Mini-Project: NutSert Installation For Rear Trunk Access Panel Fasteners

[Dan Sarandrea (Phila)]

On later model X1/9s, Bertone thoughtfully included a full-width access panel between the engine compartment and the rear trunk (aka "runk"). This is very handy for doing work on most of the engine ancillaries such as water pump, alternator, A/C compressor, intake and exhaust, etc.

The fastening method (10 panhead/cheesehead head machine screws into threaded holes in a sheet metal seam) was fine for a car with an expected normal life span of 7-10 years, but here we are 30+ years later and on my car several of the threaded holes were stripped out and it was a pain to have to rig up a way to hold either the screw or a nut in place while turning the other when removing or replacing the access panel.

So I decided to install NutSerts in the holes.

Step 1: Drill out hole to the nearest size to match the selected NutSerts (M5 x 0.8).

Step 2. Use a round file to enlarge hole just enough to allow NutSert to fit.

Step 3. Fit NutSert to installation tool mandrel:

Step 5. Insert mounted NutSert into hole.

Step 6. Operate tool by bringing handles together.

Step 7. Spread handles and use the thumbwheel to unscrew the mandrel from the NutSert.

Step 8. Check that the NutSert is fully "crushed" and that it is solidly anchored to the sheetmetal.

Step 9. Rinse and repeat.

One thing I did notice when doing the two bottom corner positions was that due to the space constraints of the "frame rails" and the wide angle of the handles, you can draw the crushable part of the NutSert unevenly and occlude the hole into which the fastener goes. It took a couple of do-overs where I had to drill out the unevenly installed NutSert and do a better job of maintaining it square to the panel.

Still doing mini-projects that require access, so have not yet replace the panel, but I have no reason to think it won't fit.

 

[kmead]

Nice modification Dan.

Thanks for thinking of it and even more thanks for documenting it. We all appreciate it.

 

[lookforjoe]

Looks good, Dan. You can also get a smaller (M3-M8) nut-sert tool that operates like a grip-handle rivet installer. Works for aluminum rivets, which is fine for the corners of an install such as this.

 

[Dr.Jeff]

Great job Dan.

Another method of setting a nutsert in limited space is with a bolt and some hardware bits. Something like in these online pics:

The nut is larger than the bolt and acts as a spacer. As you turn the bolt in it draws the nutsert tight. The star lock washer keeps the nutsert from spinning.

 

[lookforjoe]

Great job Dan.

Another method of setting a nutsert in limited space is with a bolt and some hardware bits. Something like in these online pics:
View attachment 21053 View attachment 21054

The nut is larger than the bolt and acts as a spacer. As you turn the bolt in it draws the nutsert tight. The star lock washer keeps the nutsert from spinning.

Have you actually tried doing it that way? The leverage applied by either proper tool is much crisper & more even, without that twist load. The tool I linked is definitely easier to use in a tight space than fiddling with a wrench . I'd personally only consider that as a last resort.

 

[Dr.Jeff]

Actually done it countless times with the same homemade tool. I find it easier to do than the lever tools.

 

[Dan Sarandrea (Phila)]

Great job Dan.

Another method of setting a nutsert in limited space is with a bolt and some hardware bits. Something like in these online pics:
View attachment 21053 View attachment 21054

The nut is larger than the bolt and acts as a spacer. As you turn the bolt in it draws the nutsert tight. The star lock washer keeps the nutsert from spinning.

Have you actually tried doing it that way? The leverage applied by either proper tool is much crisper & more even, without that twist load. The tool I linked is definitely easier to use in a tight space than fiddling with a wrench . I'd personally only consider that as a last resort.

Actually done it countless times with the same homemade tool. I find it easier to do than the lever tools.

I tried the homebrew technique. Did ya notice the red splotch in the foreground of the last pic---that came out of my knuckle when the homebrew slipped Ordered the tool

 

[7982X]

On later model X1/9s, Bertone thoughtfully included a full-width access panel between the engine compartment and the rear trunk (aka "runk"). This is very handy for doing work on most of the engine ancillaries such as water pump, alternator, A/C compressor, intake and exhaust, etc.

The fastening method (10 fillister head machine screws into threaded holes in a sheet metal seam) was fine for a car with an expected normal life span of 7-10 years, but here we are 30+ years later and on my car several of the threaded holes were stripped out and it was a pain to have to rig up a way to hold either the screw or a nut in place while turning the other when removing or replacing the access panel.

So I decided to install NutSerts in the holes.

Step 1: Drill out hole to the nearest size to match the selected NutSerts (M5 x 0.8).
View attachment 21022

Step 2. Use a round file to enlarge hole just enough to allow NutSert to fit.
View attachment 21023

Step 3. Fit NutSert to installation tool mandrel:
View attachment 21024

View attachment 21025

Step 5. Insert mounted NutSert into hole.
View attachment 21026

Step 6. Operate tool by bringing handles together.
View attachment 21027

Step 7. Spread handles and use the thumbwheel to unscrew the mandrel from the NutSert.
View attachment 21028


Step 8. Check that the NutSert is fully "crushed" and that it is solidly anchored to the sheetmetal.

View attachment 21029

Step 9. Rinse and repeat.

View attachment 21030


One thing I did notice when doing the two bottom corner positions was that due to the space constraints of the "frame rails" and the wide angle of the handles, you can draw the crushable part of the NutSert unevenly and occlude the hole into which the fastener goes. It took a couple of do-overs where I had to drill out the unevenly installed NutSert and do a better job of maintaining it square to the panel.

Still doing mini-projects that require access, so have not yet replace the panel, but I have no reason to think it won't fit.

I recognize the tool! Bought one a few years ago & have found it invaluable. Used it countless times. We just haven't done these particular ones yet. I will check the car when it comes back from paint to see if they need to be installed here.

Looks good, Dan. You can also get a smaller (M3-M8) nut-sert tool that operates like a grip-handle rivet installer. Works for aluminum rivets, which is fine for the corners of an install such as this.

I didn't know the smaller tool for M3-M8 was even available. I could have used that as well as I couldn't find mandrel sets for the larger tool inM4 or M3 sizes.

 

[Dr.Jeff]

I tried the homebrew technique. Did ya notice the red splotch in the foreground of the last pic---that came out of my knuckle when the homebrew slipped Ordered the tool

Hey Dan, when I first read your comment (quoted) I was a little surprised because I've not had problems with the DIY "bolt" tool to install nutserts. Yesterday I installed a bunch of them using my DIY tool, and it occured to me why it might not have worked as well for you.

Previously I used a combination of three different installation tools. Two are the 'pop rivet' style guns and the third is a large 'accordian' lever type (pictured below). But all of them presented problems for various reasons; too large to get into many places, mandrels stripping the insert's threads or the mandrel itself getting damaged, difficulty squeezing the handles sufficiently to get a really good bite with the insert, etc. So I started looking online for options. I saw a whole bunch of variations on the home made tool (like we discussed) and decided to try one. But rather than copying any one of them I incorporated several ideas into mine. The main bolt is a grade 10.9 to keep it from stripping. I welded a "coupler nut" onto the head of the bolt so I could get a regular socket fully over it with more stability. I used a larger coupler nut as the spacer to allow more working room with the wrench. Added two hardened washers with grease between them as a smooth pivot point between the components (actually S/S washers may be better as they have a smoother surface). And I use an internal star washer on the end to help hold the insert from rotating while cranking it down. Mine is also pictured below.

This arrangement allows the use of a box wrench to hold the spacer, a socket (as noted) to drive the main bolt, easy rotation of the tool, and everything stays well positioned while doing it. What I'm suggesting is there may be some difference in the actual construction of the tool and how it is therefore used that makes it work so well for me. Honestly since I made this type of tool I have not used any of the other installers. This one is easier for me to use, keeps the insert square and centered better, and allows a very good feel of how much compression the insert is getting. That was another problem I had with the other tools; it was difficult to tell exactly how tightly I had compressed the insert so at times it would be too loose (and spin) or too tight (and strip). I realize it will be a matter of personal choice but I just wanted to relay the thoughts that occured to me about it.