I'm going to be that person who revives an old thread! It seems so rare in FIRST with changing people, changing kit parts, etc, that we really get to look at the long-term results of our designs.
In 2005, FRC190 utilized a mecanum chassis for the first time on the team. We had great concerns about the CIMs overheating in this style drive (the CIMs were new to the FIRST world back then).
To combat this, we modified the casing of the motors, allowed by the rules that year, with a large hole on one side and three smaller holes on the opposite side. A fan was mounted on top and the outer casing was turned down to remove the paint on the outside. This entire process was done solely to improve the cooling of the motors.
It caused a bit of a ruckus when it was learned that we did this, with some of the folks who post on here very concerned that we were at risk for some dangerous outcomes. You can see this closed thread for the details:
http://www.chiefdelphi.com/forums/sh...ad.php?t=33313. On a side note, we DID NOT ask that Q&A, as the rules clearly stated casing modification was allowed so there was no reason to. However, another team who saw our robot asked because they didn't think it was supposed to be allowed and they misunderstood why we had done it.
Well, I'm happy to report 10 years later our 2k5 chassis still runs as happy as ever, with the same exact modified CIMs we competed with back then. The attached picture was taken earlier this season as the kids wired it up with the RoboRIO for program testing and driver practice use.
The fans have long failed, rollers have jammed and been replaced, and the encoders rarely work, but the motors have never been replaced. This chassis is used almost every year for some purpose, very commonly as an aggressively-driven defensive opponent in our driver practices. It's seen hundreds of hours of driving time more than your typical FIRST robot.
It remains to be seen if there would have been a cooling issue WITHOUT the modification, but the modification certainly never saw the catastrophic (or any) failures that were predicted.