Seized top bolt and spinning starnut

DRZRM · #1 06-05-2017, 02:29 PM

I'm reposting this question from the gallery.

I did a dirt drop experiment on one of my Zanc 29ers, because N has become a bit out of control, and with most off road miles on my full susp Ibis Ripley, how many hardtails do you need.

So I started with an uncut steerer and bunch of spacers, but my drops were still a bit too low for constant use. See image:

So I picked up and installed a LD style stem (the Velo Orange Cigne or "Swan" stem).

So, the bike rides well and I'm happy, but I've run into an installation issue I've never dealt with before.

First the pics.

So, when I switched out my stem, I needed to cut down the steerer, and I started with a pretty minimal cut to leave the option of going a bit lower later. You need 55mm of steerer with the stem (according to Velo Orange) but you can't go much over 60mm or the interior top of the stem tops out on the steerer. So you have minimal adjustability, and I figured I'd cut in small increments as I reduced orange spacers. So this was my first cut (20mm of steerer FWIW) so I hammered the starnut deeper in the steerer (I used a small screwdriver, and yes it is a metal steerer, aluminum I assume) and made the cut with a sharp hacksaw and a headtube cutting tool. All goes fine (not true obviously) but the starnut must have been a bit misaligned, and when I screwed in the bolt that would normally go through a top cap, but on this stem goes through the entire stem the bolt seizes in the starnut, which I believe is now just spinning in the headtube. I could not extract the starnut by pulling up on the stem (now loosely attached by seized bolt) so I tapped it in with a allen wrench and a rubber mallet (maybe I should have asked your opinion first) and was able to tighten the stem such that there is no movement when holding the front brake and rocking the back back and forth.

Two problems then: first I actually think I may want, sooner or later, to take out a spacer, or maybe all of them. I'm pretty flexible, and while it is comfortable as it is now, I hate the idea of a permanently installed stem...what if I don't like dirt drops after a couple rides. Even with a giant riser, I like to "slam my stem".

Second, of course, this is a problem if the bike needs to be worked on, repaired, packed up or sold. So any ideas? I can take off the wheel and see into the steerer from below, can a shop smash out a starnut backwards without damaging the steerer? If I sprayed some PT Blaster or the like up there, would I unseize the bolt? Thoughts (besides how awesome the bike looks as a dirt drop bike).

Anybody have to extract a spinning starnut before?

GScot · #2 06-05-2017, 03:11 PM

I once talked a friend through extracting a star nut. The problem he had was the starnut had a threaded center piece that was not well attached to the star teeth so it started to spin. Since the nut was reachable with the wheel and brake out he used a flat blade screwdriver with a long shank to attack each point of the starnut. With the blade tip against the tube a few of the teeth were bent upward with some strong mallet blows and after about half the stem was ready to fall out.

cp43 · #3 06-05-2017, 03:14 PM

Firstly, nice bike!

Second, buy a star nut setter before you work on this again. If a tilted star nut is really the cause, a setter would have prevented this.

I don't think that PB Blaster will help you here. It's meant to penetrate corrosion. I don't think you have corrosion between the bolt and the star nut. If anything, PB Blaster may make the star nut spin more easily.

I think my first attempt would be to remove the wheel, and try to put a long screwdriver up the steerer tube. Try to wedge it into one of the gaps of the star nut, and then try to get the bolt out.

I don't know for sure, but I don't think there's a good, non-destructive, way to remove a star nut. They are pretty cheap tho, so cutting or drilling it out, and putting in a new one may be your best bet.

FYI, if it sounds like I know what I'm talking about, don't be fooled, I've never encountered this problem, so take my advice with a grain of salt.

Good luck!

Chris

11.4 · #4 06-05-2017, 05:21 PM

I've had to deal with a lot of star nut problems. First of all, as just suggested above, next time use a star nut setter or at least install it with a long bolt that lets you keep it aligned properly. A star nut setter tends to be short so it might not have the length to do this install, hence suggesting the bolt.

Second, your star nut could have the center threaded stud simply spinning in the star nut, or the whole star nut could be twisting around. You could probably run a long bolt down and watch from the other end to see which is the case. Both can happen.

Third, to remove the star nut, you can punch it all the way through (again with a long bolt inserted into it). You can just tap it carefully (so you don't damage the steer) and make it turn on its edge, at which point it may be more amenable to being pushed up or down and out. Which ever you do, star nuts are throwaways and any shop will probably give you one for free -- they come with every headset and most forks don't use star nuts any longer.

If it doesn't come out, just tap it a bit farther down and install another star nut above it. The new, properly installed star nut, will take the bolt through the top cap and you just pretend the lower bunged up one never existed. That's if you can't otherwise get it out. I'm guessing you actually have a steel steer, and you can also get a wood dowel just slightly smaller than the inside diameter of the steer and can use it to tape the star nut out. There's no reason you shouldn't be able to do that, unless the bottom of the steer is closed. If it is, try tapping the star nut carefully so it turns on edge. Then feed a piece of brake cable through it and out again, put an old top cap on top, and start twisting the loop of brake cable to pull up on the star nut. You can also use that long bolt again, but before you thread it into the star nut, thread a couple nuts up the bolt to the top, then install the bolt through that same old junky top cap (again, there are a lot of them available and shops always have leftovers or can sell you one for a couple bottles of beer). Holding the bolt to prevent it from rotating, start lowering one of the nuts against the top cap and keep lowering it with an open end wrench. That will pull the star nut upwards. It may just dig in and solve your problem for you; you may have to knock the star nut on its side, turn it over, and then install the nut (so it isn't pulling against the tightening tension of the fins on the star nut). But it shouldn't have to be so complicated.

In short, you can get the star nut out. If you can't or aren't courageous enough to knock it through, just install another one above it. You'll do fine.

ultraman6970 · #5 06-05-2017, 06:00 PM

The steering tube is aluminum or carbon? If aluminum yes you could hammer the sucker out from behind but what I would to is just hammer it down and leave it there forever and then put another star nut or even better, a compressor.

Regarding installation, well.. you can use a socket with the right diameter to install it, looks videos and pictures, it is the same than having the tool.

Never seen a star nut that is turning all together , interesting failure.

Another way to get the star nut off is to dremel the legs of it one by one or use a screwdriver and try to bend the legs... no idea how deep the star nut is tho, you have to improvise for that.

Good luck.

ps: if the steering is carbon, well tough situation.

DRZRM · #6 06-05-2017, 07:42 PM

Good advice all around, especially thanks 11.4, your responses are always very helpful.

First, the only thing I don't want to destroy is the steerer (which I think is aluminum) and I'd like to save the stem but that's not necessarily a requirement. I get that starnuts are disposable. I should buy a setter, I just figured that once it was in straight, and it was, I could shift it straight down a bit with a screwdriver (with the blade through the hole, and the shoulders sitting flat on the starnut. I swear it looked straight, but I should have tested with a long bolt to see the head was centered. I will order a setter, its the one tool I just never justified investing in.

Sadly, I have no access to the top, and can't get the bolt out. The curved stem has no topcap, it just has a hole for the long bolt. So the whole stem sits over the steerer top, and the long bolt snugs it down. Like this. Once the bolt started spinning I tapped the bolt and starnut deeper hoping it would set properly. It didn't but I got it in well enough that the headset seems tight. Once the startnut is spinning, it is just there.

I think I do have access from the bottom. I think a long screwdriver is a good call to bend the...fins up, then I can pull the entire stem and starnut out the top. The only other way to free it would be to drill out the head of the bolt, but that wouldn't work as it is spinning. I think I can only try to drive it back out from underneath with a dowel and a rubber mallet.

Hindmost · #7 06-05-2017, 08:53 PM

Find a socket that will guide downward within the steer tube and large enough to capture the exposed bolt head. Attach an extension long enough to clear the entire steer tube to the socket. Now just bang the extension, socket, and bolt/star nut with a hammer all the way through the steer tube and out the bottom.

Just thinking out loud here.

DRZRM · #8 06-05-2017, 09:00 PM

I have a stem and long bolt attached to the starnut from the top, as long as the bolt is spinning (whether free starnut or broken core) I can't get the stem or the bolt free from the starnut, so I have no access from the top to push down, only from the bottom to push up. My question is then, can you force a startnut back up?

Quote:

Originally Posted by Hindmost

Find a socket that will guide downward within the steer tube and large enough to capture the exposed bolt head. Attach an extension long enough to clear the entire steer tube to the socket. Now just bang the extension, socket, and bolt/star nut with a hammer all the way through the steer tube and out the bottom.

Just thinking out loud here.

Hindmost · #9 06-05-2017, 09:05 PM

Ahh, got it. Please disregard.

Let me try again. With the maximum size socket and extension again can you bang it from below with a hammer?

DRZRM · #10 06-06-2017, 10:33 AM

Just dropped it at a shop. Some problems (though fewer and fewer) are simply beyond my wrenching skills.

batman1425 · #11 06-06-2017, 10:54 AM

I'd be weary of damaging the steer while trying to get it out as well. Bad failure mode if compromised. If it was me - I'd write off the stem, get out the hack saw, and cut the stem and long bolt an inch or two above the point where the steerer ends. Then you'll have access to the star-nut from above and you can devise a specific plan for getting it out. I'd start with a small grinding bit on a dremel to grind through the fins where they attach to the central core. Get a few of those cut and it should be reasonably easy to get out with out damaging the steerer in the process.