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Changing head bearings
Original article submitted by Macca

If you've got the wobbles in sweeping corners or knocking noises when braking, chances are your head bearings are at fault. The trickiest part is that during inspection or replacement the front end of the bike has to be off the ground.

How you do it depends on you, who you know and what you've got. I am lucky because i use a sling over an iron girder and winch it up, but however you do it, bear in mind that you will be working in the headstock area A LOT, so it must be as stable as possible but allow full access to every component at wierd angles. It's better to suspend it with the weight bearing down WITH the support, rather than the weight bearing down ONTO the support.

And remember the forks are coming off so it will need to be high enough off the ground to allow them to drop clear. You SO dont wanna be adjusting the support with the front end attached and flapping around.

To do the job you will need a few vital bits:

  • New bearings (no shit, Sherlock!)
  • Quality clean grease
  • C-spanner
  • A drift (straight metal bar approx 12mm dia 12" long)

First thing, take off the petrol tank and upper fairings. Loosen every bolt that attaches anything to anything from the handle bars forward ('cept brake unions!!!!) Install your method of raising the front and lift it up to approx 18". Give the bike a hard shake, it's better to find out if the system is good with the front wheel attached and the sidestand down.

Click the thumbnails to view full-size pictures
Next thing is to undo the two sunken allen bolts in the top yoke to release the clip-ons and then remove the top yoke itself.
Now is also a good time to undo the brake calipers and loosen the pinch bolts on the bottom yoke all the way out. Release the pinch bolts on the clip ons and wiggle the forks down so the bars will be able to come off the top of the stanchions. Slide the fork assembly out from the bike and stand it up somewhere.

Click the thumbnails to view full-size pictures

Now you need the C-spanner to slacken off the two locking washers on the steering stem, take them off and the top bearing will be loose on the stem, remove it and slide the bottom yoke and stem out.

One bearing will be loose on the top of the headstock (nice bearing); one is pressed onto the bottom of the stem (bastard bearing). The races are the shiny inserts in the top and bottom of the headstock (when wiped clean of grease).

Old bearings on the... erm... right. New races on the... uummm... left.

Click the thumbnails to view full-size pictures

Next thing is to remove the old races from the headstock. Use the drift and tap the bottom one out from the top of the headstock and the top one out from underneath. Make sure you tap them quite gently and in circles, they will move slowly at first, just keep tapping around the edge and they will pop out.

To remove the bottom bearing from the headstock is quite tricky. My only advice is don't be shy, the thing was pressed on at the factory and you aint gonna use it again. Just make sure you do not damage the yoke or stem in the process. Doing it by hand is preferable to using a power tool, you have more control and a better feel for when it goes. I use a cold chisel and tap round the base in the same way as the races, holding the yoke secure in a soft jawed vice.

Once you have got this far, have a smoke and a cuppa, then clean EVERYTHING you have taken off, you prolly ain't going this far in for a long time and there will be no visible signs of all this hard work so while you're here...

A big hint for installation is to use the old components as drifts to install the new ones. A bearing turned upside down is the same diameter as the new one going in and will absorb any impact damage.

Also make sure that any washers under bearings are put on before the bearing is.

Re-grease the headstock and slide the new bearing onto the stem as far as it will go. Slide the old bearing on upside down and tap the new one home until it is flush with the stem base.

Click the thumbnails to view full-size pictures

Grease the grooves the races sit in and tap home the new ones until they are flush all the way round the inner collar.

Now give all the new components a good coating of grease and work it into the bearings.
Reassemble the front end in reverse order that you dismantled it.

Once everything is back together, tighten the fork clamp bolts all the way and the headstock locking nuts finger tight, then lower the bike to the floor. This will allow the bearings to sit properly in the races.

Tighten everything to Mr Yamahamotosan's enlightened torque settings (ahem) and re-check everything is secure.

You will notice some unusual handling charactaristics shortly after carrying out this procedure but they are temporary and you will become accustomed to them quickly. Symptoms include actually going where you are pointing mid-corner, holding the line and smooth steering. The sound of a whore's headboard banging during braking is also likely to disappear.

Now you can go do stuff like this again.

Click the thumbnail to view full-size picture


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