how to support car when checking for frame straightness

[adam83]

How do you support a 71 b body when checking for frame straightness? I'll be using the service manual to get dimensions and tolerances, then using simple measuring tools, nothing fancy. Just want to make sure I'm not getting a false measurement because I put jack stands in the wrong places

 

[Bb70charger500]

That's a good ? I would be interested in an answer to this too. My cars are all good but if I can learn something new I will.
Was your car hit ? Or rusted out bad? It's kinda hard to twick these subframes

 

[adam83]

I don't think it was ever hit, but there are some pretty good dents in the rocker panels, scratches in the k member, and dents in the frame rails. They were there when I bought it. Since then we've done a mini tub and put frame connectors in it and before I go any further with rust repair or body work or roll cage I want to make sure the frame is straight

 

[1967coronet]

Just me ........... but with the work you have done { mini tub } 1st thing I would put a tape on is wheel base on each side, axel center to spindle center. then do a X measurement left front to right rear ect both sides.

find the center of the pan direct over the rear chunk and measure to each backing plate, do the same up front off a known point on the rail to each control arm end, As long as the K member is sitting straight and your mini tub job measures out. and you have the same wheel base on each side I would go on and proceed. As far as support I would put it up on a 4 post ramp style lift or if working off the floor jack stands under front leaf spring hangers, under axel tubes out next to the U bolts, under the outboard sides of the cross member & under the the front rails then the floor jack pad under the center of the K member holding engine , front end weight.
so at least 8 jack stands plus the floor jack.
Prob overkill but if trying to measure off the floor I would not want anything sagging.
As for pulling the rockers or frame rails we have a
rocker puller { will work on both }
Go to toolsource.com Wivco Rocker dr. tool source part number 50957 or wivco # TH14000.
That's the same one we use at the shop , chain your car down and this one will move stuff.

 

[mopar 3 B]

Belive all the instructions are in the FSM.
67coronet can understand the need for all that support if the frame is being worked on but for checking wouldn't it give false readings?

 

[ckessel]

It will need to be on all 4 wheels to verify dimensions. If the car is fully loaded, engine/trans/suspension/interior etc, it will sag if you have it on a two post lift to check dimensions. Frame racks are a flat platform and they have specific support areas to lift at plus hang targets from so you have to be mindful of that when the car is loaded. If you do it the old school way with tape measure/plumb bob/trammels, have it on a four post or something similar so the wheels are supported and the body is in its normal position.