nitro to brushless
 

hi guys! first, I'm from Quebec... and english is not my main language so.... be kind :)


I'm about to start a brushless conversion... The truck is a 4wd crono prima.... and I really don't know where to start... I need advice/help... I have remove any nitro stuff in the car.... Now I surely need to calculate the ratio to see what kind of motor I will put in..... For the cell, I think I will go with a123 cell.... I want a cell that is safe, I had some bad experience with li-po in plane...

So, If someone could help me out to start... some advice on motor and controller.... Thanks

Julien

welcome to the forums!

u got a link to that truck? i have never heard of it

im assuming its 8th scale? or 10th? either way a mamba max with a ubec, or a quark monster pro, those are good cells also!

and motor depends on how big the truck is

Welcome to the forums!

First, I would read some general info. Start with the third link in my sig. Then, you can play with some of the speed/motor calculators in the first link in my sig. I know you have some electrical experience since you had a plane, but the car world is a little different and this information may help answer some basic questions.

Then, some info would be handy like: weight of the truck (with nothing in it), your budget, what you already have, desired speed/power/runtime, and maybe a link to a site where we can see what you are working with.

BTW: What was the bad experience you had with lipos?

Sorry, I look for a link and find nothing... this car come from italy. The distributor is from Quebec too, 45 minute from here... This is my 4th truck (got an associate rc10gt, mrc and traxxas stampede with a novak ss5800 brushless system) This buggy seem to be pretty strong...


some info about the buggy...

weight without nitro things : Little over 5 lbs
budget : I don't care unless I have what I pay for...
Speed : I want to be in the high 30 or low 40 mph... maybe a little more... but for now, I'm pretty happy with my novak ss5800 stampede.... I want it to be faster than my stampede but not overkilled... I don't want to break it each time I run it :) I just bash...

Runtime : around 10-15 minutes would be pretty good

So now... Do I just need to put a motor/esc with good gearing and go... or do I need to modify something?


Additionnal info : take 3 completes turns of differential to make a complete wheel turn...
Spur : 51

was a rossi .21 powering it


will try to post picture this week...


BrianG : was lucky... just a "puff" lipo...was near home so I put it in salt water and leave it there for a day... I'm a little scared by lipo.... I use it anyway with good care :)

some pic of the crono prima... so, do I need to change the spur or I can find a pignon to fit? I need help... god, help me!

uarghhh, your demands are very reasonable. Your buggy looks like it would be a straight forward conversion. It's hard to tell from the pics, but is that a metal or plastic spur gear? If it is plastic, you are good. All you'll need to do is fabricate a motor mount and use a mod1 pinion gear, assuming that your spur gear is mod1 (module 1) pitch. If the spur is metal, you will need one of two things. Either a hardened steel pinion gear, or a Kyosho plastic spur gear. The Kyosho plastic spur is the best option. It also fits many different diff cups. If it doesn't fit yours, you could try the diffs from Sportwerks, Ofna, and Hotbodies to name a few.

As for your electronics, it really depends on your budget. If you want the best, I'd say go for a Quark Monster Pro with a Neu 1515 1Y (for speed) or a 1515 2.5D for something a bit less crazy. If you are going with a 5S Lipo pack, I'd go for the 2.5D. If you are going with the 4S lipo pack, I'd probably go with the 1Y motor. I don't own the 1Y, but I do own motors of similar ratings and it would be fast without being stupid. If you want something less expensive, I would go with a Mamba Max speed controller and Feigao 8XL motor. Geared at about 14/46, it should give you what you are asking for.

For 10-15 minutes of runtime, just go with a 5000mAh battery pack.

As for the motor mount, if you have access to some basic power tools, like a drill, dremel, hacksaw, jig saw, or any combo of these, you could probably make a mount.

http://i154.photobucket.com/albums/s...r/DSCF0091.jpg

http://i154.photobucket.com/albums/s...r/DSCF0090.jpg

This was the first mount that I ever made. I used 3/16" thick 6061 aluminum. It is strong and easy to work. I now use 1/4" 7075, but it is a lot harder to work with. 3/16" thick 7075 would be a good compromise.

All this mount is, is an aluminum plate with holes cut into it and it is bolted to the center diff mount. It is very rigid and survived many crashes.

Thanks a lot guys for your reply.. I have think about it... I want a combo that I can run on 7.2 volts or 14.4... so, when I bash with my 5 years old kid, I want to have nearly the same power he got on the stampede (novak ss5800). And when I ran with friends who got nitro buggy, put 2 packs (14.4 volts) and dust them :) Will this work for the Mamba and feigao 8xl?And I think for now I will run on 7.2 volts nicd pack to keep it simple...Give me your opignon about this...


By the way... I don't know if it's the good place to talk about this but, compare to A novak equivalent system, is there advantage to buy mamba/feigao instead of novak? Thanks a lot :)

Wow thats a strang brake set up I have never seen the disk on the front of the center diff? Anyway here is a link to some great info for your conversion that i think BrianG was refering to.
http://scriptasylum.com/rc_speed/

Check out the motor selector if you dont know your diff ratios just use the preset 1/8th scale buggy ratio's there's also alot of other usefull info there.

I dont think your going to find a bolt in mount anywhere for that car making one is not to hard as long as you can cut the slots for the motor if you dont feel comfortable doing this take your center diff and motor with a picture of a brushless mount or car with a brushless conversion to a local machine shop and they can fab one up for you.

7.2v to 14.4v is a big difference to find a motor that will work well on both voltages? it's basicly going to be 1/2 as fast i guess you might fry a single 6 cell pack?

Looks like you already have a plastic spur? if so your lucky thats been a problem area with some conversions. :)

Yeah; that spur looks plastic to me;

you are planning on using the mamba-maxx controller, feigao 8XL and a 14.4 volts pack; That's perfect.

you can get the MOD1 pinions from Mike, your spur looks like MOD1 to me. perhaps you can shoot a close-up pic of that spur?

yeah, it's a plastic spur.. 51 thoots.

ok for the 7.2 to 14.4... I will just go easy on the trottle :)



can someone explain me the difference between feigaeo 8xl, 7xl... x... xl... :)

The number refers to the number of turns in the motor windings.
Lower turn count=higher kv=faster per volt=pulls more current for a given setup.
Higher turn count=lower kv=slower per volt=pulls less current setup.
The "XL" is basically the motor length.

WOW that looks like the spur everyone is waiting for for there CRT.5 conversions? Is that a stock Crono spur gear?

It looks like Mod1 pitch, which would make it kinda large in diameter and wouldn't work with the stock diff mounts...

Yeah 51 is to big for the CRT.5 but it could be another option for full size truggy's?

Possibly - only if you have an extra 2.5mm of chassis clearance compared to a 46T spur...