This is how I modifed the Brakes,
They are the Tamiya
Skyline R34 GT-R Nismo Parts
Take a peice of 3.2mm (1/8") Plastruct tube, This has a hole (bore) of just under 2mm which is the same size as the pin on the tamiya wheel.
I cut a small section of Aluminium tubing (K&S) 5/32" round and inset into the suspension unit, the bore of the 5/32" tube is about 3.2mm so they all fit together nice and snug.
I will cut down the plastic tube to length on test assembly to get the wheel base just how I want it.
Hope that make some sorta sense ?