Problems with Fit on not one, but two new rear bumpers for 78 C10 fleetside

[Chebbyman]

I am restoring a 78 Short Bed Cheyenne and have run into a problem. I have purchased and installed two(2) rear fleet side bumpers purchased from a well known and customer oriented supplier located in Florida. The first one had a noticeable rise in the center of the bumper(bumper frown...). I called the supplier and they said no problem, bring it back and we'll give you another one. They brought out three and I picked the one that we both thought to be straight. After installing it, it was exactly the same as the first. I was looking for info on line and someone posted the exact same problem. It seems like all of the suppliers carry the same made in Taiwan bumpers and some admitted to problems while others said they only had one complaint in the past two years. They all offered to send a picture of the bumper before shipping. The only problme with that is that it is impossible to see the curve in a picture but sticks out like a sore thumb when installed because the top of the bumper is SUPPOSED to be parallel to the tail gate. The original bumper was not on the truck when I bought it but in looking at pictures of trucks with original bumpers you can clearly see that the bumper is parallel with the tailgate. The issue is clear in the two pictures. The curved one is the brand new one I got from my Fl supplier. The second one is from a truck for sale on the internet. H E L P! How can I fix this or where can I purchase a straght bumper?


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orida supplier

 

[PrairieDrifter]

I don't think you could miss that in a picture. I think you're gonna have to do a bunch of bracket adjustments.

I'm guessing when bolting it together everything gets sucked down with the bolts pretty good? Right? It doesn't technically rest there until you hammer it down?

Looks like the outside mounts are pulling the ends down and in towards the truck. The inner brackets should slide in and maybe down a little. The outer brackets should slide out and up.

 

[Chebbyman]

I am gonna try to put my axle jack under the outside bracket one one side and try to raise it up to the level as the center. Tighten brackets and bumper bolts on that side and then swap to the other side. If that doesn't work, I am going to take it back and buy from another supplier. I will post my results tomorrow.

Thanx for your suggestion!

 

[Ricko1966]

Does the bow come out with the bumper bracket bolts loose? As in do you maybe have tweaked frame rails or bumper brackets. If the bow comes out with loose brackets I'd shim and modify my brackets.

 

[bucket]

You also don't have the license plate pocket installed. That pocket actually adds a lot of rigidity to the center of the bumper.

Loosen up all the mounting bolts, even the ones on the frame. Then hope that the bumper returns to it's correct shape on it's own. It looks to me like the center needs to come down, rather than the ends go up.

Once the bumper is straight again, install the license plate pocket. Then snug up the carriage bolts. Then snug up the frame bolts, while setting the bumper height where you want it.

 

[TotalyHucked]

^This. These bumpers are actually very flimsy. Need to install everything loosely to start with, including the license plate bracket. If you can't get the license plate bracket in, try using 2 jacks on either end of the bumper to support and then stand on the center to coax it back down. Don't put all your weight on it to start with, just test with one leg and kinda hop up a bit, then work up from there till the bumper straightens.

 

[Chebbyman]

I have a picture of my second new bumper with the license plate bracket installed. Here is the process I followed for first and second new bumper. I loosened up all the bolts, put a piece of wood on the left side end bracket(Not the Bumper) and jacked it up until it looked as straight as possible. Then I tightend all the bolts on that side. Then I moved the jack to the right side and repeated. The Picture shows the end result. Better but not acceptable to me. Ordered a new bumper. I will try it again with the new bumper. The picture below is the second new bumper after the adjustments. Don't think the frame rails or bumper brackets are bent. New Bumper Brackets of 8 gauge steel. All of the holes on the brackets are in line on a horizontal plane. The bumper bolt holes are as well. to my way of thinking the only other possibility is the top of the bumper is bowed. If you look around long enough on the internet, you will find several posts about aftermarket rear bumpers with bows like mine. No one has mentioned their supplier, only that the bumper is made in Taiwan, which is the majority of aftermarket bumpers. If my new(third) bumper fits, i will mention the supplier of both the first two and the third bumper. Am not interested in casting aspersions at this point. As long as the company refunds my money I am ok.

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[TotalyHucked]

Here's the process I use when installing bumpers. First, install the brackets onto the bumper but leave ALL the hardware hand tight. Then, use 2 jackstands with cloths on them, slide the brackets into the frame and the jackstands will hold the bumper roughly in the position it should be. Keep a hand on it but it shouldn't fall at this point. Roll under and put the hardware in the brackets to the frame, again leaving it all loose. You'll know at this point if the bumper has that crown in it or not. If it does, stop here and call whoever you got the bumper from before going forward.

If it's straight, then move on. Now that all the hardware is in and hand tight, tighten down the bumper bolts (with a ratchet, not an impact. You'll dent the bumper real fast if you go too tight), then start adjusting the bumper in/out, left/right, up/down till you're happy with it. Here again, tighten the bolts down enough to keep things in place but not all the way tight. Then throw the tag bracket in. If everything looks good, then I crank down on the bumper bracket to frame hardware real good and it's done.

If you go through that process and the bumper starts to bow, stop right there. There's something wrong with either the truck or the brackets. You'll need to back up and punt, figure out where the problem is.

I work for AMD, that's not a complaint we have on our '73-80 bumpers and we sell alot of them. Not all bumpers come from the same place, we R&D'd our bumpers here in Ga and have our own tooling for them.

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[Chebbyman]

Thanks so much for the response. When i installed the front bumper, I used your method and it lined up quite nicely. I am 99% certain that the bumpers I bought have a mfg issue. Not knocking anyone here. I have plenty of Taiwanese parts on my 78. First problem I have had with what appears to be a mfg problem.

 

[Chebbyman]

Purchased an AMD rear bumper and it solved my problem. Just need to raise and level the left hand end. Put my harbor freight digital caliper on both bumpers. AMD is .13” thick while my Taiwan bumper was .08-.09”thick. AMD is thicker and heavier. Measure first then buy. Expect that the memory after forming the Taiwanese bumper caused the bumper to arch in the center.

 

[TotalyHucked]

Awesome, glad that fixed it!

 

[bucket]

Awesome, glad that fixed it!

Y'all keep up the good work!