Spinning bottle boss - how to fix??

[ishaw]

In my quest to diagnose a creak/clicking on a frame I've discovered a bottle boss is loose and spins in the frame. The bolt is in situ and I can't remove it. Any ideas on how to a) get the bolt out and b) repairing the boss if/when I can get the bolt out?

It's an alloy frame and I'm keen not to damage it. I'd not be too fussed normally but the clicking is annoying me and I think this is the cause.

 

[dyna-ti]

Thread.
If that is you can get under it.

Thread and epoxy resin.
Wind thread around and apply resin.

 

[mattr]

See if you can grip the flange of the boss with some pointy pliers and unscrew the bolt.
Then you can get a frame builder to crimp the rivnut (that's what it is) in properly. Or borrow a tool to do the same job.

Or drill it out and get a new one.

Anything that'll be realistic/possible/leave you with a useable boss will *probably* need the bolt removing. Leaving the bolt in place during a fix will quite possibly leave you with the bolt as a permanent fixture.

 

[02gf74]

best bet wold be to grip the riv-nut with mole grips to stop if spinning and drill the bolt out, start with a small drill maybe 2.5 mm and go larger in steps of 0.5 mm. you need a steady hand so as not to snap the dill.

A thin aluminium strip between frame and grips to avoid damage/marking to frame, cable tie mole grips and use two hand so keep drill steady.

 

[FSXStumpy]

I've wicked thin CA (superglue) into the seam between the boss and tube. Works well, at least until the bottle cage takes its next big impact. Then more CA, if needed....

The glue'n'epoxy idea above sounds good too...

J

 

[old_coyote_pedaller]

Re:

02gf74,
have you tried gripping the external part of rivnut with mole grips? There's not much you can grip as the external part is virtually flush with frame. If it's sticking up enough to grip it the chances are that you'll distort it if you grip it tight enough to hold it, then it will be tighter on bolt.


Just checked my Cannondale F800 to find that one of the bottle cage bolts/rivnut on the downtube was spinning when I tried to remove it. Gave it a skoosh with GT85 then left it for a bit. Got a flat blade screw-driver and pushed it very firmly against edge of rivnut then carefully slackened bolt. I've had to do something similar on another aluminium frame but luckily it was in the seat-tube, the bottom bolt. Again I used GT85, then I got a long flat blade screw-driver and pushed down firmly, inside the seat-tube, on the internal part of rivnut not bolt threads. This worked OK and bolt slackened. What happens is the rivnut is pushed against side of hole or even rocked over in hole so that it tightens it enough to slacken bolt. Obviously this won't work all the time but it's one way to do it that works.


If you don't have a rivnut tool, luckily I do :mrgreen: , there is a way to tighten rivnut again. Find an Allen bolt, and a nut, the same size but a decent bit longer than the bottle cage bolt. Screw the nut onto the bolt far enough that the remaining threads will reach through the threads in rivnut. Now screw it in to rivnut bolt with a washer between the nut on bolt and face of rivnut, making sure the bolt is far enough in to grip rivnut threads properly, you don't want it chewing them up. Now whilst holding the bolt with Allen key, tighten the nut on bolt AGAINST the rivnut so that it squeezes the internal part of rivnut till it's tight in frame again. A drop of lube between washer and nut on bolt will help it turn without the washer turning rivnut, keep the lube away from between washer and rivnut. If the rivnut tries to turn while turning nut push the bolt sideways to rock rivnut in hole to help stop it turning. Again, it won't always work as the hole in frame may be distorted or the rivnut won't compress any further.

 

[Woz]

Re:

See the bottom of this page:
viewtopic.php?f=6&t=170190&hilit=parkpre

 

[velofrog]

Re:

i've just done this, twice in two weeks, once on a square Pace downtube and once in a round ti frame!

both times i've used my dremel with a disc to slowly grind away the bolt head, and then VERY carefully the flat visible flange of the rivnut that sits against the tube, once its gone, the remainder just falls into the frame (only good if there is an exit hole at the BB or head tube mind, you don't want it rattling around in there!)

 

[old_coyote_pedaller]

Re: Re:

See the bottom of this page:
viewtopic.php?f=6&t=170190&hilit=parkpre

Good idea to use the mech to hold the rivnut. I'll remember that for the future. Maybe even adapt it to use 2 Jubilee clips, one above and one below rivnut.

The method for tightening the rivnut is same as I described.

Here's the pics from the link, maybe should have added whole page?

 

[Woz]

Re: Re:

See the bottom of this page:
viewtopic.php?f=6&t=170190&hilit=parkpre

Good idea to use the mech to hold the rivnut. I'll remember that for the future. Maybe even adapt it to use 2 Jubilee clips, one above and one below rivnut.

The method for tightening the rivnut is same as I described.

Here's the pics from the link, maybe should have added whole page?

Using the FD as a clamp will probably not work in case the loose rivnut is on the down tube due to different diameters.

I played with the idea of one large width jubilee clip with a hole drilled in it if ever I had the problem.

Top idea to the chap using a Dremal to gently grind it away.

Access with a normal small drill is almost impossible due to the frame triangle (perhaps a 90 degree chuck adapter could work if you decide to drill it out).

Gripping the rivnut with mole grips will most probably ruin the rivnut as they are only thin AL.