My frame is 1/2 wider than other 67-72..Need some help

[funkytechmonkey]

I am having this issue with the rear of my frame being 1/2 wider than most 67-72 frames. I am installing the porterbuilt stage 2 kit and everything is coming up short. I called nate and everything is exact on his part but come to find out its my frame that is off. I have compared measurments with other frames and every spot we measure is exactly 1/2" off.

I measured outside of the rear frame, bed mounts, and even the rivot holes for the crossmembers. Everything....1/2"

Any ideas why in the world my truck would be different than other trucks?

I bought it as a 71 GMC

Here is the delima I have.... one, have nate remake upper and lower shock mount bars that will fit my truck. or two... use nates new rear crossmembers that will pull my frame in the 1/2 I need. I need to worry about that half inch messing up my bed and cab mounts.

Comparison measurements.

-Rivot to rivot on the crooked crossmember - (friends) 31 1/4" - (mine) 31 3/4"
-Bed mount holes (Nates) 31 1/2" vs (mine) 31 7/8"
-Outside of frame at rear croocked crossmember... mine is 34" havent compaired this one.

[funkytechmonkey]

Another thing to add is my 71 was a leaf setup.
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[charx2]

I'm also having a similiar problem only I'm installing a Step notch. I can't seem to get good measurments, left and right side of frame seem to differ by 1/4"-1". I'm trying to locate what's throwing mine off but have not had time. I suspect and hope it's because I don't have the truck completely level, which is maybe putting some flex in the frame. At least that what I hope my problem is...good luck though and I'll be watching this thread. Hopefully kill 2 birds with 1 stone in it!

[N2TRUX]

Originally Posted by funkytechmonkey

Another thing to add is my 71 was a leaf setup.

I don't know why, but thats the first thing that came to mind. I have no idea why a leaf spring frame would be a 1/2" wider though.

I think you need to analize what going to be the least amount of effort to accomplish. If your bed fit fine before, moving everything in a 1/2" is going to create problems there. It sounds as if it might be easier to let Nate build your set up wider.

[funkytechmonkey]

I don't have a new bed yet. So I am not able to mock it up for the fit. As of right now it's just a bare frame in the garage so nothing should have it twisted or making it off.

Is anyone else able to give me some measurements on their leaf setup?
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[PBFAB.COM]

Brian-

The first thing to keep in mind is that the tolerances on these trucks would make any A-type personality cry. From the factory, there are many tolerances that are plus or minus 1"! They built these trucks for work, and weren't too concerned with everything coming out exact. I don't like to use this as an excuse, but it's reality.

As mentioned, we have the two options:

1. Use the new rear crossmembers I sent you and it will set the chassis to the same dimensions as the ones I have in the shop. I sent the center to center bed mount measurements for you to compare to your chassis, and get a better idea if this will be the easiest route to go. If your center to center on the rear bed mount hole in the chassis will work with the measurement I sent... good to go. It was taken off a 67-72 bedfloor from Old Aux. The cab mounts will be of no concern, as the trailing arm x-member fit just fine.

2. Second option is for us to make a 1/2 wider upper shock bar. We will happily do this, as we always guarantee all our products for both proper fitment, and customer satisfcation.

If it were my truck, I would verify the bed mount holes, and if it were close.... I would slap all the new tubular crossmember in place that I sent you, and call it a day.

We have had a handful of guys that have already performed this same conversion on a leaf sprung GMC... without any fitment concerns. It migth just be your truck that is off a bit more than others.

Let me know what you decide, and we will do whatever we need to.

Nate

[smashingchuck]

I would go with option #1.
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[cdowns]

have you ever checked the frame vin number to see if it is what you thought it was that you bught?

[cableguy0]

I would pull the frame rails in and call it good. None of this stuff is exact. The factory stuff is terrible. I deal with it everyday. Trying to put new things in straight is a huge challenge when the vehicle itself is nowhere near exact.

[gringoloco]

I would use what you have. This way, you know it's right and will fit with whatever further work you do. If you build it 1/2" off, everything else will have to be modified for that same half-inch...