semi-scale tuber build

[ToyTundra]

semi-scale Brushless tuber build

I've been telling my self i'll build a tuber for the last few years after selling a clod but I never got started. The MRC was what it took to get me going. My plan is a tuber that is a mix of scale and able to be somewhat competitive. I didn't buy the MRC kit as i wasn't going to use most of it. This proved to cost significantly more, but i did spring for upgrades like CVDs, metal rear lockouts, metal lockers, aluminum shocks, blue tires, etc. I should have bought the kit and parted out the transmission and electronics. Buying in $40-$60 spurts made me lose track. This is my first tuber, but i have brazed brass in the past for another project. Steel is significantly easier

Running gear:
MRC axles
5245 servo (frame mounted)
3 link + panhard front
4 link rear
sidewinder micro ESC
130 size brushless
planetary reduction
2s 1500mAh lipo
CCBEC or dimension engineering BEC, or maybe just the built in.
Airtronics RDS8000

I made the belly of the chassis pretty big, so i decided to run a mostly droop setup. Most of the running gear will be under the hood.

A 2s lipo will sit right behind the steering servo. The motor will be under the battery.

space is going to be tight for the panhard bar. Maybe a 4 link on front is in order. The black line on the floor pan is the tentative transfer case spot.

The cheap 3100kv motor and 104:1 reduction. I also bought a 6200Kv motor if i need more wheel speed. I used this gearbox with the stock brushed motor in a construction equipment project. It has tons of torque. The motor will never stall, but it does make the driveshafts spin on a non-keyed diff input shaft. After a successful test run i'll swap to a Park 400 inrunner, or do away with the weird driveline. I want to use a very small motor, but my second choice is a very large motor, like a standard sized outrunner.

A simple two gear transfer case. I decided to run a 1:1 ratio as wheel speed will be an issue. This case is supposed to have 3 gears (you can't see the upper one which was supposed to be the input) and a 1.5:1 ratio, but it s too tall for the chassis so I'll start over. Besides, my gear mesh was too loose.

 

[TBex]

Looks good but good luck with the motor if its a 20ish from Asia, mine got to about 300 degrees in about 3 minutes of hard use. Mine even had cloth insulation on the wires, after it got hot I pulled the insulation off and the wires were so hot they had turned purple. Non the less, still a good mock up motor, and good looking rig!

 

[ToyTundra]

Thanks for the info about the motor. I noticed it was getting hot in my hand (after 20 seconds), but figured it was the 3s lipo. I was hopping it wouldn't run too hot, but i guess they are really made for airplanes. i'll get one test run before it gives up the ghost.

As it sits at full compression. Ride height will be taller. Both suspensions are done, but i'm not thrilled with the rear. The transfer case was recut, but it needs some cleaning up and a bunch of holes tapped.

I was able to fit a three link + panhard in the front. I dunno if it wil preform as well as a four link, but it looks neat. Fully compressed the panhard touches the axle case. There is still up travel in the shocks for articulation. Ride height will be a little higher than this position.

Fully drooped out. Slight bump steer due to the unequal panhard/draglink.

driver side droop and some of the brackets required.

Are flex shots still mandatory?

Edit: forgot the driveline mock up:

 

[danielk]

looks sweet.

 

[ToyTundra]

I've been bashing the thing for a few months now. The original cheap brushless inrunner (3100kv)i had wasn't that bad. It ran warm on 2S, and the start up wasn't as bad as i had expected. I swapped to a helicopter Outrunner 4200Kv motor. It was sweet, but it burned up running through the grass. I rewound it (33 turn) and now it runs rather well. It needs more wheel speed, but i don't feel like rewinding it.

http://www.youtube.com/watch?v=YCZQ_VN9r6A

http://www.youtube.com/watch?v=yOFpn-deolo

So far i've changed:

• Steering servo to 645Mg. The flatirons killed the 5245
• Motor to a custom wound outrunner
• Added spring to all the shocks. I need lots of belly clearance as i don't have the wheel speed to free myself.
• Fiberglass body panels.
• With no spring on my throttle stick i it cruises smoothly. All i have to do is steer.

I dpn't like:

• long spool time going from forward to reverse. It has a lot of gears.
• I made my chassis too big/tall. Even a semi scaler could not hang with comp trucks. my small driveline should fit in anything though.
• Rear links are too short.