Mod Clod Twister chassis

This has already been seen at the Buxton bash, with photos by Quincey http://www.tamiyaclub.com/showroom_model.asp?cid=54430&id=2447

and Biggus http://www.tamiyaclub.com/showroom_model.asp?cid=54368&id=280

I wasn't going to put anything up until I had developed it a bit further, but as winter has now firmly set in and work is keeping me busy I thought I might as well add it to my showroom.

This has to be the cheapest Mod Clod chassis you can get, total cost so far is about £15 with enough spare material to build a few more. It was built for the Buxton bash, I have had the Clod gearboxes for a long time and been designing my own car, but it is still mainly on paper and work commitments meant I had a weekend to come up with something. Having just won an old lexan chassis 1/12th scale on ebay, the idea came to me that the same chassis design would be perfect for a crawler. A plastic U channel is rigid in all directions except torsionally, and will twist very easily. One advantage of plastic over metal is that the PVC has a natural damping effect and doesn't try and act as a spring. A rummage around B&Q later I had a length of pipe conduit which is perfect. The dimensions mean a battery pack just fits inside it. Servo posts screwed to the chassis stop the battery moving and a couple of velcro battery straps to hold it in. The radio gear fits in neatly behind it. Currently running with a 17 inch wheelbase the chassis is big enough to run two packs in there.

Next problem was how to attach it. The Clod servo saver mounting hole, which is used by lots of mod Clods as a fixing point was ideal. An M10 bolt fits inside, the only problem is getting a nut on the bottom. To do this I had to Dremel off most of one side of the nut, but it left just enough metal left to keep the threads intact. A more suitable spacer tube with a smaller diameter bolt will be made up to replace it at some point (when it isn't cold and wet outside!).

The second fixing point is a large right angle bracket that fits between the motor and the gearbox. As I'm using the standard gearing at the moment they were just drilled for clearance. The brackets are bolted to the gearbox so the chassis doesn't fall apart when you remove the motors. The fixing to the channel is on the centre line to make sure the chassis flexes the same both ways.

Steering was next on my list. I definitely wouldn't run the steering in the standard configuration. The geometry is all wrong, with the outside wheel turning more than the inside one. The servo bolted to a home made right angle bracket on the axle stays worked great, until I tried running it and discovered the tyres hit the servo the night before the meet. The lovely brackets ended up being quickly attacked by a Dremel and the servos moved further inboard. Some new brackets need to be made up again, they currently look a bit of a mess. There is just enough space in there for the servo and makes a really neat steering setup. Bit tricky to get it round the usual 4 link setup though.

And that's it. At a rough guess with this wheelbase it has about 120 degrees of articulation, with the chassis flex meaning the suspension gets proportionally stiffer the more it flexes, although it is still pretty soft at full articulation. Already got ideas to develop it further now it has been run, first job is sorting out a proper ESC that works, the Buxton bash killed this one. It was seen at Buxton with a Kyosho Lazer shell on it, the body planned for it didn't turn up in time, although since then I've changed my mind several times. Currently looking at an HPI Bug shell, something different to the usual trucks so somewhat appropriate for the chassis.

Somehow can't see it going down too well on scale4x4 though! ;)