While searching the Internet to learn what makes the baker 6 speed, how it is made and researching bearing failures, I ran across this article. Thought I would throw it out here to hear other people thoughts on this. Dr. Chaos Service Bulletin #26 speed transmission bearing failure. There has have been numerous reports on trap door bearings and the main shaft main ball bearing going bad prematurely on six speed transmissions on all makes. I have personally seen bearing damage and main shaft bending from the Rev Tech 6 speeds. I've also heard from very reliable sources that Baker and yes even Harley has have had trouble with their six speed transmission bearings. The next sentence is not entirely accurate but will suffice for this discussion. The six speed transmission uses pretty much the same design as the proven 5 speed design only with an extra gear. The problem is, is with the main shaft and the fact that the clutch pack is mounted so far away from the shaft support which is the main shaft ball bearing. The main shaft and the clutch pack is unsupported at the end. The clutch pack hangs off the end of the shaft and is flexed back and forth by the torque of the engine. The tightness of the primary chain and the secondary drive belt also contribute to stress on the main shaft bearing, which then this transfers the force to the trap door bearings. This unsupported main shaft design was adequate with a 50 or 60 hp engine putting out low torque numbers. With the recent trend in high HP and high torque engines and ever increasing and cheap affordable cubic inch upgrades, like for the Twin Cam (95 cu in.). T the 5 -speed transmission is meeting its design limits. Remember the stock 5 speed transmission in 5th gear is a 1 to 1 ratio, which turns the rear wheel one revolution for every full revolution of the engine. Now enter the 6 speed transmission with a final drive ratio in 6th gear of .83 to .89 (overdrive). Which means the rear wheel turns only .83 to .89 (roughly) of a revolution while the engine turns one complete revolution. This means that there is a lot more torque being transmitted to the unsupported main shaft with the same clutch basket hanging off of the unsupported end of the shaft. What this does is stress out the main shaft bearings and the trap door bearings prematurely before their time causing transmission failure or at the very least an early rebuild. I have seen 6 speed transmissions from every major manufacturer needing bearing overhaul around the 20,000 to 30,000 mile range. Which is way too early! I think there is something we can do to slow down this process considerably. I think we are riding these 6 speeds all wrong (me included). I think we are accelerating far too often in 6th gear and not down shifting to 5th gear as we should. We do this because we can. We now have so much more torque with these more powerful engines that we can accelerate in 6th gear without downshifting. I believe This is the problem. If we do all our accelerating in 5th gear, then once we reach cruising speed, then and only then shift into 6th for cruising. That way no excess torque is placed on the unsupported main shaft and our aftermarket transmissions will and should last longer. Just my two cents.