Okay, to dispel a few comments about my cracked M05 chassis:
1) I did use Tamiya screws to tighten down my steering (box stock)
2) I did not over-tighten.
I fully understand that with Tamiya plastic you tighten screw until it is snug, not super tight!
3) Loctite or CA Glue: NO I did not use either as the directions did not specify to use them when putting screws in.
4) I am running stock silver can motor, I have only crashed about 6 or 7 times total/period. And those crashes were more like tumbles ...as the car rolls and not really crashes at such low speeds. I have never run brushless, etc in this car.
5) all parts/upgrades have been Tamiya approved parts (per TCS / my clubs rules).
Here are my 3 theories on what happened:
1) a chemical reaction. The two known chemicals I used on this car were Simple Green to clean the car, but not a very liberal amount. I sprayed onto a rag then wiped down my car. I don't think any Simple Green got under the steering down into the area where the crack was. The other chemical I used was "Banana Lube":
It is a general purpose oil, I use it wherever there are moving parts to help reduce friction.
2) a bad run of Tamiya plastic
3) initially there was a tremendous amount of steering slop and not centering issues when I ran the stock setup. I tried adding a second rubber "o" ring inside each of the outdrives (I read this on someone's M setup as helping to get the slop out of the steering and help w/ it centering). ...This I believe could have created extra stress as the slop was removed from the steering and thus the stress placed on those two post holes -where they cracked.
I did take the o rings out though and removed the entire stock steering setup. When I did that I did not see any cracking. So not sure if the extra o rings were the issue?
I am now running the Tamiya branded aluminum steering setup, servo saver and cv steering joints.
I lean towards either stress from the O rings or a bad batch of Tamiya plastic as the leading issues that could have caused this.
My new chassis did arrive in the mail yesterday. I noticed that there are very fine mold lines running along each of the steering post holes ...so I believe that this is a spot that could be prone to crack ...as there is a manufactured mold line here.
Well, hope that I don't have to post more cracked chassis photos!