Need help with my G3-build

[JoFreak]

Hi everyone!
I've been thinking about and been planning my G3-build for a long time but now it's time to get on with it.

So, my first question is what diffs to use:
Those from the HB lightning or those from the HB lightning PRO? What's the difference between them anyway?

Second is the gear transmission ratio:
I have absolutely no idea which gear ratio to use. I'm going to use a Plettenberg Bigmaxximum motor with 5S lipo, if that helps. Hope someone could give me a hint there.

Third question is which batteries to use:
1x 2S + 1x3S for weight-saving or 2x5S for doubled run-time?

And the last question, for the time being, is the one I forgot while typing this text here

Thank's a lot everyone,
Jo

[suicideneil]

1. The pro gears are truggy ratio, which means you would have to use a much larger pinion/ smaller spur than normal to get the desired gear ratio for any given speed; normal buggy ratio non-pro diffs only need a pinion 1 tooth larger than compared to the normal emaxx diffs. Get the non-pro ones.

2.

Differential Ratio: 3.3076923076923075
Transmission Ratio: 1.7222222222222223
Other Ratio: 1
Spur Tooth Count: 66
Pinion Tooth Count: 20
Total Voltage: 18.5
Motor KV: 2300
Tire Diameter (inches): 5.75
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor coil Ω: 0
Spur/Pinion Ratio: 3.3 : 1
Total Ratio: 18.79872 : 1
Tire Circumference (inches): 18.06 inches (458.83 mm)
Total Motor Speed: 42550 RPM
Vehicle Speed: 38.72 mph (62.2 km/h)
Effective KV Value: 2300

Assuming the BM is ~2300kv, been a while since I looked it up. Think its more like 2600kv, but that would give you ~43mph on the same gearing, which is pretty reasonable for that setup- 40mph is plenty for bashing or racing really (you didnt specifcy what you would be doing with the truck).

http://www.scriptasylum.com/rc_speed/_top_speed.html most useful tool ever, thanks to BrianG.

3. Tough call- I use 2x5s in parallel on my rig for extra runtime and less stress on the lipos (Zippies, love em to bits but a safety margin is always good with cheaper lipos, regardless of brand). If you went for smaller 5s lipos, say ~3700mah or so, then 2 in parallel would be perfectly fine,- still half the weight of nimhs with much more power output and runtime. A single 2s and 3s in series is fine too, and useful for use in other vehicles, just be sure to get ones of the same specs (just different voltages obviously).
Anything able to output over 100amps is fine (e.g. 5000mah 20c), but for a hungrier motor like the BM, over 120amps is better (e.g. 5000mah 25c).

Look into the stuff Mike sells as his own branded lipos (RC-Monster), or anything from rclipos.com (Enerland based cells).

Just dont fall into the maxamps trap, or we'll disown you...

Welcome to the forum.

[JoFreak]

Thank's a lot!

1. But if I were to run a centerdiff or slipperential with sth between 40T and 46T, i would need the pro-diffs? Am I getting this right?

2. Sorry forgot to tell you what I'm going to use it for. But to be honest I don't really know yet. Presumeably "soft-bashing" until I decide if I start racing it or not, most important right now is that it wipes the floor with the nitro guys' cars round here
I have no idea on the kV of the BM, couldn't find anything on their homepage as well.

3. But.... but they (maxamps) have cool flames on their batteries!!!
Just kidding, I'm most likely going for some high-quality batteries from a, sort of, local shop.
5S; 5000mAh; 30C/55C; 2C charging; 650 grams; 164x47x48mm; ~190€ (should be about 260$ I think)
They did very well in several tests, better than comparable Kokams for example because they keep their voltage on a high level untill they are nearly empty. Combined with the LiPo-savers from the same shop this apparently works very well.
I would give you a link, but it's all in German (hey, stop hating me ) and, as you've probably noticed by now, my english isn't that good so that I could translate the website, not to mention the tests.
I think I'm going to wait what the truck's weighing when finished and then I'm going to decide whether to go for 2S + 3S or 2x5S.

4. (Anoyingly not the question No.4 I forgot while typing my first post) Anything speaking against the 17mm wheel hubs from traxxas? (5353X)

5. Neil, thank's a lot for your help so long and for the welcome

[suicideneil]

1. Possibly- smaller spurs like that would be used with smaller pinions, so the pro diffs would be better **I think**- the calculator will answer that question better than I can as there are many gearing possibilties.

2. No issues there, it'll eat them all alive whether bashing or racing- the instant backflips will have them silly nitro lovers pooping themselves with fear.

3. No person who speaks German could be evil... (your English is better than most English speakers on the traxxas forums to be honest).

Specs sound great really for those lipos, price is pretty much what I'd expect from a good brand, so you should be be fine with them. Careful with some lipo-savers though, as they arent designed to work with cars that have forwards-brake-reverse throttle, only boats or planes/helis with forwards and brake only throttles. Post up the link if you like, there are a few german speakers around here and babelfish does a good job of translating web pages.

4. The traxxas 17mm hubs are fine so far as I know, just a little pricey I think compared to the various other options- 17mm is 17mm at the end of the day though, so its better than stock 14mm and gives lots of options with regards to wheels and tires etc.

[JoFreak]

Originally Posted by suicideneil

1. Possibly- smaller spurs like that would be used with smaller pinions, so the pro diffs would be better **I think**- the calculator will answer that question better than I can as there are many gearing possibilties.

Ok, then I have to see if I find technical data for both diffs, to find out the exact ratios. And the overall ratio to aim for is about the same ratio as the one the stock maxx has?

Originally Posted by suicideneil

3. No person who speaks German could be evil...

Uuuuuuh I wouldn't say that...
and I actually am a German
But if I recall correctly that line is form "the simpsons"? At least that's where I think I once heard it.

Originally Posted by suicideneil

(your English is better than most English speakers on the traxxas forums to be honest).

Well, thank's a lot, keeps up the morale necessary to try and keep improving
How comes it that I'm always hearing bad things about the traxxas forums? Respectively the average users of that forum?

Originally Posted by suicideneil

Specs sound great really for those lipos, price is pretty much what I'd expect from a good brand, so you should be be fine with them. Careful with some lipo-savers though, as they arent designed to work with cars that have forwards-brake-reverse throttle, only boats or planes/helis with forwards and brake only throttles.

Ok, thanks for that hint! That's what I'm going to ask the guy from the shop.

Originally Posted by suicideneil

Post up the link if you like, there are a few german speakers around here and babelfish does a good job of translating web pages.

Well, I have some bad, in other words no good, experience with those translation machines. But that's another story and was a rather long time ago, maybe they got improoved. See for your self if you like to:
german link to the 5S battery
translated link for the battery
german link to the LiPo saver
translated link for the LiPo saver

Originally Posted by suicideneil

4. The traxxas 17mm hubs are fine so far as I know, just a little pricey I think compared to the various other options- 17mm is 17mm at the end of the day though, so its better than stock 14mm and gives lots of options with regards to wheels and tires etc.

When building models in Germany you get kind of used to high prices and insanely expensive parts (traxxas suggests 25$ for their wheel carriers, here they cost 30€ and that's about 40$)
But in the pictures the part of the traxxas wheel carrier where you put the wheel on looks ab bit fat to me. Sure that there are no problems with fitting standard rims with 17mm carrier?

5. Speaking of which: Maximizer bead locks are good or a no-go? Because I really really really hate to glue tires and I'd prefer standard size truck tires.

6. After the standard maxx front bumper broke into three pieces because the truck rolled against an obstacle I'm looking for an alternative. Traxxas 4935X? Or is there anything harder and/or cheaper out there?

[suicideneil]

Simpsons yeah, I cracked up when I first saw that episode...
Traxxas forum is full of idiots, I mean the worst kind who just dont know anything, cant figure anything out for themselve, and have to be spoon-fed info and advice, despite me writing several help threads and FAQs etc (which few bothered to read or look at). I got banned eventually as they just drove me insane asking the same questions every few hours- blew my top once to often.

That lipo saver looks fine- I have seen many that are very similar, and have a couple myself that work roughly the same way (3.5v per cell is little bit high for the cutoff value, but since its what BrianG would call 'passive' alarm, it wont actually turn the truck off, which is the way I like it too).

The lipos are great too- I have heard of Stefans lipo shop before, very good lipos apparently.



if you mean the threaded portion that goes though the middle of the wheel, it does look a little fat, but I think most larger hexes are like that, so that the lock-nut has something substantial to screw onto; if it was too thin, it might snap a bit too easily after jump or bump.

The Maximizers have a fairly good reputation, but sometimes even they arent enough to keep the tires on the rims, depends how fast and hard you drive, and how much the tires tend to balloon- wrap some gaffer tape around the inside to reduce ballooning.

I dont use the bumpers myself, I have a Hardcore Racing Titanium front skid that I prefer, much more durable and makes the truck look less like a toy in my eyes. There are several companies that sell aluminium bumpers though, like Integy or Traxxas. RPM sells a really good plastic bumper though thats popular:

http://www.rpmrcproducts.com/product...s/MaxxPts2.htm scroll down abit.

Those are pretty much indestructable- the mounts or bulkheads will break before they do usually.

Differential Ratio: 4.3
Transmission Ratio: 1.7222222222222223
Other Ratio: 1
Spur Tooth Count: 46
Pinion Tooth Count: 20
Total Voltage: 18.5
Motor KV: 2300
Tire Diameter (inches): 5.75
Tire Ballooning (inches): 0
Motor Current Draw: 0
Motor coil Ω: 0
Spur/Pinion Ratio: 2.3 : 1
Total Ratio: 17.03278 : 1
Tire Circumference (inches): 18.06 inches (458.83 mm)
Total Motor Speed: 42550 RPM
Vehicle Speed: 42.73 mph (68.64 km/h)
Effective KV Value: 2300
KT constant: 0.59 oz-in/A

[JoFreak]

Originally Posted by suicideneil

Traxxas forum is full of idiots, I mean the worst kind who just dont know anything, cant figure anything out for themselve, and have to be spoon-fed info and advice, despite me writing several help threads and FAQs etc (which few bothered to read or look at). I got banned eventually as they just drove me insane asking the same questions every few hours- blew my top once to often.

Ah, ok...

Originally Posted by suicideneil

That lipo saver looks fine- I have seen many that are very similar, and have a couple myself that work roughly the same way (3.5v per cell is little bit high for the cutoff value, but since its what BrianG would call 'passive' alarm, it wont actually turn the truck off, which is the way I like it too).

It seems I've overlooked a detail, you can adjust the cutoff voltage from 2.9V to 3.9V, but that's only mentiond on this page:
German
English

Originally Posted by suicideneil

The lipos are great too- I have heard of Stefans lipo shop before, very good lipos apparently.

Interesting that his shop is even known beyond the German language borders

[E-Revonut]

Depending on the esc you use the lisaver might not me necessary. The Mamba Monsters are holding up well now and with that you wouldn't need an external lvc

[JoFreak]

I'm using the Schulze 18.97KW, but regardles of the esc I think an external liposaver is better, because it's monitoring every cell on it's own, and not just the total voltage.
At least that's what they're telling in the adverts

[E-Revonut]

I'm sure it's possible but I have yet to see a lvc that moitors each individual cell. That would require a connection to the balance taps.

[suicideneil]

The li-savers that he linked to do plug into the balance tap- they arent an LVC as such, more of an alarm to warn the user that one or more cells is getting low (buzzer and LED) so you can bring the truck in to stop it, rather than the esc turning it off mid-run.

[JoFreak]

And that's exactly what this one's doing:

Originally Posted by JoFreak

german link to the LiPo saver
translated link for the LiPo saver

edit: too slow...

[E-Revonut]

sorry tried checking the links but it was going anywhere, my computer is a POS

[JoFreak]

If I only knew what a POS is???

I discovered another problem while playing with the tranny-calculator:
I have to use at least a 72T spur gear, because otherwise the BM would collide with the tranny housing.
So there's no chance getting the pro diffs together with the tranny to upgrade to a centerdiff later...

[suicideneil]

POS = Piece of Shit.

Bad luck on the gearing problem, but those BM are rather quite fat, but the cooling fins are so cool looking its not so bad having to stick with a normal tranny and buggy ratio diffs. On the up side, if you did go to a centerdiff unit eventually, you would only have to change the ring & pinion gears on the front and rear diff to make them Pro/truggy ratio, much cheaper than a pair of new diffs.