Steering head top nut.

[Ron_S.]

Yesterday I noticed a front end wobble on my '86 R65, first at about 25 mph when I released my hold a bit, then when back up to speed, too.  So, I checked the top nut, the one in the middle of the steering head.  It was loose, really loose.  Can I just tighten it or are there other problems I should look for?  I'm obviously grounded until this is properly remedied.  Any help is welcome.  

[Bengt_Phorqs]

I would ask if it was torqued properly then why did it loosen?  Suggest you go ahead and check your steering head bearings.  

[Ron_S.]

I also wondered why it was loose.  I bought this bike last August and hadn't touched that area until now.

[Barry]

The top nut wasn't torqued up properly. I don't believe for 1 second it's possible for the top nut to come loose on it's own. They are or should be torqued up seriously tight and are usually a real bear to undo due to the large contact area between the top yoke and head of the fastener.

You will need to tighten the bearing adjuster under the top yoke to achieve some degree of pre-load on head bearings so that it slows the speed at which the forks will fall from side to side. Then torque up the big Allen screw to 60 lbft but be aware it will alter the bearing setting slightly so it can need a bit of trial and error to get it right.  You should also have the top yoke stanchion clamp screws slackened off while adjusting the head bearings and tightening the big Allen screw to allow for slight repositioning of the top yoke. The stanchion clamps should be the last things to be torqued up.

[montmil]

... I checked the top nut, the one in the middle of the steering head.  It was loose, really loose.  Can I just tighten it or are there other problems I should look for?...

Are you referencing the top threaded nut above the top clamp? Before cranking down on this item, you may want to check the nut located just under the top triple clamp. This little rascal is what sets the preload on the steering stem bearings.

1986? You have the flat steel triple clamps, correct?

[Ron_S.]

Yes, I have the flat steel triple clamps.  

[Ron_S.]

OK...had to remove handlebars to get to the top nut.  Good thing because I found that one of the bolts securing the bars was missing a nut.  Gives me a chance to do more cleaning, though.  
Think I have it all except how to torque the top bolt - don't know what the proper torque is.  It's a six-point bolt, 35 mm.  I read/hear from 80 nm to 107 nm.  

[Barry]

Yes, I have the flat steel triple clamps.  

I just realised you don't have the same cast top yoke as the 78 - 84 bikes and all the talk about an Allen headed screw will have been confusing. Still the principle of adjustment is exactly the same. As far as I can make out 107 Nm is the correct figure.

[Ron_S.]

Yes, I figured that part about the Allen screw right away.  No worries.  Thanks for the clarification though.  I now dangerously, possibly foolishly, think I have it figured out.  

[Ron_S.]

I finally got a proper wrench to use on the steering head nut.  Put it all back together and tested this morning.  Low speed "weave" and a wobble at about 40 to 45 mph that goes away at higher speed.  All this only I release the bars.  So, I guess I'll go a 1/16th turn tighter on the adjustment.  Yes?  No?  
Problem is that I have to take the bars off to do this, can't even fit a flat wrench between the bars at the clamps and the top nut.  I have four holes in my top clamp for the bar clamp bolts, making two sets of holes.  The bars are bolted into the rearward set of holes.  If they were moved to the forward set I could get that wrench in there.  Is there a problem with that move?  

[Barry]

So, I guess I'll go a 1/16th turn tighter on the adjustment.Yes?No?  

Yes.

When the bearings are too tight you'll know. The stiffness will cause the bike to wander when you try to ride in a smooth line as each small steering input is over corrected for.  Hard thing to describe but when you experience it you will recognise it. In the old days we Brits used to say it "steered like a Threepenny bit" after an old coin with many small flat sides.

[montmil]

Ron,  To check steering head bearing preload, first get the bike on the centerstand with the front wheel off the ground and the front wheel pointed straight ahead. Preload on the steering head bearings is consider correct when, with just a small nudge, the wheel will fall off left and right all the way to the stops -without a hard smack into the steering stops. Over-tightening will rapidly wear out the bearings and is just as bad as loose, under-tightened bearings.

During adjustments, slowly move the bars left and right. If you feel a "notchiness" -not sure if that's a real word- then the bearing races are brinneled and should be replaced. The photo shows the outer races removed from my 1983 R65. The bearing rollers like to sit in the notches and the rider must continually attempt steering input corrections. Wobbles may ensue.

[Ron_S.]

Thank Gentlemen.  Onward and Upward.  (Or at least onward.)

[Ron_S.]

Got it.  Took just a little trial and error.  It how handles better than when I got it, back in August.  Again, many thanks for the invaluable help.  

[Dave 2]

hen the bearing races are brinneled

Monte, Now I have to get out my dictionary...D2