[Cool Kat with Hot Car]

I have rebuilt 7 Columbias using Deat's method. The first one was done over thirty years ago and is still going strong. One thing I don't get in step 2 A&B is why assemble the carrier assembly with the axles, and in the case of a Columbia why assemble the guts for this step. It seems to me that the point is to determine the crush between the carrier bearings and the housings and the addition of the extra parts just increases the effort. Any thoughts by Columbia builders?