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The Official Thunder Tiger MT4 G3 thread

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Old 01-01-2013, 01:57 AM
  #126
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Default RE: The Official Thunder Tiger MT4 G3 thread

Hi

I'm a futur owner of a MT4 G3 an want to know something.
- At this thime is it a good price to buy the MT4 G3 new for 407 € including shipping, do you know a better price in Europe ? I'm live in France.
- Wich battery is better to take ? one 4s lipo or 2x2s. I want good power and long autonomy.
- Can you give me some example of battery correct for the size to put in the MT4 in example in hobbyking store ?

Thanks for your help.
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Old 01-01-2013, 02:31 AM
  #127
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Default RE: The Official Thunder Tiger MT4 G3 thread


Quote:
ORIGINAL: speedeur

Hi

I'm a futur owner of a MT4 G3 an want to know something.
- At this thime is it a good price to buy the MT4 G3 new for 407 € including shipping, do you know a better price in Europe ? I'm live in France.
I don't know what type of prices are common in Europe
- Wich battery is better to take ? one 4s lipo or 2x2s. I want good power and long autonomy.
A 4s and 2x2s have the same power and runtime if they are the same mah. The only difference is that if one cell goes bad in a 4s, you have to throw the whole battery away, if one cell goes bad in one of your 2x2s batteries, you only have to throw one of them, so its cheaper to replace. 4s batteries are normally cheaper than getting 2x2s. However if you have a RC that can use 2s batteries, you can share the 2x2s batteries with them.
- Can you give me some example of battery correct for the size to put in the MT4 in example in hobbyking store ?
http://www.hobbyking.com/hobbyking/s...Lipo_Pack.html
Something like 2 138x46x25mm batteries with built in bullets like these will fit perfectly in a mt4

Thanks for your help.
Hi and welcome to RCU! My answers are in red above
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Old 01-01-2013, 03:15 AM
  #128
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Default RE: The Official Thunder Tiger MT4 G3 thread

Hi speedeur, I'm in Germany, and just paid €425 including shipping, which was (and still is afaik) the best price going. Normal is €450-480 + shipping.

For batteries, I'm not all that thrilled with hobbyking's offerings. None have Deans, so require buying extra plugs and soldering, and most of the 5s and big 4s lipos are borderline too big, requiring dremmeling, etc.. For size btw, I think you need to be within 143(or so)x45x45mm to be safe. Anyway, I've been searching a lot recently for 5s options, and it kind of seems you can get other brands for €10-20 more, with Deans, ready to go, etc.. I guess eventually I'll get a new, decent soldering iron, and try out some HK lipos, but for now I just want to charge up and go..
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Old 01-01-2013, 08:06 AM
  #129
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Default RE: The Official Thunder Tiger MT4 G3 thread

Just ran a pack through with the 14T pinion. Wasn't as impressed as I thought I would be by the speed. Overall though it feels a bit more balanced. Still wheelies the same, and there is a tad more speed. More of a nice mid range than the crazy top speed I was expecting though.

Is 5s with a 14T a no-no? I still don't understand why some people say that, if you go up in power, you need to go down on the pinion...

Also, somehow or other my reverse is acting up.. Sometimes I feel like I have to hold it down, sometimes it engages right away, sometimes not at all.. Any ideas?
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Old 01-01-2013, 04:32 PM
  #130
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Default RE: The Official Thunder Tiger MT4 G3 thread

If the center diff is still unloading power to the front wheels adding a couple teeth to the pinion may not make that noticable of a difference in speed. If you change from say 4s to 5s you do have to gear down. Yes you are adding power with more voltage and should use less amps in the process lowering temps. But when you add voltage you are also adding rpm to the motor and more top speed, if you utilize this new found top speed you will increase load on the motor raising temps. I'd advise using a temp gun on the motor to get a baseline and then anytime you change gearing or cell count.

Reverse in sensorless brushless can be tricky to get used to. Reverse is not instant and often is setup where the Tx must be in neutral position for a second before you engage reverse. Some esc's also get confused if the vehicle is rolling and you try to engage reverse.

Glad to hear you're enjoying the darkside a bit though.

Edit: Ran some numbers through the gearing calculator and going from a 12T pinion to a 14T should give you an additional 6mph. Going to 5s should give you more of the top end speed you expected but will probably require center diff tuning to keep it from unloading.
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Old 01-01-2013, 11:49 PM
  #131
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Default RE: The Official Thunder Tiger MT4 G3 thread

The center diff is unloading the extra rpm to the front hersavage, you need thicker oil to make use of the extra power. Try something 100K or more, some I know are using 300k even 500k

My mt4 has developed a strange noise under hard acceleration and I just can't seem to find out what it is. I've inspected all diffs and everything looks good. My hub carrier bearings are quite rough, could this be the source of the noise? My wheel hex'es are a bit stripped too. I really hope its those bearings as I have a new set on the way.
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Old 01-02-2013, 12:29 AM
  #132
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Default RE: The Official Thunder Tiger MT4 G3 thread

No idea on the sound.. It's weird checking the drivetrain on these electric things, because the motor itself is so notchy at standstill.

I do think with the 14t pinion it was faster on pavement. But on dirt, yeah, I guess something is being unloaded somewhere.

I have 100.000 on the way, so will try that. Couldn't find anything else. I also have a leaky center diff. Not sure, but almost looks like it's leaking at both ends - behind the spur gear, then at the forward-facing cup...

Also, the lipo I ran yesterday was reading 3.7 on cells 1, 3, and 4, but cell 2 was reading like 2.9 again when it cut out. Took it off, and cell 2 immediately started climbing up again. And on the charger it went up quickly.. Took a long time for the cells to balance again. Performance seems good with it though..
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Old 01-02-2013, 02:03 AM
  #133
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Default RE: The Official Thunder Tiger MT4 G3 thread


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ORIGINAL: HerrSavage

No idea on the sound.. It's weird checking the drivetrain on these electric things, because the motor itself is so notchy at standstill.

I do think with the 14t pinion it was faster on pavement. But on dirt, yeah, I guess something is being unloaded somewhere.

I have 100.000 on the way, so will try that. Couldn't find anything else. I also have a leaky center diff. Not sure, but almost looks like it's leaking at both ends - behind the spur gear, then at the forward-facing cup...

Also, the lipo I ran yesterday was reading 3.7 on cells 1, 3, and 4, but cell 2 was reading like 2.9 again when it cut out. Took it off, and cell 2 immediately started climbing up again. And on the charger it went up quickly.. Took a long time for the cells to balance again. Performance seems good with it though..
If you want to check the smoothness of your drivetrain, remove the pinion gear

My center diff leaked a bit with the stock grease but no longer leaks with the 100k, too thick to get out I guess

My batteries all read 3.5v after the voltage cutoff kicks in, which is set at 3.0v per cell. I think you should try raising your lvc to 3.2v per cell so that cell that finishes at 3.9 might finish above 3.0v

You don't know how happy I am going to be when that ugly sound is gone.


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Old 01-02-2013, 02:22 AM
  #134
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Default RE: The Official Thunder Tiger MT4 G3 thread

The manual says the default cut-off setting is 3.4 I think. I guess that's right, because it's about the average of my four cells.
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Old 01-02-2013, 05:40 AM
  #135
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Default RE: The Official Thunder Tiger MT4 G3 thread

Well, took about five packs to get sick of the obviously too-weak-for-the-job steering servo...

So the DM-1 had to fess it up:



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Old 01-02-2013, 09:32 AM
  #136
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Default RE: The Official Thunder Tiger MT4 G3 thread

A point to remember is Lipos are like any battery and voltage will drop under load. So if the cutoff is set at 3.0 voltage at rest after a run will be more like 3.2-3.5 volts. With my packs on my LST the cutoff is 3.2 and my packs will be at about 3.7 after a run. Id double check the cutoff is at 3.4 to help keep the weaker cell above 3.0 volts. Btw 3.7-3.8 is a good storage voltage.

It does sound like your one pack does have a weak cell. Lipos generally don't come back with running like a NiMh will either. But I wouldn't worry about it too much since the voltage rises so quick when charging. Just make sure the pack doesn't get too hot or look like its swelling. I have a pack with a cell like that and it's been fine for over a year, the voltage difference isn't as great as yours but it's been consistently low. I also don't usually charge all the way to 4.20, a spread of 4.18-4.20 is good enough for me, its something I've also done for years without issue on all my packs.
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Old 01-02-2013, 09:40 AM
  #137
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Default RE: The Official Thunder Tiger MT4 G3 thread

'K.. Will keep an eye on it. Also, my lipo checker and charger give pretty different cell readings, one after the other..
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Old 01-02-2013, 01:24 PM
  #138
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Default RE: The Official Thunder Tiger MT4 G3 thread

When trying to get a reading on the charger, make sure you're not charging or balancing, just viewing voltages. You're not alone in getting different readings, my voltmeter (multimeter, not a lipo checker) reads different than my Hyperion charger too. Not by much, around .05v in most cases, but it is different. Funny part is its dead on at 4.20 but lower than there's a difference.
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Old 01-02-2013, 01:42 PM
  #139
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Default RE: The Official Thunder Tiger MT4 G3 thread

Cool.. I haven't figured out how to check the voltage without setting it to "lipo balance" - ie charge.., yet.

BTW, if it's cool out, can I run 5s with a 14T?.. Just a question which gets here first - the 100,000 wt. diff oil, or the 5s lipo...
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Old 01-02-2013, 02:46 PM
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Default RE: The Official Thunder Tiger MT4 G3 thread


Quote:
ORIGINAL: HerrSavage

Cool.. I haven't figured out how to check the voltage without setting it to "lipo balance" - ie charge.., yet.

BTW, if it's cool out, can I run 5s with a 14T?.. Just a question which gets here first - the 100,000 wt. diff oil, or the 5s lipo...
You can run it, just keep an eye on the temperature of the motor and esc

BTW, I would aim for at least 20kg on the servo, I have a Savox 1256tg, it performs great. At 6v, it produces 20kg of torque and 0.15 speed.
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Old 01-02-2013, 02:56 PM
  #141
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Default RE: The Official Thunder Tiger MT4 G3 thread

The Hobbico CS170 is a rebadged Hitec 5955 - 24 kilos @ 6V..
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Old 01-02-2013, 05:39 PM
  #142
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Default RE: The Official Thunder Tiger MT4 G3 thread


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ORIGINAL: HerrSavage

The Hobbico CS170 is a rebadged Hitec 5955 - 24 kilos @ 6V..
In that case, you have all the torque needed to turn those huge wheels

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Old 01-02-2013, 06:33 PM
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Default RE: The Official Thunder Tiger MT4 G3 thread

If I have all the parameters right 14t pinion on 5s would be almost 60mph. I would have to say that the motor would heat up too much with extended running, speed runs with cool down time after a couple passes would be ok though. Running shorter and lighter truggy tires than stock would lower the load on the motor and the speed a little lowering temps. 12t on 5s would be 50mph and considering the size of the stock motor I'd say it would be more ideal for the truck. I don't have any experience with the MT4 G3 I'm just going by experience in other 1/8 scales and similar motors.
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Old 01-02-2013, 07:28 PM
  #144
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Default RE: The Official Thunder Tiger MT4 G3 thread

Adding thicker center diff oil will make a huge difference on the acceleration and top speed and should be done before considering a larger pinion. The stock center diff grease is way to thin that any extra power is just going to be sent to the front wheels.

Jang form URC received his mt4 with very light grease/oil (would barely wheelie on 4s). He said it hit 39mph on 4s and a mere 46mph on 6s. With thick oil, you can easily hit 55mph+ I believe.


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Old 01-02-2013, 09:34 PM
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Default RE: The Official Thunder Tiger MT4 G3 thread

To prove your point I ran some more numbers through the gear calc to get some more "theoretical top speeds" based on voltage, Kv, tire diameter etc. These numbers don't take into account diffs unloading, aero drag, traction etc though. Jangs review also stated his 6s top speed was off due to the center diff unloading and traction becoming an issue because of it. 6s with the 12t pinion theoretically would be 60mph on 6s, so 55mph (maybe more) should be achievable in the real world with the right setup. 6s with 14t pinion is 70mph. All calcations assume 3.7 volts per cell (nominal voltage) not 4.2 fully charged, stock tires without much ballooning factored in so the numbers are probably a little low. They're also just calculations not recommendations, check those temps with gearing and cell count changes especially when your trying to push a truck past 45mph.
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Old 01-02-2013, 10:57 PM
  #146
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Default RE: The Official Thunder Tiger MT4 G3 thread

60mph!!.. [X(]

I do want to see that at some point, but right now 50 would be cool.. I'm more keen on speed than big bashing for the moment...
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Old 01-02-2013, 11:49 PM
  #147
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Default RE: The Official Thunder Tiger MT4 G3 thread


Quote:
ORIGINAL: HerrSavage

60mph!!.. [X(]

I do want to see that at some point, but right now 50 would be cool.. I'm more keen on speed than big bashing for the moment...
I am sure a 12t pinion and 6s in a mt4 will hit 60mph if you have very thick stuff in the center diff with all 4 tires balooning

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Old 01-03-2013, 07:31 AM
  #148
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Default RE: The Official Thunder Tiger MT4 G3 thread

This lipo I ordered - Xcel 18.5v/5s 35C 4200 - puts out a constant 147A - if I understand all this correctly.. Is that OK?
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Old 01-03-2013, 07:57 AM
  #149
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Default RE: The Official Thunder Tiger MT4 G3 thread

Its a little on the weak side (in other words, as well as having a short life, it will struggle to provide what is being asked of it on acceleration, affecting performance but not massively), but it'll do. It wasn't a 'terrible' choice, it's just an 'acceptable' battery for the job. Don't expect it to last in a 1/8th MT though is all I'm saying.

I like 200A plus for 1/8th, and even they will swell eventually. 5000mah@60C (300A) is the point at which any 'more' battery is not providing any tangible benefit and such a battery would be unlikely to ever swell from normal use.
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Old 01-03-2013, 09:31 AM
  #150
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Default RE: The Official Thunder Tiger MT4 G3 thread

Well a guy on a German forum was saying another 5s lipo I was looking at, with only 30C(also 4200), would be pushing it for the ESC..

It's very hard to find 5s and 6s lipos with anything over 4000mah that will fit the tray. And I'm not going to start strapping things on top with zipties or anything anytime soon.

This lipo btw fits the bill in that it fits right in, and comes with Deans.. I'm glad to pay €15ish more at this stage of the game than hobbyking stuff to not have to solder...

Next thing will be to figure out how to program the ESC for 5s.. Kind of annoying that you constantly have to reprogram between different cell counts..

Very annoyed at the mo - my package just arrived which should have had 100,000 wt oil in it - but it was fxxxing afterrun oil.. So, no 100,000 wt in the diff this weekend to see if it really helps performance with the 4s and 14T pinion.. 100,000 wt for some reason is not easy to find here.. And nothing higher than that..

And btw, I get plenty good runtime with these 3700 4s Reedy packs. I'm fine with them - longer than I would get on a nitro tank - probably even two. And for big bashing you'd probably break something before finishing a bigger battery with 5000 or whatever(assuming you can find one to fit).. I'm more interested in speed at the moment anyway.. So they don't need huge mah's. More interested in power, but doubtful about going straight to 6s since quite a few people say it's overkill and will just wreak excessive carnage on the truck... Baby steps..
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