[atoine]

I used cross nuts exclusively for my first build and had great success with them. But lurking on the forum, I noticed many people are struggling with "spinners". I spent HOURS on forums trying to find what's the latest consensus on threaded inserts, but no luck. It's still a endless debate. It's hard to thrust someone's opinion when there is no data to back up their claim...

So I went ahead and attempted to QUANTIFY spinout resistance torque of CrossNuts and RivetNuts. In addition, I tested a few "hacks" often mentioned in forums: regular washer, split lock washer, tooth lock washer, CA glue, Red LocTite, and J-B Weld:

Notes:

• I didn't use "fixed material" between the insert and the bolt (which creates friction on the insert's head and increases spinout torque). That intentional, my goal wasn't to quantity the "real-world" spinout torque. I just wanted to compare different inserts/hardware spinout resistance, so I took the "fixed-material" out of the equation (which was one more variable).
• My test sheet is 0.032" thick and holes are 0.364" to simulate standard holes on the Transit.
• The spinout torque was recorded with a digital torque adapter.

Results:
- Rivet Nuts (alone) and Cross Nuts (with tooth lock washer) gave the best results. In fact, the spinout torque was beyond the recommended torque for a 1/4 bolt (grade 5) and I was able to shear a few bolts (or damage the crossnut/rivnut).

Observations:

• CrossNuts (without hardware) spinout torque varies a lot, and it's hard to obtain repeatable results.
• The tooth lock washer increases the spinout torque a lot, and also helps installing the crossnut straight and flush with the mating surface. Win-win.
• Rivet Nuts installation is very predictable and repeatable.

Conclusions:
- I'll probably prioritize Rivet Nuts on my next build, but still keep a few Cross Nuts handy for the oversized or oddly shaped holes (hex, square).

Learn More:
This is a short version of what you'll find here: https://faroutride.com/threaded-inserts/
In the link above I also got a 360° virtual tour showing ALL sizes/locations of threaded inserts in the Transit cargo area. I'm pretty proud of that and it should be very handy!

Conclusion:
It might not be a huge revelation, but at least I've got data to back up my decision for my upcoming build!

OK I'm done here, up to the next project!
Cheers,
Antoine

 

[Checkswrecks]

WOW - Thank you VERY much for this well done comparison!!!

 

[njvagabond]

tooth lock washer

Great study. Thanks for posting. Also for documenting all of the hole sizes in the Transit.
Do you happen to have the spec. or a link for the toothed washer that you used?
Do you have any insight/opinion on the difference in pull out strength of cross nuts vs rivnuts.

 

[atoine]

Great study. Thanks for posting. Also for documenting all of the hole sizes in the Transit.
Do you happen to have the spec. or a link for the toothed washer that you used?
Do you have any insight/opinion on the difference in pull out strength of cross nuts vs rivnuts.

For M6 or 1/4 crossnuts/rivnuts: 3/8 Tooth lock washer.
1,215lbs for the crossnuts, 480lbs for the rivnuts. In my opinion rivet nuts have sufficient pull-out strength. Unless, of course, they're installed in oversized holes (e.g. M6 rivet nuts are spec'd for 9mm hole and seems to work well up to ~10mm hole. I tried 11mm and the hole was definitely too large).

 

[Mangchi]

Atoine, which rivnuts did you use? Asking because the ones from McMaster are reportedly a little beefier than others (Amazon).


Sent from my iPhone using Tapatalk

 

[atoine]

Atoine, which rivnuts did you use? Asking because the ones from McMaster are reportedly a little beefier than others (Amazon).

I used Astro rivet nuts (same brand as the setter tool I'm using): amzn.to/3Xa6ePO

A quick look at the McMaster ones, and indeed the hole specification is different (10mm in lieu of 9mm for M6 rivnuts). The tables I've got on my page are for the Astro (and others from Amazon):

https://faroutride.com/threaded-inserts/#finder

 

[ArgonautVans]

Good post. I will add, I've found the torque during install (using the mcmaster tool) also has a big impact on spin out torque. Oversizing the install hole can actually help the insert stay in place by pulling the metal arms more into the hole of the metal. This makes them much more forgiving on accidentally oversizing the hole (which can happen using a stepped drill bit). Downside, is the pullout force is probably lower.

Star washer and crossnut would be the way to go based off this IMO.

 

[Michael Ophus]

It is in the Bemm, Ford rates the holes in the wall at 70 pounds each, 33 Kg if I remember right.

 

[Gallaher]

So you have to wonder which is really better? What is good enough?
I used cheap Amazon Rivnuts on my 80/20 build. It seemed like I used hundreds of them but probably just about hundred. I had three spinners in the whole batch and was able to go back in and “tighten” those all up. Had a few I had to clean up with a tap. All good.
A reasonable analogy is: “why have a van that can exceed the speed limit?”
By the way thank you Antoine for the plans you sold me. A bargain at the price especially for the electrical system.

 

[Bjames36]

I used around 130 rivnuts after struggling with plusnut spinning. I bought the Astro pneumatic gun and it worked great. I have not had a single spinner or bad threads. I found some of the beefier rivnuts at a local supply in Denver. They are much higher quality than the Astro brand. The shank was longer giving it a larger mushroom on the backside.

I bought hundreds of items from this place they are great and high quality

Specialty Bolt Supplier Denver - Fasteners Inc Denver CO

Fasteners, Inc. has a huge inventory of fastening systems including rivets, bolts, drill bits, hand tools, nuts, pins, keys, screws, sockets, washers and so

www.fastenersinc.com

 

[danthuente]

Thank you for sharing this!

 

[oleknz]

Thank you! What a perfect timing for me that you posted this now.
I was about to start a research on this and bam! there you go.

 

[BobCollins]

Thank you, atoine, problems for your detailed experiment.

When I was deciding, I did a much less formal study of rivet nuts (the Astro Pneumatic supplier) while using the actual body panel I cut from the roof for my fan. I came to the conclusion that they would always take 2x+ more torque without spinning. With lesser grade bolts, the bolts often snapped off before reaching my test torque.

I decided, for myself, and contrary to prevailing Internet wisdom, that rivet nuts would be just fine in my build. I am still building (and going out camping) without any problems.

 

[PNW_Camper]

Very happy with rivnuts on my build. Very cost effective compared to plusnuts, used just over a hundred and had zero spin. Also a good idea to use antisieze on the mandrel and bolt threads so there is much less risk of galling or causing a rivnut to spin when removing a bolt.

 

[BobCollins]

Very happy with rivnuts on my build. Very cost effective compared to plusnuts, used just over a hundred and had zero spin. Also a good idea to use antisieze on the mandrel and bolt threads so there is much less risk of galling or causing a rivnut to spin when removing a bolt.

Anti-seize is an interesting idea. Absolutely important if you are using SS bolts and SS rivet nuts. I'm not sure how critical otherwise. It does sound like cheap insurance though—if you can put up with the mess!

 

[PNW_Camper]

Anti-seize is an interesting idea. Absolutely important if you are using SS bolts and SS rivet nuts. I'm not sure how critical otherwise. It does sound like cheap insurance though—if you can put up with the mess!

That's exactly how I viewed it, insurance. All my bolts were stainless fwiw.

 

[BobCollins]

That's exactly how I viewed it, insurance. All my bolts were stainless fwiw.

My bolts are SS, mostly because that's what is sold on Amazon. My rivet nuts are zinc plated steel.
My understanding is that the cold-weld galling is a characteristic of SS on SS only.

 

[orton]

This subject always gets lots of posts with very different opinions. Kind of like discussing religions.

I have built two conversions. Tried rivnuts in beginning on first van but determined that the $30 McMaster-Carr tool made it very difficult to put in a rivnut in a hole in the roof rib. Three hands required. Two on the wrenches and a third to hold the rivnut up into the hole. Quickly changed to Plusnuts. Type of tool makes a difference. The advantage of the McMaster-Carr tool is its size because it is small enough to be used in places a large tool would not fit.

Another advantage of a Plusnut is the hole diameter is not critical and they work in hex holes. The Plusnut feet extend much further than a Rivnut bulge.

A disadvantage of the Plusnut is they are longer. Several places in the Transit have holes that the Plusnut cannot be fully installed because end of Plusnut hits steel behind the hole before flange seats against wall hole. I found that after Plusnut is partially installed you can start the install process to shorten the Plusnut and when it is shorter it can be pushed the rest of the way into the hole so install can be completed.

Had no difficulty installing the Plusnuts with the inexpensive McMaster-Carr tool. Used existing holes for 1/4-20NC Plusnuts. Light tap with hammer gets the Plusnut into the holes. Used plated mild steel Plusnuts with SS bolts. Did not use thread lube. Did use tread lube where I had a SS bolt and elastic stop nut in 80/20 structure. Installed without a torque wrench by "feel".

After I had completed the Plusnuts without difficulty someone here or on the Sprinter site mentioned that there is a flange under the head of the Plusnut that prevents it from seating against the hole steel. Never noticed the flange when installing them. The suggestion was to put a star lock washer on the Plusnut before installing the Plusnut. Excellent advice. I would use the lock washers if I ever need to install Plusnuts again. Makes sense when you look at the Plusnut.

I did have to use a tap to clean up the threads on a couple of Plusnuts. Probably caused by not keeping the tool perpendicular to the wall hole. Never had a spinner.

 

[cycle61]

We've been using exclusively the McMaster M6 rivnuts in our conversion. Downside is having to bump each hole out to 10mm, but with a good metric step bit that's been very quick and easy. Zero spinners so far. Interesting to see the data on pull-out forces being higher for plusnuts. Makes sense with the greater effective surface area behind the sheetmetal.

I sort of wish we'd spent the $200 for the pneumatic installation tool, but we're almost finished now and this $40 tool has done a fine job, just a little slow: https://www.amazon.com/WETOLS-Rivet-Metric-Mandrels-Rivnuts/dp/B081GDRTXP/ref=sr_1_5?keywords=rivnut+tool&qid=1668788205&sr=8-5&th=1

 

[Michael Ophus]

This subject always gets lots of posts with very different opinions. Kind of like discussing religions.

I have built two conversions. Tried rivnuts in beginning on first van but determined that the $30 McMaster-Carr tool made it very difficult to put in a rivnut in a hole in the roof rib. Three hands required. Two on the wrenches and a third to hold the rivnut up into the hole. Quickly changed to Plusnuts. Type of tool makes a difference. The advantage of the McMaster-Carr tool is its size because it is small enough to be used in places a large tool would not fit.

Another advantage of a Plusnut is the hole diameter is not critical and they work in hex holes. The Plusnut feet extend much further than a Rivnut bulge.

A disadvantage of the Plusnut is they are longer. Several places in the Transit have holes that the Plusnut cannot be fully installed because end of Plusnut hits steel behind the hole before flange seats against wall hole. I found that after Plusnut is partially installed you can start the install process to shorten the Plusnut and when it is shorter it can be pushed the rest of the way into the hole so install can be completed.

Had no difficulty installing the Plusnuts with the inexpensive McMaster-Carr tool. Used existing holes for 1/4-20NC Plusnuts. Light tap with hammer gets the Plusnut into the holes. Used plated mild steel Plusnuts with SS bolts. Did not use thread lube. Did use tread lube where I had a SS bolt and elastic stop nut in 80/20 structure. Installed without a torque wrench by "feel".

After I had completed the Plusnuts without difficulty someone here or on the Sprinter site mentioned that there is a flange under the head of the Plusnut that prevents it from seating against the hole steel. Never noticed the flange when installing them. The suggestion was to put a star lock washer on the Plusnut before installing the Plusnut. Excellent advice. I would use the lock washers if I ever need to install Plusnuts again. Makes sense when you look at the Plusnut.

I did have to use a tap to clean up the threads on a couple of Plusnuts. Probably caused by not keeping the tool perpendicular to the wall hole. Never had a spinner.

Two hands, I used a cordless impact wrench and a wrench on the McMaster-Car tool, The Rivnut/Plusnut screws onto the mandrel of the tool so there is no need to hold it.