Checking straightness of frame
 

Hey guys. I've been searching the boards trying to find a diagram of measuring points and lengths to test the straightness of a my 80 SC. It's completely stripped down. I just noticed it after I dropped it off at the shop for it's cage and other bits. When we set it on the jack stands I noticed it wasn't sitting quite right. The driver side front seems to be a little higher than the passenger side.

Now I know this could be due a million reasons (mount points, jack stands, floor angle, ect) but I want to rule out the frame being one of them. So is there any way to measure without it being on the Celette jig?

Any help would be greatly appreciated guys.

Chris

please don't take this the wrong way !!!! but i tend to be a little as a mater a fact on things . having built more roll cages than i even want to think about over the last 30 plus year and being the own of a fab / resto/ body and paint shop . the 1st thing is you never build a cage for a car if its sitting on jack stands . cars sag on jack stands you will want the car resting on its suspension pickup points only !as the car will sit when wheels are under it . the people that are building the cage should always check the car that its square and know how to do that . being a unabody car there is no frame . if it was a framed car then if it was a little out of square (more than 2.5 MM +/- ) you can shim the body and frame like all frame cars are done . on a unabody car you have to be with in its spec's 2.5 MM +/- for a total of 5MM . any more than the car is bent . its very ez to check a car for square with a tram gage any good fab shop will have on and all body shops will . they like i should have a big 1 inch thick steel plate on the floor to square the car up on before they start building the cage in the car . it should be a level floor plate so they know when the car is sitting on it the car will be square to the floor plate . they should jig the car to the floor plate using it suspension pick up points . if you measure the car and find it square and it is still sitting wrong on the jack stands and they wild a cage in it with all the welding the car can very ez pull its self out of square from all the welding . then there is what type of welding they are going to do tig or mig . a tig weld looks better but tig welding builds more heat in the weld when welding and is a softer weld . were a mig will not look as good but is a harder weld with less heat build up from welding . when ever you weld tubing it will push and pull on the other tubings that its welded to . the reason for this is that the inside of the tubing builds allot of heat and will hold it inside of the tubing because there is no wear and way for the heat to escape from the inside of the tubing . from this a unabody car may at times twist a little that it why it should be squared up on a floor plate and then the car bolted to the jigs that are on the floor plate . this would be the same floor plate that fab shops my self included build tube chassis cars on . so all they will have to do is set the car square in the plate and that will tell them if the car is square or not . if it is not then they can tram the car to see were its out of square . very ez !

No.... Very much appreciated. The cage will not be made as it sits on Jack Stands. We are just leaving it there right now as all the suspension components get there.

The cage will be made of DOM and MIG welded.

This was just something that I noticed as we placed it on the jack stands. I just want some peace of mind really.

Thank you for your expertise though, I really do appreciate it.

Chris

There is a n umber of threads with a diagram and table of measurements...so I don't really know who to thank for originally posting this diagram. This just happens to be the one I bookmarked. Anyway, it should give you the measurements you need. If you notice on the screenshot, the title says it's from the 72-83 workshop manual, so it should be correct on your 80.

Measurements

--Von

Hello everyone! I have a question is it possible to turn my convertible 1980 911 into a permanent Hardtop ?