How do I get these screws out with a spinning plastic insert?

[Baz]

Thought I would run this past the brain trust and see if there's a solution I hadn't thought of.

I'm working with motorcycle fairings. On the inside of this fairing is a plastic piece that attaches where a duct is to help direct airflow.

It uses three attachment points. These each consist of a plastic "post", an insert with threads inside each post, and a screw that holds the plastic piece in place.

The problem I have is the inserts apparently have come loose enough that I cannot either tighten nor loosen the screws.

I would like to remove the screws and the inserts and start over with new inserts that I can install with heat, as I have already done on other fairings I have.

I'd prefer not to damage the original posts. I have had to replace some on the other fairings so it is possible to do so, if necessary.

The only solution I can think of is to drill a small hole into the side of the post and insert some kind of ice pick to (in theory) hold the insert enough to be able to unscrew the fastener.

Here are photos showing what I am dealing with. TIA for any thoughts!

The plastic air duct piece:



How it looks in place:



The screws that won't tighten down nor unscrew out:



This is what the post and insert look like underneath:

[Baz]

FYI: I have tried exerting upward pressure on the plastic piece while turning the screw CC but it doesn't do anything. Just keeps spinning.

[masraum]

Cut or grind the top of the screw off?

Presumably you've already tried applying upward (away from the hole) force on the bottom of the screw head or tab on the air duct.

[masraum]

Originally Posted by Baz

FYI: I have tried exerting upward pressure on the plastic piece while turning the screw CC but it doesn't do anything. Just keeps spinning.

LOL, you're too fast for me.

Yeah, cut or grind the head off of the screw.

[Crowbob]

If I’m seeing what I think I’m seeing, grasp the post and insert with a pair of vice grips and squeeze just enough to cause the threads of the screw to get a really good bite, then immobilize the vice grips relative to the piece to unscrew it.

[porsche930dude]

Thats what I would do. Tape the pliers if you dont want it to bite in. Im sure the insets have knurling on them so they should grip the plastic pretty well with a little pressure.

[908/930]

Being a part of a motorcycle do you think there is some loc-tite on the screw? Possibly try heating screw head with soldering iron, keeping temp below the plastic melt temp.

[Baz]

Originally Posted by Crowbob

If I’m seeing what I think I’m seeing, grasp the post and insert with a pair of vice grips and squeeze just enough to cause the threads of the screw to get a really good bite, then immobilize the vice grips relative to the piece to unscrew it.

Originally Posted by porsche930dude

Thats what I would do. Tape the pliers if you dont want it to bite in. Im sure the insets have knurling on them so they should grip the plastic pretty well with a little pressure.

Tried that gents. I just used pliers - not vise grips. Was afraid of damaging the posts if I squeezed too hard. This would be a good last resort though if I tried other things that didn't work. Thanks!

Originally Posted by 908/930

Being a part of a motorcycle do you think there is some loc-tite on the screw? Possibly try heating screw head with soldering iron, keeping temp below the plastic melt temp.

Yes, thanks. I thought about heating the screw - the objective for the heat to also transfer to the insert & melt the surrounding plastic enough so I could pull everything out. Once out I could vise grip the insert and unscrew the screw.

I don't think any Loctite was used. But that insert Honda used has some kind of clasp inside, I think, different than usual.

This might be the next step I take. Stay tuned.....

[Noah930]

Ducati used this wellnut method of fastening their fairings (at least back in the 90s). But Ducati's wellnuts were metal set in rubber. If the screw and nut corroded together, it was impossible to unscrew the thing. But at least you could mangle the rubber bit enough to separate the fastener from the fairing. Just replace with a new rubbered wellnut afterwards.

I think Crowbob's idea of using a pair of vice grips to grab the plastic post around the metal wellnut to crush the plastic to the metal wellnut to get the wellnut stay put while unscrewing the bolt part is the way to go. If that doesn't work, then soak with something like PB Blaster and try again the next day?

[Baz]

Originally Posted by Noah930

Ducati used this wellnut method of fastening their fairings (at least back in the 90s). But Ducati's wellnuts were metal set in rubber. If the screw and nut corroded together, it was impossible to unscrew the thing. But at least you could mangle the rubber bit enough to separate the fastener from the fairing. Just replace with a new rubbered wellnut afterwards.

I think Crowbob's idea of using a pair of vice grips to grab the plastic post around the metal wellnut to crush the plastic to the metal wellnut to get the wellnut stay put while unscrewing the bolt part is the way to go. If that doesn't work, then soak with something like PB Blaster and try again the next day?

Hadn't thought of the PB Blaster. Thanks!

[Baz]

This fairing had a damaged post (far left) so I ground it down all the way and attached a new one plus new inserts into all 3 posts.

I am using PlastiFix to attach the posts and it works great and is very strong.

The tricky part is getting the posts to align properly with the various angles of the fairing.

I am cutting them at angles. Would prefer to keep the originals where possible.



New insert and post:



Posts I bought:



Heating iron for inserting inserts into posts:

[Zeke]

3rd pic shows a hairline crack that let the nutsert loose. For sure, taped pliers around the plastic should allow you to hold the female part while you unscrew the capscrew. It is entirely possible that the metals have suffered a galvanic migration that needs to be broken. You're in a tough situation because both enough heat or impact will have a detrimental effect on the post.

A solvent may penetrate the threads enough to work the screw back and forth to release the bond. However, you run the risk of contaminating the plastic hindering any potential repair with glues or epoxy. A light acid might help or might not. I don't know the composition of the metals. The insert could be yellow zinc plated or brass which contains copper. Copper and a lot of various metals are not very compatible when it comes to corrosion.

That's where an acid can be beneficial and can be neutralized/cleaned to the point that downstream repairs will be easier. I'm talking vinegar strength. If you had a driver that fit the screw socket attached to a multitool, that amount of high frequency vibration would hasten the process. Think along those ideas rather than using an impact driver.

When you begin selecting replacement hardware keep in mind that different metals must be close to each other in the galvanic series. Might sound a little over the top, but titanium screws are very corrosion resistant WRT a lot of metals whereas steel, even plated, is not a great choice. AL is not a lot better in a motorcycle environment. There need not nor should not be any brass alloys.

You might say well they use the hell out of brass on boats, but that's brass on brass which works because they are not galvanic especially if more nickel is present.

(Note to the chemists here, this is a generalization, not a doctoral thesis.)

[Baz]

Thanks, Milt. Lot of useful info there!

[lin7310948]

if you can reach them, i would drill a couple of very small holes in the plastic to expose the brass. then i would squeeze a suitable adhesive into the tube. with the strength of todays adhesives surely one would work. i would only try it on one post.

[herr_oberst]

I'd squirt some Kroil or PB into the gap, then wind as much waxed dentil floss as would fit in between the head of the screw and the plastic. (Along with pinching the plastic post with. pliers or tiny vice grips.)

Then, carefully back and forth the screwdriver in tiny increments to break the galvanic bond.

One thing to remember, too, those screwheads are JIS, not Phillips, so if you have access to the proper screwdriver, be sure to use it, just to give yourself a fighting chance.

[john walker's workshop]

Looks like there are a few threads visible at the bottom, so how about using a bolt/ screw with a nut run up on it, thread the screw in and tighten the nut against the insert to hold it tight, then take the fastener out?

[craigster59]

Left handed drill bit won't work?

[masraum]

Originally Posted by craigster59

Left handed drill bit won't work?

I think the problem is that the screw is going into a "nut" and the nut-to-plastic grip is gone, so when he screws in either direction the screw and nut behind it both spin.

[vash]

seem like you can reach that back section with a needle nose plier. can you pinch it tight, so it can grab the screw with more security and then back it out? I can see a crack..pinch that crack tightly closed.

[craigster59]

Originally Posted by masraum

I think the problem is that the screw is going into a "nut" and the nut-to-plastic grip is gone, so when he screws in either direction the screw and nut behind it both spin.

Sounds like a job for a nail set and a BFH.