Peggy,
Don has a good point. It did not register whem I first read this post but I think you answered the question yourself. If your ped is now 5 mph faster, you have probably changed the ratio of the belt drive by using an out of spec belt. This may also explain why it was so dificult to install. Of course, grease on the clutch or brake is bad for thier operation but could not possibly increase your top speed.
Ron