Method for measuring dimensions of chassis when repairing

[WizardBlack]

I just wondered if anyone knew of a good source to explain the basics of actually setting a chassis up to measure trueness before cutting parts out (like replacing frame rails, floor pans, dog legs, etc) and making sure everything is where it should be.

I mean, I know the basics what a frame rack has and I know lots of guys aren't using that kind of gear. How do you physically measure such long distances with precision? How do you know what to measure, etc.? I'm no idiot when it comes to learning stuff mechanical, but I've never seen that explained.

 

Mark

[geezer]

I didn't have to replace my front frame rails because they were done by the PO, but I did replace the floors, supports. outer rockers, quarters, etc. I think it would be easy enough to replace the front frame rails and position them correctly also. The dimensional body schematic in the FSM is good to have. Maybe I'm not the right guy to answer your question. I didn't use a frame rack or any type of jig but I did have the car mounted on a rotisserie, that made it extremely easy to level the car perfectly while upside down. When these cars were built, platform jigs were used to position & clamp the frame and floor components correctly prior to being welded together. Knowing this and since the rear frame & floor section were still in great condition, I used a lazer level mounted across the rear frame section to project a consistant reference point along the horizontal plane of the car. I also had taken and recorded several measurements before cutting out the rusted sections. It made it easier to position the new floors and supports. A homemade rottiserie along with a dimensional schematic and a lazer level worked great and with a little ingenuity you could do the same without the rottiserie and the car leveled right side up. I didn't take pics of the lazer level use but I think you can visualize how easy that is to do.

After I had the laser level mounted square with the rear frame section, the line projected stayed consistant no matter what position the rottiserie was in.

[cygnusx1]

Mark, I am sure you have seen the chassis dimensioning chart in the factory service manuals. Are you asking how to measure, and what tools to use? The chart references all the measurable points on the body, like holes, strut tower centers, T/C bucket locations...etc. I think most of it can be measure with a string or tape. Some of the measurements are tough unless the chassis is bare.

 

Got deep pockets? Here is the ultimate tool. http://www.creaform3d.com/lp/handyprobe/quote-video.aspx?gclid=CIyszemQq50CFZho5QodJmXIjw

 

 

I attached the 76Z body section from the FSM as an example. It is tough to read unless you have the original manual.

BF.zip

[johnc]

What I did years ago was very carefully mark a 180" x 96" x 2" grid on my garage floor. I then carefully made adjustable mounts that bolted to the chassis at the suspension mounting points out of 1.5" .120" wall tubing. The car was positioned over the grid on these mounts and a contractor's laser and plumb bobs were used to shoot straight lines across the grid to measure things.

[WizardBlack]

OK, so a regular old measuring tape is accurate enough, then? I get the feeling that suspension points should be jigged off of each other if you move them and otherwise you don't need sub-millimeter accuracy?

Anyone have a pic of a tramming jig they made, etc? The ultimate tool would be an actual frame rack, I suppose. I have access to lots of stuff in my shop including an alignment rack, but not a frame rack.

I am surprised the FSM shows that info and gives a nice little intro on how to repair stuff carefully.

Anyways, thanks for all the great info, so far! I am getting towards the body repair stage with winter coming on and getting parts ready to go.