SF1 - seized top yoke nut

C

chrissoz

Senior member
Location
Sydney, Australia
Purchased a 32mm thin spanner to get at the head bearing adjuster nut under the top yoke but that wont budge either.

Have soaked everything in wd40 and gone at the top nut with a 34mm socket on a rattle gun but it will not budge. It was in poor condition anyway so was marked for replacement. Headset bearings also need replacement.

Anyone have any suggestions for getting this apart - was thinking of just chopping the top nut off with a hacksaw then I should be able to remove the top yoke and attack the adjusting nut.

Thanks
 
Are you holding that lower thin nut with that thin spanner to stop it from turning, pushbike shops usually have these, while you're trying to undo the top nut. Those 2 nuts should touch and lock together, Maybe try a hot air gun, someone might have Loctited it. BTW I find a smack on the upper spanner with a hammer while holding that lower spanner from turning better than Rattle Gun action. None of this should be eye-popping tight, something odd is happening here. Maybe you need to tighten the lower nut a tiny bit to take its locking effect off the top nut?
 
take the weight off of the forks Chris, use a car jack or something similar to lift bike from below the engine
just so front tyre is just touching the ground, try backing off the alloy center nut once weight is off
had issues in the past with a couple of bikes with that problem

what size rattle gun are you using ?
one bike I had to resort to my 3/4" rattle gun, that fixed it
 
Vince - I have the push bike spanner - The 2 nuts do not lock together - the top yoke is loose on the spindle since pulling the forks out

Red - 1/2 inch is all my meagre workshop has - the forks have been removed so no weight on anything.

Rob - not sure what I would heat - if I heat the aluminium nut it will expand and make things worse.

20230811_185509 (1).jpg
 
I just love previous owner stories. There is something so satisfying about vicariously experiencing someone else’s struggles with incompetence. Especially since it always seems to work out OK in the end.
 
Just a thought, but if the steering head bearings are shot, there may be more than sufficient space to rotate the thin spanner clockwise? A couple of bops with a hammer might help. That'd let you establish if the top nut is sticking in the yoke, or not?
 
as previously mentioned (twice) tighten that thin nut to bejeesus and beyond, you are changing the bearings anyway, so no worries about damaging them, (get the replacement bearings from Simply Bearings in Brum) then heat the yolk and alow to cool, try again, get the thing paint meltingly hot.
CLEM
 
chrissoz said:
not sure what I would heat - if I heat the aluminium nut it will expand and make things worse.
Click to expand...
Aye, but it's attached to a steel stem. I was thinking the problem might be between the different metals rather than aluminium top nut and top yoke.

It's a bit of a bodge, but using a flat blade screwdriver in the pinch bolt slot will help open up the hole for the top nut, if indeed the two are binding.

I'm always pleasantly surprised how the application of heat helps move things along... a Pip Higham tip
 
The top yoke is actually loose on this stem it can move up and down a few mm and turn freely so that is not biding against the nuts. I suspect the top nut is just siezed in due to different metals and age and the adjuster nut is done up really tight and i cannot get enough leverage on it with the thin spanner.

I will try a bit of heat - see if that helps otherwise I will probaly chop the top nut which will allow me to remove the top yoke and get at the adjuster nut with a socket.
 
Not an easy thing to come by that alloy nut. I would check with Wolfgang, etc, if a new one is available before cutting. Heat is your friend.

While I remember, chat to Will about your brakes, he just had a set of drums refurbished with great results.
 
martymoose said:
Not an easy thing to come by that alloy nut. I would check with Wolfgang, etc, if a new one is available before cutting. Heat is your friend.

While I remember, chat to Will about your brakes, he just had a set of drums refurbished with great results.
Click to expand...
I have those top nuts in stock
 
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