When Rick Terry, of
RTHO, first announced his set of gears for the Thunderjet, it was met with equal parts of joy, and loathing. The Fray guys found the panacea, the traditionalists saw doomsday. As it turns out, both over reacted. I will leave further comment for a later paragraph
Here's how we chose to measure the qualities of these. First, take a set of stock gears, hand picked, checked for roundness, and centered hole, and Install them on a known good gear plate (donated by Steve Ward). These were lapped prior to installing. Nearly 30 gears were checked to find the 3 we used. We then hooked them to a good chassis and armature, with axle and crown gear, and spun it up. Take measurements with a tach, and see what we get. Then, with the same setup, take off the gears, and mount the RTHO sets. Again, check with a tach. We decided to see how three different sets of RTHO compared. We did this to get some idea of quality control.
We installed using the RTHO gear press. Note that the RTHO gears are all chamfered in their holes. This is excellent for pressing, and not scraping material off with the pinion and armature.
Power source was a 20 volt Aurora power pack. The tach we used gave us both highest, and average RPM readings. We decided to report both, because if the high was near the average, it did show some stability in the system. We started with the stock gears. we ran the test for 15 seconds. The figures for average/and high were 24,376/25,740.
Now we took off the stock gear, and ran through the same test with RTHO1, RTHO2, and RTHO3 gear sets. The results are as follows:
RTHO1 - 25,221/25,865
RTHO2 - 25,153/25,701
RTHO3 - 25,149/25,776
As you can see, consistency is no problem with these gears. The gain of more than 3.2% in average RPM's is fairly significant. Also, the smaller fluctuation between average and top RPM's might indicate something about driving smoothness. The gear sets were very quiet, and the fit on this gear plate was quite close.
You may wonder why we didn't race cars with them installed, but we wanted to be more objective, so we left out the subjective aspects of trying to turn laps. We also checked the gears for roundness, and found them to be perfectly cut. No discernable deviation in any respects we mesasured.
There still are a few questions about these gears, and their value. There are questions about whether or not they inflict chaos on the rules. The answer to these questions is short. To the first, as is clear by the top two finishers in this years Fray using stock gears, one can find competitive stock gears, with enough skill, time, and effort. The time saving aspect of a perfect set of gears though, is unmistakable. As to the second point, I think the price point might be a factor for most clubs, and so, these pose little threat to those racers, and tech committees. Let's also remember that with just a little bit of scrutiny, these gears are discernible from stock, or any other third party gears out there.
