I'm trying to design a rock crawler that would be completely fabricated in my garage only using a few parts from a conventional rc store such as the motor, speed control, controler , receiver , battery , wheels and tires. The other parts will either be made or puchased from a none rc related store. (metal supplier, belt and pulley supplier and so on...) A few general things in my design are to use a belt and pulley cog type to run from the center pulley set up out to the diff pulleys on the front and back axles. It will probably need a small belt tensioner to help during belt twist (articulation) . The axles I was going to use a solid hardened steel with pillow block bearings with a 2 bolt mount to attach the 4 the 4or3 link to it and in the center will be the pulley. At the the wheel end of the axle I was thinking of use a 1/4 inch swivel from a socket set or make a heavy duty dog bone type end but Im not sure on the articulation would be enough for a sharp turrning radius needed. The frame will be either be 3/16 solid chromoly or 5/16 chromoly tubing . This is one of my many questions. Solid or tubing ? Is there a ideal wheel base and turning radius ? Gearing and turn or rpm of motor whats ideal ? Tires is bigger better ? ( 9 inch over 5 inch) Remember I'm starting with a blank piece of paper and I'm still in design mode. I have a hobby building real offroad vehicles including a bajabug called bugzilla that almost looks like a life size rc car so I know the right answers in the real world rock crawler so I try to apply that to rc one but I don't have real hands on know how in the rc world of crawling to know specifics. ( I won't be competing in competions so theres know limits its just for fun plus it's alot cheaper than the real ones) I have many more questions but maybe start with that as I'm sure you will probubly have many questions and as slow as I type I only have so much time for the computer. Thanx for your help and time. Here is a picture of my bug built completly in the garage with love and a few beers.

That sounds crazy enough to be something I would design

That bug in the pictures is really cool. It looks to me like you'll have no problem building something capable and fun [sm=thumbs_up.gif]

I'd like to comment on a couple of your points:

I think the tubing size will depend upon the overall size of your design. Do you have a scale in mind? A wheelbase length? What do you expect the longest section to be? If there are enough supports, you could probably get away with using smaller diameter tubing (or rod) and rely on gusseting to lend strength. As for the turning radius, if it will be 4ws you may not have a problem needing much wheel cut. My truck has only about 26 degrees on each axle at full lock, but the overall turning circle is manageable because both axles are steering.

Just to elaborate a bit, my truck has a 21" wheelbase, 27" overall length, and the turning circle is about 80". Not that great, but it will do.