Need help with my G3-build
 

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 :sarcastic:

Thank's a lot everyone,
Jo

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. :yes:

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... :mdr:

Welcome to the forum. :yes:

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 :party:
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!!! :cry:
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 :oh: ) 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 :yes:

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). :mdr:

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. :yes:

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.

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?

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


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

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

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

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$) :grrrrrr:
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 :great: I'm looking for an alternative. Traxxas 4935X? Or is there anything harder and/or cheaper out there?

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.

http://www.italtrading.it/risorse/fo...um/5304hub.jpg

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

Ah, ok...

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

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

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

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 :neutral:

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.

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.

And that's exactly what this one's doing:
edit: too slow...

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

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...

POS = Piece of Shit. :lol:

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.

@POS: You never stop learning, do you? :lol:
To be honest, I'm rather happy that I know a lot more about computers then I do know about for example how to get a nitro engine up and running :rofl:
Comes in handy quite often :whistle:


About the gearing problem, I allready mailed mike when the slipperentials and G3-mounts will be available, hope it will be soon. :whistle:
Think I'm going for the all inclusive option right from the start. :gasp:

And those are enough smilies for today...

oh man...
I hoped to sort all thins out and get all the needed parts within the next 3-4 weeks so I could assemble my truck in the easter vacations and take part in an event from 9th to 10th of may.
But first the problem of the slipperential not fitting into the g-maxx and now I'm waiting for a reply from Mike for a few days without even knowing if he got my mail, since my mail account isn't that reliable in terms of actually delevering the message I sent :grrrrrr:
I should really get a new e-mail service...


Mike, if you should read this, pleeeeeeaaaaaaassssseeeee send me an answer to either my mail or the private message I sent you. I assume you got your hands full with handling all the slipperential stuff, but it would really give me some comfort to know if got my messages, thank's a lot!

I'm not sure about this. I have a pro 2 evo and it has standard buggy ratio, but all the gears are a different metal, some kind of special hardened steel or something comapred to the normal ones.

Hardened Diffs
Diff pinion
Diff ring gear

Notice the 'standard' and 'option' part listings.

Both the pro and normal ratio diffs will fit any given HB truggy or buggy, but the specific ones Mike sells are for the Lightning- buggy ratio ones and pro truggy ratio ones, so our man would want the ones listed as buggy ones. HB also sell hardened and standard (non-hardened), but I dont believe that effects the ratios as such (mine are hardended buggy diffs in my maxx).

Well, I think I'm going for the pro diffs, because with the non-pro diffs, the truck is getting much too fast.

with the pro-diff:

Differential Ratio: 4.3
Transmission Ratio: 1
Other Ratio: 1
Spur Tooth Count: 44
Pinion Tooth Count: 15
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: 2.93 : 1
Total Ratio: 12.61333 : 1
Tire Circumference (inches): 18.06 inches (458.83 mm)
Total Motor Speed: 42550 RPM
Vehicle Speed: 57.71 mph (92.7 km/h)
Effective KV Value: 2300
KT constant: 0.59 oz-in/A
Motor Torque: Amperage not specified...
Final Torque: Amperage not specified...
Final Power: Amperage not specified...


with the non-pro diffs:

Differential Ratio: 3.3076923076923075
Transmission Ratio: 1
Other Ratio: 1
Spur Tooth Count: 44
Pinion Tooth Count: 15
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: 2.93 : 1
Total Ratio: 9.70256 : 1
Tire Circumference (inches): 18.06 inches (458.83 mm)
Total Motor Speed: 42550 RPM
Vehicle Speed: 75.02 mph (120.51 km/h)
Effective KV Value: 2300
KT constant: 0.59 oz-in/A
Motor Torque: Amperage not specified...
Final Torque: Amperage not specified...
Final Power: Amperage not specified...


At the moment I'm considdering to move down to 4S, because with 5S this is just supidly fast, at least according to the calculator. Normally I really like stupidly fast and powerfull things but in this case I would prefer if it was driveable :whistle:

Arent you going to have a gearbox in it?

I think he was planning on a center diff/ slipperential setup. That being the case pro diffs would be better yeah- 44t spur is about the biggest you can fit though before you have to start trimming into the x-braces for clearance.

Yap, neil is right!
Since the slipperential won't fit (46T as smallest spur is too big), I'm going to use a centerdiff with a 44T.

Short update, Mike just got the list and hopefully knows what to do considering the CD-mount.
Can't tell you how excited I am!!! :yipi:

Hello again everyone!
Since my packet arrived in Germany this morning and is currently processed by customs (evil bloodsuckers!:whip:), I thought about a few things I still haven't figured out concerning the g-maxx.

1. I read that the 3605 servosaver/steering needs modification to fit into the 3606 e-maxx. But I don't understand what exactly I have to do. Furthermore I don't know if its necessary to do this modification when the parts are used in a G3-chassis.

2. What oil should I use in the diffs? Since I've never built an RC-car form scratch, I have abolutely no idea what oil is needed. Only for the CD I got an idea: 300k or 500k. Iirc 500k results in a more or less completely locked CD, I think I will use 300k oil as I want the CD to do it's job.
But on the front and rear diffs: absolutely no idea :neutral:

That's it for now but I'm pretty sure there are more questions to come:whistle:

Are you using hybrid diffs? I'd do 7k front 3k rear...

If using stock diff - I used to put 30k in F and R

This was for a Revo but similar for a max...

No, I'm using the HB lightning pro diffs, what do you mean with hybrid diffs? diffs for the hybrid bulkheads or what?

Hybrid - I meant full 1/8 scale diffs - go with 7 and 3...

Ok, and why the more viscous in the front?
What's the effect of this? Just asking, as I said I have absolutely no experience in these terms...

Here you go....

http://rc-monster.com/forum/showthread.php?t=5050

ah ok, I guess it's 30k and not 300k in the middle then...
and 7k in the front and 3k in the rear for the beginning.
thank's for the, very usefull, link by the way!

however, question No. 1 remains...

Q1 = A: I think the worst you'll have to do is just a little shimming, since the stock steering mech sits on the stock grey plastic front skid, and that has built in posts/round lumpy things for the posts to locate into/onto. If you go with an aftermarket skid set, then you may need to shim the posts or look for aftermarket ones- zillions on ebay so you wont have issues finding them.

Sorry, I still don't understand. Where would I have to place the shims? And why would I need any of them? I mounted the 3905-steering in the G3-chassis without any problems. No wheels and no servo attched to it yet, but it moves/turns smothly. Sorry, I just don't get what the problem is.

edit: the packet seams to have cleared the bloodsuckers office at 6.40pm local time. with any luck the packet is ariving on monday. seems like I have to hurry getting the diff-oils in time after all...

You said you werent sure of the 3905 steering assembly fitting the G3 chassis without modification, right? I said you may need to shim the posts a little (at the top or bottom) to remove any slack, since the 3905 front skid has mouldings on it to remove any slack, where as the G3 skids are just plain metal with no such mouldings (have a look at the exploded views on the traxxas website).

If you managed to fit the steering to your chassis without any problems, then you needn't have worried or asked about it in the first place- ask for help as issues arrize normally, unless you are certain you are going to run into problems, in which case someone is likely to have a solution (emaxx has been around for so long any and all eventualities are pretty much covered) :smile:

What? No! I only said that I read about necessary modifications, but didn't know what there would have to be done and haven't encountered any problems while assembling (except that I stripped another one of those bulls**t armorplated gorilla hex screws).
That's why I asked what there would have to be done, as I don't know how important these modifications are. And there is a difference if parts run smoothly when you move them with your fingers, or if they work while put under full stress.

Anyways, if there are points not quite clear to me, I tend to ask before I get out for the first run an everything breaks :wink:

Meh, you worry too much. :lol:

Well, it was your Emaxx FAQ which gave me that idea :whip:


:wink:

All lies, dont believe him! :lol:

I do mention that theres some slop in the stock 3905 setup (when its used in the 3905 truck), but I make no mention of modification needed to fit it to the GorillaMaxx chassis. Its always possible you may need to tweak the linkages depending on the exact posistion of the servos, or the length of the horns, but, I reckon you've been sniffing too many marker pens again... ....or I have... :wink:

I do need to update the info in there though, traxxas have improved the design a little, and no I know that the steering fits the gorillamaxx without issue, I can state that in their too :yipi:

Not so sure about the "I can" part...
If I recall correctly there is this little issue of you being banned from you favourite of all rc-forums? :angel:

I :lol: in the face of a ban... I can however state it in my FAQ though on my website, seeing as the nice moderator folks over at numpty-central deleted my FAQs there (cant think why :whistle: ).