I broke 3 pcs of these in one single novice circuit, 2 were impact from another car. Noticed the broken shafts were all along the retaining pin hole. Looks like that is the weakest point in these shafts. I compared the stock shafts and found stock retaining pin holes were much further in from the threads. Make sure to use these without any side impact.
Along with the main shaft you must definately purchase this product as well. It fits perfectly with your yeah racing main drive shaft and decreases the friction between those two parts. One of the most important upgrades for your car is main shaft that gives the full power of your motor to all four wheels drive. If you are planning to upgrade your car with more than 3-4 aluminium parts for your chassis it would be better for you to buy the full upgrade kit from yeah racing witch contains aproximately all posible aluminium parts that exist separetely and if you calculate overall comes much much cheaper than buying one by one piece separete. Also if you dont want definately the blue colour, in free shipping options you will find the conversion car kit for tamiya tt-01, tt-01e, tt-01d etc, in..