VS IROC car progress

[gordon]

Guys,

Here's an update on the cars I've been prepping for my new VS IROC class. Here are the downforce measurements (remember, cars can have downforce up to 3.5 times their weight):



And here are the cars:



You'll notice that the blue no 6 Mark Donohue Lola T70 is missing from the download measurements and has its rear axle resting on the car in the pic. Well it's temporarily (I hope) sidelined as one rear wheel broke while trying to remove the glued-on tyres. Aside from this car, all the others are ready for their first test.

Gordon

[steveaca]

Very interesting measurements. It would be even more interesting to observe their relative performance on the track.

[Killer_B]

Yes interesting....especially to see how the Daytona coupe performs ????

[gordon]

Well having tested the working cars with Luke's help after racing on Thurdsay, then spending all afternoon and evening today working on some changes to the cars, here's an update of my progress. Here are the updated weights and downforce measurements, along with lap times taken on Thursday:



I was able to get the Lola T70 ready by substituting some wheels on the rear axle, so it's included in the measurements above. Here's a pic of it:



Looking good, eh? I always loved the T70 ever since I first saw pics of it in my slot car magazines in the early '60s.

To slow the GT40 and P4 a bit, I removed the Slot.It motors and replaced them with my two fastest Scalextric 18K motors. The P4 time listed above is slower than the potential of the car with a Slot.It 21.5K motor, especially as I installed new Maxxtrac Extremes today, courtesy Luke. I also got it closer to its allowable downforce limit.

Tomorrow I plan to work on the Mk IV to try to understand its sluggishness and get it in line with the other cars. I'd like to have them all within a tenth of a second or two of each other.

[gordon]

Worked on the Mk IV today. Focused on the gear ratio as the existing gears were 10T pinion and 27T crown, a ratio of 2.7:1. Add to that, it has amongst the largest diameter rear tyres of any slot car I've seen which, when taken with the gear ratio, results in poor acceleration and high top speed in the FRC braking zones, exactly the problems we saw on Thursday that I'm trying to overcome.

Had some issues getting it done, but to make a long story short, it now has a 3.25:1 gear ratio, so it should perform more in line with the rest of the cars.

[Luke]

It seems you are getting as close as possible to a level (racing) playing field GG & glad to be of help.

Must thank you (again) for all your efforts with all these calculations (weight, downforce, gearing, motor and lap times) setting up these 8 cars (of yours) for us FRC guys to race.

Also, am I correct to think - those are CB brand rims painted in yellow

If so, they're looking real cool ...

Luke

[gordon]

Luke, they are actually some very small (14 mm I believe) Slot.It wheels with Slot.It inserts painted yellow.

[steveaca]

Some real work is going into making these cars as equal as possible. Really looking forward to driving and racing them.

[Luke]

So all in all GG,

• 1. Scalextric Ford GT40
  2. Scalextric Ferrari 330 P4
  3. MMRC Ford Mk IV
  4. Revell-Monogram Lola T70

Out of the 8 cars, these are the only (listed) ones that you should be now testing for their lap times ..

Luke

[gordon]

That's right Luke. I'll test them at the next event and then confirm the fastest times of the others too. Hopefully they'll all be very close.