I found a cool Burago die-cast E36 M3 on eBay for not much money, so I thought I would try to adapt a WLToys car to fit it.
I started off with a K989/284131, which is the pickup truck style of WLToys 1/28 RC car. I fitted an aluminium suspension kit that I found on eBay, but I found that it didn’t work great, and the suspension would bind up quite a lot.
I started by designing a solid front axle, quite similar to that found on the Fan Car v1, using a scotch yoke style steering setup, with the original servo relocated to the centre of the chassis. This axle lengthened the wheelbase to fit the body, and also included the two pins that locate the front of the body. This new front axle did not feature a diff, making the car rear wheel drive only.
I then designed a mount to connect to the screw hole in the back of the body.
At this point I decided I may as well design a solid rear axle as well. This took a bit of trial and error as I didn’t know what clearances were required to make bearings fit – on the first attempt I made the bearing seats too small, which meant the print cracked when trying to press wheel bearings in. I added a small amount of clearance and reprinted it, and it worked.
This worked well with drift tyres (hard plastic). Some problems arose when I switched to rubber tyres. The body added considerable weight – when the car had no grip, this was fine, but with the rubber tyres it quickly stripped the rear differential. I solved this problem by switching the rear pinion to a metal one from the buggy model used to make the Fan Car v2.
I also printed an approximation of the body that was far lighter than the die cast one. It doesn’t look as good, but the car drives much better with it on.