HobbyKing 4WD Big Monster 1/5th Scale Truck (ARR)

Remember it does not come in that paint job, -
Dynamite Shikoku, then it's pasta and ketchup for the rest of the month

Progress so far.

I stripped the truck back to its basic assemblies. This only took about 2 hours. All the screws bite real tight into the plastic parts and would not come loose under normal use. The tools provided are ok, however I suggest a decent set of hex drivers to save your fingers some pain.

This is what it came with



I have now re-assembled the chassis with the two diff housings and 4WD belt drive system. This took about 3 hours as I decided to do a bit of tidying up that I felt would make the belt system run in a lot quicker. From new the whole drive system is very stiff. It is actually quite difficult to push the truck along with the brake off.

1. The slot cut part way into the chassis plate to clear the main drive gear on the rear diff is only about 1mm wider than the main gear. I decided to get the Dremel onto it and make sure the slot has a good 2mm clearance either side. This is not a necessary change, but I figured while it was apart I may as well do it.



2. From the factory they use heavy weight blue grease on the belt and associated guides. I prefer to use medium weight silicon grease, so I cleaned off most of the original grease and re-greased using far less silicon grease. Again, probably not necessary as I'm sure with a easy run in with the original grease the belt and grease will "loosen up" fine. Note the belt and plastic guides do touch slightly but again this will simply wear in.

3. The rear diff has a plastic cover that pushes over the diff and is held in place by a cross member and the rear suspension frame. The plastic in this is not real uniform in thickness on the inside and does rub against one side of the diff. I again got the Dremel and some wet and dry and thinned the side wall plastic so it no longer rubbed. Another step that probably isn't necessary as during a run in of the car the plastic that is touching will again simply wear back.



4. In front of the rear diff is the belt tensioner. It consists of a split casing (plastic) with three sealed bearings pressed onto a shaft. The outer surface of the three bearings is what pushes down on the belt to provide final tension. The three bearings on mine were not pressed to a point where they were centered on the belt. I simply used a suitable sized socket slid over the shaft and lined up with the outer race and gently pressed the bearings to the middle of the shaft in my trusty vice.



The whole drive system is now a lot smoother with far less binding.



While checking the action of the diffs, I note that from the factory the rear hubs are running a lot of negative camber. Infact with no load on the suspension so it is at it's furthest travel, the Universal Joints are just at the point where they are binding. I dialed the camber back so it's only a degree or two and it's nice and smooth now.

Mark

Edited by Chrissy47 - 15/Aug/2011 at 7:51pm

would you happen to know the strength of each those steering servo's? They look like all metal with heatsinks so i would imagine high voltage. if they are 20kg+ servos, SEXY!

Thanks Owll, that sounds like a brilliant idea, I will have to have a scrounge and see what O-rings I can come up with. I may even be able to scrounge some at work.

Dynamite, I havn't checked the stall torque on the servos, but they appear to be up around the 30Kg mark when compared to a 33Kg Chris has for her Baja.

Mark

hehehehe... Well it's all run in and was working great till I had a big flip. It ended up the right way. Took off again and the rear diff went bang followed shortly after by the front diff. All stripped down reveals that I have taken out all four planetary gears. By the looks of the material and the way it stripped, I would guess they are a fairly soft casting. Time for a set of hardened FG originals.

On the grass this thing makes that much power it drifts everywhere. LOL

Awesome fun!

Mark

Edited by Chrissy47 - 20/Aug/2011 at 10:43pm