Monday, April 13, 2015

Smaller and smaller and smaller. Losi Micro Desert Truck

First, lets set the mood.  Smaller and smaller - Faith No More.

The Losi Micro Desert Truck is one the remaining trucks in the 1/36 scale lineup.  So what makes it the Desert Truck (DT) instead of a Micro-T? The DT has bigger tires, with a different tread pattern.  They look scale.  The chassis is stretched in the middle, which makes the battery compartment larger.

Yes, that's the truck sitting on my battery charger.  In spite of being small, it's a very serious truck.  Fully independent suspension, slipper clutch, classic 3 gear transmission, fully proportional everything, with a brake and reverse.


Wheelbase - 3.5"
Length - 5.5"
Front Track - 3.5"
Rear Track - 3.5"
Rear Travel - 0.5"
Front Travel - 0.39"

So, while we are on the subject of travel.  Something I've noticed while reading reviews on the truck note that "the back end sags."  The proper setup for the rear end of a buggy, truck, whatever, is dogbones level, or nearly so.  The truck sags about 3/16" of an inch.. which puts those dogbones level under acceleration.

Now... the proper way of dealing with the back end slapping the ground is damping.  Which is something that this truck is sorely lacking.  Losi appears to sell some oil filled shocks... but at a cost of nearly $30.  Well.. that'll happen soon enough.

The lengthened chassis provides a much bigger battery compartment.  There's a little block of foam in there, to keep the battery forward.  If you pull out the foam, there's room to fit the 220mah battery from the High Roller, or the Trail Trekker.  I just so happen to have a Trail Trekker, and some reasonably accurate scales.

First off, lets compare batteries:
150mah - 15.9g (I have two of these, they were within .1g of each other)
220mah - 23.2g

Empty truck - 98.0g
Truck with 150mah - 115.0g
Truck with 220mah - 121.3g

The battery is between 14 and 19% of the total weight of the vehicle.  That's, a big lump of weight to move around.  I think that might make a significant difference in the handling.

150mah Forward: 39.9f / 60.1r
150mah Rearward: 36.3f / 63.6r
220mah Only:  37.8f / 62.1r

So far, I've driven the truck with the 150mah pack forward, and the 220mah pack.  I can't say I've developed a good feel for both setups yet.

Now, the upgrades have already begun.  I found out how bad dealing the e-clips are.  So I swapped out for the threaded axles.  That's a good excuse to examine how serious of a truck this is.

Ah, the classic R/C car pose.  Topless, and no shoes.  And e-clip axles.  That is about to change, at least in this narrative.

So we'll do the hard ones first.  Now, these i'm describing as "the hard ones."  To pull the front axles, you unscrew the kingpin, and pull it out.  The kingpin retains the axle in the hub.  So once the kingpin is out, you can pull, or push out the front axle.

And the back end is a whole lot easier.  You just unscrew the upper control arm, and when you pivot the hub down, the drive cup and axle can just be pushed out the back of the hub.  Sadly, I didn't take pictures of that.  However, here's what that rear a-arm assembly looks like.

Looks just like a big r/c car.

And here we are, after the conversion.

Now having threaded axles introduces some new things to be concerned with.  Since the front hubs have no steps in them, you can over tighten the nuts and bind against the bushings in the front wheels.  The case is similar in the rear.  You want to tighten the nuts just enough that the slop goes away.  My usual method for dealing with things like this is to over tighten them just a little, then back off 1/4 turn at a time until things spin freely.

Bearings for the truck are in the mail....  And I fully intend on destroying some batteries in this thing.  I'm also trying to find reasonably priced 180mah 2s LiPos to put in the truck.  Not that it needs to be any faster... but it's r/c.  "Need" is such a dirty word...

Now that I think of it... .I don't think I actually reviewed the truck.

The Losi Micro Desert Truck, feels like a 1/10 scale stadium truck.  Everything from the backend squat, to how it likes to be under power in corners, feels just like my old LXT.  The only thing that disappoints is the lack of damping.  

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