Drivetrain limitations for big power? 4S+

[fastmachine]

For those of you who have upgraded to a big block motor and a better ESC like the Mamba Max Pro, are you running into drivetrain issues with 4S+ power? I don't mind spending money on an upgraded motor & ESC to handle big power, but I don't want to be replacing other drivetrain parts all the time like the differentials, etc.. I don't want to have to be constantly replacing parts because it's just too much power. I understand more speed equals bigger crashes, but I know that going in.

So how are the drivetrains holding up to big power? If they're not, what aftermarket solutions are available? Should I just stop at 3S? I want a reliable rocket.

[jimbo74]

i have run 4s on my merv, witht he 380 vxl motor... it is stupid fast, too much for me to control, wheelies too much, and the tires seem to like to spin themselves apart......

[WesselDoubleT]

Well if you really want to run 4s, then I would definitely recommend the getting the Traxxas cvds

[jimbo74]

Well if you really want to run 4s, then I would definitely recommend the getting the Traxxas cvds

i agree.... when i first started runnign 4s, i kept popping the yokes on my rear driveshafts.... i was also running a rear spool, but the problem continued after i swapped the diff out


the traxxas cvds 7151x are the best..... they are the most expensive, but worth it

[Petertje60]

There are limits to where you can push a car. I think the 380 motor with 3s LiPo or 2 NiMHs in series is sort of the max what you should use.

[daravelli]

For those of you who have upgraded to a big block motor and a better ESC like the Mamba Max Pro, are you running into drivetrain issues with 4S+ power? I don't mind spending money on an upgraded motor & ESC to handle big power, but I don't want to be replacing other drivetrain parts all the time like the differentials, etc.. I don't want to have to be constantly replacing parts because it's just too much power. I understand more speed equals bigger crashes, but I know that going in.

So how are the drivetrains holding up to big power? If they're not, what aftermarket solutions are available? Should I just stop at 3S? I want a reliable rocket.

I'm running a mamba max pro with a castle 5700kv on 3s (5700 is limited to 3s) with 31/50 gearing. I have a steel center drive shaft installed and have front and rears ready for when the stock shafts break. So far though, I haven't broken anything. I've had some nasty wrecks too!

[KILO-DELTA]

simple solution is set the punch control low on your mamba and it will be fine. It just lets the motor spin up slower if you pull the throttle right back instead of giving it full power and snapping your driveline or stripping a diff.

[fastmachine]

So here's my list so far.

T-Bone Chassis Brace (ordered)
Traxxas Center Differential (ordered)
Integy Center Steel Driveshaft (already on)
Traxxas Constant Velocity Driveshafts (will order if they break)
Larger Wheelie Bar Wheels & Tires

These foam tires look pretty good.
http://www3.towerhobbies.com/cgi-bin...&I=LXVCB0&P=ML

What's the largest pinion gear and smallest spur gear that fit the stock setup?

[_jono_]

You might wanna get 100k diff oil and 50k diff oil. Because the center diff will be junk other wise. traxxas just lubes things up instead of filling it up. And 50k sends alot of power to the front. mix 50k and 100k together and its perfect. Dont alot of testing with the center diffs. Its perfect at 75k

[BigGrump]

Using 4S is just fine. I took my center diff out, threw away the T-Bone chassis brace and calculated the gearing to the speed I wanted to atttain. Diffs hold up to the use. I also don't like things breaking all the time either, so I try to moderate my driving style so the parts can hold.

Absolutely worst thing you can do is up the battery voltage without re calculating what gearing is necessary. You can almost never go to more voltage with existing gearing. It simply is too great of speed increase. Just think, if you were going 50 mph on 3S lipos, would you really expect to have the Merv go almost 70 mph with 4S? Absolutely not, but if you re-geared to get 55 to 60 mph out if it, you could handle the Merv and get all the fun of increased "spirit" from it.

Most of the time, I read people changing battery cell levels, then find problems with out of control Mervs and tires turning way too fast. This is all a direct result of not calculating gearing for targeted speed. Learn how to do that and the Merv will begin to hold up, refuse to learn how and you can either continue expensive repairs, or you will limit yourself from some of the most fun the Merv can offer.

Dennis

[fastmachine]

Why did you remove the center diff and chassis brace?

[dskobli]

I'll let him speak for himself but I've been reading that the chassis brace transfers stress to other parts. That's pretty much the case with any aluminum parts though. I run RPM parts on all my cars. they're the lightest, strongest, and lifrtime guarenteed. Just wish they'd come out with some a-arms for the slash's! And many don't like the center diff due to a loss of wheelie popping capabilities and a loss of overall top speed. I also heard someone say the center diff makes for an almost undrivable truck offroad which doesn't make much sense to me but I did read it on a forum? I haven't ran either of these things but actually just ordered a center diff for my vxl mini slash since it doesn't really pop to many wheelies anyways unless I'm going like 30 and crack the throttle. Then it will pull the front wheels up and half of the time right over backwards. I've seen vids of people running the merv with thicker oil in the center diff and they have no problem wheelying or flipping. I run 3s and 4s on my stock slash all the time with no drivetrain upgrades at all and haven't broken anything besides axle carriers (upgraded to the RPm's and no more problems here). I know better then to beat on my cars by cracking the throttle and slamming them into reverse and so-on from running my mamba powered rusty.

[BigGrump]

Why did you remove the center diff and chassis brace?

If you are trying for all the speed and performance 4S Lipos provide, you are driving on a hard surface like the street or parking lot. I found the center diff hurt handling and when there was a wheelie, th front wheels would naturally speed up, and when the front end returned to the ground they never hit at exactly the same time, and the fast front wheels would pull the Merv into another direction from what it was going. Ruined any fun or control.

The T-bone chassis brace only added weight I did not want and made the Merv less peppy, and because of the extra weight, more stress went to the drive line to compensate. I used the T bone for a long time, and when I took it off it felt like a relief. Also, there is easier access to the drive line etc, with it not there. Maybe crashing around off road it may be OK, but for me on road it was not.

Dennis