A rake or a blade will only scrape the high spots, & deposit loose stuff in the low spots. The washboard will quickly re-appear even in good conditions, as wheel traffic pops the loose stuff right out again. The best thing to do is to cut down a few inches & start over with the roadbead, remaking the top of your road. A rake can't do that.
A regular duty blade can barely handle it. And it takes time & work & maybe new gravel.
In any case, the wheels would be of _much_ advantage, and you want to angle the blade (or rake) as much as possible & make several passes to level out the washboard.
If you take a blade (or rake) without wheels & leave it perpendicular to travel, you will actually increase the washboards, as your tractor bumps up & down, that is transfered to the blade.....
As much art as science in all this, what kind of surface are you starting with, what kind of weather do you deal with? A blade or rake can help maintain things & keep them from getting out of hand, but if you really have washboards & want to solve the problem, it will take some work.
--->Paul