Adding Firewall Grommet

[harkco]

I am officially out of room on the stock firewall grommets / boot. I worry that cramming anything else through at this point would just damage what is already there. Just wondering if anyone here has added their own grommets in the firewall. Something like this....

https://www.amazon.com/gp/product/B004K2285E/ref=oh_aui_detailpage_o00_s01?ie=UTF8&psc=1

 

[spetka]

I am officially out of room on the stock firewall grommets / boot. I worry that cramming anything else through at this point would just damage what is already there. Just wondering if anyone here has added their own grommets in the firewall. Something like this....

https://www.amazon.com/gp/product/B004K2285E/ref=oh_aui_detailpage_o00_s01?ie=UTF8&psc=1

I used to do that all the time when I installed car audio and alarms etc. Just make sure you are drilling through single wall metal and avoid any brake lines or other wiring looms.

I recommend using a Unibit type of drill bit, either the Irwin or something like this:
https://www.amazon.com/Neiko-10194A...ie=UTF8&qid=1516808880&sr=8-2&keywords=unibit

 

[Aengis]

Glad you asked. I'm running into the same situation. Very helpful suggestion.

 

[harkco]

I used to do that all the time when I installed car audio and alarms etc. Just make sure you are drilling through single wall metal and avoid any brake lines or other wiring looms.

I recommend using a Unibit type of drill bit, either the Irwin or something like this:
https://www.amazon.com/Neiko-10194A...ie=UTF8&qid=1516808880&sr=8-2&keywords=unibit

Thanks for the response. Just curious, what is the advantage of using that type of bit?

 

[spetka]

Thanks for the response. Just curious, what is the advantage of using that type of bit?

Well, I installed car stereos and alarms for several years, worked with all kinds of people. I've seen people drill through brake lines, gas tanks, brake boosters, power steering lines, main wire harnesses, you name it. What tends to happen when drilling firewall is you have to drill at an awkward angle, regular bits and hole saws tend to walk/bind then its hard to get the hole actually started(can alleviate this partially with a pilot hole). The thing with the a regular bit is as you are drilling, putting enough pressure to drill through the metal and when it gets to the end the pressure tends to make it pop out and through the firewall a few inches. If you have a clear view of whats on both sides, this isn't a problem. These step drills allow the first size to pop through the firewall just barely, then you can leave it in and go look on the other side, then keep repeating this process as each step goes through further and further while making the whole bigger. Just a lot less chance of drilling through something, especially when working alone.

 

[sigepbiker]

Thanks for the response. Just curious, what is the advantage of using that type of bit?

The bit is called a Step Drill Bit. And as the name implies, it's easier to use this type of drill bit to increase your hole size by staring small and incrementally increasing size until you get to your desired size.

In practice, you should always drill a pilot hole for larger drill bits to help reduce drill bit wobble. This bit removed the need to swap drill bits as you increase the hole.