[BAracer]

Contrary to the impression I picked up from the chat, SportsRacer's winning car was only 87g, so not a heavyweight by any means.

[Nonfractal]

It's not just the weight that's perplexing. It's the placement
I just don't follow why there is lead stacked vertically against the motor, clearly jacking up the Centre of Gravity.

Something going on with the tyres that I just don't understand.

Alan

[BAracer]

Perhaps Brumos's Clio is a more familiar template to adopt?

As ChrisW pointed out, raising the CoG places more load on the outside tyre. Obviously Paul's car dynamic benefits from that characteristic.

[OXO cube]

It's the placement
I just don't follow why there is lead stacked vertically against the motor, clearly jacking up the Centre of Gravity.

Something going on with the tyres that I just don't understand.

Alan

exactly ????????????????

[Brumos RSR]

Perhaps Brumos's Clio is a more familiar template to adopt?

As ChrisW pointed out, raising the CoG places more load on the outside tyre. Obviously Paul's car dynamic benefits from that characteristic.

I have typically built light cars.  What I’m learning not everyone can drive the car.  I will be adding 5-8 grams as my best performing cars on average are 73-83 grams. Hopefully, a lower Cg will make the car more drivable.  Understand, we are at a significant disadvantage in this proxy as several participants drive these tracks every week.  The tracks are highly abrasive and I had horrible luck truing down urethane tires as a rookie and had more success with NSR Supergrips and less motor.

[Nonfractal]

So, 2 ways to go...

Lighter car
- can use NSR tyres without destroying them over the long stages.
- lighter car may be more difficult to drive because they accelerate and brake faster than some drivers can handle. 
Would longer ratios be an effective alternative technique to calm the car down?
Longer ratios would also be kinder to the tyres but may raise motor temperatures.

Heavier car (87g IS heavy for a short can car) 
- works the tyres harder 
(leading to the need for urethanes) 
Urethanes are not as high grip as nsr rubber on wood, therefore engineer the car to lean more.

Truing urethanes: I use Ortmanns when racing on (painted)  scaley sport track.
I find that skimming (dry) on the axle works best slowly, slowly with only the car weight pushing down on the tyre.
Adding oil based  fluids to true urethane doesn't work for me. (Zippo etc) 
I only ever use domestic degreasers on urethane.

Testing is required. I don't do "home tracks" so can't wait till MiltonKeynes RaceWars is open so that I can do some testing on wood.


Alan

[BAracer]

Looking at the top 5 from last year (ignoring Brumos!) most had body weights in the 25g - 30g range, which might have forced them to raise the chassis weight to compensate.

Yellow Dog tyres are available from electric dreams, but $17 postage makes for an expensive pair of hoops. I have fitted some locally made urethanes, and have some G25s sitting in the spares box. 

Like you say, some different thinking required. I'm thinking as the Civic is tallish, I can't be going for a super light car. I'm currently at a starting point of 17g for body with lexan interior, and 56g for the chassis...73g total. Listening to Brumos, I think I have around 10g ballast to play with, but based on actual testing rather than theory.

I need to get to Racewars as well!

[BAracer]

Might be able to get to RW on Monday 21/06...the longest day. Ominous!

[BAracer]

Posted to Aus lunchtime!

   

Over to the Proxy Race thread to follow our progress...