CRT.5 conversion Need advice
 

I should be getting my CRT.5 roller soon and will convert it over to brushless power. I will be using a Mamba Max with a MM 5700 motor and a Maxamp 3s lipo. My question is should I go for a 5000mah or an 6000mah lipo? I want to keep the as truggy light as possible because it is pretty small, but is the extra 1000mah worth the extra 100oz? The 5000mah 3S is 345grams and the 6000mah is 443grams.

what packs are you looking at?

I run the maxamps 3s5000 on my crt .5 with the ofna extended chassis - it fits very nicely on its side.

This is the build thread with photo's.

http://www.rc-monster.com/forum/showthread.php?t=9036

rgds

Serum, looking at Maxamps 5000 or 6000mah 3S lipo packs.

Arct1k, yeah I am kind of leaning towards the 5000mah pack. Runtime is secondary to performance and the ligther 5000mah pack will be less weight for the CRT.5 to pull around.

Just want to verify that there is no performance (power) difference between the 5000 and 6000mah packs, just more runtime with the 6000mah pack, right?

The system you are planning on using will be too much for a crt.5 and probably run very hot. If you are going to use a MM & 5700 then 2S would be a much better choice. If you really want to use a MM system on 3S then the 4600 motor would be a better choice.

My crt.5 runs a Novak GTB & 6.5 on 2S. With truck tires (3.8" dia) it goes about 40mph and easily clears the 25ft triple at my local indoor track that does not have much of a run in.

If you really want 3S in the crt.5 then look for a 2700 to 3000 kv motor and run a larger pinion to get the top speed you want.

Go-Ride, I am still leaning towards getting a 3s lipo but I do have a couple of Maxamps 2s lipo packs that I will try first with the MM 7700 and 5700 motors.

The maxamps 5000 packs deliver more punch than the 6000's. Their 6000 packs don't hold up their voltage too well on a high load.

CRT .5 with extended chassis is a must. I'm running a Velenion (3500) with a MM Controller and a 2S-5000 and it runs great (not overpowered). I have run a 3S-5000 and its insanely fast. Stock Spur and mod1 18T pinion.

I'm looking for an easily removable wheelie bar for street use. Anyone found one? (pics)

You could ask swami to make you one without the mount holes drilled - you could then drill out to the rear chassis diff mounts....

http://www.swami-rc.com/WheelieBar.htm

CRT.5 Brushless Truggy
 

This is my soon to be finished crt.5 it has the extended chassis with a Nemesis 7L brushless motor. I have a Mamba Max ESC and a 3s lipo battery,The battery tray is bolted in 3 spots using existing chassis holes.The battery has velcro on the tray to hold it firmly inplace in addition to the tekno straps.I bought a piece of 4mm carbonfiber plate to fabricate a ESC and receiver mount to go on top of the center diff mount.

http://img251.imageshack.us/img251/6...2686zr8.th.jpg


http://img251.imageshack.us/img251/8...2682db5.th.jpg

Looks nice but personally I'd stick a piece of lexan down the side of the battery...

I wouldn't like to see a metal spur and lipo connect!

I agree with the spur gear barrier, but I think the CRT.5 motor mount has a "bulg" on the side of it that helps keep things from contacting the spur gear. It would hit the motor mount before the gear, but for saftys sake I would still put something in there myself.

Sweet looking build though. Wheres the ESC?

I am going to put the esc on top of the center diff.I will be fabricating a carbon fiber plate to replace the center diff top plate it will be big enouigh for the esc and hang over the back of the diff.I will use a carbon fiber plate on the side of the battery pack.

Thanks for the replies and info. So far I have mounted the motor. I made and mounted a battery tray as well. Waiting for my extended chassis before I continue. I designed the battery tray to mount using the exisiting holes so the brushless parts can be removed and the truggy can be converted back nitro if desired. Here are some pictures of the project so far.


http://i142.photobucket.com/albums/r...413/roller.jpg
Rolling chassis with motor mounted.

http://i142.photobucket.com/albums/r...13/trayraw.jpg
Starting on battery tray

http://i142.photobucket.com/albums/r.../trayparts.jpg
Fisnished tray

http://i142.photobucket.com/albums/r...13/washers.jpg
Adding the strap

http://i142.photobucket.com/albums/r...3/trayback.jpg
Back of tray showing strap mounting

http://i142.photobucket.com/albums/r...rk413/foam.jpg
Some EVA foam padding

http://i142.photobucket.com/albums/r...3/sidedone.jpg
Finished tray with battery mounted.

http://i142.photobucket.com/albums/r...3/bodyon-1.jpg
With the battery mounted on it's side the body easily clears.

looks nice. but i ran a 5700 for a while, and it was get`n a bit hotter on my 3s lipo. so i ended up get`n a 8L and will hopefully be get`n to try it out this weekend on the track

I tried the BCE chassis also.I thought the servo was a little to close to the end of my 7l fiegao.Nice battery harness.

What pinion are you using with the 5700 on 3S? Even with a 12T that would be a 50+mph car with the stock tires. I can see why that would run hot.

Let us know what you think of the 8L vs the 5700. I'm mostly interested in handling differences. I'd like to go 8L or 9L on 3S for the punch, but I don't want to loose the smooth handling my GTB/6.5 has at my local indoor track.

I was running the 4600 on 2s and the ESC and motor got too warm for my liking even geared 46/12. IMO, this truck needs a real "S" size motor, or an L...

Hey Brian, would you give me some examples of a "real S size" motor. Would my Novak 6.5 be a real S size? It runs great in my truck at the local indoor clay track, but it I'd like to get more punch for the jumps. From what I've read an L can seems a bit much, on the track, for the 5 pound crt.5, but if I could find something better than my Novak 6.5 I'd consider it.

Thanks for the help!

The Feigao S is a real S motor. For one thing, the MM motors are 6mm shorter than an S can. Second, the MM motors have shorter windings (internally) to make room for the connection between the windings and the noodle wires that go outside the can. So, the MM motor is more like a sub-S motor if there were such a thing.

I really don't know the length of the Novaks, but they have the sensor area, so that takes away some room for the windings. IIRC, they's probably midway between an S and an L coil-wise. Also, I believe the Novaks use a smaller 380 size rotor (anyone want to confirm?). The 6.5 could probably benefit from higher voltage like 3s or 4s, so if you are running just 2s that may be the cause of the lack of punch you are experiencing. You could also be overgeared to compensate for lack of rpm...

Thanks for the info. I'm running 46/12 gearing with the 6.5 and smallish 2.2 truck tires (3.8"). I tried a 46/13 for kicks and lost more punch, plus it was still gaining speed at the end of the straight. Maybe I need to try an 11 or 10 tooth pinion. I don't think the Novak 6.5 could handle 3S. It is rated at 6400kv. The GTB/6.5 I have is not the HV system.

I'd like to get a MM system and a S or L can Feigao to run on 3S, but I'm not sure if it will really be an upgrade (at the track) from my Novak system.

Updates:

Still waiting for servo saver arm and extended chassis, but I added a center plate and mounted the ESC and RX to it. It's hard to tell, but the plate is bent at both ends so the ESC and RX sits lower for more clearence and better cg placement.

http://i142.photobucket.com/albums/r...ark413/003.jpg

http://i142.photobucket.com/albums/r...k413/002-2.jpg

http://i142.photobucket.com/albums/r...k413/001-2.jpg

GO-RIDE: i went sold my 5700 a while back, and got me an ammo brushless 2600kv motor. had it geared up to 19t and it ran pretty well. the track that i normally run on is rather harsh in terms of really able to get on the throttle, but it isnt bad w/ that ammo brushless. but if the weather gets better and i take it to the track i'll tell ya how that 8L works for me. but i went w/ the ofna ext. chassis and some truck size bowties instead of the stock buggy one, and man talk bout such better handling, although i sorta stoled riceman's idea for the tire and wheels from this post http://www.rc-monster.com/forum/showthread.php?t=9200 something bout the low profile wheels and tires just look awesome.

sHARK413: just curious where did u get the piece of alu to make ur top plate and battery holder?

dark96, the battery tray is 6061 aluminum which I got fron Onlinemetals.com and the top plate is a softer alloy (non-weight bearing piece, easier to bend) that I got at the local hardware store. Onlinemetals is pretty cool, because you can get almost any type of metal (aluminum 2024, 6061, 7075, titanium, brass, steel, plastic) in all kinds of shapes and no minimum order plus they cut to any size.

Just wondering as an alternative to the prolines - Would these work? They look like the wide rims and low profile 2.8s.

http://www3.towerhobbies.com/cgi-bin...&I=LXKMJ2&P=FR

Yep, jato rear wheels and tires work great on the crt.5. I used a set of the on road anaconda tires on my first crt.5. They are about as tall as the truck wheels and tires, IIRC.

ya just like lincpimp says. the rears will work. i went the w/ bowties cause the work well on the track i run on.

Look what showed up today. The Jammin extended chassis kit and a servo saver parts kit arrived, now I can complete the project. I compared the stock chassis, a BCE chassis and the Jammin extended chassis, check the pictures. The BCE is just a tad longer than stock the Extended chassis is 15mm or so longer and wider. I have a Jammin CRT.5 wheel next to my Kyosho ST-RR 1/8 truggy wheel.

http://i142.photobucket.com/albums/r...13/parts-1.jpg
Parts are here.

http://i142.photobucket.com/albums/r...hassisside.jpg
Stock, BCE and Jammin extended

http://i142.photobucket.com/albums/r...assisontop.jpg
Extended chassis is longer and wider

http://i142.photobucket.com/albums/r...k413/tires.jpg
Jammin CRT.5 wheel next to my Kyosho ST-RR truggy wheel.

Wow that Jammin extended chassis is quite a bit wider as well. Probably could almost lay the lipos don flat on the chassis for a lower cog.

How much heavier is the Jammin extended vs the stock Jammin chassis?

jhautz, the chassis is wider but when laying down the battery it still hangs over the side of the chassis. Which means the body won't fit without bowing out and makes it vuneralble to a side impact hit.

I weighted the chassis and here is what my trusty digital postal scale came up with:

Stock chassis (bare) = 5 oz
BCE chassis (bare) = 5.8 oz
Extended Jammin chassis (bare) = 7.2 oz

yeah i liked the ofna ext chassis compaired to the original. all you need now Shark are some 2.2 truck tires as opposed to the 2.2 buggy tires :D

Nice work so far. thanks for the side by side picks of the chassis. I was debating on a bce or ofna ext chassis (since the rcm chassis rules out my custom bodies). Looks like I'll get the ofna.

Shark,

Thanks for getting that info. Very rare that someone has all 3 chassis stripped like that and easily weighed for comparison.


Anyone know the weight of the RCM chassis?

I was finally able to get everything together. Took all the parts off the standard chassis and added them to the extended chassis. Installed the battery tray, ESC and rx. Added some foam padding for the battery tray, a rear skid plate, new servo saver arm, Hitec 5645MG servo, linkage, etc. Now if it would only stop raining I could take it for a spin.

Current configuration:
Mamba Max, 7700 motor, FASST rx, extended chassis, 13T harden steel pinion, 46T steel spur, Proline CF, Maxamps 2s2p lipo.


http://i142.photobucket.com/albums/r...413/side-1.jpg
Battery tray without the foam padding
http://i142.photobucket.com/albums/r...413/foam-1.jpg
EVA foam 1/4 on the bottom, 1/8 on the side.
http://i142.photobucket.com/albums/r...k413/top-7.jpg
Top view
http://i142.photobucket.com/albums/r...3/bottom-3.jpg
Bottom, notice the battery tray uses the stock motor mount holes.
http://i142.photobucket.com/albums/r...13/battery.jpg
With a 2s2p lipo strapped in.

Looks like a slick setup. Make sure you get some vid when you get to run it.

I'm also interested to heare how it does on the 7700kv motor. That sounds like it could run a little on the hot side.

Looking nice Shark, looking very nice. you get to run it yet?

Nah it's been raining here since Wednesday and it is supposed to rain thru the weekend. Bummer.

Yeah I am curious to see how hot the 7700 on 2s2p will get. I have a 5700 I want to try as well. Most people have been saying it is going to melt in the CRT.5, I ran that combo in my Kyosho Lazer 4wd buggy but it is about a pound lighter. The smallest pinion I have is 12t and the largest is 14t, so not much in gearing choices. Stay tuned.

if ya end up deciding that its getting to hot, another option for a motor u can use is this on. I believe its close to the Feigao 9L, and not a bad price either if u dont wanna spend the cash for Feigao right off the bat.

dark96, the specs on that motor look promising and you can't beat that price. Thanks for the info.

Ammo's are pretty nice motors, and tower's prices are insanely low for a few of them. For some reason the larger motors are cheaper than the smaller ones.

Shark, you don't happen to live in Nor Cal do you? Its been raining here almost all week. If you don't care about being cold/wet, and having to clean your truck after, just balloon everything. I keep a waterproof basher around for days like this. Just in case I feel brave enough to take on the weather.