Roeich

How can I determine if my 71's rear bumpers are original or repro?
It's time to rechrome, but not if they are repro.

Thanks

Alan 71

Hi R,
If they happen to be Paragon reproductions they will have PR stamped on one of the brackets.
So, I'd start looking for that.
Often other reproductions were 'wavy'. The original bumpers didn't have very plating but the surfaces were quite smooth and even.
Regards,
Alan

0Willcox Corvette

Kind of a hard call... Alan, most of the wavy is gone from the imported reproductions now... The issue the imports was having was bracket placement and if these are already on the car then that's not going to be an issue. The PR bumpers are great quality but every now and then we get a bummer there too.

The original bumpers when they were available from GM still had signs of seam lines on the bottom side. IMHO, the current reproductions are way better quality than those that were being made when the bumpers discontinued.

I have original bumpers on my 70 and I have a set of the cheap repro's on my 72 (purchased by the po)... both look to me better than anything I ever saw from GM.

Post a picture of your original bumpers... but post one of the bottom and post one of the inside rear edge. I've seen enough bumpers in my lifetime, I feel pretty sure I can ID them for you.

Willcox

loup68

Didn't the imports have a weld seam in the middle of the back bumpers? Lou.

0Willcox Corvette

The original bumpers and the reproductions can have weld seams... it wasn't in the middle though, it was more toward the down turn about 2" - 2.5 " before the down turn. I'm not exactly sure how far it was from the turn but I have stacks of original cores that I can check if the exact distance is questioned.

Like I said above, I have the original bumpers on my 70 and it's been a "lift and garage queen" since the early 80's... so documenting the quality of these is pretty easy for me, it's just getting to the car that's a problem.

The seam was part of the manufacture process. With GM, the chrome plating specifications were lacking... so it was common to find one that didn't have chrome running all the way to the edge on the lower section. It was also common to find grind marks on the lower side since this was not a "specified" zone for a clean finish. The bumpers remind me of the mid year tail lamps in the fact that GM only specified to General Plating that the lamps needed to be chromed within 1/2" of the back wall. This lead to a ton of lamps where the finish.... for lack of a better word.... sucked.

In bumpers.. .when they were available from GM, we'd take 15 rear sets with us to Bloomington in the mid 80's to 90's and then we'd have customers that would want to look at each bumper to pick the best quality. It didn't seem to matter though because we'd always sell out of them before shows end and the same held true with tail lamps... The early bird got the choice but they always seemed to sell out.

Willcox

Z06LMB

The original bumpers had some waviness on the face side where the bracket bolts are welded on the reverse side. This was a result of an incomplete polishing by the refinisher. If the bumpers were never removed or past work was carefully treated there should be a few round shims on the fronts between the brackets and the fiberglass. The rears had none.

A fellow at the museum told me that the originals were not finished around the cut edges of the bumpers. The punch-out shearing machine made a very sharp edge that someone was supposed to ease-over but usually rushed by piece work qoutas.

Alan 71

Hi Z,
Not all cars had 'shims' on the front bumper mounting locations.
Regards,
Alan

Z06LMB

Yes, I interchanged the word "may" with "should" about the shims according to the 1970 - 1972 NCRS Technical manual.

kenba

I have original bumpers on my 70 454 & there are streaks of no chrome on the underside of both rear bumpers. Also the front bumper fits tight where it wraps around the front fenders. The repos I have seen flare out as they wrap around.

DABall

My thought is that if the bumpers fit well, I would have them chromed. That way you know they will look good and they will fit right.

loup68

I had one of my original rear 68 bumpers that I scrapped before moving to SC. I remember that it was about 1/3 thicker material than the GM OEM replacements were. And those were very old replacements from the 80's. Lou.