Subframe alignment

[absintheisfun]

Okay, so before I go through the pain of aligning my panels and getting the gaps perfect, I figured it would be a good idea to double check my frame alignment...and it is off.

Now, I know that these things didn't come from the factory "perfect," but I am trying to get it that way.

My frame is off by 1/8 of an inch. Is this an acceptable degree of "off?"

I have tried everything from loosening the mounting bolts and shimmying and shaking to beating the frame with a sledge hammer (actually a piece of wood against it) to get it to move that 1/8" but nothing I do is working....

How difficult will it be to align the panels, and align the vehicle so it is going to drive straight?

[John Wright]

1/8" off in which direction?

[John Wright]

Just so we are on the same page refer to this....

https://static1.pt-content.com/images/noimg.gif


I used 5/8" dowels on my 70 to align the body to the subframe....Sort of go-nogo type of deal

[absintheisfun]

I did a quick approach. Everything matches floor to body shell, but to make things easier I dropped a plumb line from the rear leaf shackle points and the front of the sub on both sides (see picture) and then measured the lines of the "X" The passenger side is 1/8" longer than the driver side.

and the dowels do line up...not perfect, but fairly close.
https://static1.pt-content.com/images/pt/2010/09/framespecs-1.jpg

[John Wright]

Ah...1/8" in all that distance ain't nuttin to worry about IMHO.

[absintheisfun]

well, that definitely makes me feel a little at-ease. Because I can't sit still too long, I went out and put the left side on...didn't end up too bad (needs some gap work, but not too bad) I only thought that was a PITA. now that I am on the right side (still with NOTHING TIGHTENED) I am realizing how easy the left side was!

[Rod]

1/8" off!!! hell that's better than factory !!

[PhillipM]

I ended up getting mine to be about 1/16th off.. But it took pulling pretty hard and then nailing it in place. 1/8" should be fine.

[aany001]

that is nothing so start hanging sheet metal:cheers:

[absintheisfun]

I just had a thought....is it going to effect the alignment of the driveline? Below is a MS paint to show my concern--obviously an overly dramatic example to exercise my point...but will this not cause vibration at speed and wear on the U-joints?

Thanks
https://static1.pt-content.com/images/pt/2010/09/frame-1.png

[John Wright]

http://www.1stgencamaro.net/frame.htm#MEASURMENT

You originally told me it was off 1/8" on the diagonal from corner to corner.....which is nothing when you figure how long the diagonal dimns are, but now it seems you are saying that it is off 1/8" from side to side which is an 1/8th in a much shorter distance and makes a more dramatic effect.

[Type73LT]

The center should still be the center. Why did you show the rear so far off. It should still go down the center. Clearance in the bolt holes will keep it there.

[John Wright]

U-Joints...they will be fine until you get past 3-4° out of align, then the joint is starting to get to a point where breakage might be a concern.

1/8" is nowhere near enough to place 3-4° on the driveline. To get 3° in 18 feet you would have to be off 11 5/16".....LOL

[absintheisfun]

http://www.1stgencamaro.net/frame.htm#MEASURMENT

You originally told me it was off 1/8" on the diagonal from corner to corner.....which is nothing when you figure how long the diagonal dimns are, but now it seems you are saying that it is off 1/8" from side to side which is an 1/8th in a much shorter distance and makes a more dramatic effect.

no, it is still 1/8 on the diagonal from corner to corner. I was just using an extremely dramatized picture to highlight the possible problem I was concerned it would make.

I figured out the problem-the mount point under the driver's seat is very tight. The sub bolt has no free movement to allow adjusting of the frame. I am half tempted to cut the seat frame cage nut loose and shift the hole a little to give it a bit more room to move around...maybe 1/4 inch.

But then again, I may just say to hell with it. Just the inner annoyance in me telling me to align it perfectly that I have to get over.

[overZealous1]

an 1/8 diagonal is only 1/16 adjustment to correct. so you are only 1/16th off. square subframe to rear rails, then rear end off front suspension mounts. i personally just went from suspension mounting points to square it.
you really have nothing to worry about. that is uber close.

[BuzzKillian]

an 1/8 diagonal is only 1/16 adjustment to correct. so you are only 1/16th off. square subframe to rear rails, then rear end off front suspension mounts. i personally just went from suspension mounting points to square it.
you really have nothing to worry about. that is uber close.

Ya Beat me to it... I work for a company that makes check fixtures for the automotive industy.... +/- 3mm is pretty standard on assemblies (3mm = .118) (1/8 = .125)