It is well documented on other websites that the main problem with adding metal tracks to any R/C tank that has been designed for plastic tracks, is the insredible extra stress placed upon the motors and gearboxes.
I have already had to replace a few gearbox bearings and 1 motor so far.
It has been my intention for quite some time to try and eleviate some of the stress caused by the use of metal tracks. To this end I purchaced a pillar drill and a few drill bits that i thought would suffice to complete the mission in hand.
The mission- To add support and reduce the friction caused by the add on brass drive shaft support.
I purchased some correct sized bearings and set about drilling the hole necessary to accomodate the bearing (14mm).
My plan was to drill out the hole to 13.5mm then heat up the brass drive support so it would hopefully expand to the required 14mm and then drop in the bearing, the cooling of the drive shaft support would then lock the ball race bearing in place.
I could not have been more wrong!
The thought had already occured to me that heating the brass support (a disc with a hole in it) would mean that the outer diameter would increase and a possibillity that the inside hole would get smaller with the overall expansion, but i carried on regardless to see what would happen.
My worry was well founded...after heating the support the inside hole did indeed shrink in diameter!!
So, with there now being only half a millimeter (radius) to play with to get the bearing to fit, i resorted to gently grinding the tiny amount necessary to enable a tight fit.
With the tight fit gained i then used super glue to keep it in place.
Just to make sur i gave it a belt with a hammer and i can asure you it aint coming back out
The picture below shows the original drive shaft support 
The picture below shows the modified support with bearing in place. 
Stay tuned for more homemade upgrades gang!!!