let me tell you a short story,i to this day have no explination for this.i got a bunch of 767 brushes about 7 months ago that really sucked.i left them in my box and have not used them since.i went to running 4499's that i had and they were good.then i went to a good batch of F's and they were a little better.then 2 weeks ago just for the hell of it i decided to try those crumby 767's again.let me tell you,they were off the charts.hands down the fastest my motors have ever been.my only guess is that they may have shelf hardened over time but when i say they were better,it is drastic.before,they would draw 5 amps at 2 volts at 6000 RPM in a KD.normally i would throw that motot out.2 weeks ago,that same batch made my motor draw 10 amps at 10000 RPM.i geared the piss out of it and my god,the fastest 19 turn i have ever had in my 1/12th.sorry for the rant,i just found this amuzing.

i have run xxx brushes and i ran them for a while.they work very well.i change up sometimes just to try different combos.i have a ton of them though and i plan to run them again soon.i believe i still have about 150 pairs left
i will be trying some different cuts and spring combos in them to see what i can accomplish with them.they do work well though