Recently I volunteered to build some T-Dash cars for an IROC style charity benefit race that will be held at LenJet Raceway later this year. The cars will have vintage Indy bodies like so:
I did a total of eight rolling chassis using mostly the stock parts, I also used Rutherford wheels and tires, Slottech pickup shoes, new style Wizzard shoe springs and Slottech motor brushes. The gears were lapped for 60 minutes using Simichrome. The pickup shoes were adjusted to ride flat on my MaxTrax and the shoe spring tension was adjusted to read 2.8-3.0 grams using the Scale Engineering gauge. All of the cars were track tested using the body shown in the picture. The cars proved to be good runners, the chassis were numbered and their respective lap times were recorded. The average lap time was 6.5 seconds, which is good for a car of this sort.
I ended up with a spare chassis so I decided to do it in T-Jet SS trim with a drill blank rear axle, Oogan shoe springs, Anchor front end, RT-HO crown gear, a 12 tooth RT-HO drive pinion and Wizzard white tires. Lapped stock top gears were used.
The magnets were weaker than I use in an SS car and they were not matched. The armature measured 17.4 ohms across all three poles, When I was doing the IROC cars the one arm that I measured was 16.3 ohms, but that might have been under the 16 ohm limit if the room temperature was lower. I faced off the commutator and checked the balance, which was good, but some Dash arms have perfect balance. I added epoxy to a couple of the poles and got the balance up to very good at least. I could have fussed a little more but I did not think that a 17.4 ohm arm would be worth it.
I took the car for a spin and it is very nice indeed, gear noise was minimal and the car has good punch. What was lacking was top speed on my long straight. The best lap time was 5.558 seconds, my best T-Jet SS car can do it in 5.4 seconds, but that cost nearly $200.
For a start I tried a matched set of older 900 gauss Dash magnets. I was plan on ordering some of the new Dash Killer Bees yellow and black magnets, so I will try those in the future. The high ohm armature was also probably holding the car back, I will try to get one with a lower ohm value.
With the 900 gauss magnets and a small adjustment to the motor brushes the best time was a 5.460.
These cars are still available if you are on Dan Cashmer's customer list. If you race Fray or T-Jet SS cars you might try building one of these.
