Pinewood
> Derby 
> 
> this year - could he pick a more bulbous car?  Oy.  We're nearing
> completion
> and 
> 
> ready to mount wheels.
> 
> 
> 
> Question for the Geekdom here - what is the 'fastest alignment' for a
> car
> that 
> 
> only has to go down a straight hill?  I'm thinking maximum negative
> camber
> (to 
> 
> decrease wheel surface friction on track) and zero toe - F&R.
> 
> 
> 
> Am I right?
> 
> 
> 
> Also - rules state cannot add bearings.  I just got the genius (I
> think)
> idea to 
> 
> separate the wheel from its integral hub via a cut, and then glue the
> 'hub'
> onto 
> 
> the car, polishing both contacting surfaces of wheel / hub.  Think 1)
> this
> would 
> 
> be effective and 2) think it's legal?  We're not 'adding' anything
> and using
> 
> 
> what's provided.  I do have a note in the Cubmaster on it, I can
> pretty much
> 
> 
> guess the reply of course but figured I'd ask anyway.
> 
> 
> 
> Any other hotrodder tricks appreciated - we're already polishing the
> axles
> and 
> 
> wheels and hubs best we can, using graphite lube, etc.
> 
> 
> 
> Insight appreciated - by Tyler 8-).
> 
> 
> 
> We pretty darn well nailed the 930 look - esp. the rear flanks and
> profile,
> and 
> 
> front nose.  Unfort. rules dictate must use OE axle locations and
> then they 
> 
> limit max width, result is a 930LWB.  Hindsight would have me
> approach the
> front 
> 
> flares different and run them further into the doors - next time. 
> And the
> front 
> 
> wheels are so close to the nose our ride height is more Rothman's 959
> than
> 930 
> 
> (maybe I should strip the Guard's Red and go with the Livery heh
> heh?) as 
> 
> tucking the wheels any more up would hit them into the headlight
> area.  Ah
> well.
> 
> 
> 
> But it came out pretty darn kewl.
> 
> 
> 
> TIA!
> 
> 
> 
> -Paul
> 
> 
> 
> 
> 
> 
> 
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