After a few years with the RC Crawlers both my son and I were ready for something different.  Cam kept hinting at a monster truck so I started doing some research the month before X-mas in 2011. I found the above 1/10th scale Losi Desert trucks had been reduced down to $149 each so we picked up two for X-mas.  Little did I know the price drop was a precursor to the trucks being discontinued after X-mas. Luckily these share the same basic chassis design with a bunch of other Losi vehicles so there is no shortage of spare parts, a fact I would soon discover.  

The week before X-mas I turned some of my scrap metal in the garage into a small jump for the trucks. Out of the box the trucks worked pretty well but they were anything but fast.  I'd say they topped out about 22-25mph.  I really liked how versatile the suspension was. We found that by adjusting the shock collars we could set them up in "street" mode by lowering them down 2 inches which made them corner really well. A few days into running I had issues with first one and then both Duratrax 5000mah NIMH battery packs I bought for the trucks. This led to a brushless motor upgrade for the trucks so we could take advantage of the longer run times afforded by the latest LIPO batteries.

Now the trucks were doing closer to 40mph thanks to a Castle Creations 3800kv brushless motor and speed controller with runtimes over 30 minutes thanks to the Turnigy 5200mah 2S lipo pack I was running.  Of course with the higher speeds came the carnage.....

First we broke a shock tower due to a barrel roll at high speeds.  The quick fix was a reinforcing plate I cut out with some sheet metal shears.  The quick fix then gave was to a cleaner bracket I cut at work on the big stomp shear and corner notcher. I also ended up pulling both front ends apart to locktite all the steering ball studs.

It turns out that was good practice for changing out the front bulkhead.  Both cam and I broke one in a nasty head on collision, then he broke another taking a nose dive off a jump. One of the big problems with these is the mfg. just uses standard #4-40 socket head cap screws as self tapping screws and they tend to pull out of the holes in the upper bulkhead. I have an aluminum upper bulkhead on order which I hope will take care of this weak point.

I braced the front shock towers in an effort to keep the bulkhead from flexing too much on the big hits but it wasn't enough.

At this point I am convinced the front end needs a larger bumper that can absorb more impact energy.  The stock bumper while realistic looking just doesn't absorb any impact forces effectively and for the most part was falling apart until I added some an aluminum reinforcing plate. The final solution was a nylon bumper from T-Bone Racing.  You loose the realistic truck look for the front end but gain a lot more durability.  Since installing TBR bumper I have ran into a garbage can and face planted the buggy on a few poor jumps with no damage to the front end. The TBR also affords more protection for the front a-arms which are rather delicate due to their length.

The stock all terrain tires look good and work ok on most surfaces.

I tried a pair of Pro-Line 2.2 Dirt Paws mounted on a set of HPI Mesh truck wheels (HPI2196) and was amazed at the added grip in the loose stuff..  Unfortunately the front wheels are backordered so I haven't gotten to try the ribbed front tires yet.

For street use I also got a set of Pro-Line Speed Hawg's.

One other must have mod is a wheelie bar if you go brushless.  The wheelie bar from a Losi Speed-T fits with no mods and would have saved my trucks body/rear cage from some of the grindage if I had installed it earlier.

Outdrives were the next thing I noticed that were wearing out. We had been setting up the suspension for off-road driving by adjusting the ride height up but this may have accelerated the wear due to the added angle on the dogbones. I installed some new outdrives and now set the ride height in the middle of shock travel which keeps the dogbones level most of the time.

At this point the steering seems to be the weak link in the truck when bashing it off-road.  I have knocked steering bell cranks out from under the hold down a few times. I am going to try this Exotek steering to see if it helps.  Just testing it on the bench I can see it eliminated all the flexing on the plastic hold down piece as I cycle the steering by hand.

 Also working to fit a metal geared servo after breaking the gears on one of the stock servos. The servo fits but the servo arms I have all have various interference issues. When I swap out the front bulkhead for the aluminum version I will look into spacing the servo back. I am actually tempted to convert this chassis for primarily on-road usage.  With the suspension dropped down it works pretty well on the asphalt and can turn out some impressive speed runs on pavement with my best being a radar verified 50mph run (CC 5700kv motor, 15 tooth pinion and Venom 3S 50C lipo).  I think another 5-10 mph is possible with a larger pinion, aerodynamic body and some street tires.

Update 2-7-11

Been working on converting one of the desert trucks for asphalt usage.  I picked up a Pro-Line Desert Rat body for $20 shipped off of EBay which fit perfectly after swapping out the two rear body mounting posts with a pair of rear posts from a Losi Speed-T.  I also fabricated some small brackets to utilize the desert truck LED lights.  We found they really work well at alerting drivers of the presence of the rc car, plus they make driving at dusk much easier because you can tell which way the car is pointing.

After losing the cross pin and cylinder from a brand new rear axle on it's first run I made some slip on steel bands to retain the cross pins. A dab of bearing retainer secures the band very well after about an hour of set time.   Ironically the Losi CVD has a ton of clearance around it but not much flat on the bell of the outer axle shaft itself which is why the band is so narrow.

It's been a while and it wasn't looking like the front HPI Mesh wheels were ever going to be back in stock so I ended up converting the front end to a floating axle w/ 12mm hexes using parts from my sons Traxxas Stampede.  This means I can now use the rear wheels up front.  I also picked up a set of Losi Speed-T shocks along the way which have stiffer springs and a shorter stroke than the Desert truck shocks.

With the new wider rubber and stiffer/lower suspension you can now turn hard at very high speeds and drift the car around turns. I haven't had a chance to borrow the radar gun again but it is definitely a bit faster and much more controllable at high speeds.