Gearing Help
06-06-2003, 08:02 PM
#1
Gearing Help
i have a Matt Francis XXX and i just installed a 9T Doulbe Speed Gems Pro in it and I was wondering if someone could give me some help with the gearing. I am trying a 12 tooth pinion and a 90 tooth spur. When i did this the truck didn't seem like it really got to it's top speed and the connection from my battery and my esc got scorching hot. can anyone give me some advise? thanks.
06-12-2003, 09:45 PM
#3
You are geared WAY too low, and the motor is running flat out all the time. This will burn up any motor and/or connectors.
If we had a 9 X 2 in our truck (which we wouldn't have) we'd start with a 17/86 and adjust from there depending on the track.
If you're Matt Francis you could maybe run a 9 X 2 in a truck, but I don't think even he does that. Paul qualified 4th in Sportsman Mod at the Losi race with a 12 X 2 geared at 20/86. Main straight was about 115' long, and Paul was as fast as anybody.
If we had a 9 X 2 in our truck (which we wouldn't have) we'd start with a 17/86 and adjust from there depending on the track.
If you're Matt Francis you could maybe run a 9 X 2 in a truck, but I don't think even he does that. Paul qualified 4th in Sportsman Mod at the Losi race with a 12 X 2 geared at 20/86. Main straight was about 115' long, and Paul was as fast as anybody.
06-12-2003, 09:49 PM
#4
I agree, that is much too fast a motor for that truck, you'll get to enjoy it the first couple runs before it needs to have the comm trued and new brushes to get back up to speed. Gearing isnt so much your problem as having the wrong motor is.
06-14-2003, 08:32 AM
#5
Thanks for your support on the motor thing, Randman. 9 X 2 maybe in a 4WD on a long track, but nothing lower than a 10 in a truck, and that only at a really long straight like Hot Rod Hobbies (130'). Usually 11 or 12 turns for truck. Keep the single-digit turn motors for on-road.
I do stand by what I said about the gearing. We don't even possess a 12 tooth pinion. I think 15 is our lowest, and I can't remember when we used it with a mod motor. Normal starting point is a pinion 8 teeth over the wind. That is, a 12 wind motor gets a 20 tooth pinion for starters.
His final drive ratio is over 18!!! Normal is 9 - 14. That motor is screaming everywhere on the track -- it never slows down. I'll bet the run times suck too because the motor is demanding full power from the batteries constantly.
This heats up both motor and batteries, further decreasing both performance and run times. Of course it heats up all the electrical connections. Worse yet, it kills the life of the motor and the batteries. The final blow is slow lap times, as the truck can't reach a decent speed on any straightaway
I do stand by what I said about the gearing. We don't even possess a 12 tooth pinion. I think 15 is our lowest, and I can't remember when we used it with a mod motor. Normal starting point is a pinion 8 teeth over the wind. That is, a 12 wind motor gets a 20 tooth pinion for starters.
His final drive ratio is over 18!!! Normal is 9 - 14. That motor is screaming everywhere on the track -- it never slows down. I'll bet the run times suck too because the motor is demanding full power from the batteries constantly.
This heats up both motor and batteries, further decreasing both performance and run times. Of course it heats up all the electrical connections. Worse yet, it kills the life of the motor and the batteries. The final blow is slow lap times, as the truck can't reach a decent speed on any straightaway
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