Posted on Friday, October 16, 2015 - 02:37 pm:

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quote:

Posted on Tuesday, June 30, 2009 - 10:30 pm:

I have spoken with folks at Buell that are quite knowledgeable on all of this, and can provide the following info.

1) The original FAG bearings (black) [comment- used on early XB's] were replaced by NTN bearings that had better seals and less hygroscopic grease. The new KBC bearings have yet again better (stiffer) seals and still better grease. They also have a better lines of communication into the bearing supplier themselves. Bottom line, the change to the bearing isn't just some cost cutting move..they ARE better.

2) The design of the wheel shoulders and internal spacer tube are such that in the worst case tolerance stackup of NEW wheels, bearings, and spacer tubes, the inner race on the bearing OPPOSITE the caliper/rotor will be seated against the inner spacer with just less than 0.5mm clearance between the rear wheel shoulder and the outer race, and just less than 0.25mm on the front wheel. All of this assumes that the bearings are installed correctly (rotor side bearing seated in wheel, spacer installed, opposite bearing installed until inner race seats against spacer tube). What this means is that IF the bearings are installed correctly, AND the spacer tube is not damaged, overtorquing the axle slightly shouldn't cause an inelastic deformation of the spacer tube. If Mongo gets a hold of it and gets brutal with the breaker bar during installation, all bets are off.

3) The bearing installation tool is designed to push on BOTH the inner and outer races in a plane. During installation of the opposite rotor side bearing, if the installation forces are applied to EITHER, but not both, of the races, you can potentially damage that bearing. If you use the old "socket on the outer race with a hammer" method, you'll probably ruin that, and possibly both bearings. You'll likely coin the bearing races, and might damage the spacer, if you seat the outer race against the wheel shoulder on that side. And regardless of the potential bearing damage, if you walk that bearing in which is easy to do with the hammer method, your interference fit of the outer race into the wheel may be compromised. Buell doesn't utilize thermal methods (i.e., hot wheel, cold bearing) for installation, they rely on process control and proper tooling.

4) When a bearing goes more than a little bad, it is possible and likely that the end of the spacer tube can be damaged. In this case, the margins afforded by the design as described in 2) above can be affected. Some bearing removal tools can also damage the ends of the spacer. So inspect that spacer tube with each bearing change.

5) Related to 4, future service manuals may provide for an inspection dimension on that spacer tube. But it isn't there now, so here are the nominals:
Rear Spacer Tube: 202.8 +/- 0.05 mm, 7.984 +/- 0.002 inch
Front Spacer Tube: 107.9 +/- 0.05mm, 4.248 +/- 0.002 inch

Hopefully this is helpful info.

Al

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