I just changed the lower control arm on my 2007 Accord EX today. I bought the part from Amazon: Moog RK640290 Control Arm, I checked the new part with the old part and everything look identical but I noticed the ball joint did not go in as deep on the new lower control arm (maybe like 5mm shorter) because I could only put one side of the pin in instead of both side. I want to ask if it's normal and ok to drive like that?
Is the ball joint nut torqued up to spec?. The ball joint should fit very closely to the way the previous one fitted, and you should definitely be able to insert the split pin normally. You need to double check that the arm is indeed correct and that its specs are comparable to the original one. Thicker material around the ball joint socket or a narrower hole in the lower arm will cause this issue. Something is not right here so measurements need taking to identify the exact issue. I would suggest perhaps a faulty new part has been supplied.