jwalk33

Hi,

I just bought XTM Xterminator 2 at my LHS and was given the MRPRipper ST for free. I am wondering if it can handle a mild brushless system, if so what do you recommend? I want to keep this ST but I want to make it faster and possibly add a few upgrades to the over all design and toughness.

Me and a few friends do straight line/drag racing, and I understand that this ST is not going to handle very powerful ESCs and mortors, but I do want to go as fast as possible without many issues. I'll probably try some different gears also.

Any suggestions for faster speed and more durability will be greatly appreciated

Thanks,
Jwalk33

Foxy

Due to the limited complexity of 2wd drivetrains and the fact the gearbox is sealed, if properly shimmed and greased, you'll probably find it can take any motor you like. A 550 might be pushing its capabilities, but I bet you can put a fast 540 in there if you wanted. If you wanted to always run cool, use a 4000kv motor, if speed is your need, you can go all the way up to about 8000kv (9000+ are really considered on road only) if your ESC can handle it.

Given the nature of the model, I would probably say get a 5000kv and then play with gearing.

This for example... http://www.hobbypartz.com/ezrun-35a-9t-3650-motor.html

jwalk33

Hi and thanks for quick reply Foxy,

I haven't run electric in quite some time but I am a bit familiar with them. What exactly do you mean by "proper shimming", where do I need to put the shims?

Also, how much faster do you think the brushless setup that you suggested would make this ST? I'd hate to spend close to $100 bucks on this thing and its not much faster?


Jwalk33

Foxy

Even on the stock gearing this brushless set will make the car fast on a 2 cell lipo. Add a 3 cell and you'll be going ridiculously fast, but taking a risk with the speed controller. In either case, you can make the car faster at any time by changing the pinion gear for one with more teeth. You still need to be careful to make sure the motor isn't overheating, but I would think this combo would accept gearing for about 45mph on 2S lipo without giving you major heat issues. 45mph is fast enough for you, right? You can go faster if you want, but you'll have to let the motor cool sometimes.

Shimming by the way is the process of adding thin washers or 'shims' to the internal gears of a gearbox and differentials to reduce unwanted lateral play and movement.

jwalk33

what brushless set are you talking about?

jwalk33

Hi again,

Here is what I came up with for the Ripper ST upgrade possibilty, please let me know what you think/suggest?


Motor = Tacon 3200kv 36mm x 50 mm or the Tacon 3930kv

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Batteries = GENS ACE 5000mAh 40C 7.4V Hardcase Lipo Battery Pack or GENS ACE 5000mAh 20C 7.4V Hardcase Lipo Battery Pack

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ESC&&Motor = Hobbywing EZRUN-60A Brushless ESC For 1/12 1/10 Scale RC Car or the Hobbywing EZRUN Brushless System Combo B2 W/35A ESC and 9T4300KV 3650M brushless motor

Thanks,
Jwalk33

EXT2Rob

My Feedback: (1)

I HAVE that EZrun combo Foxy linked.  It's a great deal for the price.  If you go with 3s, the fan on the ESC needs to be replaced.  But if your Ripper is anything like my Evader, 3s would be a waste of money. WAY too much power for such a light 2wd car. Better to get 2s packs with a higher C-rating.  We started with Gens Ace 20C, then to 30C, and now 40C.  BIG jump in performance going from 30C to 40C!!  I have my Evader geared a little lower than stock (87/19 vs 88/20) and we just GPS'ed it's top speed as 38mph.  More than enough for off-road racing/bashing.  But it could be geared higher. Just get yourself an infra-red thermometer to monitor your motor temps. Don't let it get over 160F.

jwalk33

Hi Ex2Rob,

I will be running this car on road and would like to reach the greatest speeds possible, idealy 40-50 mph. I thought about what you mentioned last night and you're right, this is a very light weight ST. So 2S will be my best bet for this setup.

Do you have any motors/gearing suggestions that would be pretty fast with the EZRUN 35A ESC, I saw a video on youtube of a Tacon pushing a 1/8th scale 4wd SC truck really fast with one that I beieve was 3200kv. I'm thinking it would really make this thing Ripper ST fly.

Do you see any overheating issues with a motor like this and the EZRUN 35A ESC and different gearing? I saw a guy smoke his ESC because the motor was pulling too moch juice through it, this is why I would go with the 60A EZRUN ESC.


Thanks,
Jwalk33

jwalk33

Hi,

BKoz559

My Feedback: (3)

The 120A ESC won't overheat with those motors because they probably only draw up to 40-50amps tops. It's better suited for the 1/8 truggy you're planning for in the future anyway. In this case the motor is the limiting factor, as long as you use the recommended voltage for the motor. You might, however, have trouble mounting it because of its larger physical size as it may not fit as well as the smaller ESCs.

EXT2Rob

My Feedback: (1)

The EZrun system linked has a 4300kv motor, the same one Ihave. It will spin 1100rpm/volt faster than the 3200kv. If you're primarily running on-road, the higher kv motors would give you higher top speed, and since you wouldn't be dealing with off-road "drag", you could gear it a little higher without worrying too much. Still, I think anyone in RC should have an IR thermometer. It's just another way to monitor your system, nitro or electric. My buddy has the same system in his truck, but Ithink he has a couple more teeth on his pinion gear. He exceeded 40MPH. If you wanted to get closer to 50mph on 2s, you'd probably have to get a higher-kv motor. BTW, that 35A ESC has NEVER gotten hot, ever. Not even warm. If you end up getting that combo, and later, want to get a different motor (perhaps a higher-kv) just be sure the bullet connectors are compatable, that is, the same size. The ones on the EZrun are either 3.5mm or 4.0mm (can't remember off the top of me head). Castle, for instance, uses 5mm. Not sure what Tacon uses. Just pay attention. Have fun!

Rob

jwalk33

Hi,

BKoz559

My Feedback: (3)

The second system seems to have more programming options but, they're both 3000KV motors and the first package has a 45A ESC. That one might have a slight performance advantage but, it's negligable. You can apparently run 3 cell LiPo packs with either system so that will help you achieve your high speed.

EXT2Rob

My Feedback: (1)

Nah man, you want this one at least....
http://www.hobbypartz.com/ezrun-35a-9t-3650-motor.html
That;s the 4300kv motor/esc combo.  That one may get you to 50mph, geared right.  Or if ya got a little more scratch...
http://www.hobbypartz.com/07e-4-5t-3...-120a-lcd.html

That'll get ya there for sure, and you'd prolly never have to worry about motor temps.  But you'd better get at least 40C batteries, maybe 50C, for that 120A combo.

But that 35A system would do you fine for while you're getting a handle on the car again, and getting it dialed in.  HobbyPartz doesn't seem to have any single motors available higher than 4300kv at the moment.  But like I said, you could find a tacon with the same bullet connector size and a higher KV, later.

jwalk33

EZRun setup it is, thanks fellas.

jwalk33

Hi,

Whats a good 2s lipo for this setup, I would ask about 3s but but do you feel that will be too much power for the car?


Jwalk33

EXT2Rob

My Feedback: (1)

Drive-ability-wise, it would probably be too much.  But if yer just going to be making speed runs, a 3s pack would be possible PROVIDED you REPLACE the FAN with one that can handle 11V.  (I always thought it odd that HW would make an ESC capable of 3s, but put on a fan that ISN'T!  ***?)  For the kind of driving my buddy and I do with our Evaders, 3S would be a waste of money.  We're happier with a higher C-rated 2S.

jwalk33

What is some good all around chargers for lipos 2s to maybe 6s for a great price?



Thanks,
Jwalk33

Foxy

Look for the Thunder chargers at hobbypartz.com, the ac6 is a good choice if you need something cheap and effective that works off a wall outlet.

jwalk33

How about this http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1 ?

EXT2Rob

My Feedback: (1)

This will do ya better.  Doesn't require a big wall-wart power supply AND will charge your LiPos at SIX AMPS as compared to 5A. That will charge your 5000mah in less than a hour.
http://www.hobbypartz.com/73p-ac680-accharger.html

My buddy just got this charger and loves it.  So do I.

BTW, if you're new to LiPo batteries, be sure to charge them to a "storage" state (the charger has a storage mode).  LiPos like to "rest" at 3.86V/cell.  If you keep them charged fully all the time, it will shorten their life and capacity.

jwalk33

High EXT2Rob,

I alreadly ordered the other charger from Amazon, however after carefully reading the specs on the charger that I ordered I found that it says "Please do NOT use this charger with any pack that doesn't have a built-in protection circuit board/module (PCB/PCM)"


What exactly does this mean ? The battery that I ordered is this one : http://www.hobbyking.com/hobbyking/s...dProduct=16477

I will be ordering another battery that is 4000-5000 mAhs and want to make sure that its compatible with the charger. I ordered that battery because I was given about $160 of instore credit from an order that I cancled from hobbyking.



Thanks,
Jwalk33

Foxy

Charger and battery are fine, don't worry about that warning. I don't pretend to know exactly what it means, but I am sure that it either; doesn't apply to us, or our batteries fulfill the requirements, many people on Amazon have used it to charge standard lipo batteries like the one you've picked up and said its fine.

jwalk33

Ok thanks Foxy,



Jwalk33

jwalk33

Hi,

I about have evrything ordered for the MRP Ripper ST. The last thing that I need to get are pinion and spur gears. I believe the Ripper has 87T Spur and 17T pinion installed on it.

I orderd a 120A ESC, 9T 4370kv motor and 2200mAh 2S1P 45C lipo.

What I think I should've done was get a lower kv motor around 1500kv-2200kv small pinion and bigger spur. Wouldn't this give hi speeds while also reducing the most strain on the motor thus reducing heat issues, vs going with bigger pinion and smaller spur ?

I guess I can order a lower kv motor as described above as well as pinions and spurs.

What are you guys thoughts on this, maybe I tottaly screwed up here? I'm not looking for the most powerfulest/fastest bottom-end... more like a desent bottom end and fastest top end possible.

I saw a setup on youtube of a brushless duratrax evador with a 25/80 and 3S lipo get 50mph.

Here's a vid on youtube of one with 25/80 claiming 50mphhttp://www.youtube.com/watch?v=Lml_dwmhTQ8

Just need some good ideas/advice and this should set me on the correct target setup path.


Thanks,
Jwalk33