simplechamp's Jammin X2 carbon on-road GT - Page 5 - RC-Monster Forums

snellemin · 03.14.2011, 07:03 PM

Any chance of you putting the ESC in between the battery's somehow? ESC looks kinda out of place on that sweet setup.

el tomaso · 03.15.2011, 03:41 AM

What type of motor are you throwing in there? Sensored tekin maybe?

Sweet ride!

Thomas G

simplechamp · 03.15.2011, 05:39 AM

I can flip the center diff brace around if wanted, but for now I'm going to leave it as is. I agree it does look a little wonky but the wiring works out very well this way. And I already shortened the RX wire on the ESC LOL!

Motor will be sensored, a Viper or Tekin. I was going to run 4S with a 2650kv, but I just picked up some 3S 3200mah hardcases, so now I'm going to run 6S with a 1700kv.

snellemin · 03.15.2011, 02:45 PM

6s on 1700kv. I'm guessing the Cheat mode will not be used then.

I got some parts to start on my jammin truggy conversion. It will be my platform to try out the cheat mode on 4s with a Tekin 1400kv motor. I know it works in my Rustler with 30 degrees Cheat. But the Jammin is a whole lot heavier.

simplechamp · 03:10 PM

I'm a little stuck with the gearing options with the Ofna cam motor mount. The max pinion with a 46T spur is 16T. Even with 1700kv on 6S that only makes for about 47mph. I thought that would be fine but I was told I'd need about 50-55mph to keep up with nitro GTs. Is this right? I'd like to use lower kv but I'll have to ditch the mount (although I did just buy a Nexx8 that it can go in). I do have the RCM mount still, just need to straighten it out, maybe it will allow a larger pinion.

What is the max RPM you can use CHEAT with?

I made a CF center diff spacer today, which is needed because the diff is flipped around. It covers the stock spur clearance hole, and allows clearance for the spur on the opposite side. It raises the center diff by 3mm.

snellemin · 03:33 PM

Max rpm with cheat? Dunno. Max timing for the motor was 30 degrees. Motor wasn't hot after a pack. But it was cool to see the Rustler pop a wheelie when the CHEAT kicked in. That was something the LRP 2500kv motor couldn't do. I'll mount the Rally body on the Rustler for more weight and play with the settings some more. I'll probably slap on the heavy beadlocks for more resistance and see what the ESC does.

simplechamp · 03.15.2011, 03:55 PM

What I'm mainly getting at is you said for 6S and 1700kv motor you assumed I wouldn't use CHEAT. Why is that?

snellemin · 03.17.2011, 02:19 AM

Finally had some time to myself and did some measuring for you. I bench tested the 1400kv Tekin motor with the MMpro on 4s. Seeing the data I believe you can pull of the 6s with Cheat enable.
I used my Rustler with 58/25 gearing with the wheels suspended. I can only see the rpm in live mode and for some reason can't get the rpm readings to save.

4s Regular 10 degrees timing was a bit more than 22000 rpm.
4s CHEAT 30 degrees timing was a bit more than 33000 rpm.
Cheat 50 degrees timing on 2s was a bit more than 33000rpm. This was pulling 70+ amps and got hot really fast.

So I looks like I went from 1400kv to 2000kv with 30 degrees timing. Pretty cool.

simplechamp · 10:45 PM

Excellent info, this is good news. I switched my mount back to the RCM mount so I can fit a larger pinion (Ofna cam mount will go in the Nexx8 I just got). With that and CHEAT mode I can get away with a lower kv motor. Gotta play with the speed calc a bit more now, but I think a 1400kv will do the trick.

I was comparing my 2S 5000mah hardcases and the new (to me) 3S 3200mah hardcases, and they both weigh 277g. Pairing them in series the 4S setup would be 74Wh and the 6S would be 71Wh. So the 6S should provide similar runtimes to the 4S, or even reduce current draw a bit to squeak out a little extra time.

EDIT: Looks like with the 6S and 1400kv setup I can gear 46/20 and get about 48mph. Then I can dial in a little CHEAT to hopefully get to around 50-55mph. Should shape up to be a pretty decent setup. It's about time I jump on the higher voltage, lower kv bandwagon.

simplechamp · 05.04.2011, 01:17 AM

Not much to update. Still waiting on a motor. Been waiting for the Viper sensored to be released, but I think it's time to just go for a Tekin.

Leaving for Orlando next week, so I'll probably pick up a motor at one of the LHS down there and head out to the Kissimmee track for some testing. I really need to get this thing on the road!

simplechamp · 05.25.2011, 08:36 PM

I was all fired up after work today to get the GT finally out on the road for some testing. I bought a Tekin motor on RC Tech that showed up today and also stopped by the LHS to pick up a new SR300 RX. The motor is great, but the RX was a dud right out of the box. Called Horizon and they were kind enough to send out a new one right away, no questions asked. They told me to toss the other one, but I'm going to tinker with it a bit to see if it's fixable.

The guys at the LHS said they are going to run at Kissimmee Raceway on June 5. I'm going to do a bit of road testing beforehand and then hopefully get it dialed in on the track.

Here's a few pics of everything RTR minus the RX.

el tomaso · 05.26.2011, 12:47 AM

A work of art! Every piece is chosen for perfection and I really hope you'll have lots of fun with it

Thomas G

brainanator · 05.26.2011, 01:03 AM

daaaaaaaaaaaaaaaang
looks really sharp!

simplechamp · 11:25 PM

I weighed it today and it turned out a little heavier than I thought, right about 3550g RTR. Not a pig by any means, but I thought with all the CF it would come in a bit lighter. The only parts I know of that are heavier than stock are the alloy diff cups and hardened steel internals. Maybe the tires are heavier than off-road buggy tires since the rubber is thick and dense. Guess I'd have to weigh them separately.

I pulled an RX out of one of my other vehicles because I couldn't wait any longer. Just zipped up and down the street about 5 times, and I learned:

A) As expected, this thing absolutely screams!

B) The sensored operation is awesome (currently set to smart sense mode). No cogging at all even rolling forward at a snails pace. I was pretty amazed at how slow it could actually go, definitely glad I went sensored.

Next up will be digging out the EagleTree to find out what kind of power this thing makes. I really wanted to go for a 6S lower kv setup, but I found a good deal on the Tekin 2650kv. Beside that, I have many pairs of 2S packs, only one pair of 3S. Even if the runtimes are a bit shorter I'll be able to run more without waiting on packs to charge. Eventually when it's time for new packs I'm definitely going for 6S though.

Thomas · 05.27.2011, 05:46 AM

Nice build, I like the appearance and the layout. Do these rallygame bodies require a longer wheelbase than 1/8 offroad or are they the same?

Personally, I would place the batteries as close to the centerline as possible, to minimize roll inertia. If you switch the location of the RC and ESC, the COG will be lower, also reducing roll (better handling). Then the power wires look like they could be shortened a lot (less power loss). Further, I would check if the shock standoffs are stiff enough. With the shocks this far from the shock tower, they see a lot of bending load. Shorter standoffs or some with a wider base would reduce compliance.