allenshawn1, I build quite a few of these bakers a year and have built a quite a few for the members here. The problem is most often the bearing going out. The heli cut gears push the shaft out futher than the clutch apply spring can hold and it will start to slip. In some cases if the clutch is out of adjustment it will only take a little bit to make it slip in 4th gear if there is any play in the bearing at all. Fact is it depends on a few things as to why some of the DSSC transmissions fail within a few thousand miles and others make it much futher. Some of it to do with the bearings used,the input shaft having the proper heat treat, and cut, the clutch basket, shims etc. Feel free to call me if you have any questions at all. 704-989-2294 Bobby Schulz. Leave me a message and I will get back to you.