Body flex causing top fitment and window issues, On lift I get 25 1/8" and on the ground it changes to 25"? Options

[Steve]

What is the consensus on flex regarding the roll bar to windshield flange measurement?
Item "F" on the body dimensions page.
http://www.914world.com/specs/bodydims.php

My car was fine until I had a shop weld in the Engman long kit. The car is much stiffer, but the windows and top no longer fits right when the car is on the ground.
On the lift I get 25 1/8".
Off the lift I get exactly 25"

How much should the car flex when on my scissor lift versus on the ground?
The scissor lift is using the four jack pods to raise the car.

Should the car be like 25 1/4" on the lift and 25 1/8" on the ground?
Is 1/8" flex normal? What is everyone else seeing?

I will post some pictures tonight.

[rick 918-S]

The Engman kit does nothing for sag. It will assist slightly with torsional twist introduced more from the hard corner loading in the front suspension vs the opposing forces from the mid-engine weight.

Your issue is at the base of the "C" pillar at or just rearward of the jack post. Remove the rocker covers and fix the rust or fatigue in the chassis. Engman does nothing for that.

You need to go deeper now to see if the chassis was twisted during the welding process.

You need to think about this in 3D. F and X are good. Y and G will tell a different story. G will tell you side for side if someone over time bent the windshield frame up or down to get a fit to the window frames or targa top. Y will be a more accurate measurement than X because the windshield frame is easy to bend out of place.

In most cases we are checking chassis' for sag from rust damage not collisions. So if you get a good G AND the door fits the front fender line AND the windshield frame fits the vent window,

(set the frame to spec, fit the door to the fender, adjust the vent window frame to the windshield frame)

Then you will be able to have confidence in your F and X measurements.

At that point you can address the sag at the jack post, install door opening braces and fix the soft chassis causing flex.

Oh, BTW: if your fixing crash damage the picture changes entirely.

[Steve]

The Engman kit does nothing for sag. It will assist slightly with torsional twist introduced more from the hard corner loading in the front suspension vs the opposing forces from the mid-engine weight.

Your issue is at the base of the "C" pillar at or just rearward of the jack post. Remove the rocker covers and fix the rust or fatigue in the chassis. Engman does nothing for that.

You need to go deeper now to see if the chassis was twisted during the welding process.

You need to think about this in 3D. F and X are good. Y and G will tell a different story. G will tell you side for side if someone over time bent the windshield frame up or down to get a fit to the window frames or targa top. Y will be a more accurate measurement than X because the windshield frame is easy to bend out of place.

In most cases we are checking chassis' for sag from rust damage not collisions. So if you get a good G AND the door fits the front fender line AND the windshield frame fits the vent window,

(set the frame to spec, fit the door to the fender, adjust the vent window frame to the windshield frame)

Then you will be able to have confidence in your F and X measurements.

At that point you can address the sag at the jack post, install door opening braces and fix the soft chassis causing flex.

Oh, BTW: if your fixing crash damage the picture changes entirely.

(IMG:style_emoticons/default/pray.gif)
Thanks Rick for the help!! Question.. Should there be any sag at all or should it always be 25 1/8" on or off the ground? Same thing with the other measurements?
There is no visible rust under the rocker panels. The car had a GT kit welded on 20 years ago and this problem came up after the Engman kit was welded in.
I will check the other measurements.

thanks again for the help!!!

Steve