Deep groove ball bearing preload?

[Andrew Stein]

I'm working on the front wheel bearings of a Lola T200, which are a pair of deep groove ball bearings (6208-2RS, SKF#) mounted in the upright. The old bearings, which are sealed both sides, had eventually expelled their grease on the inside of the upright and the spacer between the bearings had remnants of some very thin shim material that no longer had contact with the inner race. My question is if the spacer should be set with any preload or not. Another thread, on a Lola from 1999, had a 0.0025" preload specification, but I don't know if that was a deep grove ball bearing, taper bearing, or angular contact ball bearing. https://www.apexspeed.com/forums/sho...earing+preload

[R. Pare]

.001 - .0015 preload is more than enough. The side loading capacity (axial) of deep groove bearings is only a fraction of their radial capacity, so the load on the balls from the preload is additive to the axial loads from your cornering, so the preload needs to be kept very low. Unfortunately, I don't remember what amount of preload we set to with one of our old upright bearing designs.

For the spacers, get them heat treated, otherwise they possibly will crush down some in use.