One of the projects I have been working on had its genesis in an impulsive purchase of a Tamiya fighter Buggy RX hard body on eBay in about 2000. At the time I thought it might make a good space ship cockpit.
More recently I did another rough sketch to try and figure it out. you can see why I called it the grasshopper, the shape of the rear wing on the body and the angle of the suspension remind me of the back legs of an insect. Of course there was a Tamiya GrassHopper which was the first RC car for many. It used to mimic its namesake quite accurately as the horrible rear suspension set up caused it to bounce out of shape over every bump and rut, making it extremely difficult to drive in a straight line on any offroad track.
Hence the trial layout below. I was thinking I would need a pretty large arm to hold 2 steerable wheels so I tried out a set of Traxxas Summit rear arms. After checking out a lot of crawler builds, I thought I would build a solid rear axle with a 4 link set up for the rear. The biggest off the shelf solid axle is from a Kyosho Twin/Mad Force which would do the job but is way too expensive at around $250.00 a set. I then had a look around at some cheap DIY solutions on the crawler pages and found some guys using Maxx diffs and suspension with some metal work added. I took the Maxx diff idea and came up with my 25mm aluminium tube sandwiching a Maxx diff with Revo Axles and Revo/Summit/Maxx Knuckles. Maxx diffs are amazingly cheap on EBay from the people that buy up new kits, disassemble and part them out. Most of my parts come from these eBayers and I like Traxxas parts for a couple of reasons. One is they are metric, they've always been metric and I like metric. Here in Australia we have been metric since the mid seventies but you are only just now seeing metric fasteners in hardware stores and its all because of the buying power of the USA. Most stuff we get is made for the US market and they are stubbornly Imperial. As soon as the US sees the sense in the beauty of metrification the world will be a better place... for people that like to make stuff that is.
The other reason I like Traxxas for custom jobs and mods is they have a product line that uses many interchangeable parts, for instance the Revo E Revo, Summit, and Slayer are all based on the same platform. The Rustler, Bandit and Stampede share a good many common parts, so you can mix and match away to get what you want. The other important reason is that the parts are plentiful and cheap. You can afford to buy a part to try out and if it doesn't quite work out as you had hoped, you can consign it to the parts box for a later day and another project without feeling ill from wasting so much cash on something you didn't use.
One added tip to this, is to resist buying the expensive aluminium upgrades at first. Get the cheap plastic parts while you are prototyping, not everything will work as you intend. You may have to drill or enlarge holes or carve away plastic depending on the mod, then find actually it would have been better to go about it a different way and you have trashed the part. Once a part it is in and working satisfactorily then you can think about the bling because you know it will work. I speak from experience here, I am a sucker for bling, after all, in a manner of speaking, the SciFi thing is all about the bling.
If there is no other way to join pieces then I use this method but if it can be mechanically joined I prefer to use fasteners.
The two main links are Super Crawler machined aluminium links. I happened across them on one of my many eBay trawls.They worked out to be in the range of the length I needed. I have put a couple of rubber O-rings at the axle ball joint to prevent them from flopping sideways on suspension compression. The other red anodised links are leftovers from the Creeper 6x6 project.
I may make some sort of detailed hubcap insert to go into these rims eventually.
The front Tyres are 2.2 Imex Claw Dawgs forced onto my favourite wheel the Venom Creeper Bead locks.