13th January 2007
For about the last 12 months the bearings on my shimano Hollowtech II XT crankset have been loose and graunchy giving a bad pedalling experience.
Replacement bearings are hard to come by and even if you do get hold of some it's unclear how you press the existing bearings out of the shell. Anyway, I finally tracked down some replacement cups and bearings from a great little place in the states; Enduro Fork Seals.
They also do replacement bearings on their own plus a bearing press but I ordered a set of oversized bearings inside replacement cups which duly arrived and I got down to fitting them yesterday.
They have made a real difference to the ride being really smooth and have much improved the whole feel of pedalling now that the grinding, wobbling motion has disappeared. I hope they will last a lot longer too because of the oversized nature of the bearings.
Straight out of the packet; includes two replacement cups with installed oversize bearings plus a selection of spacers/seals in various sizes and thicknesses.
Here are the existing bottom bracket cups. Loosen the bolts holding the non-driveside arm first
Use the Park Tools external bottom bracket tool to remove the plastic pre-load screw which will be all that is now holding the non-driveside crank on the axle and then remove the crank.
Push the axle through the bottom bracket. If it won't move then a bit of gentle persuasion with a wooden or rubber mallet will help. Remove the crankset completely.
Using the Park Tool again remove the non-driveside bearing cup. Remember, for non-driveside it undoes anti-clockwise. Make a note of whether any spacers have been used (plastic shims between the cup and the frame).
Now undo the driveside bearing cup. Remember, for driveside it undoes CLOCKWISE. Again, make a note of any spacers used.
Note that because the new cups use oversize bearings they are wider than the original shimano bearing cups. This affects the chainline and meant that I re-assembled the new cups without using the spacer I had on originally.
Install the non-driveside bearing cup first. Use some good quality grease on the threads. Note the quality casting on the titanium frame bottom bracket shell. No need for facing here. Tighten using the Park Tool.
Install the driveside bearing cup. Again, grease the threads and tighten. Note, the driveside Enduro Fork Seals bearing does not have the plastic sleeve seen on the shimano version. The inner race of the Enduro bearing has a smaller circumference and contacts the axle directly.
There's no need to grease the top of the sealed bearings but a bit of grease helps the red spacer to stick in place as required. Place a red spacer on each bearing surface with the 'gold' colour facing inwards. I usually tuck the chain behind the bearing cup now so it is the correct place when you replace the cranks.
Grease the axle, ensure a red spacer is in place and push the axle through the driveside bearing cup. Again, a gentle tap with the mallet will ensure it is fully seated.
Push the non-driveside crank onto the axle ensuring a red spacer is in place. Grease the axle end cap and using the Park Tool screw into the end of the axle. Very little pressure is required to pre-load the bearings and overtightening can cause premature wear. Tighten to approx. 4-6 inch pounds.
Tighten the crank arm bolts, alternating between each bolt to ensure an even load.
Put the chain back in place and go out to road test.
photos and content copyright of Richard Sear 1999 to 2015
all photos and content copyright of Richard Sear 1999 to 2015