Friday, January 22, 2010

Get your bearings

[Note: My apologies for the layout of this post. Blogger's content editor is really unhelpful and unpredictable.]

As much as I miss riding outside at this time of year (my indoor CompuTrainer is a necessary evil), I appreciate the downtime to inspect and repair gear more deeply than the riding season normally allows. Suspension bearings are a case in point.

Last winter I disassembled my KLR (bravely: inside my office) and discovered, to my horror, that almost all the OE bearings were contaminated and in some cases scorched and pulverized. (Those little blackened toothpicks in the photo? Those are heat-charred rollers that fell out of the bearing. Check out the scoring on the bearing shaft beside!) Given the mileage on the bike (some 25,000 km) and its previous rider history (mainly commuting), I expected the bearings to be in much better shape than this. However, some internet research suggested that the OE assembly is somewhat lacking in grease, and these kinds of problems have sometimes shown up after only a few thousand km off the showroom floor. Ouch.

I spent the next few weeks disassembling my KLR so I could bash out the suspension and bearings. It really was bashing: hidden corrosion had seized things that should've moved with gentle persuasion. Pulling the bearings wasn't too big of a deal. Finding replacements proved otherwise. The obvious first stops, the local dealer and some online parts stores, led to costs that would represent a significant portion of the bike's value. For example, the dealer wanted something like $150 for ONE BEARING! And I had many to replace. Forget that.

Next I tried the local bearing suppliers. Upgrading to a -2RS bearing (double rubber seal) is a significant improvement over the single-seal OE crap. A good replacement bearing averaged about $8-$15 depending on size--one tenth the dealer pricing and available off the shelf! In the end, I found that Industrial Solutions in Ottawa (613-731-6161) had just what I needed for about half the cost of bearings from General Bearing. Sure they were lower-quality parts--but this is suspension we're talking about. The bearings don't need to be very precise since they don't even make a full revolution, never mind hit high speeds. It's more cost effective to have them sealed and greased properly in the first place, and replace them more often if necessary.

I reassembled the KLR using a high-quality marine grease on all internal parts that could be exposed to water. The resulting suspension was buttery smooth and seemed more compliant, and close inspections after some filthy dirt rides showed the grease sealing well.

From my KLR experience, I knew it was time to give my Giant Trance X some equal loving. I've had just two hard seasons of riding on this frameset, and the bearings seemed to have no play. But I wanted to get my hands dirty now rather than risk a mid-season rebuild which most likely would be required during the only nice weather.

Sure enough, disassembling the suspension and inspecting the bearings revealed some indexed movement and a less-than-fresh feeling. Time for a rebuild.

Pulling the bearings was a bit of a challenge. Using a fine threaded bolt and some carefully sized washers and nuts, I was able to wind out the bearings in most cases. Failing that, a strategically placed socket, wood blocks, and hammer blows drifted out the rest. Try to avoid this latter method if possible. The aluminum is fragile, and you risk ovalizing the bearing seats if you mess it up. I managed fine, but I don't like hitting bikes. It just feels wrong.

As with the KLR, OE bearing kits proved ridiculously expensive--over $100! A trip (actually several trips--I had problems counting to eight) to Industrial Solutions got me hooked up with approximately $4 bearings that were perfect--double seals and all. I saved at least $50 over alternatives I found online.

Reassembly proved challenging using the bolt/washer method alone, so I fired up my metal lathe and quickly spun off aluminum bearing presses for the three sizes of suspension bearing. These greatly aided pressing in the new bearings square to the seats. You could probably rig something using sockets and a really long threaded rod, but this worked for me and eliminated any risk of damaging the seals.

What a difference new suspension bearings make on a mountain bike! Because it's such a light machine, any misalignments or unnecessary friction has a dramatic effect on your ride. With the new bearings my bike regained its original plush travel and responsiveness to fine trail features. It's amazing how over time you become habituated to gradual loss of performance.

Not sure what bearings you need or how to replace them? Drop me a line and I'll be glad to help.
Here are the suspension parts I replaced on the KLR:
- 2 needle bearings on dogbone coupling shaft: IKO/Nachi TA2025Z. ID 20mm, OD 27mm, L 25mm. $9.94 each at Industrial Solutions
- Sleeve for needle bearings: Kawasaki 42036-1205; 15x20x8mm. Approx $22 at dealer.
- 2 large bearing seals on rear shock linkage: Kawasaki 92049-1181; Approx $14 at dealer.

I also replaced the F&R wheel bearings with good aftermarket parts. Again, much cheaper than dealer.

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