When I raise the rear of my '78, the wheels deflect a lot more than I remember on my '75. I seem to recall being able to run the drive train on the old one without raising the trailing arms with a jack to bring the half shafts to a more nearly normal angle. When I powered the drive train on the '78 without supporting as above, I got all sorts of banging and binding, so I "shut 'er down" right away. Also, at that angle, trying to rotate the wheels by hand was very hard, some loose areas, then binding. Anyone have any insight on this?
Also, can anyone explain how to post pix with these messages? I went to FAQ column, and from there I deduced that there is a "manage attachments" button hidden somewhere. I've never found it, and the "insert image" icon prompts only for a http address. I know some of you have posted pix, but I'm not getting it! Help!!
Thanks, U. M......

 

Your rear shocks are too long allowing the trailing arms to droop excessively. The half shafts are binding at the u-joints.

Running a car in gear with the wheels hanging is always a dangerous thing to do, binding or not. There's no good reason to do it.

 

Your 75 might have had a 7 leaf spring leaving less droop. Some of the composites are really flat.

EDIT-Here a couple links explaining how to post pictures.
http://forums.corvetteforum.com/help...tep-guide.html
http://forums.corvetteforum.com/help...es-thread.html

 

Thanks, guys, for all the help, especially about uploading pix. I was able post the pic of the seatbelt/key-in/headlight buzzer I need for the '78 in the WTB section.
As for the rear wheel question, what I meant by deflection was the amount of angle (camber) on the wheels themselves. Remember the early VW bug, and the Corvair with their "swing" axles? I thought the 'Vette suspension was supposed to keep the WHEELS nearly in the vertical plane as the suspension moved through its range of motion. The "roll-under" was what doomed the Corvair and what VW sought to eliminate as a cause of accidents. What think ye?
To the question of the dangers of running the drivetrain while in the air, I must agree that unless done properly and by someone who knows how, the situation could result in disaster. I don't recommend it for the uninitiated, but sometimes it's the only way to diagnose a problem. I've often had to work with live, high voltage electricity for the same reason, which is also dangerous. As Dirty Harry said, "A man's got to know his limitations.". Thanks, again!

 

I disagree on running the car in gear, but that's a side issue.

With the wheel off the ground, is there play when the tire is pushed in and out at the 12 and 6 o'clock position? Can you see movement of the diff yokes while doing this?

 

My wheels sagged when it was put on the ground. I've done a lot of work on it since and what I found was the bushings at the front of the trailing arms were not installed correctly (bushing not flared) which caused the wheels to go all "knock-knee'd". I rebuilt my t-arms and installed new, correctly flared, bushings and now the change in camber is gone...