Not really having too much of an idea beyond a "typical" carpet set up, I initially had the car in a transverse battery configuration. I was also using the T bar instead of the links, and the short wheelbase, which are both not typical, but worked very well on asphalt. This is not to say it would be right for high traction carpet as well, but I wanted to give it a go.
Right off the bat, the car got around fairly well. The main problem became lifting of tires, and a tendency to over rotate out of the corner on power. The over rotation stems from the tires getting light, since I had pegs in the diff to lock it into a spool. As a tire comes up, it just rotates the car off the outside wheel.
The car was driveable, but touchy in areas and not stable enough to attack. I tried changing side dampening and t bar settings at first. 5000, 7000, and 10,000 in the damper tubes provided enough feed back to see that lighter would be better, and really the T bar needed to be tightened. I settled on 5K in the tubes and moved on to the t plate.
There are a few ways to change the t plate characteristics even without changing the t plate. I started with an orange o-ring, which is fairly soft. Going to a stiffer black o-ring, and then even the outer o-ring in combination with the black o-ring, as was used on the F104 T bar cars still was not quite enough. The t bar needed less tension so it could pivot, but the overall travel was a bit too much. In this case, I replaced the smaller black o-ring with a similar thickness nylon washer. The larger o-ring was retained. Now the t bar could be set with less tension, but the washer reduced the overall travel as it pivoted. This made the car feel more stable and reduced the tire lifting.
The first qualifying run I made was not bad, but as the race wore on and the tires heated up, the tire lifting came back into play. There was some time to practice, so I was able to try a longer wheelbase on the car. Surprisingly, the car did not lose much steering at all, and the tires stayed in contact with the carpet much more consistently. I tried a few other things, including raising the rear ball stud on the upper arms of the front end. This usually helps to quell a bit of the tendency to traction roll while taking a little steering away, and indeed, it did help. This car seems to have plenty of steering, so it was a worthwhile trade off.
By this time, the track was about to close for the night, so any more experimentation would have to wait until morning. Reflecting on the car's main problems, it seemed an overabundance of weight transfer was happening at the pivot point of the t bar. There is really no forward/aft movement of the battery in a transverse setup on this car. This left me with an inline setup as the only alternative to change the weight bias. I have not been a big fan of the inline battery over the transverse on carpet, though there has been quite a few racers using an inline battery on high traction very successfully over a range of different cars. On day 2, I decided to test it out.
Arriving at the track the next morning, I ran through a couple quick changes before reconfiguring the battery. Mostly front and rear width, which was maxed out close to 190mm at the end.
After fighting the wiring and electronics onto into a suitable configuration, I dropped the battery into the car inline and went out onto the track to test. In the past, I have found inline cars to be overly aggressive off center, even a bit jittery, so I was apprehensive. Imagine my surprise as the car was very docile and had to be thrown around to make it want to pick up a tire. The over rotation problem was gone as well, and I could drive it hard through the chicane leading onto the straight with fear of having to make a correction and upsetting the car. A miscue was met with a smooth response instead of a jerky reaction when corrected. My car was now a good .3 seconds a lap better, being able to drive it confidently at all points on the track.
For the final qualifier, I was able to move into P2 for the mains, and lap times were much closer to the TQ driver. The car handled in traffic very well.
What really capped off all the progress I made was a small change to my tire dope strategy. I began applying more tire sauce, but wiping it off about 5-6 minutes before the race, as opposed immediately before setting the car down. The front tires were more or less dry, though they had been sauced for about 10 minutes wet time. This really settled the car, but still provided enough steering throughout the race. Starting second in the main, I was also able to be ready to fight and apply pressure immediately, and twice I made a pass on the first or second lap to get into first place at the start of a race. I had one first place and two seconds, for a second place final position. In the second main, I actually had first place for a bit, but I crashed when a marshall screened my view of a chicane. I probably should have gave myself a little more room there, but I was going for the win. For the third race, I did not have quite as good of a start, and made a mistake on the left side of the track, costing a little time. Ultimately, I was able to close down on the lead car, but never get close enough to try to pass. The winning car and driver were very good, so congratulations are in order.
Overall, I was really happy with how quickly the car setup came together, and even more, how easy it was to drive the car at race pace. It's also encouraging as this was outside of the body, a TCS legal setup. For typical races, you could use an aftermarket spool or gear diff, and also front end pieces that could offer more caster and camber settings than the stock parts. There are more tenths to be had out of the car, but this was a good weekend. I plan to also try the link setup as well for comparison, but I have always liked the solid feel of a t bar car. Don't be afraid to try it if you own the TRF 103.
EDIT: Turns out I also managed hot lap of the weekend!! Not bad.
Inline car
Please excuse the somewhat disheveled wiring...lol
Note the short shock configuration. Also, 42 g of lead was added to the car to make weight with a standard short pack. Lead was distributed close to midship.
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