Is this a myth?
 

I understand the argument for having the chassis weight on the suspension when installing SFCs and it makes sense, but I'm not convinced.

I have the car stripped down to the shell right now and I'm thinking, "perfect time to install SFCs." Is there any proof that installing them in this state would be inferior to having them installed when I get the rolling chassis together with a drivetrain and proper weight?

I'm not sure what you mean by "proof"? Difference in corner weights? Seat of the pant guess? Doors lining up differently?

Every chassis has some flex in it, no matter what, and most race cars are gutted when installing cages, so you are either stiffening the chassis before it flexes, or after. Conventional wisdom says to have the car loaded on the suspension equally, but as long as you don't have the shell twisted (i.e. on two jackstands on the drivers side, and only one on the passenger side), it should be just fine. Try to keep the way the car is loaded symmetrical. If it's got wheels on it, an open deck trailer is a very easy way to get under to weld the SFC's.

I'm not sure the engine would need to be in it. But a rolling chassis would be highly advised.

Well, one plus if you did it at this state would be no carpet or anything to catch fire inside, the other would be no fuel in the lines if it's just the body.

I personally believe for you to benefit putting them on at this stage, you would have to make sure it is completely squared, then it might make a difference.

Just make sure that it's not twisted or flexed. As in lifting one wheel off the ground does.

Thanks for the replies.

I still find it hard to believe that there would be any difference at all. Whether the car is all together and on a drive-on style lift sitting level or I just the shell, still supported from the areas where the suspension normally lies, there is still at least around 2000 lbs. being supported.

I have a nice 6 ft level I can use, so I'll make sure the two front and two back frame rails are level before I do anything.

so having the rear axle on 2 jackstands, and the front wheels on ramps is ok for welding these on? I still haven't installed my SFC's because i honestly wasn't sure how.

As long as the car is sitting level from left to right then I would say that's fine. It wouldn't matter if the front is higher or lower than the rear.

Mark.

+1

As long as it is sitting level or near level.