Installing door wire boot/bellows

[Pyrotechnic]

My truck did not come with power locks or power windows. I am going to drill the wire holes in the cab and the door, and install the rubber wire bellows.

I bought two new ones from LMC. One end of the bellows has a large opening, and the other end has a smaller opening. Does anyone know which side the larger opening goes to, the cab or the door?

I've been to the junkyard to try and check this out and investigate other aspects of the PL/PW conversion, and the closest vehicles I could find were a few 88-91 Suburbans. Unfortunately, the bellows is riveted in place. Can't really get a drill in there without removing the door.

Has anyone done this conversion before?

[75C10]

I have done this several times. Carefully remove the doors, drill the holes, feed the wires thru and then carefully reinstall the doors. Use screws to remount the conduits (bellows). Its not that hard with a 4x4 and a floor jack. I did mine by myself. Be careful and don't drop the door. Clean up sharp edges or you will have issues.

[Pyrotechnic]

Originally Posted by 75C10

I have done this several times. Carefully remove the doors, drill the holes, feed the wires thru and then carefully reinstall the doors. Use screws to remount the conduits (bellows). Its not that hard with a 4x4 and a floor jack. I did mine by myself. Be careful and don't drop the door. Clean up sharp edges or you will have issues.

Do you remember which way the bellows were installed? One end has a big hole and one end has a small hole, not sure which end matches up to the cab.

[75C10]

I think the big end goes on the door pillar as the factory wire harness goes thru a big bend at this point. It comes down the inside of the door jamb from the top and bends kind of 90 degrees to go thru the conduit. I used a large hole saw in the jamb with a smaller hole saw on the door. File edges smooth. You can rivet it shut but it makes access harder if you have wire issues. This is common in the jamb.

[Pyrotechnic]

That makes sense, I'll go with that. Thanks.

Did you find that either the door or cab had dimple marks where to drill? I think I saw some on the door but I need to confirm that they match the hole spacing on the bellows.

[75C10]

Yes the locations are already marked in the door jamb and I think on the door as well. Thats a very good point.

[Dads79GMC]

If you look inside the door, you'll see the same dimples! Not sure if the circle represents what size the actual hole should be.

Pictures:
1. Inner NOS door on my 79.
2. OEM door on the 78. Can't really see the dimples, but you can see the outline of the circle in both pictures.

Thanks Mike

[gmachinz]

You need to cut a 1.75” on the outside, then a 1.5” hole on the inside of the cab. I’ve done his quite a few times when converting from manual to power using my harnesses-it’s as close as you can get to how GM did it. I did my father in laws 77 GMC this way....

[Pyrotechnic]

Thanks gmachinz, I was looking around that area wondering where wires would come through. Is the positioning of that hole critical or is it all open space within? On my drivers side plastic kick panel, it looks like there's a raised shroud for where the wires could come out and up but I'm not sure if that was the intended purpose, I'll get a picture later.

I did some measuring on the rubber bellows, looks like a 1.5 and 1.75 hole saw will be what I need, and I can use the 1.5 for the kick panel wire exit too.

Has anyone else seen 4 dimples on the cab door jamb area like I am seeing?

[75C10]

Can't improve on whats been said. I can't remember if my door jambs had four dimples or not. But you are on the right track. Good luck.

[gmachinz]

Use the 1.75” on the outer first-when the bit goes just through to the inside panel-you’ll have a nice pilot hole to use the 1.5” from the cab interior side. I recommend drilling the 2nd dimple from the top-this way the wires go straight into the cab. Here’s my before pic:

[gmachinz]

Make sure to ream both hole edges really good-the metal is pretty thick there.

[Jaysonb]

This is what the factory hole in the piller looks like,

[Pyrotechnic]

Excellent! Not sure what process they used to cut the hole at the factory, but the oval hole at least somewhat explains why there's 4 dimples in the cab instead of just three.

I think I can get away with center punching between the outer holes and then using a 1.75 hole saw.

[Pyrotechnic]

The last detail is the kick panel hole. The location gmachinz posted seems lower than what the factory did, but probably makes it easier to route wires through the bellows. Maybe less strain on the wires too since they stay straighter

I found these pictures that show the wires coming out closer to the dash. It looks like GM placed the wires in the molded area in the kick panel cover where the fresh air vent pull handle would go.





I'm not sure if I can get the drill that close to the dash to cut the hole in the factory location.

[Pyrotechnic]

Last weekend I took both doors off, cut the holes, and got the bellows installed on both sides. Thanks to everyone that contributed here. I still need to cut the kick panel holes, but once I do that I will start another thread as a how-to so that all the information contributed here and my experiences will be in one place and easy to find.

[blazer2007]

Did you ever start another thread ,I,m going to do this some time this year

[gmachinz]

The factory had the luxury of using a shear punch to create a nice smooth oval-but on manual cabs this isnt an option-even using a step bit its a pita because there are 2 layers of metal to go through on the outer side and they arent welded together very well. You must seal the harness with a grommet on the inner kick surface which means the outer hole must must slightly larger so that a grommet can easily pass through. This means 2 things:

1.) Drilling straight through to keep the travel straight and:

2.) DO NOT use a step bit but instead a hole saw

I used a fine tooth hole saw to create a 1.75” on the outside and a 1.5” hole on the inside.

[gmachinz]

Here’s what I came up with.

[Hammered 77]

gmachinz where did you find the rubber grommets for the inside?

Rick

[RADustin]

what does the door to pillar gap look like?

I need to run wires in my '76 doors.

[GMC Guy]

curious also about the inner grommets, looking to add remote power locks to mine soon

[blazer2007]

New door bellows $80 ouch U.S. that,s about $120 Can.

[SunSoaked]

Originally Posted by blazer2007

New door bellows $80 ouch U.S. that,s about $120 Can.

Huh?
I paid a whopping $12.95 per side. LMC

[blazer2007]

I checked yesterday and was 77.00 or so. Better re-check ,thanks. Might have not been LMC, just did a quick Google search