Stripping urethane plastic bumper cover from a 77 firebird trans am or camaro

Schroeder

Schroeder

Promoted Users
What do you guys do to strip these. Through my searches I saw one thread on these forums where someone recommended blasting. Would this fine grit black diamond (black beauty knock-off) at 60psi be a good solution? I'm currently sanding it and it's going to take ages of I continue this way.

Another thread I found someone saying they only sand with 220grit to start. I have many, many layers from many, many previous moron owners who didn't do things the way anyone including myself would do things. There are tons of layers and tons of products. Blasting seems to be the way to take care of this. I'm not using powered air or electric sanders. If you remember or search my thread history you'll see I did that on the back bumper cover and gouged the hell outta it! I saved it and it looks amazing, but man I added a lot of work for myself. I'm hoping to skip a few hours on this piece.

Here are some pics showing all the layers of garbage I have to remove as well as the back flanges of the urethane cover, to confirm that it is indeed urethane.
PXL_20230226_191739722.jpg
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Chris_Hamilton said:
If you have someone who soda blasts that would be the ideal process to do that cover.
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I kept searching after posting this, and in my own thread from the past I realized I blasted the rear bumper cover with black diamond. That was only 1-1.5 years ago. I'm only 32. How bad will my memory be in 20 years?

Sorry for wasting everyone's time. I gonna get some of this fine grit black diamond and blast the cover. I did it once with the front cover and it turned out amazing. I'm gonna give it a go here. I'll post pics when finished.
 
Schroeder said:
I kept searching after posting this, and in my own thread from the past I realized I blasted the rear bumper cover with black diamond. That was only 1-1.5 years ago. I'm only 32. How bad will my memory be in 20 years?

Sorry for wasting everyone's time. I gonna get some of this fine grit black diamond and blast the cover. I did it once with the front cover and it turned out amazing. I'm gonna give it a go here. I'll post pics when finished.
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Just go easy with it as you can and will remove the actual bumper material along with the paint.
 
I’ve done about half dozen 77/78 firebirds and have both a 70 and 73 by which I’ve had the bumpers sandblasted. It’s the best way to go. You need to use a fine grit for best results. This not only removes paint, but also a weak layer of material as it deteriorates from any sun damage. All spiderwebing and cracks are exposed. Next step i spray a thick build up of epoxy and then spread some flexible filler on them to work out any flaws.
 
Alright guys. Next verse same as the first? I did some Holy Saturday sand blasting. It sucked as blasting always does, but the weather was perfect!

Is this front cover worth saving? I'm no expert and have never seen any of these stripped aside from the rear cover I already completed, but this looks pretty good to me. I used the fine black diamond from tractor supply. Removed lots of layers of crap from the previous owners!The plan will be the same as the last time: wipe down with waterborne wax and grease remover, let sit for a week, reassemble, fit, build up with 3M EZ Sand (05891), sand down to fit, shoot with SPI epoxy and sand down 3-7x until satisfied. What do you guys think about the piece and the plan?


PXL_20230408_202804819.jpgPXL_20230408_202809270.jpgPXL_20230408_202759839.jpgPXL_20230408_202832895.jpgPXL_20230408_202837270.jpgPXL_20230408_202819057.jpgPXL_20230408_202826372.jpgPXL_20230408_202847443.jpg
 
*bump*

Anyone have any options or insight on the front bumper cover that I pictured above? Is it worth saving? It looks good to me. Maybe I'm missing something though. I don't plan on vee-ing any of the cracks or anything. I'm just going to use the regular SPI method that's been outlined many times on this forum for endura and urethane bumper covers.
 
dhutton01 said:
Your plan seems fine to me. I’ve done a few bumpers that way.

Don
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Thanks don. Did you take a look at the pics. Does the piece look to be in good condition in your option opinion or would I be better off trying a fiberglass piece. I actually have one and I haven't even tried fitting it up because of how horribly the rear cover fit. It was over 2" too wide. Total waste of $700 between to two. A hard lesson learned.
 
Yes I took a look. I think it’s worth repairing. It’s not too much different from one I repaired.

Don
 
The epoxy will do a good job of bonding now to that fresh surface without worrying of cracking due to weak or aged paint and primers. It will also cover up those fine cracks. Next what I do is apply a flexible two part epoxy to areas that are low like the spot over the LH headlights. Feather in your repairs and spray more epoxy over it to seal it up.
 
Dave C. said:
The epoxy will do a good job of bonding now to that fresh surface without worrying of cracking due to weak or aged paint and primers. It will also cover up those fine cracks. Next what I do is apply a flexible two part epoxy to areas that are low like the spot over the LH headlights. Feather in your repairs and spray more epoxy over it to seal it up.
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Yea this has been covered in depth here. I'll have to re-review the lengthy threads. One was my own thread ( http://www.spiuserforum.com/index.php?threads/77-firebird-endura-bumper-cover-restoration.8571/
) concerning the procedure for the rear bumper cover on this same car. That turned out beautifully. I thought I applied the repairing/leveling/replacement material BEFORE epoxy paint so that the material bonded to the actual substrate. I'll have to re-read things. Epoxy went on after that if I remember correctly, and I use 3M EZ Sand. It's a really cool, amazing product that bonds right to these urethane and endura bumper covers while remaining flexible. I can't stress how cool it is. It's fun to work with.

EDIT: I looked over my thread for the rear bumper cover. In the very first post I outlined my plan on that piece. Indeed, I put the EZ Sand material directly onto the blasted urethane surface. That's what I'll do here too. The consensus on SPI forums continually seems to be that when applying to a cleaned surface as I've done according to berry's method there is no reason to give the hairline fractures any special attention. There's no need to vee-groove them out and fill with the EZ Sand. Just shoot with a bunch of epoxy, block, and shoot again.
 
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Do you guys ever clean and paint this inner bumper structure on the 2nd gens!? Again, this is off a 77 trans am. It's listed as "plastic fiberglass" on firebird central.

www.firebirdcentral.com

1977 - 1978 Firebird and Trans Am Headlight Headlamp Mounting Support Panel, Used GM

headlight headlamp mounting support panel for your Firebird or Trans Am. Exact fit for all 77 - 78 models. This is the plastic fiberglass piece that goes directly behind your bumper and holds the head lamp buckets. Your adjust screws and springs mount to this part.
www.firebirdcentral.com

I was thinking about spraying it off with water, sanding with 80grit, cleaning with waterborne wax and grease remover, letting it sit a week, and shooting with epoxy. Another part of me says that's a waste of time and a lot of work for nothing. I don't think any of it actually shows once the outer headlight insert trim with the honeycomb pattern is installed. PXL_20230415_174846222.jpgR (3).jpeg
 
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