1970 Challenger rear bumper installation?

[750-h2]

I finally found a straight OEM rear bumper for my 1970 Challenger.  Body shop installed my rear valance after the car was painted. I really do not want to remove the valance unless I have to. My question is, can the rear bumper be installed with it on? If it can, do I first install the bumper brackets to the car or do I install the bumper and brackets as an assembly?  Thanks

[JH27N0B]

No, you have to take the valance off to install the rear bumper.  It's not that big a deal even with a freshly painted valence.  Just put some painters tape on the sides and the edge of the quarters so you won't scratch the paint when removing and reinstalling. Btw, the fasteners attaching the valence to the 2 valence brackets are actually supposed to be phillips head machine screws not bolts.  Many shops don't know any better and use bolts.
And you install the brackets to the car, not the bumper when installing iirc. Keep everything a little loose until you are sure you have everything the bumper aligned correctly.  I did it about a dozen times when reassembling the car, only to eyeball it later and decide it still wasn't perfect.  Eventually had to remove and bend a bracket to get one side high enough!

[RUNCHARGER]

I tape rags everywhere and place a portable bench up there to help hold the valance when installing it. I guess having a helper would be good too but I always work alone.

[750-h2]

I just looked at my valance and it looks like a real PITA to remove without scratching all the bracket mounting hardware. Also the valance center bracket looks like it will be next to impossible to unbolt with the gas tank and exhaust already in place. This is what I'm thinking, let me know if you think this would work.
-to protect body, tape up bumper area of car with painters tape
-mount both brackets securely to bumper
-place the 4 large bolts with washers through the bumper brackets
-secure these bolts to the brackets with thin lezan push on washers that will keep them in place, yet permit the bolts to slide for adjustability.
-mount bumperettes to bumper
-with the help of two helpers [one underneath the car to guide bolts through body holes] position bumper on car.  Install nuts with washers hand tight until they bottom out, lineup bumper, protect bolt threads with painters tape, attach vise grips to bolt ends and tighten nuts with open end wrench.
-attach L bracket to bumperettes and tighten 

Seems easy enough ? What do you guys think?

[750-h2]

No comments from anyone. I guess this means my plan might work. As soon as my bumperettes come back from the chrome shop I will attempt to install the bumper without removing the valance. I will let you guys know how it goes.    

[JH27N0B]

Is your car a real early in the model year build?  I'm trying to make sense of how you describe your installation, and not having any luck. So I'm wondering if they did an early design change of the mounting.  I just went out to my garage and crawled under my November 69 built convertible and the April built car I removed the valance and reinstalled at least a half dozen times when I was restoring it, and don't see a center bracket blocked by the fuel tank. 
There's 2 valence brackets mounted just outside of the right and left sides of the fuel tank, which I didn't need to remove because the valence was attached to them by 2 screws per bracket and some sort of captured nuts in the brackets the screws threaded into. Simply remove the 4 screws. The resto shop used small bolts I replaced with correct screws and then touched up the paint marred by the bolts.
Then there are 2 nuts and one screw on each side attaching the valence to the quarter panel. 
I was wary of removing my valence repeated, being a clod sure I'd drop it or a gust of wind would blow it off where I'd set it, and really screw things up, but didn't see any way way to get at all the hardware for the bumper trying to install it with the valance on and brackets installed etc.
I'm really curious as to how yours is installed because there really wasn't any drama involved with mine.

[JH27N0B]

Another related thing that comes to mind.  Assuming this is a project car you are reassembling?  If the rear suspension hasn't been installed, or even if it has, I'm not sure you can get good access to the rear shackles to install, and adjust when you are setting ride height, with the valence installed.
Even if you can come up with a way to install and adjust the bumper with the valence installed, you still may need to figure out how to remove and reinstall the valance at some point down the line to get at the shackles.

[anlauto]

Pack your patience and prepare for a lot of skinned knuckles and swearing, but I believe you can do it !

[RUNCHARGER]

It's been awhile but I'm not so sure your idea will work. Let us know I guess, Removing the valance isn't that hard, you just need to be slightly creative with tools is all.

[750-h2]

Here is a picture of that center bracket which is spot welded to the valance. The top mounting bolt is located high above the gas tank seam. The nuts securing this bracket are simple flange nuts and pretty well impossible to get at unless you drop the gas tank. This valance is an AMD repro so likely center bracket is incorrect for a 1970 as JH27N0B and runcharger do not have it on their cars. Other than the rear bumper the car is 100% assembled and all of it was done with the valance attached.

[1 Wild R/T]

Yup, that bracket doesn't belong on a 70. And when they started using it the nuts were attached to the body....

If I were dealing with that I'd probably add a couple nutserts so it could be easily R&Red..

[750-h2]

Yes, nutserts would have been the way to go.

[anlauto]

Okay now I see the rear valance you're using, I can understand better why you would want to leave it on, especially if those two blots just have nuts on the inside...

I would at least try doing the bumper with the valance in place.

[750-h2]

Yes Alan that is my plan. I honestly do not expect it will be very difficult.  

[750-h2]

UPDATE:  Bumperettes came back from the chrome shop last week and yesterday I installed the bumper. With the help of two friends to hold the bumper in place it is an extremally easy and straight forward procedure to install the bumper with the valance in place. All mounting hardware is easily accessible. Total time spent on installation and alignment 15 minutes. Just thought I would share this info in case anyone else needs to install the rear bumper without removing the valance.