Today some friends came over to help me put the chevelle on stands ( I recently had surgery on my shoulder) and everything seemed just fine... they positioned the j-stands under the frame just behind the front wheels... and just in front of the rear wheels.....After everyone left... and I was looking around.......I notice that some body panels are not aligned like they were when the car was on the ground !! And then I notice that my windows (while rolled up) don't line up properly !!! What gives ??!!! It is a convertable... but the stands are under the frame !!!

Today some friends came over to help me put the chevelle on stands ( I recently had surgery on my shoulder) and everything seemed just fine... they positioned the j-stands under the frame just behind the front wheels... and just in front of the rear wheels.....After everyone left... and I was looking around.......I notice that some body panels are not aligned like they were when the car was on the ground !! And then I notice that my windows (while rolled up) don't line up properly !!! What gives ??!!! It is a convertable... but the stands are under the frame !!!

All that weight on the front end ahead of those stands is making it sag. I always put my front stands on the frame at the front.

YEP, that is exactly correct!!!!!
The stands SHOULD have been positioned under the rear axle housing AND under the front lower A-frames. This method would have placed the weight of the car on the stands in the same way the weight of the car would be when sitting on the ground.
Convertibles are WORSE about flexing-----------------THAT'S WHY THE FRAME HAS THE ADDED REINFORCING PIECES WELDED TO THE FRAME RAILS!
As it sits on the stands now, for example, the weight of the rear section of the car, along with that heavy ole axle assembly is "hanging" out over and behind the point where the rear stands are positioned under the frame. The same for the frontend/heavy engine hanging out over the point where the front stands are positioned under the frame. Now, your frame, as well as the much more flexible convertible body is somewhat bowed.
This will also occur in a body with a steel roof, but not nearly as bad because the steel roof has somewhat of a truss structure support to prevent the front and rear of the body/frame from pulling apart.

Here's my 70 conv up on stands. As you can see the front stands are under the lower A-frames and the rear stands are under the frame, ahead of the rear axle housing (as yours is). When up on stands like this, mine is not as bad as yours (because the heavy front is well supported), but because the rear stands are under the frame, instead of the axle housing, the doors still do not quite match up with the body as they should.
http://i65.photobucket.com/albums/h219/DZAUTO/100_1216-1.jpg

It's apparently putting stress in the wrong spots. The engine is very heavy, and that weight so far in front of the jack stands, is tweaking the frame, which bends the whole car, and knocks the body panels out of wack, especially with a rag top. There's no roof to help support the body. I'd move the jack stands in front of the front wheels and see if . The best thing to do is to put blocks under the tires if possible.

Ok.... that was kinda crazy.... i've jacked many a cars up on stands in my life-time....but never seen that ! LOL.... Here's the funny thing... there is no engine or trans in the car !!! My buddy just positioned the front stands under the A-arms... the weight is on the suspension... just like the pictures of your car Tom (thanks for the pic) and it seems that panels have re-aligned... and my windows are back to normal. I imagine when I put the car back on the ground... things may go back even more. I was almost sure that the frame without the engine & trans. would not sag in any way ! Well I was wrong LOL.
Thanks for your imput guys... I will post a pic in a few minutes.

MAKE SURE THAT YOU DON"T TRY TO OPEN YOUR DOORS...... The fenders may be close enough to the doors, with the body flexed, that you might take the paint off the edges of them, or worse, catch the fender with the door and bend them....

Thanks for the tip....I noticed that when I started to relize what was happening.... I did see on the drivers side that indeed the door had gotten pretty close to the fender ! LOL
Here's what it looks like now.

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Mine does the exact same thing, and I have a standard coupe. As already stated watch out for the doors, will go back to normal when you put it on the ground.

Just like what happens when you use a jack under the cowl area of the frame to close up a door/fender gap.

Mine does the exact same thing, and I have a standard coupe. As already stated watch out for the doors, will go back to normal when you put it on the ground.

Exactly. I've seen the frame flex on my coupe when lowering the car onto stands.

Truth be known...the frames under these cars aren't that ridgid. :noway:
Two guys can easily pick up a frame. The chassis depends on the sheetmetal that's bolted to it to add strength.

Truth be known...the frames under these cars aren't that ridgid. :noway:
Two guys can easily pick up a frame. The chassis depends on the sheetmetal that's bolted to it to add strength.
SO VERY TRUE.

The frame is so flexible that if you disconnect the body mounts, you can flex it by grabbing hold of it and lifting yourself up off the creeper.

FIRST GUESS: Your body bushings are shot.

http://www.chevelles.com/techref/body_bushings.html

What's the big deal? Do you have any idea how much the car is going to flex when driving it on the uneven surface of the road? What about when you pull into a driveway or parking lot on an angle and encounter a grade transition? Of course it's going to flex. Forget about it.

What's the big deal? Do you have any idea how much the car is going to flex when driving it on the uneven surface of the road? What about when you pull into a driveway or parking lot on an angle and encounter a grade transition? Of course it's going to flex. Forget about it.
There's a HUGE difference between loading a frame/body combination that is 1) properly tied together; and 2) being loaded from the suspension attachment points, as opposed to loading a frame/body that ISN'T properly tied together and is being loaded from some semi-random part of the chassis.

In the case of my El Camino (which has the boxed and therefore stronger frame to begin with) putting in new body mounts DRAMATICALLY reduced flex on the jack stands; and rattles when driving.

There's a HUGE difference between loading a frame/body combination that is 1) properly tied together; and 2) being loaded from the suspension attachment points, as opposed to loading a frame/body that ISN'T properly tied together and is being loaded from some semi-random part of the chassis.

In the case of my El Camino (which has the boxed and therefore stronger frame to begin with) putting in new body mounts DRAMATICALLY reduced flex on the jack stands; and rattles when driving.

I'm aware of frame construction. I've had the pleasure of working on frame machines in collision repair. My point is like you said if the car is structurally sound and components are in good condition, jacking in a particular spot is not detrimental to the vehicle. Common sense would dicate not to open a door because it may hit the fender. That's easily observed when they are jacked up. When the car goes back on it's feet all will settle back where it was, unless the car is a POS and needs an overhaul. What happened to them over the years when they were using bumper jacks to change a tire? People who did not know better would be running back to the dealer if they looked at the gaps in their car when it was jacked up on the side of the road.

I had my 66 on stands one time to change wheels and went to open the pass door to get something out of it and you guess it. Ended up doing some real paint damage to the front edge of the door and the rear edge of the fender. Was quite ticked that day.

What do you guys think about a car that's been on stands for 10 or more years. Blocked up behind the front wheels and in front of the rear wheels on the frame, wheels hanging. Body lines looked good then and now. Hard top.

I never gave it any thought. Seems O.K.

Ron

That's why you NEVER do body work to a car on a lift! You'll take it off the lift and wonder why nothing lines up anymore.

That's why you NEVER do body work to a car on a lift! You'll take it off the lift and wonder why nothing lines up anymore.

That's another reason god made 4 post lifts :D

i don't like putting jack stands under the lower control arms, especially if there is an engine in the car. the way the arm swings can cause a jack stand to kick out as you drop the jack to lower the car onto the stands. without an engine the front suspension doesn't move at all, so it's not a big deal.
i always try to either put the front stands right under the crossmember or on the framright next to the front lower control arm mounts, with the rear stands under the rear axle tubes as far out as i can get them. this keeps the chassis loaded almost exactly like it would be if it was sitting on all 4 wheels.
but there are times when i need to put the stands at the 4 corners of the frame- in front of the rear axle and at the firewall- for room to maneuver around under the car or let the rearend hang for whatever reason. i've never seen a car flex enough to cause the doors to not open or fenders to pop out of alignment. but i've also never worked on a convertible, either.

That's why you NEVER do body work to a car on a lift! You'll take it off the lift and wonder why nothing lines up anymore.


I think most body shops use drive on lifts.

I don't know why nobody has mentioned it but you can just use 3 pair of jack stands.

If it looks like the front end is going to sag, I just put another pair of jack stands in the front.