Has anyone else experienced this problem with vehicle design?

[soonerfan237]

So, I built a nice rocket. I took it into orbit around the Mun and brought it safely back to earth. I figured I was now ready to actually land on the Mun so I made a couple minor alterations to the rocket (basically added landing struts and an RCS). However, this new rocket swerved out of control on launch. I verified that all the new parts were symmetrical and to make a long story short I basically tried removing each new part one by one to see which was causing the stability problems. But even after removing all the new parts (so that it was exactly the same as the rocket that successfully made it to the Mun) it was still swerving out of control. I reloaded the original (good) rocket and again had successful launches every time. As a test, I removed a single part and then reattached it exactly as before and the rocket started swerving out of control again. So the exact same rocket which was working beautifully 1 minute earlier, suddenly stops working if I simply remove and reapply a part. From what I can tell, nothing has changed with the staging or symmetry. I\'m kind of lost right now. Has anyone else experienced this?

[what-the]

I\'ve had ASAS cause stability problems with large rockets. The constant corrections it makes causes large (long) rockets to wobble and veer out of control. Also have you tried using launch clamps? I find that rockets sway on the pad and the small angle from vertical can be catastrophic. At least add more struts to connect lower stages to the higher stages.

[soonerfan237]

Thanks for the reply. I tried using a launch clamp but when I connected it to the top of the rocket it would intersect with the rockets on the lower stages (maybe it\'s too wide?). Is there a way to make the clamp reach out further laterally? Clamping it to the bottom stages didn\'t seem to help. I can try using more struts. But the biggest problem is that I already know the rocket is stable (it got me to the mun and back), but even if I just remove and reattach a part exactly as before it becomes unstable, which makes me think that any modification I make will just cause it to be unstable. Maybe my rocket is a bit too complex and I need to simplify things a bit.

edit: I ended up adding struts all over the place and it works great now. Thanks for the advice! I was hesitant to use struts earlier because I assumed they wouldn\'t disconnect when I jettisoned a lower stage. I\'m on the way to the mun now. Hopefully all goes well!