Firewall wire harness installation

[chevyrestoguy]

This question is for all of the guys who have replaced their wire harnesses, notably the Main Feed and Engine Feed harnesses that go through the firewall:

I've done harnesses in the past, and each car has it's own trick for installing these without damaging the rubber firewall grommet in the process. On our trucks, is it best to:
1): Install the grommet in the firewall first, and then push the harness connector through.

2): Put the grommet on the harness connector first and push them both in together at the same time.

On some Chevy vehicles, I have fished the connector through the firewall to the engine bay side, installed the grommet with the beveled side facing the firewall, lubed the grommet, and used a large socket the size of the grommet and and lightly tapped it into the hole.

Any tricks or tips regarding our trucks?

[earl84]

I can't really recall which way I did it, but at first I tried to use the 48 year old grommet. Bad idea. A new grommet and it went in much easier. I do remember using silicon spray to get it to slide in easier.

[rideblue00]

i installed the grommet first and pulled the connector into the grommet. silicone spray or....water based lube...

[ConradBSomething]

Where does a fella find a new rubber grommet? I too tried to reinstall an old one and it's in pieces.

I usually have luck putting the connector in the grommet first, then using some lube (usually silicone water base) to get it in the fire wall.

[chevyrestoguy]

I tried to pop the connectors in last night, but had no luck. About a year ago, after I painted my firewall, I installed my new grommets so I wouldn't lose them. After a year, those things have gotten so hard they will not flex at all, plus they were starting to crack. I am going to be ordering new grommets before I attempt to re-install the harness. I'm thinking that the only way to get the connectors through the grommets is to have fresh, new rubber.

ConradBSomething-
Most every specialty parts shop that deals in our trucks carries these grommets. Many of them sell them as a kit, which includes both firewall electrical grommets, the choke cable/oil pressure line grommet, speedo cable grommet, and the emergency brake cable grommet.

[chevyrestoguy]

Well, I just had a good laugh.

I was going through some parts boxes and found a new firewall grommet. I decided to give it a try and the connector popped right in.

I had been trying to install my firewall connectors using my original 50yr old grommets! They were in perfect condition, except they were as hard as a rock. All of this time, I was assuming that they were the new ones! Hahahahaha.........what a moron.