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BrianG · **Update -** 01.06.2009, 11:42 PM

I had placed the CRT.5 for sale but there were no takers, so I figured I would redesign it.

First off, there were several goals I wanted to achieve:

Address the motor/ESC heat issues. Some people like the Mamba Max combo, but it got too hot for me, even geared low (46/12). Obviously, top speed was crap and things were still a bit warm. So, I went with a Medusa 36-50-3300, MM ESC, DE BEC, and 3s lipo. On 4s with all the settings turned down, this will easily flip the truck on its lid, yet stays quite cool.
Reduce weight. I cut a lot of extra material from the motor mount, redesigned the battery tray so there was no bottom layer, and some other minor areas.
Lower center of gravity. This version still has the ESC over the CD, but this time, I lowered the ESC shelf by around 12mm. Not a huge deal, but it looks better. The receiver is much lower as well.
Come up with a better battery tray. My old one would sometimes throw the pack if I crashed hard enough because there was nothing to keep the bottom of the pack in place and would slide out. The new tray is similar in design, but longer, deeper, and the velcro is routed differently. Also, I started heating the aluminum with a torch before bending and that decrease stress cracks tremendously (the old tray had strain marks and stress cracks).
Come up with a solution to always breaking bodies. This was annoying. I don't like prepping and painting bodies to begin with, and the first time out, the body would crack right in the front fenders right where that little cut out for the upper arm is. I believe this was caused by the combination of poor driving, less material at that spot, and the leverage due to body post position. Well, I made new body post mounts that 1) raise the body by ~7mm, 2) spread the front mounts apart by 10mm total, and 3) move the body posts more towards the windshield. Even with my taped body, it seems MUCH more sturdy when I push down on the shell.
Do something with the steering servo wire. It is VERY close to the CD and routing is a PITA. So, I modded the CF servo brace and routed the wire under it and up. Much cleaner.
Replace the CD fluid. This should have been done out of the box. The factory uses just enough to lube the diffs and even that is super thin. Due to my driving style, I opted for 5k in front/back and 120k in the center (yes, 120k). I love how that handles. At the same time, I noticed that the outdrives move in and out by 1mm. So, I added one shim (6x14mm from Ofna Hyper) to the gear inside the cup (as opposed to the one on the spur/bevel gear). Not only did this help that extra play, it helps tighten the outdrives from moving up and down in the diff "sleeve".

Now for some pics:

The new battery tray. It's hard to see, but I JB-Welded the chassis openings to keep rocks and stuff from hitting the lipo. Then, I added a layer of lexan to further shield the pack. The hole in the tray is to access the tray mounting screw:

And some of the typical pics. Don't mind the crappy electrical tape on the motor - that's temporary:

	(#415)
BrianG RC-Monster Admin Offline Posts: 14,609 Join Date: Nov 2005 Location: Des Moines, IA	Update - 01.06.2009, 11:42 PM I had placed the CRT.5 for sale but there were no takers, so I figured I would redesign it. First off, there were several goals I wanted to achieve: Address the motor/ESC heat issues. Some people like the Mamba Max combo, but it got too hot for me, even geared low (46/12). Obviously, top speed was crap and things were still a bit warm. So, I went with a Medusa 36-50-3300, MM ESC, DE BEC, and 3s lipo. On 4s with all the settings turned down, this will easily flip the truck on its lid, yet stays quite cool. Reduce weight. I cut a lot of extra material from the motor mount, redesigned the battery tray so there was no bottom layer, and some other minor areas. Lower center of gravity. This version still has the ESC over the CD, but this time, I lowered the ESC shelf by around 12mm. Not a huge deal, but it looks better. The receiver is much lower as well. Come up with a better battery tray. My old one would sometimes throw the pack if I crashed hard enough because there was nothing to keep the bottom of the pack in place and would slide out. The new tray is similar in design, but longer, deeper, and the velcro is routed differently. Also, I started heating the aluminum with a torch before bending and that decrease stress cracks tremendously (the old tray had strain marks and stress cracks). Come up with a solution to always breaking bodies. This was annoying. I don't like prepping and painting bodies to begin with, and the first time out, the body would crack right in the front fenders right where that little cut out for the upper arm is. I believe this was caused by the combination of poor driving, less material at that spot, and the leverage due to body post position. Well, I made new body post mounts that 1) raise the body by ~7mm, 2) spread the front mounts apart by 10mm total, and 3) move the body posts more towards the windshield. Even with my taped body, it seems MUCH more sturdy when I push down on the shell. Do something with the steering servo wire. It is VERY close to the CD and routing is a PITA. So, I modded the CF servo brace and routed the wire under it and up. Much cleaner. Replace the CD fluid. This should have been done out of the box. The factory uses just enough to lube the diffs and even that is super thin. Due to my driving style, I opted for 5k in front/back and 120k in the center (yes, 120k). I love how that handles. At the same time, I noticed that the outdrives move in and out by 1mm. So, I added one shim (6x14mm from Ofna Hyper) to the gear inside the cup (as opposed to the one on the spur/bevel gear). Not only did this help that extra play, it helps tighten the outdrives from moving up and down in the diff "sleeve". Now for some pics: The new battery tray. It's hard to see, but I JB-Welded the chassis openings to keep rocks and stuff from hitting the lipo. Then, I added a layer of lexan to further shield the pack. The hole in the tray is to access the tray mounting screw: And some of the typical pics. Don't mind the crappy electrical tape on the motor - that's temporary: