DIY: Lower Airbox Thread Inserts

roastbeef · 11-19-2019, 04:54 PM

I finally did this and it worked well. My inserts are a little delicate, but they seem more durable than the plastic threads and oem screws. I used titanium hardware for extra bling and lightness.

drrust · 11-20-2019, 05:30 AM

That looks great! I recently changed air filters and my threads are still holding tight.

roastbeef · 11-20-2019, 05:42 AM

thanks! when i was testing the first one, i had the anchor back out once i got it pretty tight. now they are just snug but pretty secure.

roastbeef · 02-05-2022, 09:23 PM

i've had my airbox out probably about ten times for various tasks since i did this. i just started to have some minor issues. one of the anchors broke and fell out, and i have another one that is coming loose during fastening and the bolt is pulling it up out of the seat before it gets tight. i just have to press downward as i'm tightening it to encourage the anchor to bite.
other than that, the lower airbox is holding up well.

drrust · 02-06-2022, 07:03 AM

I had an issue where a shop over torqued the screws and pulled out the inserts. Bought a set that gets pressed in from the back. There is one position in the back where the brass lip needs to be filed a bit.

Ajolives · 02-06-2022, 08:34 AM

I did mine with some random inserts and machines screws I found at Ace hardware. I dapped a bit of JB Weld on the inserts before installation and the ones that didn't blow out hold on pretty tight. I plan on doing it again within the proper sized inserts when I come across a cheap air box.

drrust · 03-20-2022, 07:56 AM

Updated initial post to include info on inserts that install from the back.

t_lvnd · 10-30-2024, 11:30 AM

Reviving because I found this super helpful. Used the McMaster Carr inserts that drrust linked (first post) which install from the back and they worked perfectly with the 7/32 bit. Used a longer steel screw to pull the insert into place.

Saved me from having to purchase an entire new airbox to replace one that was otherwise completely undamanged, so a total win.

Honda · 10-30-2024, 01:04 PM

Quote:

Originally Posted by t_lvnd

Reviving because I found this super helpful. Used the McMaster Carr inserts that drrust linked (first post) which install from the back and they worked perfectly with the 7/32 bit. Used a longer steel screw to pull the insert into place.

Saved me from having to purchase an entire new airbox to replace one that was otherwise completely undamanged, so a total win.

Thanks for your review. What is the length of M4 screw you bought and where did you get M4 screw from?

t_lvnd · 10-30-2024, 01:21 PM

I just ran down to Ace Hardware for screws (they generally have a great selection of metric hardware) and tried 25mm, 30mm, and 35mm and like drrust found that the M4x30 seems to be the ideal length. I used a 40mm length screw to set the inserts in place.

I am going to swap them out with these titanium ones - for looks more than anything:
https://www.amazon.com/gp/product/B09ZPQP7PN/
and will update when I get them.

11-19-2019, 04:54 PM	#23
roastbeef Lieutenant General 11838 Rep 12,878 Posts Drives: E92 M3 Join Date: Nov 2010 Location: Orange County, CA iTrader: (4)	I finally did this and it worked well. My inserts are a little delicate, but they seem more durable than the plastic threads and oem screws. I used titanium hardware for extra bling and lightness. Attached Images __________________ Instagram; @roastbeefmike
	Appreciate 2 DrFerry9253.00 Drifter2090935.50 Quote

11-20-2019, 05:30 AM	#24
drrust Captain 343 Rep 725 Posts Drives: E90 M3 DCT Sedan Join Date: Jun 2016 Location: Cincinnati iTrader: (0)	That looks great! I recently changed air filters and my threads are still holding tight.
	Appreciate 1 roastbeef11838.00 Quote

11-20-2019, 05:42 AM	#25
roastbeef Lieutenant General 11838 Rep 12,878 Posts Drives: E92 M3 Join Date: Nov 2010 Location: Orange County, CA iTrader: (4)	thanks! when i was testing the first one, i had the anchor back out once i got it pretty tight. now they are just snug but pretty secure. __________________ Instagram; @roastbeefmike
	Appreciate 0 Quote

02-05-2022, 09:23 PM	#26
roastbeef Lieutenant General 11838 Rep 12,878 Posts Drives: E92 M3 Join Date: Nov 2010 Location: Orange County, CA iTrader: (4)	i've had my airbox out probably about ten times for various tasks since i did this. i just started to have some minor issues. one of the anchors broke and fell out, and i have another one that is coming loose during fastening and the bolt is pulling it up out of the seat before it gets tight. i just have to press downward as i'm tightening it to encourage the anchor to bite. other than that, the lower airbox is holding up well. __________________ Instagram; @roastbeefmike
	Appreciate 2 CHSe92256.00 DrFerry9253.00 Quote

02-06-2022, 07:03 AM	#27
drrust Captain 343 Rep 725 Posts Drives: E90 M3 DCT Sedan Join Date: Jun 2016 Location: Cincinnati iTrader: (0)	I had an issue where a shop over torqued the screws and pulled out the inserts. Bought a set that gets pressed in from the back. There is one position in the back where the brass lip needs to be filed a bit.
	Appreciate 0 Quote

02-06-2022, 08:34 AM	#28
Ajolives Captain 1134 Rep 1,048 Posts Drives: E90 M3 Join Date: Mar 2019 Location: Tampa iTrader: (0) Garage List 2019 BMW M5 [0.00] 2008 BMW M3 [10.00] 2019 Audi SQ5 [0.00]	I did mine with some random inserts and machines screws I found at Ace hardware. I dapped a bit of JB Weld on the inserts before installation and the ones that didn't blow out hold on pretty tight. I plan on doing it again within the proper sized inserts when I come across a cheap air box.
	Appreciate 1 DrFerry9253.00 Quote

03-20-2022, 07:56 AM	#29
drrust Captain 343 Rep 725 Posts Drives: E90 M3 DCT Sedan Join Date: Jun 2016 Location: Cincinnati iTrader: (0)	Updated initial post to include info on inserts that install from the back.
	Appreciate 2 roastbeef11838.00 DrFerry9253.00 Quote

10-30-2024, 11:30 AM	#30
t_lvnd New Member 9 Rep 19 Posts Drives: 2011 E90 M3 Join Date: Jun 2022 Location: Denver iTrader: (1)	Reviving because I found this super helpful. Used the McMaster Carr inserts that drrust linked (first post) which install from the back and they worked perfectly with the 7/32 bit. Used a longer steel screw to pull the insert into place. Saved me from having to purchase an entire new airbox to replace one that was otherwise completely undamanged, so a total win.
	Appreciate 1 Thumbie290.00 Quote

10-30-2024, 01:21 PM	#32
t_lvnd New Member 9 Rep 19 Posts Drives: 2011 E90 M3 Join Date: Jun 2022 Location: Denver iTrader: (1)	I just ran down to Ace Hardware for screws (they generally have a great selection of metric hardware) and tried 25mm, 30mm, and 35mm and like drrust found that the M4x30 seems to be the ideal length. I used a 40mm length screw to set the inserts in place. I am going to swap them out with these titanium ones - for looks more than anything: https://www.amazon.com/gp/product/B09ZPQP7PN/ and will update when I get them.
	Appreciate 2 DrFerry9253.00 Zhirm3e9257.50 Quote