The HPI RS4 was HPI's first attempt at building a 1/10 scale sedan from scratch. Their efforts are laudable, however, with the car being the company's pioneer sedan, it inevitably had flaws. However, it has to be said that the flaws are not in handling, but the car's overall contruction - it was too weak!
Out of the box, the RS4 had understeer, not necessarily a bad thing for beginners. This can be traced to the fact that the RS4 used very hard shock springs (as hard as a 1/8 onroad gas car's, as a friend put it), and the fact it came with M-compound Radials instead of HPI Super Grip Radials.
| Chassis | Standard FRP Double Deck |
| Motor | Matrix 15-turn Double |
| Gear Ratio | 28/106 |
| Front Tires | Tamiya M-Grip Radials, Molded inner sponge |
| Rear Tires | Tamiya M-Grip Radials, Molded inner sponge |
| Front Springs | Tamiya Blue Springs, one 3mm spacer |
| Rear Springs | Tamiya Red Springs, one 3mm spacer |
| Shock oil (F/R) | 50 wt/50 wt |
| Camber Angle | 1 degree negative |
| Castor Angle | One spacer in front, one spacer behind upper arm |
| Toe Angle | Neutral |
| Miscellaneous | No roll bars, slipper clutch locked |
| Additional Hopups | Ball Bearings |
Driving notes: This set up was the last one I used on this car (before I sold it). In that race, traction was scarce, hence lean toward understeer, to be safe, rather than oversteer and drift. The car had a good balance, though, and when pushed hard, will drift. Steering was immediate, with no nasty tricks whatsover. There was no tendency to suddenly whip around and spin out. I would recommend such a setup for low traction surfaces, or new drivers. Interestingly enough, I briefly tried the RS4 with this setup on relatively smooth asphalt, and it handled like it was on rails. However, the lack of "drama", ie, drifts, made the car rather uninteresting for me, to drive.
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