Hi Mike. The old style carbide inserts fused to the end of the tool bit work good. The tooling for the little detachable inserts is quite expensive. One thing I learned is the old style cutting tools, including high speed and cobalt steel, will work with ti if cutting speeds are kept low.
The oil seal around this aluminum rear wheel spacer wears out quite fast. The spacer is a loose fit in the worn seal and water can get inside of the wheel assembly. This is bad for the wheel bearings and the corrosion it causes makes it hard to remove the axle. The solution has been to pack all crevices with blue waterproof boat trailer wheel bearing grease. This works and it is a messy and mickey mouse solution. It is time to make a legitimate repair.
The worst thing a builder can do is to hop to conclusions about oil seals. The obvious are checked first. The seal is the correct size, type, and material. It is installed properly and the seal material is compatible with the outside environment and the goop it needs to contain. No problems here.
Next, seal info is obtained. This is a page off of the i-net. Shaft tolerance is checked first. The writing on the seal says it is made for a 35mm diameter shaft. The shaft diameter is the outside diameter of the spacer and it is less than 4 inches. The shaft tolerances are 35mm plus or minus 0.003 inches. This is 1.375 to 1.381 inches. The spacer O.D. is 1.372 inches diameter. It is 0.003 inches too small. A problem is found.
The seal rests in its own circular bore. The bearing fits in another bore. The centerlines of these two holes should be close together. The Shaft Offset table on the technical information page says the offset between the two centerlines should not be more than 0.008 inches for a 1.38 inch diameter shaft. This measurement is made by removing the seal, installing the axle, and measuring the distances between the sides of the axle and the seal housing at different locations. The measurements show the seal housing and axle centerlines to be really close, and within 0.0001 inches. No problem here.
Now all of the items under the "Configuration of the Bore" heading on the technical paper are checked. This is pretty straight forward. All are OK.
Shaft runout is checked last. Silicon rubber seals are the blue line on the graph. The other seal types are on the red line. This seal is NBR as best as I can tell by looking at it. The wheel turns just over 2,000 rpm at 150 mph. The chart says the maximum shaft runout is 0.007 inches for this speed and material.
The clearance between the axle and the inside diameter of the spacer is 0.017 inches. This means the spacer can be installed in a way that makes the shaft runout as great as 0.017 inches. This is far too much. The excessively offset spacer was wearing out the oil seal.
The solution is to make a new spacer. It is turned to 1.378 inches OD and this is right in the middle of the recommended tolerance range. The inner diameter of the spacer is turned to give 0.005 clearance between it and the axle. Problem solved. It is always good practice to check all of this stuff before putting anything together. It saves a lot of trouble later on.