4wdRustler
Here are the updates for the 4wdRustler project. Accounts
are in reverse chronologial order.
9/17/04
- Phase II Pictures / Comments
I
was very excited about installing the EVX from my Emaxx,
and using the cheap Permax motors. Using 19/90 gearing,
this was very fast. It was close to 30mph, although no
GPS. Very torquey. First run went great. Second run lasted
only about 10 minutes before the rear motor failed. This
caused a severe glitch that ran the 4wdRustler right into
a neighbors garage door (damaging the door!).
I
would not recommend using this motor at 19/90 gearing.
I
decided to go with Traxxas Titan motors geared 19/90, and
I have about 5 runs in on this setup. Its not quite as
fast as the Permax motors, but everything runs very cool.
All of the great handling characteristics of the previous
setups, but now using relatively inexpensive non-rebuildable
motors, and running a lot cooler.
Phase
II includes the use of some optional mounting holes on
a new front plate. This new plate allows the use of either
4" or 3.5" shocks.
Coming
up in Phase III is making this dual Brushless. I just recieved
the Master Car Sport Controller (Thanks Cliff!) that I
needed to go with the one I already own. Now I just need
another Lehner 5300 and we'll be good to go!
Another
future mod worth considering would be a custom chassis
that allows for the 2 packs to lay down (lower CG).
8/20/04 - Phase I buildup
Everybody
should have one of these. I've toyed with the idea of making
a 4x4 for a long time. Lots of folks have done the Stampede
4x4 conversion before, but I had never even heard of a
4x4 Rustler (apparently it has been done before though!)
The concept
is very simple. Find a way to attach a transmission to the front
of the vehicle, and find a way to make the steering work.
I would dare say this is quite a bit easier on the Rustler than
the Stampede. On the stampede, you've got a choice of an entire
new chassis, or a very weak extension to the chassis. On
the Rustler, since the whole chassis is flat on the bottom,
it makes it fairly easy to attach a plate that extends the
chassis, yet is very strongly mounted. We're already
setup to work with this 2" wide aluminum, so making
the plate was extremely simple.
Angling
the front transmission back encroaches on the top plate some.
The topplate must be cut back around a half-inch or so to
make room. See the closeup below:
Setting
up the steering was the only real challenge, and not much
of one at that. It so happens that Devestator2k makes some
hardcore C-Hubs just for this purpose. They attach onto rear
arms (now on the front), and allow for the mounting of the
standard, or upgrade (RPM) rear carriers. These are intricate
handmade parts, that require a lot of cuts. As such, they
sell at around $60. You can email Mike at his website, DefianceRacing. These
parts are not listed on the website currently.
The
bearing carriers are simply turned 90 degrees to become steering
knuckles. The lower hole must be trimmed off or it will not
fit inside the new C-Hub. 78mm links are used for the steering
and 90mm for the camberlinks.
The
rear arms are turned around, to allow the use of the stock
shock mounting holes. At first I attempted to simply lean
the shocks all the way back to the shock tower. This created
a lot of friction on the shock shafts, and is completely
unusable. If you could attach a properly angled mount (or
better yet a ball) on the shock tower, you could lay
the shocks back. Another way to "fix" the shock setup is
to extend the top mount out about 1.625". You want to extend
the top mount just enough so that the shock can line up with
the arm and not be flexed out toward the front at all.
Extending
the mounts like that allow for never-before-seen leverage
on the shock tower. Way too much flex. This plate was added
in order to stiffen everything up. Simple and brutally effective.
Soon this plate will be replaced with one that has some lower
mount points on it. Then a 3.5" shock can be used, which
will be perfect for the front end.
There are two major chioces for the powerplant
on a two motor 4x4 project. You can do a 7.2v system or a 14.4v
system (you can also pick somewhere in between, but that would
use the 7.2v equipment). The 7.2v system is likely to be powered
by a Novak Super Rooster, or similar two-motor ESC. The Novak
EVX is a widely available choice for dual 550 sized 14.4v motors
such as the Titan.
I didn't want the weight (and cost) of two packs,
so I elected to do two 540 motors (Speed Gem Pro Titantites)
in a 7.2v system. They were run by the ever-popular Super Rooster
ESC, and one 7 or 8 cell pack. This setup is brutally fast
for a brushed setup, but the batteries do not like it. After
a full run, the batts were over 180 degrees. The ESC was 145
and the rear motor 200.
While
I am touching on the subject of performance, let me say how
fun this stuck is, even in its prototype stages. Massive
traction compared to the 2wd truck. It has the ability to
go full throttle in just about any situation, and the backend
still wont bust loose. Just trying to take off in a straight
line with a fast 2wd truck is a real challenge. Not with
this guy. Still no dirt testing however. Should be fun.
One way to combat the battery heat issue is to
run parallel packs. This did increase the weight quite a bit,
but performance increased marginally. Two batteries can deliver
twice the amperage of one pack, and huge spikes of amperage
are needed to change speed quickly (the fun stuff). When run
in parallel, the packs were near ambient temperature! Quite
an improvement.
Now
being forced into the heavy-two pack configuration, the next
logical step is to go ahead and try out the 14.4v system.
This will be accomplished shortly. The EVX and Permax
Multiplex motors have already arrived! These permax motors
are only 8.49 on tower. They are reported to be slightly
stronger than the Titan. Not for use with 14 cells though,
smoke is sure to roll. Thats fine, since its really hard
to fit more than 12 cells on a Rustler anyway.
Thats about all there is to tell at this point.
I will be sure to post up what happens when I go 14.4v on this
sucker.
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