I need advice on the best way to install the axels )I'm helping my son). I was told to run a drill thru the axel slots first. What do you say? Also, what is concave in regards to the axel? What's it mean and how to do it?
If you have enough time, I would order a Pro-Body Tool (Pine-Pro or Maximum Velocity has them). This would be the easiest way to ensure that the 'pilot holes' you are drilling into the stock axle slots are perpendicular to the car body as well as being inline with each other (right to left). It also comes with the correct sized drill bit - a size not everyone has in most stores. If you don't have enough time and have a drill press, you could first make sure that the drill press doesn't have a lot of run-out. Run-out is when the part that holds the drill bit wobbles as it spins. If it does, don't use it. If that looks okay, make sure that the table of the drill press is perpendicular to the drill bit. If that is okay and if you have a fence, install it and clamp the pwd car to the fence to drill. If not, clamp the pine block to the table and drill. If no drill press, you will have to use what you got (hand drill, Dremel tool, Roto-Zip, carpenter's brace,...). Say a little prayer before drilling and drill away as staraight as you can - or don't drill at all and just use the stock slots. If and when you do drill and the bit is long enough (most aren't), drill all the way through the pine block. This will ensure that the front or rear axle holes are in-line with each other. Otherwise you will have to take very accurate measurements as to the loaction of the axle holes on one side and transfer them to the other before any drilling.
If your rules allow it and you still have time, don't use the stock axle slots and drill your own axle holes. If you get the holes drilled straight, you are well on your way to having a pwd car that runs straight too. After all, you don't want junior's creation banging against the guide rails all the way down the track do you? That would scrub off speed!
If you have to use the slots, try using Stan Pope's axle shimming method. His web site:
Be an honest person and send in the donation to help his Council - it will be money well spent as he has all that and more. A tried and true expert in the field if there is one.