XRAY - Model racing cars

Hi,

I am just re-assembling my car and two of the driveshafts are ok.

The other two move freely up and down about the pin, but not up and down about the actual coupling, it is very stiff.

Any ideas?

I hAd the same problem last week, I found some flash around the actual coupling and the drive shaft. it wasn't so stiff but not as free as the other three, after a while I replaced the grub screw and now it is as free as a bird.

Hope this helps

Yes, my guess would be the grub screw too. They are a little shorter than the normal grub screws used in pinions. Pretty easy to make a mistake and put the wrong size in...