New to the CRT.5 have some questions
 

I bought a used crt.5 that had been converted to brushless last weekend however I didn't get any of the powerplant gear with it. After doing alot of reading and searching on the web for e-crt.5 conversions and mods this place is by far the most useful that I've found. With that being said I need some input.
This is what I've started with:
http://i69.photobucket.com/albums/i4...n/IMG_0283.jpg

It was a CRT.5 RTR, now it has a blue groove kit for a brushless setup. Very different from what I've seen on this forum. Motor mounts where the original nitro motor was on a beefy aluminum mount. It mounts up higher, but closer to the center line of the chassis. Which is OK for now, I have an RCM motor mount for it as well, just no battery box or things to go with it. I'm going with the usual MM esc with CC bec. I can readily get a feigao 9L motor. But I'm stuck on what to do for batteries. :neutral:
I've wanted to go with A123 M1 cells by assembling my own packs using the M1 cells from dewalt 36v tools, but would a 2s2p be enough to run a 9L? I've had great luck running the smaller A123 cells from black and decker VPX packs in my vendetta, they're able to push alot of current which allows me to gear it higher and still have the punch for take-off.
Are LiPo's the only choice or is it possible to fit enough M1 cells to make the truggy get up and go reasonably well?

Edit: I'll be running 2.2's if it makes much difference

The trouble with nitro-mount schemes is that any chassis flex changes the mesh. I don't know why it never seems to be an issue with the nitro setup (power maybe?). The mounts that Mike makes places the motor mounting plane on the same spot as the CD so any flex does not affect mesh. Even with the chassis braces, you do get flex (try it and you'll see). If this concerns you, you might want to consider making a top plate that goes from the front diff to rear diff and also connects to the CD. From experience, this makes it VERY sturdy. Don't know if this will be an issue, but something to think about. The motor mount itself may help stiffen the chassis, as well as whatever battery tray you use.

The 9L is a good choice for the motor. The CRT.5 is small, but it is kinda heavy for its size, especially once you mount all the goodies on there.

For batteries, A123 cells are good, but they are heavy in something so small. You might find yourself upgrading the shocks to compensate.

I'm looking for 10 minute run times, so super high capacity isn't really that necessary and I figure 4600mah is enough even if drawing more current for taller gearing.
Edit: and the bluegroove motor mount is good piece of metal and it held up to a novak 6.5 for racing without ruining any pinions.

Like I said, I have an RCU mount, but I expect it would cost me more for the extra parts to use it. If chassis flex becomes a problem I'll switch, but I have to have a power plant and battery first:smile:

That's exactly the way my CRT.5 looks last weekend. I bought it used as a roller from a friend in our r/c club. It also has the BlueGroove Conversion. I have been disecting the CRT.5 threads as well and noticed how the other conversion's appear quite different from the BGC.

I am running a Velineon VXL system in mine for now so I could run my NimH packs. I will switch to my spare MM esc once I get a 2s Lipo. I've noticed a handful of guys running the MambaMax esc with the Velineon 3500KV motor.

From your picture that could easily be my CRT.5 if I didnt know better. Wow!!!! I want to run 2.2 wheels also. Cant find anything that doesnt look TOO BIG just yet. Hopefully some of the other's "in the know" will chime in and help us both.

With a 9l motor, run 4s1p a123 cells. Should give you colse to 10mins, and will not be too heavy. Make a few packs and you can play for a while. Gearing should be around 14t pinion, stock spur for the 9l on 4s a123. That will give you speed close to 40mph...

The perfect answer!
I kinda wanna buy 1 dewalt pack and make a 3s and 4s pack, change the gears around a bit and see what works with 2.2's. Playing for a while shouldn't be a big deal, if I have a pack for the CRT charging I can always run my brushless detta ST :mdr: that thing really flys.:lol:

Edits:I was going to wait till this weekend to order the parts from tower to get this rig fixed up right, but I figured why wait? :party: Now all I'll be missing is a motor and a battery; MM is already in the mail.:yipi:

Mamba Max came in today. That's one less part!
I have a bunch of 2.2 t2/t3/t4 wheels (pro-line velocity) that don't use a hex, but rather just a pin (1mm shorter than the CRT standard pins). But the inside spoke barely hit the suspension arms as they turn, is there a way to shim them out a bit to get them to clear or should I shave a bit off the suspension arms where they hit?

You could dremel the wheel to give it some clearance.

I thought about that, but then I'd be creating weak spots in the rim and possibly throwing off the balance. I decided just to get some RPM rims and use some oven cleaner to take off the chrome.
BTW: 2.2 Gladiator tires look MEAN on this thing:diablo:

I got the majority of the rest of my parts in today. CC BEC, tires, rims, connectors, Jato shock mod parts, and 2 pinions from robinson racing (14t and 16t mod 1 hardened steel). All that is left is a battery and a motor. I hope to have it running next weekend for a race against some other CRT.5's :yipi:

New pic
http://i69.photobucket.com/albums/i4...n/IMG_0302.jpg

Hey there, Willy! I'm glad you found RC-M and decided to keep your CRT.5 brushless. (He was considering converting it back to Nitro.:gasp:, so I advised him to come here first and check out the killer brushless conversions.)

Have a blast with that thing and welcome to RC-M!

I'm falling behind in my project. After thinking it over...and over and over and over, I'm beginning to consider buying a Neu. Less hassle in the long run and the motor would be big enough to use in other projects if I so desired. I've only seen 1 person on the forum with a Neu in their CRT.5 and I can't seem to find the link. How would a 1509 1.5Y run this little monster I'm trying to create, and what would be a good battery option?

I actually just recently bought a Neu 1509/1.5y for my CRT.5. :yes: Haven't gotten a chance to solder up the connectors and such, but soon enough I'll get a chance to test it. :wink:

Hey Jnev, did you ever get a chance to try out that Neu in the crt.5?

I would look at a medusa 50mm - High quality and plenty for a .5

I should be able to try it this weekend... I know its been a while. The final part I need should be coming by the weekend, and then I'll install everything in to the truck. I will post an update in this topic about my thoughts on it. :yes:

Well even with the lack of input I've decided to step up to the plate and go with the Neu 1509 1.5y. I hope it gets here soon!

Now to get a dewalt 36v battery and tear it down and rebuild it into some useable packs. I plan on attaching balancing leads to the cells, is there a particular balance that works with A123 cells through a charging port on a battery charger (IE inline balancer, [charger]->[balancer]->[battery])?

I got a chance to install the motor and get all the connections on the truck done. However, it was dark, so I only got some limited testing done in the garage. Looks to be very powerful, and start ups were as smooth a brushed set up. :wink: One problem: I just found out (after testing in the garage) that the front drive shaft is bent. I think it happened with my old motor while running it a while back. So I guess I won't be able to test it this weekend after all, as I ordered a drive shaft tonight and am expecting it next Monday. I think you'll be very happy with the motor though. :yes:

Okay, I need to replace the turn buckle end balls, does anyone have a link to the replacement part, or a better/upgrade for them? I attempted to use some end balls from my 1/10 nitro truck that never gets used any more but they are too big. A tower hobbies link would be great because I have to order some other stuff through them anyways.

Edit: also, an aluminum servo arm would also be nice.

jnev, what battery are you using to run that 1509 1.5y? I'm looking at the dimensions of a 4s A123 pack and it seems it might be a bit large.

He has a flight power 4350 evo lite pack, 18C

Fitting A123 cells in a .5 would for sure be hard to do, but you could probably stand them up, and they would fit fine. But would be heavy...

Its actually the 4370mah pack, but close enough. :wink:

BOR - when are you gong to show us your sweet new build!? :wink:

I have changed it around so much. Pm me if you want to know lol, but its going to be extremely different then all the other crt.5's! And no, its not the out runner .5, im going to have my buddy do that to his, its cheaper for him:mdr:

After some careful thought and consideration, I've decided to stay the coarse and go for A123 cell project. Initial cost will be more, but additional packs and life time of the packs might make it worth it. Plus, don't have to worry about discharging too far, over charging, fire, puffing.

4370 is a big pack! Is that a 3s or 4s?

Its a evo lite, 18C, so its super light! Im sure he gets some crazy runtime! It is 4s

Sounds good! Make sure you get some pics going!

man i want one of these, will my 1512 fit of is it way to big for the .5?

A 1509 size motor is plenty for a CRT.5. A 1512 would be more suited for 1/8 buggy. As BOR said, the pack is 4s and is very light. And yes run times are awesome. :yes: It is probably a little more now, but when I weighed it with the Lehner motor in it, it was sub 5 pounds. :wink:

thats cool, i figured it would be alittle to much, im looking at a 1509 and i am really trying to decide how big of a pack i need

maybe someone can help

i rember someone was running a 5 cell 2500mah pack and had about 15min of run time, thats all i really need is 15min

can some one post a link?

Some guys have enough had good luck with the 1509 in 1/8 buggies :surprised:.

Does anyone know what happened to the rear endbell covers for the Neu 1500's? I can't seem to find them.

I think mike removed them as he's working on a new design - They became impossible to make with the new nue endbell arrangement

Sure hope he gets them out soon cuz I'm gonna need one!

Update: With all the stuff I just got in the mail this afternoon it feels like Christmas morning!
I was expecting to only get my Neu today, but my 80w weller showed up as well as my Dewalt 36v pack!

After $45 in a123 cells wasted I've determined I'm getting pre-made packs next time rather than building my own.

Wheres the pics?

I want to see the NEU in there!

Me too....I am running a Medusa 3300kv in mine w/a mm esc on 2or 3s, not sure which one yet.

Give it time...patience is key :wink:. I've almost got the balancing leads wired up!

Well I just found a glorious screw up....seems my LiFe charger only charges up to....3s:cry: So I'm looking for something to charge them. Looks like I'll be waiting another week before I get this thing rolling :tongue:


O
M
G

What have I created?!?!

I finished the battery pack and balanced it. Then found out my charger wont do 4s and I was...more than a little upset. But I wanted to try out my monster being that I could now bring it to life. The cells came precharged at 3.3v per cell which is enough to get a feel for the motor. Plugged everything in and too it out into the dark streets to see just how much power it had.

I "blipped" the throttle, not even to 30% and the front wheel hopped OFF THE GROUND. That seems like some serious punch. More to come. I WILL have my new charger by friday... even if I have to drive to the local shop and buy it there. I can't wait!!!


More to come:
http://i69.photobucket.com/albums/i4...n/IMG_0355.jpg

Ok, I ordered an FMA Cellpro 10s so I should be set for a long time for a battery charger.

I ran it some more to get an idea of what the temps were going to be like. The ESC is heating up much faster than I expected. Batteries and motor barely warm to the touch.
Did some searching and found that maybe my center diff fluid is too loose. Running it in about 100 foot stretches the front tires ballooned a lot more than the rears. Not sure what fluid the previous owned used in the center diff so I'll have to go out and get some.

Would a loose center diff cause the ESC to heat faster than the motor?

When the ESC is hot, it actually usually means that you are overgeared. But the ballooning of the front wheels would cause the motor to actually get hot because it is spinning so fast (high RPM's) with no resistance. I am running 10K weight oil in the center, as I like the feel of the car with the thicker oil, but most run anywhere from 5K to 10K in their BL CRT.5's.

I can't see why at 16T pinion and stock spur would be over gearing. A low KV motor like the Neu 1.5Y with 13.2v with ample current ability should not be geared lower...should it?