XRAY - Model racing cars

I'm in the process of building a FK. If I leave the mounts loose it operates nice. As soon as I tighten the screws it binds. I'm considering sanding the plastic a little. What do you guys think ?

Tony thanks for the input. I have the aluminum rear hubs and they are fine. It's a binding in the inner rear suspension mount. I'm thinking it is caused by the angle the hinge pin is on. The arm pivots smoothly by it self on the pin and when I loosen the screw.

Well, given your statement I can only assume you are using the plastic holders that come with the T1R, not the holders with the metal inserts that are used on for instance the T1FK. The T1R holders are numbered with the numbers indicating the toe-in angle you will get with each holder. With the T1FK et al we use spacers to set the toe-in. If you have only limited or preferably no toe-in the pivot pin can rotate in the holders, but the more toe-in you set, the more the pivot will be pushed tight in the holders as the pivot pin is now angled but the holes in the holders are still parallel with the bulkheads. Hence it is very important that the arms can rotate freely!

That's quite possible. The key is that the suspension moves freely, both at rest but also when it is under pressure during cornering. If you've got that then you're ok. In fact, best would be if the pin can rotate freely in both the piston holders AND the arm as this will make the suspension even more free.