Thanks for the reply, the overall model isn’t too heavy it’s a small AWD car, which is why I was surprised when this design didn’t work too well. I plan on using the wheels part no. 56904.
I found that the 11L beam helped to stop the wheels from bowing outwards, luckily the wheels have a slight lip on them allowing the them to just clear the beam. Thanks for the suggestion, I’ll try replacing the grey pins with the friction ones and see if it improves it.
I think the main problem is that the universal joints slide along the axle, so I might have to sacrifice a bit of ground clearance in favour of making it more secure.