2002Scoob

Favorite Spots to run cables through the firewall?

15 posts in this topic Last Reply

Recommended Posts

I gotta be honest, there aren't too many options I've found to run larger cables through the firewall on these cars.

I'd kill for a plug on the passenger side right now to run the fat cable required for my wide band AFR sensor I'm putting in the glovebox.

What openings do you guys use to pass larger cables through? I feel like I've just about run out of spots on mine.

Sent from my iPhone using Tapatalk

Share this post


Link to post
Share on other sites

How large is "large"?  

 

I've passed wire bundles and other cables up to 3/16" through the rubber grommet that surrounds the steering column.  Also, if you have a squarelight or a late roundie with the two barrel Solex, IIRC there's a rubber plug in the firewall where the choke cable passes through on Euro cars with single barrel carbs and manual chokes.   I know there was one on my '73 because I used it for the choke cable on my manual choke Weber when I installed it

 

And there's nothing that says you can't carefully drill a hole through the firewall that's below the heater plenum and below the glovebox. That's where the A/C installers cut rather large (1+ inch diameter) holes for refrigerant hoses...just make sure that before you start drilling you're not gonna hit something important on the other side, and use a grommet to protect the wire you're passing through.

 

cheers

mike

Edited by mike

Share this post


Link to post
Share on other sites

It's a rectangular plug about 12-15 wide. I'm leaning more and more towards popping a hole in there, but would like to avoid it if I can.

No choke cable hole I can find either, I feel like I've used every possible pass through on the drivers side.

Sent from my iPhone using Tapatalk

Share this post


Link to post
Share on other sites

I enlarged an existing hole that was either just above, or just below where the speedo cable passes through the firewall to get the plug for the Innovate AFR gauge through the firewall  

 

I believe this hole was used for the choke cable (not used on a US 1974 car) but not 100% certain. 

 

In hindsight, punching through on the passenger side would probably make routing the cable easier since you'll want to install the O2 sensor on the right side of the down pipe. 

Share this post


Link to post
Share on other sites

Yup, so I went with punching through the passenger side. Was a slightly mind wracking thing to do, but came out alright. I drilled through where there was a crack in the insulation, ahead of where the firewall meets the trans tunnel. I had an oversized silicone grommet lying around that worked nicely, but has a large gap between the wire and the ID. Once I get the cable length dialed I'll silicone it shut with high temp.

Much easier and less visible than trying to go anywhere on the driver's side. Between running power for the fuel pump and stereo/amp everything on that side was pretty much taken.

7304a65773890f9c60f01a8a1c2a2801.jpg

78d4deef087ae8ece2777d740d737d24.jpg

Sent from my iPhone using Tapatalk

Share this post


Link to post
Share on other sites

There is a factory hole with sealed plug on the right side just under the insulation.  I use it for the WB cable on both my cars.  I'm guessing it is there for the steering column of RHD cars....

 Be careful if poking or knocking the plug from inside the cabin- the two brake hard lines are very close to the plug.

Share this post


Link to post
Share on other sites

do you then need to put a hole through the insulation on the engine side?

006.JPG

I dug up this photo from fixing my floors and suspect I see the plugged hole you are referring to.

Thank you for that Jim.  I might not have thought to dig it out, without your tip.

Tom

Share this post


Link to post
Share on other sites

Great picture Tom!  There it is with all the tough seam sealer.  Yes you will have to make an opening in the firewall insulation.  Another good reason to route the cable on the right side is it can be secured to the brake pipes then down into the tunnel to the (right facing) o2 sensor.

Share this post


Link to post
Share on other sites

Your picture shows the hole toward the tranny tunnel - guess that is too far inward for a RHD column.

Share this post


Link to post
Share on other sites

Is it an AC hole?

I have heard they put them in all cars and plugged them, if not in use.

Anyway, I think I will use that with my AFR wire, when I finally get around to installing it.

(spark first, then fuel... but getting the ignition right seems to take a long time for me!)

 

thanks for the photo compliment Jim.

Unfortunately my trusty camera has developed a couple big spots on the image, apparently on the inside somewhere.

That is a very important tool, for me.  : (

Share this post


Link to post
Share on other sites
13 minutes ago, '76Mintgrun'02 said:

Is it an AC hole?

I have heard they put them in all cars and plugged them, if not in use.

Anyway, I think I will use that with my AFR wire, when I finally get around to installing it.

(spark first, then fuel... but getting the ignition right seems to take a long time for me!)

 

thanks for the photo compliment Jim.

Unfortunately my trusty camera has developed a couple big spots on the image, apparently on the inside somewhere.

That is a very important tool, for me.  : (

My tii with Behr a/c uses two other holes just above that plug. I removed the factory plug when adding the WB sensor.

Share this post


Link to post
Share on other sites

+1 on Jim's location.    Ran the 123 Ignition USB through there.  I ran the AFR line through the tunnel.     It is really, really close to the brake lines on the firewall, but you can pop it out judiciously. 

 

jb

IMG_4827.JPG

Share this post


Link to post
Share on other sites

I had a hole right above my steering column, there was a rubber plug in it.

I removed the wires from the O2 sensor connector, passed them through and re-attached the connector (with a rubber grommet), I think I may have passed something else through there as well.

I tie-wrapped the APSX WB module to the steering column, hopefully it doesn't impede anything from being installed... still in the assembly process.

 

If this interests you, I can snap a photo tonight.

Edited by MildSeven

Share this post


Link to post
Share on other sites

I decided to open up that hole in my photo above and also cut a matching hole through the firewall insulation.

As mentioned above, be careful of the brake lines.  Mine were right behind where I was drilling.  I started with about a half inch hole and then ran this reamer through to match the plugged hole.

025.JPG021.JPG027.JPG (I notched a rubber plug, so it fits the hole, with clearance for the brake lines.  I am not running anything through the hole yet).

 

Once the firewall insulation hole was cut, I reinstalled the fiberboard insulation and cut a hole in it, from the engine side, using a hole saw.

I learned that there are three layers to that insulation.  The fiber board and open cell foam on the outsides and a layer of tar mat in the middle.  No wonder they are heavy.  I was torn about adding the hole through that stuff, but decided to do it, for ease of access to the hole.  If I run wires through it, I will not be able to remove the fiberboard, without removing the wires first; unless I notch the board down to the hole.  Getting the fiberboard out from behind the heater box and up and over the retaining clips on the floor is a bit of a pain, so I drilled it.

029.JPG

I am thinking of adding a longer tube to my stethoscope and running it through this hole, so I can listen closely for engine knock, while driving, as I adjust the timing (on the fly).  To adjust the timing, I have run a push pull cable through the hole that MildSeven mentioned above; next to the steering column.

021.JPG

Share this post


Link to post
Share on other sites

This is great info!

 

I'm going to re-visit this plug location soon I think. The hole I punched for the AFR works pretty well, but I see myself doing more ignition upgrades in the near future, namely 123 Ignition as well, and some other things. I currently have a few wires that are run kiiiiinnnda sketchily through the driver-side. I ran out of holes, and actually ran one through the slot where the hood-latch cable is for the power-wire of the amplifier. I know, I know... I'm not proud of it. One of the few corner-cuttings I've done on the car.

 

It was meant to be purely temporary till I could find an easier pass-through, as it's proximity to the release-cable is just ASKING to cut through it's jacket over time, but It's not huge current, and is fused. I also slipped some of that Chinese finger-trap abrasion sleeve stuff over where it passes to prolong the inevitable. 

 

Who knows. Now that my roof-rack project is almost done, maybe I just re-wire that afterwards. In all honestly, it is a COMPLETE pain in the ass to assemble and disassemble the drivers side cardboard panels, re-stuff all the wiring that's under there, etc. etc. The passenger side is a breeze thou, so I'm happy if I can avoid the DS dash if possible. 

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now