How did you route your Motronic harness in a long hood 3.2 upgrade

[wjdunham]

Having some trouble figuring out how to best route my 3.2 Motronic harness in a 1969 car. The one issue I'm having is that there is not enough room behind the cross member to which the top of the shocks mount to thread either ends of the harness from the lower part of the rear firewall up to the engine compartment. This may be a '69 thing as I know there were changes to that cross member in the later long-hood cars and maybe there is more room behind that cross member in the later cars?

Anyone have any thoughts/pics as to how to best route the harness from the hole I'm going to put below the rear seats up to the engine bay. It will have to come up underneath the cross member between the engine sheet metal and the big rubber seal, but I want to make sure I don't have interference issues with my SSI exhaust, transmission, etc...

Thanks as always for any help.

Bill

[Solamar]

Hi Bill,

I'm not at my computer, so searching past threads is tricky, but a few years back when I did my 3.2 swap I wrote a similar thread looking for routing advice.

I went the "standard" route through the left side of the rear seat kick area.

There was a different suggestion that I almost wish I had followed.

The goal is to get the harness to the upper left engine compartment, below the fuel filter area. If you go through the foot kick area, you have to route the harness, under the car, exposed, and dodging around multiple obstacles.

The suggestion, that I didn't take, was to pull the carpet and trim from left rear of the car and put the hole through the firewall, near the left shoulder area of a rear passenger, popping the harness out right below the fuel filter. This way most of the harness is inside the car, protected and covered by the carpet and trim.

Hopefully that makes some sense...

[78-911SC]

I have a 70T. Did mine on the Passenger side and had to bend the path to get the harness thru. Sorry I can't remember if I took off the connectors or not.

[rattlsnak]

The factory did it on the left rear passenger kick wall, so that was good enough for me to route mine that way..

[wjdunham]

The problem I have is that there is no way to route the harness above the cross member like it is in this photo without removing a bunch of the plastic connectors anyway. I would need to route it into the engine compartment underneath the cross member, and I'm worried about interference issues and/or heat from the SSI's which are pretty close to that area.

Originally Posted by 78-911SC

I have a 70T. Did mine on the Passenger side and had to bend the path to get the harness thru. Sorry I can't remember if I took off the connectors or not.

[tperazzo]

I just did this in a 67.
I clearanced the back of the shock turret cross member with a carbide Burr. Only in the pinch weld section.
I also enlarged the indent in the rear seat area with a large round pry bar.
The new harness runs right next to the stock harness now.
All my work is on YouTube if you're interested in the entire 3.2L swap.

[wjdunham]

Thanks, I did think about that option, was worried that reducing that pinch weld would weaken the structure. How much did you need to take off given that you also moved the firewall (good idea too).

Is your youtube channell "Garage Time"? If not, can you post a link to the content.

Thanks!
Bill

Originally Posted by tperazzo

I just did this in a 67.
I clearanced the back of the shock turret cross member with a carbide Burr. Only in the pinch weld section.
I also enlarged the indent in the rear seat area with a large round pry bar.
The new harness runs right next to the stock harness now.
All my work is on YouTube if you're interested in the entire 3.2L swap.

[Solamar]

Here's the thread from my install -
Carrera 3.2 DME harness route

The first reply from Timmy2 is the alternate route I mentioned. May get you above the cross member.

[tperazzo]

Originally Posted by wjdunham

Thanks, I did think about that option, was worried that reducing that pinch weld would weaken the structure. How much did you need to take off given that you also moved the firewall (good idea too).

Is your youtube channell "Garage Time"? If not, can you post a link to the content.

Thanks!
Bill

Here's the video regarding the wiring.
https://youtu.be/hhCwGG-Ob1Q
The pertinent info is in the first few minutes.
Putting a moon shaped relief in the pinch weld isn't going to weaken the car very much if any
It's more to prevent a sharp edge that could cut the harness or fuel line.
Best of luck,
Tom

[wjdunham]

Thanks guys, those links are super helpful. I will update after I've spent some Ahh, Garage Time of my own working it out :-) I didn't think about just buying a factory rubber seal for the rear firewall hole, so that's on order now.

Bill

[Tea Tray]

WJ:
What is this in the heater box?
Thanks!

[wjdunham]

Posted this in another thread as well, anyone have the part number for the harness grommet for the firewall hole (something like 1.75" OD) ?

[wjdunham]

Success, pretty much followed the recipes offered here, so thanks very much for the help as always!

Here are the tools involved:



Bottom view looking up at the cross member - Grind away the seem welded flange on the cross member


Top side behind the harness I moved back the firewall metal a few mm with the BFH and punch to allow the larger connectors to slip through. Still took a lot of fiddling to get everything through as there is very little room left for the last few connectors once the wire bundles start coming through, and the stock harness is already pretty thick and tough to move out of the way far enough to get good clearance.