30mph? How?

[nitrostarter]

If we're calculating 27-30 mph, how are people getting 40mph?

I'm not complaining about the performance, I love it. Its crazy fast acceleration and speed. I'm just looking for a little more top speed.

[mt_enthusiast]

I've been trying to get some speed runs done with the GPS strapped in, but it has been raining all weekend. There are theoretical calculations and then there is real world. Serum's calculation had 1.05 volts per cell instead of 1.2. This is an example of what really happens. RCM Mike said 1.05 was more realistic with NiMH under load. The kV rating on the motors might not be accurate either under load. Temperatures look to be a better indicator of what truly can be done to fine tune gearing.

[nitrostarter]

Well it looks like I'll be going with the Strobe slipper soon, so I'll be running 12 or 14/51 since there isnt a 13T.
I also think I'm going to pick up a GPS or find someone's I can use. I just dont think the radar is too accurate.

[Rtsbasic]

If the theortical gearing agrees with the speed your getting, it can't be that far off the mark..

[coolhandcountry]

How I got the 40 mph was a 7xl with 22 pinion and 66 spur 18cells. I think it was a little more than 40 LOL

[lipomax]

Running my excel sheet says that you'll top out around 33 mph in second gear. You just got the wrong gearing. However, if you go with an 18 tooth or 20 tooth, you should be around high 30's and if you go to 22, you'll hit 40 then. However, when you run a pinion that large, you'll easily draw 100 amps or more in second gear so be careful. I end up running mostly in first gear when I have large pinions.

BTW, the radar gun is very accurate. I have both radar gun and GPS and they always give me the same number.

[nitrostarter]

So 14/51 or 18/66 should do better, give higher top speed, and motor should run cooler? Those 2 gear ratio's I just mentioned ar about the same right?

[aqwut]

yeah that's pretty much the same gearing.. but that's good for 36MPH.... what diffs are you using the supermaxx or the regular... regular is 2.85:1 and supermaxx is 3.31:1

try goin' to a 20 tooth...

[nitrostarter]

I'm using UE diffs.

[squeeforever]

then i think you have it WAY under geared. not possitive on that though...

[RC-Monster Mike]

I can do 12-15 gears with 5mm bore now-no problems. I will update the site to reflect this. I can get temp guns, too.
the radar gun doesn't lie. Your gearing is on the short side, so more speed is definately available.

[mt_enthusiast]

7xl, 14 cells, hyper7, 15/51 in 2nd gear with Moab 40 tires calculated as 37MPH..........GPS max MPH when running on pavement read 36.3MPH.

When I run this gearing in grass and dirt hard, ESC temp is 130F and motor is 170F. I'm afraid to gear higher on the pinion with these temps. Is this reasonable?

[coolhandcountry]

The grass is hard on you. If you want more put 16 cells on. The esc temp is good the motor is a little warm. You could try a 16 pinion just keep a close eye on temps. I was just thinking of asking you about your set up to. Weird

[aqwut]

Yeah, Gass is hard.. unless you're running 36 cells like ProMod.. hahaha.. his truck, was flyin' on grass.... Try 20 Teeth... :)

[mt_enthusiast]

Originally posted by aqwut
Yeah, Gass is hard.. unless you're running 36 cells like ProMod.. hahaha.. his truck, was flyin' on grass.... Try 20 Teeth... :)

hmmm......36 cells and 20 teeth. Who says I have to buy a separate airplane. Just need to zip tie some wings on too. :D