Alot of trial and error. I put the top bolt thru casesaver and loosely screwed it in then pushed the bottom towards the case until it made contact. The areas that it touched are where I filed it down. I took a little off and checked, then took a little more off, always following the contours of the case. I continued this until the lower bolt fit in the groove in front of the lower mounting hole of the case saver. Once it was filed, the lower bolt seemed to fit perfectly thru the top of the casesaver groove. It holds tight with close clearance to the sprocket. Anyone who's running the stock casesaver and a 15 tooth without grinding it is doing alot better than I was because mine would not go toghther without modding something. Hope this helps.