[QUOTE=Frank L;10650452]I have built many many serpent 811 vehicles and have not had an issue with the sun or spider gears. I would build it and run it. I'm sure it will settle in.



Thank you so much for your kind reply. I have figured out a foreign material inside the diff fluid that was causing the issue , I fixed now and it is okay..

I have finished building the rear end totally, the diff gear and the pinion was working fine until I mount the rear end on the main chassis with 4 screws. after that the diff box was more tight and when I rotate the main rear shaft , at some point the diff gear and pinion make rattling sound and harder to rotate. after that point it is smooth.. do you think this is normal until break in? I used the shimming exactly mentioned in the extra sheet of serpent. many thanks.