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GMT400 Door Support for Towing Mirrors

dbrannon79

dbrannon79

I'm getting there!
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Seguin, TX
I finally got around to fixing up a set of lighted tow mirrors and installing them on my rig. I had them on there once before, but I broke one of the glass mirrors, decided to pull them and put back the factory ones for a while, but now that I have them installed and wired up I have noticed that there is a decent wobble in them where the actual door skin below the mirror flexes a bit causing the mirrors to shake moving down the road.

I know others have experienced this and there are many reviews on new sets online where folks complain about the shake in the glass. my mirrors seem to be solid where it's not the glass that shakes, but the entire mirror. both inner support brackets are installed but the door needs the extra support for the added weight.

while I had the panels off, I noticed a 5/16" hole in the door inner skin that had some reinforcement around it. straight across from this hole there outer door skin in that area also has some extra reinforcement as well. I was thinking of getting a nut insert in the hole and installing a short piece of allthread with a rubber foot on the inside so that I could run it down to apply some pressure on the outer door skin pushing outward to help make the outer door skin more rigid for the mirror since the weight is pulling down on it.

one thing I also noticed is that the outer door skin flexes even more when the window is down. any ideas or tricks others have done to strengthen the doors on these rigs?

1676853349567.png

Here is a random pic of the inside of the door I got online where I circled about where the hole is in the inner door frame, location I was thinking of adding the above rubber feet to push on the outer door skin for some support.

1676853588667.png
 
I will have to take a photo of mine and how they are. I know there are two different styles out there for our rigs. mine are the ones that mimic the 2015+ style mirrors with the forward facing marker lights and rear backup lights in them. I have thought about investing into the other style that should be lighter in weight only having the two mirrors in them.

the movement in them aren't that bad, I can still see through them on the road. I'm more afraid of the added weight causing damage to the doors over time. years ago I had an El Camino where cracking started in various areas in both doors due to the weight of the whole door. it wasn't cracking at the spot welding but everywhere else that they were under stress. You could literally see the door flex in areas as the window rolled up and down. something I am beginning to see in both the doors on my truck now.
 
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Big T said:
We put the towing mirrors on both the ‘99 and the ‘94. Both shake, but the ‘94 is worse.
Click to expand...
can you tell if it's just the upper glass or the entire mirror assembly? mine don't shake so bad that I can't see thorough them but it does bother me. my biggest pet peeve is someone driving behind me at night where their headlights reflecting in the mirrors with the shake. almost makes for a flashing light in the corner of my eyes while driving.
 
dbrannon79 said:
can you tell if it's just the upper glass or the entire mirror assembly? mine don't shake so bad that I can't see thorough them but it does bother me. my biggest pet peeve is someone driving behind me at night where their headlights reflecting in the mirrors with the shake. almost makes for a flashing light in the corner of my eyes while driving.
Click to expand...
I’ll have to take a video. Has not bothered me like your description.
 
When I was on the tool truck, i went into different GM dealerships and saw the mechanic’s cutting up and stuffing a foam behind these style mirrors.

I asked one guy and he said it was a mold proof foam and the purpose is to limit the vibrations while driving.

I thought he was on crack until I went to another dealership and saw two guys doing the same thing right next to each other. They just cut this foam into strips and pushed it behind the mirror with the plastic interior removal tools.
 
I had Dodge mirrors on mine for a while. I think there are photos here somewhere. They didn't shake and I had some vibration isolators - rubber washers, I think. I took them off because I simply didn't need them any longer since we sold our slide-in camper.

I still have the slip on style from way back if I need something wider than stock. They were electric, so I had to undo all that when I put the stockers back on.
 
Will L. said:
When I was on the tool truck, i went into different GM dealerships and saw the mechanic’s cutting up and stuffing a foam behind these style mirrors.

I asked one guy and he said it was a mold proof foam and the purpose is to limit the vibrations while driving.

I thought he was on crack until I went to another dealership and saw two guys doing the same thing right next to each other. They just cut this foam into strips and pushed it behind the mirror with the plastic interior removal tools.
Click to expand...
Behind the mirror glass? You would lose the adjustability.
 
Big T said:
No compliments on how well the ‘94 sounds?
Click to expand...
it does have a nice low tone to it.

I haven't tried to address the vibration yet. I still need to get a photo or video on them first. hopefully I will get to them sometime this week or the weekend.
 
I have never noticed any shake, rattle or roll to the mirrors on My truck, they seem firm and solid when I’m on the road. Even at 80 MPH they are solid.
I didnt have in my hearing aids when I watched the video.
Tomorrow the son will be driving me to Billings, I will have in My HAs so I will watch the video again and listen for the sound of the truck.
 
Big T said:
Behind the mirror glass? You would lose the adjustability.
Click to expand...
Nope- they just stuffed it in (yes behind the glass) and shuffled it around. Basically fit in as much as they could until it wouldn’t adjust then pull out a little bit with the tiny needle nose pliers. Foam is black so ya can’t really notice it .

Seemed pretty hokey to me.
 
Will L. said:
Nope- they just stuffed it in (yes behind the glass) and shuffled it around. Basically fit in as much as they could until it wouldn’t adjust then pull out a little bit with the tiny needle nose pliers. Foam is black so ya can’t really notice it .

Seemed pretty hokey to me.
Click to expand...
How about shoving soft auto upholstery type foam in there which would retain the ability to adjust?
 
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I bought a sheet of closed cell foam from McMaster Carr when I installed mine. I trimmed to fit and when I installed, I had about 1/16" that stuck out all the way around the perimeter of the base. The foam was 1/8" thickness if I remember correctly.
Something like this:
www.mcmaster.com

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.
www.mcmaster.com www.mcmaster.com
 
SnowDrift said:
I bought a sheet of closed cell foam from McMaster Carr when I installed mine. I trimmed to fit and when I installed, I had about 1/16" that stuck out all the way around the perimeter of the base. The foam was 1/8" thickness if I remember correctly.
Something like this:
www.mcmaster.com

McMaster-Carr

McMaster-Carr is the complete source for your plant with over 595,000 products. 98% of products ordered ship from stock and deliver same or next day.
www.mcmaster.com www.mcmaster.com
Click to expand...
Did it work?
 
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