Engine Performance This section is for discussion on all engine building related questions.
Sponsored by:
Sponsored by: KPower

Wiring harness firewall passthrough

Thread Tools
 
Search this Thread
 
Old 05-30-2020, 10:40 PM
  #1  
Junior Member
Thread Starter
 
dsamani's Avatar
 
Join Date: Dec 2018
Posts: 254
Total Cats: -51
Default Wiring harness firewall passthrough

Hello friends, I am adding an additional 5-wire harness wrapped in fire sleeve for my extra oil pressure and oil temperature sensors. This assembly is roughly 3/4" thick.

I would like to pass this into the cabin for wiring into ECU/Gauges, but I need a suitable location to pass the wires through. The car does have A/C so using those grommets is not possible. Likely would need to drill a new hole into the firewall and use a rubber hose as a grommet. Has anyone done this, and do you have any suitable locations for me to drill through OR pass these wires through?
dsamani is offline  
Old 05-31-2020, 01:05 AM
  #2  
Senior Member
 
Gee Emm's Avatar
 
Join Date: Jul 2014
Location: Canberra, sort of
Posts: 1,099
Total Cats: 184
Default

That's pretty thick for five wires .... ?

I have used the main harness rubber grommet mostly, or any other harness grommet convenient to my routing. Stop the sleeve ahead of your chosen grommet, restart after, IF needed, and it should be doable without major drama.
Gee Emm is offline  
Old 05-31-2020, 01:08 AM
  #3  
Junior Member
Thread Starter
 
dsamani's Avatar
 
Join Date: Dec 2018
Posts: 254
Total Cats: -51
Default

Originally Posted by Gee Emm
That's pretty thick for five wires .... ?

I have used the main harness rubber grommet mostly, or any other harness grommet convenient to my routing. Stop the sleeve ahead of your chosen grommet, restart after, IF needed, and it should be doable without major drama.
It's the five wires plus the sleeve, I wanted to try and use it to wrap the harness to keep it all together. Probably could have just used heat shrink, tbh.
dsamani is offline  
Old 05-31-2020, 01:44 AM
  #4  
Junior Member
Thread Starter
 
dsamani's Avatar
 
Join Date: Dec 2018
Posts: 254
Total Cats: -51
Default

UPDATE: Removed the sleeve. Honestly it was just getting in the way. I can wrap the harness in specific spots if necessary.

However, the thickest part of the harness is where the insulated crimps are, and that's about 1/2 inch thick. Still a decently sized turd to pass.
dsamani is offline  
Old 05-31-2020, 10:17 AM
  #5  
Senior Member
 
Gee Emm's Avatar
 
Join Date: Jul 2014
Location: Canberra, sort of
Posts: 1,099
Total Cats: 184
Default

Originally Posted by dsamani
UPDATE: Removed the sleeve. Honestly it was just getting in the way. I can wrap the harness in specific spots if necessary.

However, the thickest part of the harness is where the insulated crimps are, and that's about 1/2 inch thick. Still a decently sized turd to pass.
Can you pass it through from the other direction? Or pass them through one wire at a time, then tidy up the bundle after they are all through?
Gee Emm is offline  
Old 05-31-2020, 11:37 AM
  #6  
Junior Member
Thread Starter
 
dsamani's Avatar
 
Join Date: Dec 2018
Posts: 254
Total Cats: -51
Default

Originally Posted by Gee Emm
Can you pass it through from the other direction? Or pass them through one wire at a time, then tidy up the bundle after they are all through?
Probably best to keep them together
dsamani is offline  
Old 05-31-2020, 12:26 PM
  #7  
Elite Member
iTrader: (1)
 
matrussell122's Avatar
 
Join Date: Sep 2016
Location: Seattle
Posts: 1,859
Total Cats: 516
Default

Kinda late for this but with crimps you dont want them all in the same spo . You want to stagger them to prevent the bulge issue.
matrussell122 is offline  
Old 05-31-2020, 06:16 PM
  #8  
Junior Member
Thread Starter
 
dsamani's Avatar
 
Join Date: Dec 2018
Posts: 254
Total Cats: -51
Default

Check out this short video, what do you think about this idea?

http://imgur.com/gallery/WXDmM2E

EDIT: On second thought, while convenient, this is a bad idea. Great way to let water into the cabin.

Last edited by dsamani; 05-31-2020 at 07:45 PM.
dsamani is offline  
Old 06-01-2020, 12:18 AM
  #9  
Cpt. Slow
iTrader: (25)
 
curly's Avatar
 
Join Date: Oct 2005
Location: Oregon City, OR
Posts: 14,232
Total Cats: 1,149
Default

You could also try a bulkhead connector, otherwise just buy a grommet and punch a hole. For oil temp and pressure, those wires only need to be ~18-22 gage, make sure you're not using bulky wiring when it's not warranted.
curly is offline  
Old 06-01-2020, 12:22 AM
  #10  
Junior Member
Thread Starter
 
dsamani's Avatar
 
Join Date: Dec 2018
Posts: 254
Total Cats: -51
Default

GOOD NEWS:

There is a HUGE empty space just behind the washer tank. In addition, if you remove the glovebox and look straight in, there is a spot that is exposed with no insulation behind it. If you remove the washer tank, you've got plenty of space to drill through it.

You can mark the spot you need to drill with a punch. I didn't have a punch available that was long enough, so I "made" a punch with two 12" extensions, a 1/4" socket, and a phillips driver bit. I then used a hammer to imprint the area to drill the hole.

I then used a stepped drill bit to drill it out to 7/8" and made a grommet by taking a 1" vacuum cap and drilling out the top of it with the stepped drill bit. To get it in, I cinched it down with a hose clamp, put it into the hole, then removed the hose clamp. Worked like a charm!!!!!1
dsamani is offline  
Old 06-01-2020, 10:49 AM
  #11  
Senior Member
 
themonkeyman's Avatar
 
Join Date: Nov 2016
Location: Los Angeles, CA
Posts: 554
Total Cats: 77
Default

I mean you can also just buy a rubber grommet, they‘re very common in hardware stores in most standard sizes
themonkeyman is offline  
Old 06-01-2020, 12:02 PM
  #12  
Junior Member
Thread Starter
 
dsamani's Avatar
 
Join Date: Dec 2018
Posts: 254
Total Cats: -51
Default

Originally Posted by themonkeyman
I mean you can also just buy a rubber grommet, they‘re very common in hardware stores in most standard sizes
Yeah but it was 11:30 at night and I wanted to get this **** done
dsamani is offline  
Related Topics
Thread
Thread Starter
Forum
Replies
Last Post
Ciclonvnz
WTB
4
04-06-2020 12:09 PM
Samakhan
General Miata Chat
7
04-16-2012 01:43 PM
Hot_Wheels
WTB
3
03-30-2012 11:39 AM
hustler
Race Prep
18
11-23-2011 12:54 AM
pusha
Race Prep
4
03-10-2010 08:03 AM



Quick Reply: Wiring harness firewall passthrough



All times are GMT -4. The time now is 05:13 PM.