brushless 1/5 4wd conversion about to begin! couple questions. - Page 15 - RC-Monster Forums

Ryu James · 04:01 PM

i think that 40t spur is gonna be perfect actually. i ordered the 36t and i think that is gonna be too small but i will try and see. i just dont want my esc overheating cuz its geared to high. and with a 36/18 it is just insane speed. i actually have a 16t, 17t, and 18t pinion gear so i can play around a bit with those but i think like a 40/16 is gonna be the ideal setup on 10s. it will be fast. probably in the 50mph range when its actually on the street. i am heading to the machine shop in like an hour and gonna get the gear cut. i am milling out the center are 6mm so that the gear will sit like the stock gear and shed some weight. i am just gonna save the CAD files so then when i get that 40t spur it will be a quick fix. the 48t is way too big. in fact, i bought a 48t gear already remember? that 48t FG gear. i thought it would work but it was WAAAAY too big. go with that 40t and it will be perfect. or if you want Kaz, i will order 2 of them right now, get them machined and hardened, and you can just pay me the actually cost of everything. the gear is $20 if i recall and i will know today how much to CNC will cost and hardening i will have to find out. i dont think it would be more than $50 for everything though. of course, i have already paid for the machinists time for drawing and stuff so you would only actually be paying for machining time. let me know

also SuicideNeil,
what do you think is gonna be the best gear ratio on these things? you seem to know alot about that stuff. keep in mind the largest spur gear is 40t. 10s, 750kv Neu. what do you think as far as pinion?

if the motor is torquey enough it might not even matter what gearing we run...within reason of course. i was just hoping that with the 36t my temps would be ok still cuz i figured this motor has enough torque that it would be fine. i am gonna order that 40t spur just to be safe though.

btw, i just ran the rc-calc. and with a 40/16 gearing on 10s, 750kv and 7" tire it comes out at 53mph. with 36/16 gearing it is 59mph. 36/18 = 67mph. i was gonna run this gearing if temps are ok. 36/18. 2 to 1 ratio. could be crazy.

KaztheMinotaur · 05:09 PM

Yeah, LMK how much it will be and I will decide.

What am I getting such higher speed on the calc then ? Were you using 3 for a diff ratio? What battery voltage?

Ryu James · 07.29.2009, 02:02 AM

i was using standard truggy diff ratio of 43/10 or 4.3. i thought that it was the rampage runs, isnt it? if i put in buggy ratio of 43/13 or 3.3 it jumps way up in speed. 36/18 goes from 67mph to 87mph. do you know exactly how many teeth the front and rear diffs/pinions have?

suicideneil · 07.29.2009, 07:18 PM

Cripes, 1/5 scale is beyond the realms of my 'expertease' Im affraid. I know one thing though, 70mph gearing is way too much as a starting point, I cant see the electorincs liking that much, or the tires. If you cant lower the gearing with a larger spur/ smaller pinion, IO would cdoncider dropping the voltage, just for inital testing.

And hit up the other 1/5 scale builds, tons of info in those regarding gearing and whatnot (a 1/5 scale tranny may be needed to drop the gearing perhaps, rather than a straightforward center diff)...

KaztheMinotaur · 08:00 PM

I found some smaller pinions...12T brings the speed down to 58

KaztheMinotaur · 11:40 PM

I think Mod 1 gears is the way to go...there are a lot more gearing options.

The bore on the 60T mod 1 spur is 10mm though...shouldn't be that hard to drill it out to 12mm.

Mod 1 60/15 brings the speed down to 48.33 mph.

qtcgears.com also has some good choices.

florianz · 07.30.2009, 03:53 AM

I'm afraid but I also think you should switch to mod one gearing. it's easier to get the right spur gear, and further the difference between eg. a 12 and 13t pinion is less then with mod 1.5.

there is a certain calculation to find out the number of teeth of a spur gear, with a specific diameter. but dunno that calc. just measure the maiximum diameter that would fit.

_paralyzed_ · 07.30.2009, 05:00 AM

Quote:

Originally Posted by florianz

I'm afraid but I also think you should switch to mod one gearing. it's easier to get the right spur gear, and further the difference between eg. a 12 and 13t pinion is less then with mod 1.5.

there is a certain calculation to find out the number of teeth of a spur gear, with a specific diameter. but dunno that calc. just measure the maiximum diameter that would fit.

there is an app. to find gear diameter in BrianG's speed calculator.

Ryu James · 03:47 PM

Quote:

Originally Posted by KaztheMinotaur

I think Mod 1 gears is the way to go...there are a lot more gearing options.

The bore on the 60T mod 1 spur is 10mm though...shouldn't be that hard to drill it out to 12mm.

Mod 1 60/15 brings the speed down to 48.33 mph.

qtcgears.com also has some good choices.

if youre gonna go with mod1 gears you will want to get a 5mm shaft 2215. there was 2 of them on ebay recently that didnt sell. they were brand new and were up for like $350 if i recall. the seller was jvmaxx. i have bought several motors from him and he is a great seller. anyway, i want to stick with mod1.5 and 8mm shaft myself. if all else fails i will switch to mod1 as a last resort but i think the mod1.5 setup is gonna work just fine. i think a 40t/15t setup is gonna work. i could be wrong but i will know soon. also, Mike initially said that he was gonna have mod1.5 pinions from 11t - 22t. i imagine he just got in the most popular sizes initially since everyone was hounding him about getting these mod1.5 pinions. perhaps he will have the less common sizes like 11t - 14t shortly. a 40t/11t mod1.5 setup would put the speed at 51mph which i think would be reasonable. or there may be a way to get a 42t spur somewhere. i think a 42t spur would fit in the ramp. you could even go with one of those 48t spurs if you wanted to build some shims for the center diff mounts and mount your motor a little higher off the chassis maybe. the center driveline would be angled a bit but it could work. idk, basically there are a lot of options to make the mod1.5 work. same for mod1 also. i had considered going with mod1 myself but i figured they must use mod1.5 on 1/5 scales for a reason and was worried that the mod1 gears wouldnt be strong enough to handle the torque.

edit: i just saw those 8mm bore pinions in mod1 that you found. i didnt see those before i mentioned having to get the 5mm Neu.

nitrostarter · 08.04.2009, 05:33 PM

those controllers are actually being put through their paces in the boating world. Despite their huge size, they are actually doing great and handling the power requirements of the larger HV boats.

KaztheMinotaur · 05:56 PM

Yeah, I know thats why I got it. I was trolling around on OSE and RRR and read about them. As you said they seem to be doing well so far.

Lots of heat sink space on which to put a fan or peltier cooler.

Anyone see a problem with the dual 12 guage wires?

suicideneil · 08.04.2009, 08:35 PM

Dual 12g wire = 6g wire? Or is it done differently on that scale of wire diameter?

I dont see too much of an issue myself, those wires should carry plenty of current before they start to warm up, just have to solder on a nice fat 6-8mm bullet plug good n proper.

KaztheMinotaur · 08.04.2009, 10:02 PM

I have some 6mm bullet connectors coming.

I'm having trouble getting the programming file to extract though. It came as a .rar not a .exe

08.04.2009, 11:54 PM

Quote:

Originally Posted by suicideneil

Dual 12g wire = 6g wire? Or is it done differently on that scale of wire diameter?

every 6awg sizes it doubles in dia. so not quite a 6awg

Metallover · 08.05.2009, 12:49 AM

You need to find the area of the wire. Just using 12 "units" as the diameter because it's 12 AWG.

Area = pi times Radius squared

pi(12)^2 = 452.41 units

pi(6)^2 = 113.10 units

The 6awg is 4 times as big as the 12awg as the area of a circle increases expodentially.

To find twice the size of 12awg, take the area, 113.10, and multiply it by 2. Then take the resulting 226.2 and divide it by pi. You'll get about 72. Find the square root of 72 and that's the gauge wire that is double 12awg.

If my assumptions are correct, twice the size of 12awg is 8.51awg. So 7 or 8 gauge wire will be twice the size of 12awg.

Yes, I do feel pretty cool.