Hub conversion to tapered roller bearings

[m_e_jablonski]

When converting to tapered roller bearings in the front hub it's important to realise that you can't just assemble the bearings with the old spacers. The tapered rollers have an offset between the inner and outer races which results in a longer space between the inner races of the two bearings than the length of the original spacer. This offset needs to be compensated for by making up an additional short spacer 2.5mm long. I made mine the same diameter as the narrow end of the spacer tube. I also machined up a thinner inner spacer, the one the seal runs on, to bring the hub back into the same position it would have been in with the original bearings. The offset of 1.25mm in the bearing pushes the hub out by that amount so I made the spacers 1.25mm thinner than the originals. The seal still manages to run on the spacer as it should. The hub needs to be trial-assembled and the end float or bearing clearance measured with a dial test indicator. I opted for about 0.002" to 0.005" on the recommendations of a bearing supplier. This is also the way the hubs on an MGB are set up. I have seen some recommend that a slight preload should be present between the bearings. This is probably OK since the TC does not have the heat input which a disc brake would provide. Whichever way you choose, you then have to use shims of varying thicknesses to achieve the correct endfloat or preload. I started by assembling with excess shims, measuring the endfloat and then subtracting the appropriate number of shims. It's amazing how, when you do that, even though the arithmetic is correct, the endfloat does not end up what you thought it would. So it's an iterative process to some extent. I've now run my car for about 200 miles on the converted bearings and everything appears to be running OK. I'm soon going to recheck the endfloat to see whether there has been any "bedding in" under cornering loads. Mark Jablonki Melbourne Australia