[Daves67GTO]

I am trying to check the measurements on my 70 GTO frame and in the GTO restoration guide there are three diagonal measurements labeled X, Y and Z. All other measurements are listed EXCEPT for X, Y and Z.

Since these are the diagonal measurements I need them so that I can accurately check the dimensions.

I also looked in the Service manual too.

Any help is appreciated. Thanks.

[Held for Ransom]

"The dimensions given in (Fig. 2-3) may be used in checking frames. Dimensions for X, Y, and Z are not given, but are used merely to illustrate points for taking diagonal measurements for checking squareness of frame. Holes or rivet heads are located on the frame at approximate terminal point of arrowheads, and can be used for this purpose."

[Daves67GTO]

So the X, Y and Z measurements aren't needed to check the frame? I have the frame at the body shop and they said they need those measurements to fix the frame. When I stand at the rear of the frame, it looks tweaked to me and I dont want to have the body put back on a bent frame. Thanks.

[Held for Ransom]

Yes, they are. As long as X and X are the same numbers, Y and Y are the same numbers and Z and Z are the same numbers, you're good to go. If your frame shop didn't know this, I think you picked the wrong shop!

[TJH]

Obviously, you have never laid out or checked a house/foundation for square. The dimension itself does not matter- only that it is the same across both diagonals. Same with a car frame, as HFR noted.

[70 PEPPER GREEN]

DAVE GLADE TO SEE YOU GOT THE ANSWER YOU NEEDED.
TJH DOES IT MAKE YOU FEEL POWERFUL ????? TO LEAVE A WISE ASS REMARK TO A LEGIT QUESTION????

[Daves67GTO]

Thanks HFR, now I understand what x, y and z are and it makes perfect sense.

TJH, I've never laid a foundation but am quite familiar with geometry and have no problem understanding the use of diagonal measurements to check for accuracy. I just wasn't sure if there were predefined measurements for x, y and z. Now I know.

Thanks for the help!

[TJH]

Pepper Green- Does it make YOU feel powerful, to type in all caps? Or, do you just like to appear as though you're too clueless to find the "Caps Lock" button on your computer? (Hint: It's on the left side, about midway down the keyboard).

Dave- In terms of frame assembly tolerances, I would think that GM would likely NOT want to provide specific diagonal dimensions, since they would not have been well controlled. The side members, crossmebers, and hole locations would be held close on each detail, due to the stamping/welding fixturing, but when you're assembling multiple parts to complete the frame, with each of these parts having its own manufacturing tolerances, the build-up of tolerances would render a tight dimension useless (or, impossible to achieve). Inaccuracies would be taken up by the oversizing of the body mount holes, so as to end up not mattering.

[Daves67GTO]

Thank you for all the help. X=X, Y=Y and Z=Z on my frame but it was bent. The rear of the frame was about 1.5 inches out of tolerance and it was an easy fix. The frame is together and the body is back on the frame. The front end has been fitted and so far everything is looking pretty good.

Again, I appreciate the help. Thanks.