I took some measurements of a set of MG+ 1.7 IROC cars with Modified paper bodies, but other than that, stock out of the box cars with rear tire upgrades, including various sizes of Super Tires and a couple with Viper low-pro MG+ tires.
The average change in downforce when flipping a traction magnet is roughly .7 grams of downforce, which is reasonably significant. The measurements of the orange car are a bit suspect, but the others are fairly consistent. The Yellow lane car measurements were a bit of a surprise, but we’ve seen up to 6.3 in tech recently, which would definitely indicate a high-downforce orientation of N30 magnets in a Modified chassis.
| MegaG+ 1.7 “Modified” IROC Set (stock rear axles, super tires, low-pro VSR tires) | ||||||
| Yellow | Blue | Orange | Green | White | Red | |
| VRP Meter (grams) | 5.8 | 5.2 | 5.8 | 5.1 | 4.7 | 4.5 |
| Flipped | 6.6 | 6.1 | 5.7 | 5.9 | 5.4 | 5.4 |
| Change | 0.8 | 0.9 | -0.1 | 0.8 | 0.7 | 0.9 |
| Average Change (grams) | 0.7 | |||||
| Gauss Readings | Gs Range | VRP Meter before/after flip (grams) | Change | |||
| N30 (Stock) | 2700 – 2800 | 5.5 | 6.8 | 1.3 | ||
| N42 | 3200 – 3290 | 7.5 | 8.8 | 1.3 | ||
| N52 | 3400 – 3600 | 9.7 | 10.8 | 1.1 | ||
The above N30 measurements were from one of my Modified platforms with N30 mags and a VSR replacement rear axle assembly with double-flange (.250) hubs and VSR PST Silicone soft Rear Tires (.432). Some run the Lo-Pro VSR tires in both the Lites and Modified classes, which are slightly taller (.445). Aftermarket parts are only allowed on the Modified version of this car, so we shouldn’t see “Lite” cars with downforce much greater than 6 grams on the VRP meter and “Modified” cars with downforce not much greater than 7 grams on the VRP meter.
Of course, different VRP magnet meters can vary by up to +/- 5%. So, the maximum downforce for each class is as follows:
-
-
- MegaG+ 1.7 Lites: 6.30 grams
- MegaG+ 1.7 Modified: 7.35 grams
-
If a car’s downforce measurements exceed the above before racing, resolve the excessive downforce by using larger tires/hubs, or flipping a traction magnet. If a car has downforce greater than the above after a race, the car is disqualified from any races completed.
Note: If you're looking to get more downforce out a chassis, reduce the size of the rear tires (lower rear of chassis) to get more downforce. Lowering the chassis too much will result in slower top speed and usually slower lap times. It's a trade-off between speed and handling, find what works best for your driving style.
We may encounter modified-rules cars exceeding this maximum downforce limit due to unforeseen tire and/or hub sizes, or other factors. We’ll address that if/when it arises.
Please feel free to comment or discuss this addition to our MG+ rules here on the site or at our next event. Keep in mind, any rule can be changed if a majority of drivers/teams support it.
MG+ “Lite” Rules
MG+ “Modified” Rules
