New to the CRT.5 have some questions - RC-Monster Forums

Snipin_Willy · 10:22 PM

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:

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.

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

BrianG · 08.12.2008, 10:44 PM

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.

Snipin_Willy · 11:03 PM

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

RCShocker · 08.12.2008, 11:42 PM

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.

lincpimp · 08.13.2008, 12:02 AM

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...

Snipin_Willy · 02:19 PM

Quote:

Originally Posted by lincpimp

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

that thing really flys.

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?

Now all I'll be missing is a motor and a battery; MM is already in the mail.

Snipin_Willy · 08.13.2008, 11:24 PM

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?

08.15.2008, 04:07 PM

You could dremel the wheel to give it some clearance.

Snipin_Willy · 01:09 AM

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

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

New pic

kulangflow · 08.21.2008, 11:11 AM

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.

, 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!

Snipin_Willy · 08.27.2008, 10:03 PM

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?

jnev · 08.27.2008, 10:23 PM

I actually just recently bought a Neu 1509/1.5y for my CRT.5.

Haven't gotten a chance to solder up the connectors and such, but soon enough I'll get a chance to test it.

Snipin_Willy · 09.10.2008, 09:00 PM

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

Arct1k · 09.10.2008, 09:51 PM

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

jnev · 09.10.2008, 10:53 PM

Quote:

Originally Posted by Snipin_Willy

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