The beast lives! V4 scratch built straight axle truck.

[Mod Man]

Hey Guys,

Well, the truck is finally finished (or, at least mechanically finished).

Anyway, many of you are familiar with this truck or so you may think. It looks alot like the previous version, but believe it or not, the only parts this truck shares with the previous truck are the roll cage (with changes), tires, center CVDs, and a few gears in the axles. But, every other part is new including all electronics. So, with that in mind, here are the specs;

The electrics are;

-Neu 1512/2D/F
-Flight Power EVO 25 2170 pack (4S).
-MGM Com Pro ESC set for forward/reverse/one second throttle ramp up. The ramp up protects the gears from the abuse of the 1512.
-Two JR DS 8711 steering servos (403 ounce inch torque)
-Two CC 10 amp BECs run parralelled. I learned this from the crawler guys. 800 ounce inches of turque really draws alot of current. So, these two BECs eliminate any chances of running out of current.
-Inet RC aluminu axle housings. This things absolutely ROCK! The design and machine work is absolutely unreal. I cannot say enough good about them.
-RC4WD spools. I know, I know, RC4WD makes some junk. But, not these spools!
-MIP CVDs in the axle housings.
-Dynamite T-Maxx center CVDs cut and rewelded for the correct length.
-3 racing T-Maxx shocks.
-Aluminum knuckles steering on ball bearings.

I think that wraps up the aftermarket goodies.
The custom parts are as follows;

CNC transmission. I made this at my shop on my CNC. You will notice the pinion cover is missing. I have that made, but I need to buzz 1mm off the motor shaft for clearance. The transmission uses standard 48 pitch Kimboro spur gears. And no, I have never stripped one. The truck is geared low enough not to worry about stripping the spur gear.

CNC transfer case. That part is made out of CF plate. It runs a XL pitch belt from a 10 tooth upper pulley to a 40 tooth CNC aluminum 40 tooth lower pulley. The transfer shaft carrying power from the tranny to the transfer case is a 7mm diameter grade 5 titanium shaft.

All CNC machined suspension including shock towers, 4 link mounts and all other related suspension components.
The suspension pivots on large diameter bearings at all pivot points. It is a sort of 3 link setup that uses the upper CF forked swaybar as the upper link. It is tough to describe this suspension system other than to say it is elegent and solves alot of problems with typical 4 link setups that use swaybars.

CNC machined steering components. The servos are mounted inboard rather than on the axle housings. This makes for a very uncluttered axle. The belcranks also pivot on large 5X11 bears (two per belcrank).

CNC machined CF/Plywood chassis side plates.
CNC machined transfer case mounts.

There are a bunch of other little bits that are not worth mentioning here.

I plan on making a CF body for it with gullwing doors and racing seats inside. But, that is a prject for later on this summer.

For now, it runs fantastic! I have it setup currently for full 4 wheel steering and a top speed of about 12 MPH for crawling and running inside the house. I will gear it for about 25 mph this summer and mix out the rear steering at high throttle. Right now, it gets hairy at high speed with the rear steering. But, it is alot of fun to do typical "Real" monster truck running.

So, any questions?

Matt

[Mod Man]

Some more pics.

[johnrobholmes]

Pretty cool project! I must ask why you are using a 1512 if it is geared so slow. You could get the same job done with a much smaller motor.

[Takedown]

Originally Posted by johnrobholmes

Pretty cool project! I must ask why you are using a 1512 if it is geared so slow. You could get the same job done with a much smaller motor.

Its a crawler...

[Mod Man]

The reason for it is multifacted;

#1 I had that motor lying around from a previous project.

#2 I am planning to gear it up this summer and will need the power to move a 16.5 pound truck.

#3 I am sick of running small motors at their limit. I have had much better luck running motors that are overkill. They run cooler, more efficient, and have no cogging problems. Also a large motor tends to run low RPM better for low speed running, yet will still twist when needed.

This truck is not a crawler, not a racer, not a shelf queen. It is something I have always wanted to do, sort of a semi scale (motor under the hood, roll cage, straight axle) truck I can mount an interior in and just have fun running inside or out. This is what I wanted ever since Tamiya came out with the Bruiser.

Matt

[brushlessboy16]

can we get more pics of the drive train?

[PowerRocks]

Go into business and start selling these parts;)

[Mod Man]

These are the best pics I have of the drivetrain.

Maybe I will take the whole thing out so you can see it as a whole? It is hard to describe otherwise.

Matt

[Mod Man]

Originally Posted by PowerRocks

Go into business and start selling these parts;)

I love mechanical design. But, I do not like production. I manufacture RC heli parts (and complete helis). I have made thousands of parts for customers and I do not really like it.

I enjoy developing things and, maybe, selling a few. But, doing it full time is not my cup of tea.

Of course, I hate tea!

Matt

[suicideneil]

I've finally figured out the steering mech and suspension linkages now!

Man, it truelly is a work of art and engineering madness. A scaled down version of the belt driven tranny would be really nice for the Gmaxx chassis I reckon, plenty of room for creativity to create the required gear reduction, maybe with a main tranny section, and a smaller spur/pinion section... **plants seeds of interest, hopes for something cool to grow**

[DRIFT_BUGGY]

Top Work

[brushlessboy16]

AWESOME! Great job

why are you running two bec's though?

[Mod Man]

Originally Posted by brushlessboy16

AWESOME! Great job

why are you running two bec's though?

The crawler guys turned me on to that. I have two 403 once torque servos for steering. One 10 amp bec should be enough. But, I have seen crawler guys having problems with running only one. So, for a $18 (I get a discount) BEC, it was cheap insurance from under volting the radio system.

Matt