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Believe it or not, some local cops will do favors. I've seen local state boys clock snowmobiles for top speed and help test radar/laser detectors. If you approach them in a reasonable way and aren't on their most wanted list, they might do you a favor.

Approach them packing donuts and it's probably going to go well.

Lol, for sure!

So just re ran 3 heats and the first 2 I purposely did at less than top speed. Results were 33, 44 and 59 mph.

So seems like the app is accurate.

I will try again after charging the battery and do it using a stop watch and a 100 ft speed trap section.

Did I mention this is a lot of fun?

Coelacanth wrote:A track has to be pretty big to make full use of 40+ mph speeds in a 1/10-scale car, I think. Just my 2 cents.

Mine was uncontrollable at 38. Only fun for top speed runs.

RC104ever wrote:

floodx wrote:Assuming a few things - http://dhrc.rchomepage.com/RolloutCalc.htm:

54 tooth spur (but if not stock this would be wrong)
14 tooth pinion (???)
1.83 internal ratio (6-gear - this right?)

2.6 inch outside rear wheel diameter

this is for 8.4V battery 4900kv motor

gives you 40 mph

If I change the inputs as follows:

70 tooth spur
24 tooth pinion
1.83 internal gear ratio
2.75 inch outside rear wheel diameter (just measured)

That gives me 60.9 mph. Wow, so maybe the iPad measurements weren't that far off after all.

Hunh....cool.

So I actually took the time to count the teeth on the spur and I got 86. Now that I have an original stealth in there, I'm told the gear ratio of it is 2.25 (so I changed the transmission ratio)

This gives me a new theoretical top speed of 40.1 mph - that would seem to support my observation that the car is 'slower'. So what do I change now to make it faster again?

I saw a thread that says I can switch to the B4 top gear etc. But there are different pitches...what is that exactly? Do I want to just go with a bigger spur gear and a pinion with more or less teeth? Would that help?

You need a smaller spur and a bigger pinion.

I just strapped our GPS into my car and did a couple of top speed runs. Got a final speed of 44.95 mph or 71.2 km/h.

CONGRATS haha the GPS works good for you too I'm waiting for the cops to show up in a parting lot here

Thanks! I'm planning my conquest of 60 mph right now though

RC104ever wrote:I just strapped our GPS into my car and did a couple of top speed runs. Got a final speed of 44.95 mph or 71.2 km/h.

Just did this again with a new Gens Ace Lipo 7.4V, 5000 mah, 40C battery. Wow. Its like driving a fully charged nimh 8.4V battery - all the time. It certainly SEEMED faster, and so to check, did the GPS thing again.

This time results were a top speed of 45.919 mph or 73.9 km/h

That's fast, that's real fast. Take the wing off, raise the springs to lower it and put skinny tires on it. Turn this into a bonneville salt flat runner hhhahaha. Glue solid discs on the outside of the wheels

Hmm...well, I'm thinking of getting a 3s Lipo and keeping the same gearing I have at the moment. Should be interesting, just looking at the Gens Ace options. Let's hope it doesn't burn anything out, lol

RC104ever wrote:Hmm...well, I'm thinking of getting a 3s Lipo and keeping the same gearing I have at the moment. Should be interesting

Yikes! I think you'd probably nuke the tranny if you went 3s wit the same gearing.

Well I did buy a smaller pinion gear (21t) and was going to move up to a bigger spur as well. I haven't decided yet

45.9 is pretty killer, congrats
-Kevin