Best places to run wiring through the firewall?

[Sask84gt]

Wanting to mount my MSD street fire ignition module in the interior somewhere. Some options I'm looking at are under drivers/passenger seat, under dash etc. What are the best places to run the wiring through the firewall? I've read some people go through the steering shaft boot and some drill new holes and install grommets. Any suggestions?

[wraithracing]

I personally don't like running anything thru the steering shaft boot. I don't like wires that close to something that rotates and only recently is that part reproduced, so I never wanted to add holes to it.

Personally I would look under the dash near the driver's door and consider adding a new hole in that area with a rubber grommet. It is much easier to gain access to that area under the dash, then just about anywhere else. I used to be able to twist and contort into odd positions to get under the dash. NOT so much anymore, so I don't try to make things any more difficult for me than I have to if you know what I mean. Good Luck!

[badnightrain]

I did a wire tuck on my car. The msd box I put under the fender on the rail. I passed the wires thru the door jamb near the hinges.

[gt4494]

I personally don't like running anything thru the steering shaft boot. I don't like wires that close to something that rotates and only recently is that part reproduced, so I never wanted to add holes to it.

Personally I would look under the dash near the driver's door and consider adding a new hole in that area with a rubber grommet. It is much easier to gain access to that area under the dash, then just about anywhere else. I used to be able to twist and contort into odd positions to get under the dash. NOT so much anymore, so I don't try to make things any more difficult for me than I have to if you know what I mean. Good Luck!

and as we get even less flexible we realize that removing 4 bolts that hold the seat opens a whole new meaning to laying around. Throw a blanket on the floorboards and you can lay/look any way you need to work under the dash.

[quickshift]

If I remember correctly, I used the grommet surrounding the A/C line going into the interior to run my lines and wiring for my dash mounted gauges. This was easier than crawling around the drivers side.

[gt4494]

If I remember correctly, I used the grommet surrounding the A/C line going into the interior to run my lines and wiring for my dash mounted gauges. This was easier than crawling around the drivers side.

and you won't interfere with any pedal functions or steering.

[Sask84gt]

If I remember correctly, I used the grommet surrounding the A/C line going into the interior to run my lines and wiring for my dash mounted gauges. This was easier than crawling around the drivers side.

Is that this grommet?

Attachment 130752

[MERCURY MOTORSPORT]

Sask84gt - I believe that is the cowl drain. Maybe someone will confirm

[Sask84gt]

Sask84gt - I believe that is the cowl drain. Maybe someone will confirm

This the passenger side under dash. Sorry picture is sideways.
Attachment 130754

[MERCURY MOTORSPORT]

Here's a Yootube video (by Basin Motorsports who is a member here) with a decent look at all of the firewall openings, might give some good ideas on various locations of all of the openings . . .

https://www.youtube.com/watch?v=M10IVHkNaYE

I'd also Goggle Image search Fox Mustang Firewall - and - Fox Mustang Engine Bay as there's plenty of images (and videos too) of various Foxes with the engine bay empty which is really handy as it gives a really nice peek at the various openings and is great for wire routing ideas etc

Here's a few for starters . . .

[MERCURY MOTORSPORT]

Here's the last couple of photos (the forum only allows 5x pics per post!) . . .

[Sask84gt]

Thanks!