Repair worn threads for floorboard screws.

[Trapdoor2]

Having had the floorboards out a time or three whilst recently speedometer cabling, I was wondering how to repair the 12-24 threads for the floorboard screws. Several of mine are barely there. A couple appear to have been beaten into submission with a body dolly and a ball-pein hammer (and then badly re-tapped). It appears to me that floorboard removal/replacement is one of those jobs that just never end. I'd like to have screws that actually work (the screws are actually fine, and I have a full set of washers too).

I suppose there is a "correct" way and...everything else.

Having done my time with sheet metal, I was thinking it should be a good place for a rivnut. McMaster-Carr sells a bag of 10, 12-24 rivnuts for ~$8. I actually think I have a rivnut tool around here somewhere...but surely not specific for 12-24.

Are rivnuts taboo? Should I use acupuncture? Chair Tai Chi? Cinnamon and vinegar?

[Joe K]

Heli-coil inserts.

Ebay search Helicoil KIT 12-24

The kit including the tap and an insertion wrench is a little pricey at $38.67 plus ship. But the helicoil "spirals" are sold separately pack of 12 for $10.96 free ship.

You should look around both Ebay and Amazon. You may find a better deal.

Doing helicoil is one of those things I LIKE to do. Almost flawless - as long as you don't break off the tap.

Joe K

[Oldgearz]

I replaced mine with metric screws slightly larger than existing size. Tapped new threads Therefore only had to buy screws and tap. Pretty cheap and not too much work

[Trapdoor2]

Originally Posted by Joe K

Heli-coil inserts.

Ebay search Helicoil KIT 12-24

The kit including the tap and an insertion wrench is a little pricey at $38.67 plus ship. But the helicoil "spirals" are sold separately pack of 12 for $10.96 free ship.

You should look around both Ebay and Amazon. You may find a better deal.

Doing helicoil is one of those things I LIKE to do. Almost flawless - as long as you don't break off the tap.

Joe K

I have 12-24 Helicoils on hand...but this is sheetmetal...well, the ones that have been beaten flat are. I might get 2 complete threads.

[Oldbluoval]

Never done it……re-tap to 1/4-20??

[Y-Blockhead]

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I'm a fan of rivet-nuts. Bolt Depot has a good selection plus installation tools but I don't see 12-24? McMaster-Carr does not list a 12-24 Rivet-nut either. www.boltdepot.com

[figment]

You could replace the D nuts and order a set original screws from one of the suppliers. Snyders or Berts should have the D nuts . It shouldn't be to hard to remove the bad ones and all you have to do is pean the new ones to hold them in place .

[nkaminar]

Instead of going all the way to 1/4 screws, you could go to 14-24 screws which are slightly smaller.

[Synchro909]

Even if your are chasing originality/judging, do the judges even look at those threads? I very much doubt it. My cars are drivers so none of that matters a skerrick. I put a 1/4" X 20 tap in the battery drill and ran it through the old holes. Those weird "gauge" screw sizes puzzle me and 1/4" W is (or was) readily available. It was a no brainer for me. As for the washers, I took a few ordinary 1/4" washers and with one whack from a hammer, made them conical. The floor boards didn't complain!

[David in San Antonio]

I bought a set of floorboard screws and they fell into place with no turning required. Maybe one grabbed a thread. It seems the original D-nuts were wallowed out. So this thread could prove useful.
Now I have to look up the original meaning of skerrick.

[1crosscut]

I rather like Oldgearz solution in post #3

[Jim/GA]

I did a helicoil on a couple and I was not impressed. There is nothing there to hold the coil in place. It wants to screw all the way through as you install the floorboard screw. I tried a drop of thread lock but it didn’t hold.

Tapping to a larger size screw works.

Or replace the d-nut before you paint.

[katy]

Originally Posted by David in San Antonio

Now I have to look up the original meaning of skerrick.

Skerrick = smidge

[Trapdoor2]

Originally Posted by Y-Blockhead

I'm a fan of rivet-nuts. Bolt Depot has a good selection plus installation tools but I don't see 12-24? McMaster-Carr does not list a 12-24 Rivet-nut either. www.boltdepot.com

https://www.mcmaster.com/products/ri...ad-size~12-24/

I would not have an issue with going to a larger fastener, such as 1/4", if I had to. My Coupe isn't and won't be a show car, even though I prefer keeping it as "stock" as I can. I try to not use obviously modern drive types, such as Phillips but I might make an exception for heavy-use pieces like the floorboards. The screws are hidden under the carpet anyway.

[gdmn852]

Hello, the d nuts with 12-24 threads are also available from Snyders, I just drilled out the original stripped out ones and replaced them with the d nuts, penning them over to hold them in the body , also had to do this on some of the cowl nuts that hold gas tank. The 12-24 threads are rarely used anymore, normally go from 10-32 to 1/4 -20 or 24 , more recently metric. 6 mm might be used to retap the existing threads.

[Bob C]

Time-sert has a 12-24 kit that may work better than a Helicoil.
https://time-serts.com/store/12-24-thread-repair-kit/