Ummmm.....I want to do this bad!
http://www.beatyourtruck.com/forum/showthread.php?53826-Hpi-MT2-Conversion
http://www.beatyourtruck.com/forum/showthread.php?53826-Hpi-MT2-Conversion
Jammin eCRT Pro RC build-up.
- Thread starter Thirdgen89GTA
- Start date
This dude kept the radio box which simplifies things like servo mounting.
http://www.beatyourtruck.com/forum/showthread.php?42343-MT2-18ss-Rock-Racer!
http://www.beatyourtruck.com/forum/showthread.php?42343-MT2-18ss-Rock-Racer!
Well, its 95% there! Getting really close now.
Things to do:
Things to do:
- Solder the Traxxas plugs onto the batteries and ESC.
- Make the Series and Parallel adapter harnesses.
- Find flat graphite stock to replace my ad-hoc ESC mounting system. Tray will extend from bulkhead to steering brace to mount ESC and Receiver.
- Drill holes in chassis and countersink them for battery tray mounting.
- Modify battery tray on motor side to shorten it. Its about 10mm too long and interferes with the pinion.
Motor is about 415 grams. Servo is 60 grams. ESC and Rec aren't listed but are featherlight so they don't count for much. We'll say 25grams for the ESC/Recv.
Each 3S pack is 442grams.
Front: 500grams.
Rear: 884grams
Each 3S battery pack is 442grams. Each 2S battery pack is 288grams.
With the 3S packs thats almost 900grams in the rear of the truck, nearly twice as much as whats in front.
I don't know how much the center diff weighs, but its smack dab in the middle so either way it doesn't affect things too much.
All told the ESC/Motor/Batteries come in near 3lbs on their own. Trucks weigh heavier than it used to be. Even with the blue hard springs which are 3.77lb/in" the truck barely comes up to bones level ride height. I am thinking of moving the shock position further upright to increase the effective spring rate. But that will also increase the damping and thats already too stiff I think. I was told to use 60wt because of how heavy it will be. But the rebound speed is horrible.
I am going to order the Team Associated springs. They go up to 5.07lb/in" which is probably too strong, but they have some middle of the road springs from what i have now.
I had to shim the center differential up so the spur would clear the chassis. I either need to grind away some metal on the chassis, or switch to the Jammin X2 diffs so I can use a standard 48t buggy spur and not the 62t behemoth that is the Jammin spur. I also have a concern that there may be to much angle on the CVDs now. If I clearence the chassis that will fix that.
I need to pick up some drill bits for my dremel and a countersink bit too.
Each 3S pack is 442grams.
Front: 500grams.
Rear: 884grams
Each 3S battery pack is 442grams. Each 2S battery pack is 288grams.
With the 3S packs thats almost 900grams in the rear of the truck, nearly twice as much as whats in front.
I don't know how much the center diff weighs, but its smack dab in the middle so either way it doesn't affect things too much.
All told the ESC/Motor/Batteries come in near 3lbs on their own. Trucks weigh heavier than it used to be. Even with the blue hard springs which are 3.77lb/in" the truck barely comes up to bones level ride height. I am thinking of moving the shock position further upright to increase the effective spring rate. But that will also increase the damping and thats already too stiff I think. I was told to use 60wt because of how heavy it will be. But the rebound speed is horrible.
I am going to order the Team Associated springs. They go up to 5.07lb/in" which is probably too strong, but they have some middle of the road springs from what i have now.
I had to shim the center differential up so the spur would clear the chassis. I either need to grind away some metal on the chassis, or switch to the Jammin X2 diffs so I can use a standard 48t buggy spur and not the 62t behemoth that is the Jammin spur. I also have a concern that there may be to much angle on the CVDs now. If I clearence the chassis that will fix that.
I need to pick up some drill bits for my dremel and a countersink bit too.
This is my jury rigged ESC mount. Its pretty wobbly and slightly too tall.
For its protection I'm also considering buying some decently thick piano wire and bending it into a rollbar to protect the ESC in case of a lid impact.
Moving to the X2 differential would lower the ESC by a good half inch too.
For its protection I'm also considering buying some decently thick piano wire and bending it into a rollbar to protect the ESC in case of a lid impact.
Moving to the X2 differential would lower the ESC by a good half inch too.
I didn't think the 3S packs would be that heavy. Looks like it will be balanced similarly to the Nitro version just with a more overall weight. It could not be any heaver than the 12 lb JTSuperMaxx I used to have.
clearance that chassis for sure.. the front center cvd is probably close to the limit does it bind at all? either way less angle on it the better. It will have a lot of rotational torque traveling through it.
60wt with stiffer springs would be alright. the stiffer springs will quicken the rebound anyhow. You'll have to do a lot of Test'n'Tune to get it dialed though. I bet just swapping form the 3s to the 2s will require a change in springs and shock weights at least in the rear. either way it should be a rocket!
clearance that chassis for sure.. the front center cvd is probably close to the limit does it bind at all? either way less angle on it the better. It will have a lot of rotational torque traveling through it.
60wt with stiffer springs would be alright. the stiffer springs will quicken the rebound anyhow. You'll have to do a lot of Test'n'Tune to get it dialed though. I bet just swapping form the 3s to the 2s will require a change in springs and shock weights at least in the rear. either way it should be a rocket!
It doesn't bind, its smooth rolling all the way. Because of the 62t spur its already at a higher angle than it should be, with the space even though its still smooth I'm concerned about the power the 6S setup is going to put through.
Based on the calculators out there, during peak acceleration the axles will be experiencing almost 10lbs/ft torque at 200amps. Which is entirely possible to see for a short time, such as acceleration from a stop. I've already dialed in the punch control to the middle setting. I figure start off with the punch settings so they limit initial throttle to reduce stress on the drivetrain.
At 160amps the system makes a little over 4Kw, or about 5.4hp. If it ever hits the batteries current rating of 200amps then it would be nearly 7hp and almost 5kilowatts. At 120amps the rated current of the ESC the system makes almost 4.1hp.
The old modded rossi 528xr couldn't come close to that on its best day and the torque off idle nowhere near what an electric system can do. So I'm concerned that the high angles of the CVDs will cause them to snap like twigs.
_________
I brought some parts in with me to weigh so I could get an idea of the differences between the two.
Electric Parts:
- 125g - ESC
- 425g - 2200kv motor
- 442g - (1) 3S battery
- 288g - (1) 2S battery
Nitro parts:
- 370g - Novarossi 528XR
- 115g - Jammin JP-2 pipe
- 55g - throttle servo
- 30g - fuel tank
So the electric parts come to 1,434g with the 3S, and 1,126g with the 2S packs.
The Nitro parts come in at 570g.
The electric setup with 3S is 1.9lbs heavier, and with the 2S its 1.22lbs heavier.
Thats actually not as bad as I thought it would be. I didn't weigh the brake parts because i figured the discs and pads would be negligible. I also forgot to bring in the engine mounts to weigh those. So its not actually as bad as I thought it would be.
Can I say FUCK YEA!!!
First off, the wiring isn't finished. My 60w soldering iron crapped out on me, and all I have is a dinky 30w iron which is nowhere good enough to solder the kind of electrical connections this is. I also just spent $100 on another electric accessory, a 18v cordless drill plus bits and a countersink bit so I could mount the trays and such. Grr.
Future plans. Pickup rigid carbon fibre sheet so I can run a sheet from center diff to the rear of the truck. I'll install a water proof receiver box there along with a switch thats accessible from the rear of the truck. For the center diff forwards I'll replace the aluminum plate that the ESC will be mounted on with another sheet that extends from the center diff to the steering brace. I hope to accomplish 2 things with that, clean up wiring and provide wire management, as well as add some stiffness back to the truck. Without the Z-brace that was installed near the motor, and the the stiffness the motor mount provides to the car I'm afraid that a hard landing at an odd angle or a head on collision would bend the chassis.
I was going to use 2mm carbon fiber, but since I'm doing it for structural reasons as well as wire management I'll use 3-3.5mm thick CF and it won't add that much weight.
First off, the wiring isn't finished. My 60w soldering iron crapped out on me, and all I have is a dinky 30w iron which is nowhere good enough to solder the kind of electrical connections this is. I also just spent $100 on another electric accessory, a 18v cordless drill plus bits and a countersink bit so I could mount the trays and such. Grr.
Future plans. Pickup rigid carbon fibre sheet so I can run a sheet from center diff to the rear of the truck. I'll install a water proof receiver box there along with a switch thats accessible from the rear of the truck. For the center diff forwards I'll replace the aluminum plate that the ESC will be mounted on with another sheet that extends from the center diff to the steering brace. I hope to accomplish 2 things with that, clean up wiring and provide wire management, as well as add some stiffness back to the truck. Without the Z-brace that was installed near the motor, and the the stiffness the motor mount provides to the car I'm afraid that a hard landing at an odd angle or a head on collision would bend the chassis.
I was going to use 2mm carbon fiber, but since I'm doing it for structural reasons as well as wire management I'll use 3-3.5mm thick CF and it won't add that much weight.
My solder station finally came in late last night. So I converted all of the batteries and soldered the leads on the ESC too. I also had to head into work so I brought the truck with me to use the UPS scale.
10.22lbs w/o ESC. ESC is 125g, bringing the Ready to Run weight up to 10.5lbs.
Its about half a pound lighter than I was told to expect, and its actually the LIGHTEST conversion for a Jammin truggy I've read about by nearly 1 full pound. I have a set of twin 2S batteries coming shortly for "track days" when I don't need super insane stupid power.
Those will reduce the RTR weight to 9.8lbs! Under 10lbs brushless. Excellent!
Pics for proof.
10.22lbs w/o ESC. ESC is 125g, bringing the Ready to Run weight up to 10.5lbs.
Its about half a pound lighter than I was told to expect, and its actually the LIGHTEST conversion for a Jammin truggy I've read about by nearly 1 full pound. I have a set of twin 2S batteries coming shortly for "track days" when I don't need super insane stupid power.
Those will reduce the RTR weight to 9.8lbs! Under 10lbs brushless. Excellent!
Pics for proof.
Well, after the Berwyn bash session I had today I had to clean up the truck! Man there was crap everywhere. And I think some of it was real crap, from a dog, or maybe a goose. 
So here's the "upgraded" wiring. My X2 mount is still in the mail, so the center diff is going to drop further soon enough. One of the nice things about this layout is how clean it is, and how easy it is to take the ENTIRE motor system out. I'm going to cut and mount the tray in front of the center diff so I can mount the receiver there. Once that is done with 5 screws I'll be able to completely remove the entire motor system and the only thing I'll have to unplug is the steering servo!
Here's the original wiring as of this morning:
And here's the cleaned up wiring with some close ups of the ESC tray I made. I decided NOT to extend the tray back to the rear diff mount because of the complexity of working on the truck then. The battery trays themselves act as stiffeners. I may drill out a larger hole for the holes though so I can use a washer and a small nut for a stronger clamping force. Repeated tray removal seems to weaken the screw holes so the screws don't grip as tightly.
So here's the "upgraded" wiring. My X2 mount is still in the mail, so the center diff is going to drop further soon enough. One of the nice things about this layout is how clean it is, and how easy it is to take the ENTIRE motor system out. I'm going to cut and mount the tray in front of the center diff so I can mount the receiver there. Once that is done with 5 screws I'll be able to completely remove the entire motor system and the only thing I'll have to unplug is the steering servo!
Here's the original wiring as of this morning:
And here's the cleaned up wiring with some close ups of the ESC tray I made. I decided NOT to extend the tray back to the rear diff mount because of the complexity of working on the truck then. The battery trays themselves act as stiffeners. I may drill out a larger hole for the holes though so I can use a washer and a small nut for a stronger clamping force. Repeated tray removal seems to weaken the screw holes so the screws don't grip as tightly.
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