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Rear Fascia Sag

Ken

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1987 Z51 Silver Coupe
I've often wondered if there was a fix for the sag in the rear fascia (bumper) of my C4 (evidently it is common for some C4s to suffer this malady!), and the other day somebody at the Corvette Forum clued me in to the NHTSA site:

Service Bulletin Number: 87-176
Bulletin Sequence Number: 142
Date of Bulletin: 8707
NHTSA Item Number: 93533
Make: CHEVROLET
Model: CORVETTE
Year: 1987
Component: STRUCTURE BUMPER ASSEMBLY: ATTACHMENTS/SUPPORT BARS
Summary: REAR BUMPER FASCIA SAGS - CORRECTED BY ADDING A REINFORCEMENT-CENTER REINFORCEMENT, P/N 14069615, BETWEEN EXHAUST OUTLET NOTCHES IN FASCIA - POP RIVET REINFORCEMENT TO INSIDE SURFACE OF FASCIA USING FOUR (4) 2436998 RIVETS - ALL CHEVROLET 1987 CORVETTE MODELS

Has anyone ever installed this part or found it using the part number?
I stopped by the Chevy dealer the other day but I didn't have the P/N with me and "Victor - The Parts Man" didn't have a clue. Of course I can't blame him, after all the car is fourteen years old. :D
 
M

Moffitt

Guest
When you get it why don't you post a picture of it?
I'm curious as to what it looks like.
And if it really works?
 

Ken

Gone but not forgotten
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Messages
8,237
Location
Hermosa Beach, CA
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1987 Z51 Silver Coupe
Moffitt said:
When you get it why don't you post a picture of it?
I'm curious as to what it looks like.
And if it really works?

You can be sure of it! ;)

Oh yeah, BTW - I ordered the part today. I forgot about this post; I updated the related post that I have going in the want ads section but negleted this one.
Perhaps I should leave it as a message to others that a "fix" is available? Whadaya think, Rob?


[Edited by 1987 Z51 on 02-07-2001 at 12:39 AM]
 

Ken

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1987 Z51 Silver Coupe
I mentioned some time ago that I picked-up the part mentioned in this bulletin to correct the sag found in many rear bumpers of '87 Corvettes.

Well I installed the piece yesterday and it did correct the problem. You need pop rivets that are at least 1/4" long to get through both the fascia rubber and the reinforcement piece.
Installation was a snap, and the part was only about seven bucks! :cool:

I thought that I had a "before" picture to compare here, but I can't find any that are clear enough to see the sag. Here is an "after" picture.

 

Ken

Gone but not forgotten
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Messages
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Location
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1987 Z51 Silver Coupe
NHSTA Bulletin

84c4 said:
Ken,

Where can I get a copy of this fix and the parts?

Dave

Home Page - Tech Center - Service Bulletins
My local Chevy dealer was able to order the part.

Ken
 

TAC

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Feb 18, 2002
Messages
252
Location
Bothell, WA
Corvette
1987 Yellow Callaway TT Convertible & 2003 MY Z06
Ken said:
I mentioned some time ago that I picked-up the part mentioned in this bulletin to correct the sag found in many rear bumpers of '87 Corvettes.

Well I installed the piece yesterday and it did correct the problem. You need pop rivets that are at least 1/4" long to get through both the fascia rubber and the reinforcement piece.
Installation was a snap, and the part was only about seven bucks! :cool:

I thought that I had a "before" picture to compare here, but I can't find any that are clear enough to see the sag. Here is an "after" picture.


Ken: How bad was your sag? :D Mine sags about 1 1/2" down and it takes a lot of pressure to push back into place. I have the cheap aluminum piece but it doesn't feel strong enough to hold it. When you riveted it can you see the bottoms of the rivets while standing behind the car? I though about using a flat head bolt or something similar and paint the head yellow to match before installing. Your after pic isn't working for me.
 

Ken

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Messages
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Hermosa Beach, CA
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1987 Z51 Silver Coupe
This is the "after" shot:

I couldn't find a very good "before" shot, but the image that shows when you click the picture gives a fairly good representation of how much it was sagging.

The GM piece pulled it up alright, but be sure you have the long-head pop-rivets when you install it; the bumper material is pretty thick. The "cheap aluminum" does the trick by spreading the load out over a greater area.

And no, you can't see the rivets if the piece is installed correctly. ;)

_ken :w
 

TAC

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1987 Yellow Callaway TT Convertible & 2003 MY Z06
Ken: Thanks...that looks like about what I have. I got no instructions or help with the piece so if you could answer these questions it will really help me out. The piece I got is an aluminum strip of metal with a small rolled lip and 4 holes. The strip is slightly bowed in on the lip side.

1) Proper orientation. It looks like the proper placement is lip side up placed on top of the fascia with the lip side snugged up against the inside lip of the fascia. Seems obvious but I gotta ask if that's how you fit it.

2) How did you drill the holes? From above or below the fascia? The curvature makes it somewhat difficult to accurately compute the holes from below the facia and I don't see how you can drill them from above with the piece in place acting as a template. Did you do just one hole first and try to cinch it up before doing the others?

3) The sag is quite pronounced and I thought there should be a fastener at dead center to be more effective in cinching it up. However, there is no hole in dead center of the strip. This makes it somewhat difficult to mark the very first hole. How did you go about measuring where the holes should be drilled.

4) Did you heat up the fascia at all to make it more pliable?

Thanks much for your help. Not knowing if this strip is truly effective has stopped me from drilling into the car. I suppose any fix will look better than it does now, though.
 

Ken

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1987 Z51 Silver Coupe
Man, you're really making me think here aren't you? :L

It's been so long since I did that (actually, it may not have been that long, it's just that my memory is so short ;)), but if I remember correctly, I held the aluminum piece up to the bumper as a template on the outside while I drilled the holes. You'll have to push the bumper sag up, and hold it fairly close to where you'll want it, before you drill the holes. I see no harm in doing one hole at a time; I believe that is the way I did mine.

It sounds like you understand the proper positioning of the lip side of the strip. There's no need to heat the bumper, I don't know how that would affect the urethane, not to mention the paint. ;)

_ken :w
 

CorvetteArchives

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Apr 19, 2001
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Carbon County, PA
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1984 Z51 Silver/Gray & as Much SS & CFibre we find
Darn it Ken.....got me all excited!
Thought the post was about the TOP sagging.....our 84 is wavy in back...cant think of anything other than replacing with fiberglass since we noticed many other C4's have same problem with urethane.
But your prob and fix reminds me of the FIX we came up with for the front facia. Believe it or not....... stuffing plastic trash bags in worked in providing support between the facia and the bumperpad! No move wavy facia 4 years now. :D
:w
 

Ken

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1987 Z51 Silver Coupe
Corvette1984 said:
...cant think of anything other than replacing with fiberglass

Nope. there ain't no cure for that waviness except to replace the bumper cover with fiberglas or one of the other materials. But then you run the risk of it easily being damaged if someone nudges you in a parking lot. :(

...stuffing plastic trash bags in worked in providing support between the (front) facia and the bumperpad! No move wavy facia 4 years now. :D

:cool Good idea!

_ken :upthumbs
 

Baldie88

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551
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Waterloo, IL USA
Corvette
2016 triple black vert.
Calling Ken

Got a similar problem on my 88. Not too bad but I wanted to fix it. Figured the rear facia would be the same between 87 and 88 so I called the local Chevy dealer and gave them the number you listed on the first post. Said they couldn't find it. Any ideas on what the part number might be? Parts guy only found rear facia supports for the outer edges, nothing in the middle.

From your description, wouldn't any old flat piece of metal (something light like aluminum) work?

Appreciate any help. I looked through Carfiche.com and couldn't find anything on this part either.

Baldie88
 

Baldie88

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Waterloo, IL USA
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2016 triple black vert.
Thanks Ken and TAC

After getting nowhere on the part number Ken listed I reread TAC's comment and thought I'd try to fashion the support myself. Went to the local Lowe's and bought a piece of aluminum angle about 1/4" thick and about 3/4" on each side. It was three feet long and cost $1.84. Cut it to go between the current supports and wonder of wonders, there are already 4 holes on the back side lip of the rear bumper (it's an 88). Drilled 4 holes, lined up the holes with those on the bumper, pulled up the sag and popriveted the angle piece in place. Took me all of 10 minutes and no sag!

Thanks for the tip Ken and TAC :D

Now if would have only been this easy to replace the carpet on my doors. Spent most of the day on that. Managed to break the lamp lense and bulb on the passenger's side. Then when I shut the door I heard something fall loose. Oh well, I've got to take it off again to replace the lense. ;stupid
 

TAC

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1987 Yellow Callaway TT Convertible & 2003 MY Z06
One question--did you drill a hole in the very CENTER of the sag? That should be at virtually dead center between the sides. The reason I ask is that my aluminum piece from GM has the 4 holes about 2-3" apart and it straddles the center. I would have thought there should be a fastener right at dead center but if I drill a hole there too, the fasteners won't be evenly spaced unless I completely redrill the piece.

Got any before and after pics?
 

Baldie88

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2016 triple black vert.
TAC, sorry I don't have any before and after pictures. Still haven't modernized the camera yet. Anyway the sag wasn't too bad since the car has been garage kept most of it's life. I'm guessing 1" to 1 1/2". On the back side of the facia there was a lip that already had holes in it. As I remember there was a round one in the exact center and then I think 2 oblong holes on the right side and one on the left. But since I wasn't using the Chevy piece, only a piece of angle aluminum, I just put the piece under the fasia against the lip, pushed up the sag so it was even and marked where to drill the holes in the aluminum piece. I would agree that the Chevy piece should have a hole in the center. And mine is an 88 so maybe older years don't have these pre-drilled holes in the facia. I had bought a 3' piece of aluminum and cut about 18" off of it to go between the facia supports. The holes pre-drilled in the facia were about evenly spaced across this almost 18" of angle so there were more than 3" between holes.

Hope this helps. I'm just suprised that my senile brain even figured out how to do it but I wouldn't have done it without our description of the Chevy part. Thanks. :)
 

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