55.2-59 1959 rear bumper brackets, inside or outside of frame rails?

[nikwho]

Hello all,
Dumb question, but I'm curious if the bumper brackets go inside or outside of frame rails. I would assume inside, but that's simply an assumption. Ive got bumper brackets, but my bumper is a few days away.

The reason that I am asking is that when I installed fuel tank between my frame rails, I wasn't running a back bumper. For safety, I welded a 1 3/4" DOM tube between the frame rails, to protect the fuel tank in the event of a rear end collision. So, I'm going to have a LOT of grinding ahead of me, if that tube has to come out! I would also have to remove the fuel tank for said grinding to take place.

In fact, if the brackets are indeed supposed to go inside the frame rails, it will probably be FAR less work to modify the brackets to run them on the outside. Any one know? Anyone have photos of how the brackets install? I'd like to start work now, so that I can be more or less ready to install the bumper when it arrives!

[nikwho]

BTW, I'm not defending welding the tubing into the frame... in hindsight, that was a foolish move. This was my first major hotrod project. But, being here, now, if it doesn't need to come out, its not hurting anything.

Perhaps the two brackets on each side are supposed to sandwich the frame? One inside, and one outside. Im hoping that if I install both brackets outside of the frame rails, that there will be enough material in the brackets to elongate the holes. If I have to cut and weld the brackets, I will, but would prefer not to. Actually, if the two brackets are intended to sandwich the frame rail, I may mock it up with only the outer brackets, then modify just the inner brackets to mount directly to the DOM tubing between my frame rail.

[nikwho]

Okay, upon looking at the brackets and my frame more, I'm realizing that I also need to locate where to drill the holes for the bumper brackets! My truck was originally a long bed, and I cut it down. So, frame rail was removed when I shortened the frame for the long bed to short bed modification. Does any one have a template for where the bumper holes go in the frame. I will be able to fit it by eye, but would be easier if someone were able to confirm hole locations. Perhaps measurements from spring perch to hole, and from back of spring perch to the end of the frame rail? Mine should be near the same, but I chose an arbitrary location to cut the end of the frame rail, based on clearing the bed. I'll attach a photo of where the end of frame rail extends to. Also, if someone were able to grab those measurements, I would also love to get a measurement on the elevation of the holes, or the distance from the top or bottom of the frame rails?

Any help would be very much appreciated!

[_Ogre]

Originally Posted by nikwho

it will probably be FAR less work to modify the brackets to run them on the outside.

does it matter? you only have the outside to mount to so plan on modifying brackets. as i remember they both go inside, but so do the fronts and i ended up mounting 1 in, 1 out

[nikwho]

Well, yes and no. Trying to figure out how they were intended to mount, so that I can determine the correct path to take. If need be, I can pull my bed and fuel tank and get the plasma cutter out and remove the tubing that was welded in place. I'd prefer not to for obvious reasons, but trying to assess how much work each of my options would be, then move forward from there.

Right now, without the bumper in hand, I am thinking that mh best option will be to mount the outer brackets outside the frame rail, then notch the inside bracket to fit to the tube that is welded between my frame rails. Will be incredibly strong, continue to provide extra protection to my fuel tank, and be a clean install option. I don't see any reason to run the truck without a bumper, so may just notch and weld the brackets to the tube. Or, I may build tabs to boot the brackets to. Will just need to figure that out once I start the install with my bumper. I was hopeful to choose my path and start on the prep work for my install.

My front bumper will be different. I did not weld the factory front frame sections onto my Camaro sub frame when I installed the sub-frame. I ordered a front bumper bracket set and will modify those, accordingly to get the bumper mounted securely. Was hopeful that the rear would be a simple bolt in install. It may still be if I can get some good measurements for the bumper bracket hole locations.

Thanks!

[Black_Sheep]

Mine are mounted on the outside of the frame rails FWIW

[nikwho]

Thanks Black Sheep! Thats super helpful! If anyone has measurements to help me determine the proper location of the holes, that would be very helpful!

Nik

[Black_Sheep]

Still running the factory frame?

[nikwho]

Originally Posted by Black_Sheep

Still running the factory frame?

Yessir! However, my truck was a long bed, so I had to cut a bit off of the rear frame section when I shortened it.

[MiraclePieCo]

Chevy pickups are notorious for the rear bumpers hanging out farther than necessary. If it were me, I'd just mock it up where it looked best and drill the holes there. That way you can improve on the factory positioning.

[Black_Sheep]

Originally Posted by MiraclePieCo

Chevy pickups are notorious for the rear bumpers hanging out farther than necessary. If it were me, I'd just mock it up where it looked best and drill the holes there. That way you can improve on the factory positioning.

He'll probably have to drill some new holes anyway.

Nik if you want I can crawl under there and measure from a point on the rear spring hanger to the bumper bracket bolt holes and from the bottom of the frame.

[nikwho]

Black Sheep, thank you for the offer. I suppose that I'll just clamp the brackets and bumper to the frame and play with it, to get it where it looks the best.

Actually, if you end up down there, I would be curious on the height, from bottom of the frame, to get the bumper at the factory height, but I'll play with the fore/aft based on what looks the best.

Nik

[dsraven]

this should show the detail but, like said above, lots of guys don't like how the factory mounted them so far away from the body plus you have modified the frame already so you really only have the outside of the frame to work with. I would stick the bumper on some stands or stacked lumber where ever you like it to sit, them modify the brackets to match or make new brackets. I believe my brackets were on the outside of the frame when I got my 58 but it also didn't have a factory bumper so, there you go. improvisation from back in the day when it didn't matter (like now).

https://www.trifive.com/55-59Assy.pdf

section 14 sheet 5, shows a frame extension on the inside of the frame then outer brackets bolted to the outside of the frame. we all get a star...…..

[Johns327]

I put one inside and one outside of the frame. I did not have a standard bumper or brackets when I bought the truck. It was a big diamond plate animal.
I found that the brackets and the bumper do not fit as well as one would hope. A lot of grinding at the bumper mounts was needed to round those sharp edges and I put in some rubber washers at the bumper mounts to make it all go together.

[nikwho]

Interesting. Anxious to see how it all ends up going together! Got a confirmation that my bumpers were delivered. Still waiting on one set of brackets. Ive owned this truck for 12 or 13 years and I have never had a bumper on it! LOL. Feel like its finally going to be complete!

[Johns327]

If you zoom in on the bumper mounts you can see the rubber washers. Also you can see the mount ends were thinned. If I didn’t do that the corners of the mounts would tweak the bumper since the mounts metal is thicker than the bumper metal.
This truck is a standard bed, some call it long bed, that has not been cut.

[57tailgater]

Here's what the assembly manual shows. Outside the frame rail.

[nikwho]

Thank you!!