Sub Frame Measurements

[Iowa Jon]

Hi All,  My subframe appears to be bent?? With the subframe attached my car would lean to the passenger side. From Ground to fender lip the Drivers side is a 3/4 higher.  I ended up replacing the rear suspension first.  Did not help.  Checked tire pressure in all tires multiple times, no help.  Took the Sub frame back off and replaced all the frame mount bushings/hardware with new ones,  no help. Replaced all the upper and lower a- arms and springs/ shocks,  No help. 

So i took the subframe back off the car today and did some measuring.  With the Subframe rear mount locations on cribbing and the wheels and tires on the ground the front of the subframe where the radiator would mount is level. 

Where the subframe mounts to the firewall,  the mount pads are level. 

The rear mounts on the subframe, when I placed a level across are 3/4 inch higher on the drivers side.

When attached to the body it cause the drivers side to be  3/4 inch higher than the passenger side. 


1. My question is should the passenger side subframe rail be 3/4 higher or should the drivers side subframe rail be 3/4 lower.

2.  How should i go about fixing this issue?  I don't want to mess up the rest of the subframe because it is level. 

 
Body shop was a no go. 

Thanks,  Jon

[Dave69rag]

The sub frame measurements can be found here:
http://www.pozziracing.com/Media/F_gen_Firebird_sub.jpg

https://lateral-g.net/forums/showthread.php?t=50407

[Iowa Jon]

Thanks Dave,  It appears that all my measurements for square are +- within dimension.  The measurement that is not included in the diagram is the floor to the top of the rear sub frame mount.  One would assume that they should be the same height across both subframe rails so that's why it is not needed in the diagram. 

From the concrete floor to the top of the passenger side rear subframe mount I have  12". The drivers side is 12 3/4inches.  So it raises the drivers side rear by 3/4 inch and lowers the passenger side rear by 3/4 inch.  If it was not noticeable i would not care but you can see it leaning.

Logically I just threw 3/4 worth of shims under the passenger side subframe mount area thinking it would fix the problem.  It had little to no affect. It just filled in the gap created by the other side between the subframe and the floor board. 

The whole front of the subframe is level and sqaure.  If I jack up the front passenger side radiator mount area I can make the car dead level in the rear but it would throw all the front sheet metal out of alignment.  As the car sits now it is dead level in the front.

 Might be able to create a jig on a welding table and use a porta power to pull it down?

I am going to try a few more body shops to see if they will take a look at it. 


 

[Iowa Jon]

Hi Dave here are some picture that may help explain. 

In the second picture I had been playing with shims and levels to see if things would change if i adjusted the coil springs.  You can see in the background how the drivers side is raised.  Its not even contacting the cribbing. 

[Sauron327]

The measurement that is not included in the diagram is the floor to the top of the rear sub frame mount.  One would assume that they should be the same height across both subframe rails so that's why it is not needed in the diagram. 

Just add to the 5-1/2" dimension on the frame sheet to find the dimension "not included". I was a frame tech for years and still have to be when restoring these cars. Last 67 I did was t-boned, bent and needed to be yanked. Any decent frame shop can straighten your subframe; but most collision shops do not want to bother with old cars that require basic common sense frame straightning techniques. It's not hard. Fix it at home...Block, tie down, jack, whatever it takes. This is why I tell people to put anchor pots in their shops when pouring a floor. They can be installed afterward also and come in handy for many tasks.

Or buy another subframe. There's 2 or 3 near me now.

[Iowa Jon]

Thanks Sauron,  I just looked up anchor pot,  had never heard of one.  I going to try and find some tomorrow.  That's definitely something I need in my building.  I am trying to come up with a way to use a block and jack or my Porta power. 

Jon

[Iowa Jon]

The sub frame measurements can be found here:
http://www.pozziracing.com/Media/F_gen_Firebird_sub.jpg

https://lateral-g.net/forums/showthread.php?t=50407

Thanks Dave,  I just clicked on the David Pozzi link.  So it only showed me Horizontal.  Sauron, replied to me about the Vertical.  I went back and clicked on the other link and that's what i was looking for. 

[Iowa Jon]

Sauron,  i was trying to figure out the 5 - 1/2 measurement you referenced.  When Dave sent me the links I only clicked on the David Pozzi link.  It only showed me Horizontal dimensions.  Had I clicked on the other link I would have seen Vertical and Horizontal. I guess its been a long day.  Ugh