Hey All, as the title says. The steering head bearing keep coming loose on me, never had it happen to Me on any of the other bikes I've fitted new bearings to in the past, the once or twice after fitting is normal but this K is doing it constantly. The next time I do it it's going to be around the 6th maybe 7th time!!

Slacken off the pinch bolts and the top yoke nut then get a grip of the big knurled cover underneath the top yoke and tighten, finish by tightening everything back up.

Am I missing something?

Did you do a head bearing job recently and maybe the bottom bearing isn't fully seated or the top bearing is not fully seated downward? I have had that happen on a bike years ago. Methinks the most likely cause.

The alternative is triple tree coming apart, check that when you are tightening the knurled nut that its not pulling the tube out of the bottom yoke. It's unlikely and shouldn't happen though....unless you get a less than expert machine shop to pull the whole lot apart.

bettyswolloks wrote:
Slacken off the pinch bolts and the top yoke nut then get a grip of the big knurled cover underneath the top yoke and tighten, finish by tightening everything back up.

When you slack the pinch bolts, are you sure that the fork tubes can freely move into the top tee?
My way to do is:
slack the top yoke nut(#4). Remove the two pinch bolts(#6) and insert a wedge (A screw driver works) in the slots (both sides). The top tee should be able to move up and down freely.
Adjust the big knurled nut(#7) and tight the top yoke nut(#4).
reinstall the two pinch bolts and this should be OK.
The knurled nut is kept in place by the pressure of the top tee on it. If the fork tubes are binding on the top tee, you may not be able to push the tee far enough on the knurled nut.

Also, check that the center tub is not coming apart from the bottom tee.

I have just done my steering head bearings! The biggest challenges were getting the front mudguard off: bolt and nut had rusted on, and, I managed to strip the thread of the soft ally brake pipe union with the banjo! Gonna do a thread repair shortly and see if that solves it! I've heard it said that "slightly tighter" is better than "slightly looser" re adjustment? While I'm here, does anyone happen to know the thread size of the banjo bolt in question?
Thanks.

Thread repair size is what I'm actually after, if that wasn't clear!

The K brake fittings are threaded M10 x Imm pitch.

Paul.

Thanks! Is the thread insert I need a M10x1 spec?

Yes.

Standard 10mm is 1.5mm pitch
Standard fine thread 10mm is 1.25mm pitch
10mm x 1mm is also a standard fine thread but not as common as the 10 x 1.25
It may be difficult to find a tap.

I would not use a thread repair insert on anything to do with the pressure circuits of a brake system, it's looking for trouble.

BooG - PM me. I've got a good condition headstock brake pipe you can have. I hated the damn thing and replaced all of my lines with braided hose that runs outside the headstock.

Crazy Frog wrote:

bettyswolloks wrote:
Slacken off the pinch bolts and the top yoke nut then get a grip of the big knurled cover underneath the top yoke and tighten, finish by tightening everything back up.

When you slack the pinch bolts, are you sure that the fork tubes can freely move into the top tee?
My way to do is:
slack the top yoke nut(#4). Remove the two pinch bolts(#6) and insert a wedge (A screw driver works) in the slots (both sides). The top tee should be able to move up and down freely.
Adjust the big knurled nut(#7) and tight the top yoke nut(#4).
reinstall the two pinch bolts and this should be OK.
The knurled nut is kept in place by the pressure of the top tee on it. If the fork tubes are binding on the top tee, you may not be able to push the tee far enough on the knurled nut.

Also, check that the center tub is not coming apart from the bottom tee.

Cf when I did this I had the forks bottomed out so as to keep everything inline

Had to tighten them again today, as the mark I put in the big knurled nut is going further round I can only assume the bottom bearing wasn't fully home, even though it looked like it was. If it wasn't it must of only been by a couple of points, and I cant imagine a couple of points taking up this much space on the thread.

king youbettyswolloks wrote:Had to tighten them again today, as the mark I put in the big knurled nut is going further round I can only assume the bottom bearing wasn't fully home, even though it looked like it was. If it wasn't it must of only been by a couple of points, and I cant imagine a couple of points taking up this much space on the thread.

Don't be kicking yourself on that. The object of checking it after a bit is in case it wasn't fully seated, among other things. Far less risk of damage to the bearing too, some methods of driving them home can be heavy handed and end up damaging the new bearing. Can be scary but when you think of the pitch of the thread on the nut even a quarter turn feels like a lot but in fact is very little.

There's a knack/procedure for fitting taper rollers, assuming you haven't bought/made the tool for doing it.

The first one is to tap the outer race in as far as possible, then fill the inner race with grease. Reassemble everything as necessary (in your case, refit the yokes), tighten it down until you think its fully home, then give it another 1/8th turn; no more than this because you don't want to brinnell the outer. You'd be surprised how often there is still movement in the outer race. Continue until you are certain that there is no more movement, then back off gently until you have free movement but no play.

The other is to save an outer race from the previous bearing change and use that as a drift. There is a complete and distinct change in tone when the new outer race seats correctly. If you want to make life really easy then weld a bar across the old outer race and weld a handle to that. Voila - a factory tool for the sake of spending half-an-hour, rather than half a fortune.

Thanks for all the advice so far! Regarding the thread repair on the brake circuit; I'm gonna wrap the thread on the banjo bolt with ptfe tape, as well as the insert itself. If it leaks, then its "get a replacement" time! Won't be able to do it till next Saturday now so I'll tread water till then.

Some research tells me it is Ok to use ptfe on brake circuits. It will not brake down on contact with DOT4, and will resist temperatures well above what a caliper will subject it to.

Some experience tells me not to use PTFE on any brake circuit, It can and usually does break up and foul the seals and cause leaks which ultimately lead to failure.

I'm with Rick. Sufficient pressure and the whole lot will just fly straight out.