Thursday, September 20, 2007

Race Face X-Type BB bearings upgrade

Before clocking 900 km (562 miles), the Race Face X-Type Bottom Bracket (BB) bearings began to squeak and drag.

"DO NOT DISASSEMBLE" is stamped on each BB cup, but the units can be successfully taken apart by anyone with average mechanical aptitude. I will not duplicate Hercubus' excellent write up on the procedure (also applicable to Shimano External BBs). Chewieez also shot a 24-step pictorial of the process.

A combination plastic dust-cap-and-shim sits on both BB cups.

After the plastic dust-cap-and-shim is (carefully) removed.

There was no grease left in the cartridge bearing, only water. I never wash my bike using a pressure hose, or even a garden hose; all I use is a scoop; and I remove the seatpost and flip the bike upside down thereafter.

The non-drive side was pretty much in a similar state. There was almost no grease left, just a milky film. What do they use in there? Half-and-Half?

To have this occur within 563 miles (900 km) is unacceptable. Not surprisingly, the Race Face X-Type BB scored very low in MTBR Reviews.

Peter Verdone has an interesting take on the design flaw in Race Face's X-Type BBs:

Bryan and I did a little research on my failed Shimano and Race Face bottom brackets, and this is what we learned. The Shimano bearing cartridges were labled HIC (Japan) 6805RD, (25 ID,37 OD,7 WD) with 15 x 1/8" bearings and a steel retainer. The seals were superior to the Race face unit in every way. The side that failed did so because it was contaminated solid with grit, but the bearing still worked and not too poorly either. The good side was clean and greased and rolled very smooth. The Race Face bearings on the other hand had branded seals (always a bad sign) labled RACEFACE X-TYPE 6805 LLU MAX. This is a full complement bearing, meaning that they forgo a retainer and put as many balls in the bearing that will fit. These bearings for example had 30 x 1/8" balls. Full compliment bearings are only meant for high radial loads. They are very prone to failure under axial loading due to the cutout required to assemble the bearings. These types of bearings have no place on any part of a bicycle (not even for suspension links). The reason that the Race Face BB froze was because the full complement bearing only left 0.050" of gap for all of the bearings to share. Besides the fact that these bearings were rubbing against each other almost contiually, once the seals failed and some dirt was allowed in, the unit resembled more a mortis and pestle than a bearing. No gap was left for the dirt to go, so it was just go ground in by the bearings until everything locked up.

Since there wasn't any grit in the bearings (unlike this), I decided to try and salvage the bearings. Here, a grease gun proved invaluable.

Repacked non-drive side BB bearing.

Repacked drive side BB bearing.

Bearing seal replaced.

The salvage operation turned out to be a failure. Despite the introduction of fresh grease, the non-drive side bearing was pretty much gone.

Options available at this point:

Complete units:

Shimano XTR M970 External BB (fully compatible with Race Face X-Type) US$29.95 x 2 (much cheaper in Singapore at SG$60 a set)

Enduro Ceramic Hybrid Outboard BB Bearing Cup Set US$109.99

Enduro Chromium Steel Outboard BB Bearing Cup Set US$56.99

Reuse (fragile) dustcap/shim and BB cups:*

Boca Stainless Steel Bearing Kit US$94.95

Boca Ceramic Lightning Yellow Bearing Kit US$118.95

Boca Stainless Steel Race, Ceramic Hybrid Bearing US$67.95 each (need 2).

Phil Wood Part# PWX05 Mfg# 6805 Bearing US$23 each (need 2).

Reuse BB cups:**

Enduro Ceramic Hybrid Outboard BB Bearing Upgrade Kit US$65.99

Enduro Chromium Steel Outboard BB Bearing Kit US$14.00

* = Bearing press required. E.g. Phil Wood Outboard Bearing Replacement Tool.

** = Proprietary bearing press required.

I went for Enduro's Chromium Steel Outboard Bottom Bracket Bearing Kit and had them pressed in locally at Chapter 2 Cycle.

Race Face BB bearings (bottom) have an inner diameter of 25 mm, and require a 0.5 mm plastic shim. The red seal faces outwards, and the black seal, inwards. Shimano External BBs also employ a plastic shim.

Race Face X-Type BB bearing specs:
6805 LLU MAX
Outer Diameter (OD) 37 mm
Inner Diameter (ID) 25 mm
Width 7 mm

Enduro Outboard BB bearings (top, pressed into BB cups) possess a smaller inner diameter of 24 mm, doing away with the plastic shim.

Enduro Outboard BB bearing specs:
Outer Diameter (OD) 37 mm
Inner Diameter (ID) 24 mm
Width 7 mm

There are 2 problems with the plastic shims employed by Race Face and Shimano. In addition to rendering the crank spindle / Bottom Bracket assembly less rigid, it also makes cleaning and repacking the bearings more difficult. As the picture evinces, the plastic shims are also fragile. The one on the right broke when I removed it for the second time. The shims are critical for proper spacing of the crank spindle. Without them (or with a broken shim), the crank spindle would rattle around the bearing and ruin itself in short order.

Integrated plastic shim + dust cap specs:
Dust cap OD 40 mm
Shim ID 24 mm
Width 9.3 mm
Shim thickness 0.5 mm

BTW, if you think removing the plastic shim / dust cap without it breaking is difficult, wait till you try putting it back in  :-P

Doing away with the plastic shim / dust cap, Enduro supplies 2 pairs of auxiliary silicone seals with their outboard bearing kits.

Auxiliary seals (use one or the other)

Blue seal
OD 37 mm
ID 24 mm

Red seal
OD 40 mm
ID 24 mm

Both types of seal have an angled "lip" on the circumference, and a V-shaped, double-contact lip on the inside.

The instructions (PDF) state that the steel-backed o-ring seal outside the bearing MUST be removed. Some local vendors mistakenly reinstall them and then, upon discovering that the 40 mm red seal no longer fits, direct you to use the 37 mm blue seal instead. This is wrong. Enduro clearly states that the o-ring seal must be removed or it will interfere with the new sealing system.

Again, as official instructions (PDF) exist, a duplicate write up is unnecessary.

To reinstall the BB cups into the frame, I prefer Park Tool's new BBT-19 instead of the more common design, BBT-9. Sonny's Bike Tools makes a similar tool, X-Type / Outboard Bearing Cup Installation and Removal Tool, but it is made of aluminum and costs more.

In addition to offering a more secure grip, the other advantage of the Sonny's Outboard Bearing Cup Tool or the Park Tool BBT-19 design is that it allows the use of a torque wrench. Zinn and the Art of Mountain Bike Maintenance suggests a range between 35 to 50 Nm. I tightened mine to 42 Nm.

Enduro bearings are packed with Super-Web Grease. This grease is incredibly sticky and stringy — think Natto or chewing gum on asphalt on a hot summer day. However, as stipulated by Chris2fur (of Enduro) on a forum, additional grease MUST be applied outside the bearing seal:

You should apply grease on top of the cartridge bearing so the silicone seal is lubricated.

Lacking a tube of Super-Web Grease, I used Finish Line's Premium Grease. Again, a grease gun is a very handy tool to have here.

Slip on the red auxiliary seal, install the crank, and torque to 30 ft/lbs. OEM instructions here (PDF), or continue following Enduro's instructions (PDF). Check for side-play or side-loading:

Anytime you change anything on your outboard bottom bracket setup, you ALWAYS have to re-check the bearing side-loading. If you have the Hollowtech II, this is easy, since all you have to do is snug up the spindle end cap. If you have an outboard system that uses a standard crank bolt that gets torqued down, then you must test the tension as you torque the bolt down. Since the reddish orange silicone seals are slightly thicker than the blue spacer/seals, a Race Face type setup using a crank bolt may require the removal of a spindle spacer. Our online instructions (PDF) for this type of outboard system are pretty clear about this.

It will take a couple hundred miles (320 km) for the bearings to break in, but the increased stiffness in the cranks was immediately apparent.

Sometimes new is not better. While the external bottom bracket designs may be stiffer, bearing life seems to be significantly shorter. In comparison, traditional square taper bottom brackets last forever. The Shimano UN-71/72 lasted 8000 miles (12800 km) on Michelle, my 1992 Bridgestone MB-3.

With regards to square taper-spindle-to-crank-arm durability issues, I have a suspicion that loose or rounded square taper crank arms are principally the result of improper assembly procedures. E.g. not employing a torque wrench during installation, and consequently, failure to torque the crank bolts to proper specifications. Or, greasing the BB spindles — square taper bottom bracket spindles must never be greased. Square taper bottom bracket spindles should be cleaned of oil and grease before crank installation. Grease may allow the softer aluminum crank arm to slide too far up the steel (or titanium) spindle, causing it to round out.


Anonymous said...

Great, just what I was looking for getting rid of the plastic shims.

Rach said...

Thanks so much for this! I have had so much trouble with mine. I will upgrade. :)

-ben said...

Happy trails!


Anonymous said...

Thanks a lot for the solution to plastic shims.Mine broke after only 20-30 miles.I expected more from race face

-ben said...

'Glad it helped.

The Enduro replacement bearings are much more robust and shouldn't give any trouble when installed according to specs.