Bicycle Mechanics - Main bolt on threaded fork won't budge! Any suggestions?

Hi all,
I am trying to swap out forks on a friend's mountain bike. I've already taken out the vertical bolt for the headcap and handlebars but I'm stuck now trying to loosen the main locknut holding the fork (not really a bolt like it says in the title). I'm using a good adjustable wrench, but I can't seem to get any leverage to be able to crank hard to loosen the nut. Any tips that you know of for this problem?

Thanks

1. Reinstall the handlebars, that gives you something to hold on to and MUCH more leverage.

2. Use two wrenches, there are two nuts on there, the one on top, and one below it. You will need a thin wrench to get to it.

3. PB Blaster is your friend.

how long is that adjustable wrench? you may need a big beefy one that is longer.

I never use adjustable wrenches for the headset locknut. Not secure enough grip. I use this tool and never have a problem: http://www.cambriabike.com/shopexd.asp?id=39838&page=Park+Tool+Hw-2+Pro+Headset+Locknut+Wrench

Of course it is a bit pricey though.

Are we really certain about which kind of headset he's talking about?
Vertical bolt sounds like the long one connected to the wedge on a quill stem, but could be the one for the top cap on an aheadset stem. Or even the pinch bolt on an old style stem.

Main bolt holding the fork could be the locknut for the upper headset race on a threaded fork, but I can't remember meeting one of those stuck on particularly hard, and I don't think I've come across it being called a bolt before.

By vertical bolt, I meant the the one for the top cap on a headset stem.

The first two posters understood me right, as I can see how there suggestions make sense with what I'm trying to do.

I should have referred to the one stuck as a locknut. The bike is old and a tad rusty so the "locknut" is not budging. From demos I've seen on youtube of taking a fork off, it seems like loosening this locknut should be pie like you say, but it hasn't budged at all for me.

Update: I've changed the original question to be more clear.

Thanks for the help

as 531phile asked, how big is your wrench? most headset wrenches are a bit over 12-13" long for leverage.

are you turing it the correct way? Counterclockwise? that thop nut is also a jumnut. so it you can get a wrench on the flats for the uppercup you might try tightening that as you try to loosen the topnut.

you can never go wrong with posting a few pics

9/8" threaded 1,125" headsets have a 36mm nut for their headsets, 1" its a 32mm.

You need a 1/8" thick headset wrench + an adjustable spanner, to keep the adjustment from from loosening

meaning of Jam nut is 2 are tightened against each others.

Shifters aren't really ideal for use on anything which requires alot of leverage to loosen. There is too much risk of slipping and rounding the nut off. Sorry if that isn't much help, but I always try steer clear of shifters, and instead use the correct spanner for the job.

If there is a washer (or reflector bracket) between the locknut and h/s adjustable cone/cup then the two wrenches are not absolutely necessary. You can immobilize the fork by using a good solidly mounted vise, padding it with hardwood or similar to protect the fork and inserting the fork all the way to the crown. Tighten down gently and get a long wrench or a pipe as an extension. If you don't have a good wrench the right size a high quality adjustable will work, but if the locknut flats are narrow the wrench needs to have sharp jaws, not badly damaged by slipping off of nuts previously.

Put some penetrating oil in between the top of the nut and the top of the fork column and tap the nut several times to get the penetrant worked in. If a reasonable amount of force still does not break it free then carefully hacksaw the nut vertically on one side until you can remove it.

Take the wrench you have to the hardware store and find a piece of PVC pipe that will fit over the handle. Cut a 2 or 3' length and use that over the wrench. It will greatly increase your leverage.

By vertical bolt, I meant the the one for the top cap on a headset stem.

But aheadset stems don't go onto threaded forks unless someone has fitted a quill stem adapter, which of course is a possibility. Or can the quill stem adapter be interfering somehow?


.. The bike is old and a tad rusty so the "locknut" is not budging. From demos I've seen on youtube of taking a fork off, it seems like loosening this locknut should be pie like you say, but it hasn't budged at all for me.

Well, in that case it might be time to look at destructive disassembly instead. Wrench flats on headset nuts don't look big enough to take serious torque. My weapon of choice would be a Dremel to make a vertical cut with, should be easy enough to pop it right off after that.

UPDATE: Thanks for the many good ideas. Thankfully the first and easiest suggestion this time did the trick for me. I put the handlebar back on and the added leverage thist gave me enabled me to loosen the locknut. Actually, it didn't even come off that hard. It was such an obvious solution I wish I would have thought to try it myself in the first place.
A couple other things: The adustable wrench I have is a good one, about 10" long on the handle so it gave me a decent amount of leverage. Also, like CNY-bikeman said, two wrenches weren't required in my case. There were spacers and a cantilever brake bracket between the two nuts.