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My experience changing the steering bearings


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gepe

 
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My experience changing the steering bearings

Mon Jan 27, 2014 9:18 pm » Post: #1 » Download Post

Ok, probably the super mechanics amongst you all know this (just skip this post) but I assume there are others like me with little experience who will appreciate this post.

Over the weekend I changed my steering bearings.

Disassembly is quite straight forward. Instead of removing the lower inner race by brute force I cut a slot in the race with something like a dremel. Because the Dremel cannot cut it entirely, I use a screwdriver blade which I drive in the cut slot and the blade acting as a wedge busts the ring. This also saves the lower dust seal.

Now getting the outer races in the steering stock is something different. A lot of books and other instructional material tell you to use a threaded rod, big washers and nuts to pull the races in. I tried this, it did not work in my case because the race would not be pulled in squarely. After thinking about this it is obvious it doesnt work: if a race tilts, the nut and washer cannot counterforce the tilt.

The method I used: I carefully tapped in the upper race with a piece of hard wood, a hammer and a lot of patience. I tapped it in a cross pattern, measuring now and then that it wa still square.

The method for the lower one is probably quite unconventional and I know there are some who will yell "NO". I just pulled in the lower race using the steering stem, adjuster nut and with the two (well greased) bearings in place. This arrangement makes sure the lower race is pulled in square. Tighten half a turn, turn the steering stem to the left and right to squarely seat the race, then the next turn and so on.

Now doesn't that overload the bearings? Not in my case. Honda specifies that at the end the adjuster nut needs to be tightened with 25 Nm. As long as you stay below this value it should be fine to pull in the lower race with this method.

I tightened the adjuster nut with a cheap stamped sheet metal c-spanner. I had attached a digital fish (or baggage) scale to it. This arrangement had an effective torque arm of 15 cm, i.e. I needed to stay below 16 kg to be below 25 Nm.

When everything was in place I tightened the adjuster nut with the c-spanner/scale arrangement to 16 kg, added the lock washer and the counter nut. Done.

Sorry for being verbose.

gepe.
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gepe

 
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Tue Jan 28, 2014 2:50 pm » Post: #2 » Download Post

I forgot to mention that I also checked with a spring scale that after adjusting the adjuster nut to 25 Nm the force needed to turn the front fork lies in the range that Honda specifies for road bikes.

I found a web site which has basic maintenance info for loads of Honda bikes; for road going bikes the force needed to turn the fork should lie between 1...1.8 kg (depending on model), with smaller bikes being at the lower end and bigger bikes at the upper.
I attached my fish scale to one of the fork tubes between upper and lower clamps and pulled on the scale. The reading was a consistent 1100 g. Test passed.
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greggo
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Wed Jan 29, 2014 1:08 am » Post: #3 » Download Post

If I was to use your method of installing the lower head race I would do that first using the old bearings and races everywhere else.

Eg remove lower head race
Cut slot in lower head race.
Position new head race
Place old over new and clamp into place.

That way only old parts are under pressure and at risk of damage. The only contact between old and new race is on the non bearing surface. And you can remove the slotted race very easily with a slotted punch.
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