Center of gravity for a 510

[grannyknot]

I'm at the stage where I'm just about to get the 510 up on the rotisserie and wondering if someone knows where the center of gravity is on a 510, how many inches above the bumper mounting bracket holes?

I'm guessing about 3-5", my rotisserie isn't adjustable so I have to make the mounting brace right the first time.

Thanks

 

[thisismatt]

Here is where I mounted mine with a completely stripped shell.  Sorry, I don't have better pictures of the front and I can't give you any exact numbers, since this was over 10 years ago and I no longer have it. I'm 99% sure this was still top heavy, but not too much for one person to handle. So, you would want to mount the axis a little higher to fix that.

[grannyknot]

5 hours ago, thisismatt said:

Here is where I mounted mine with a completely stripped shell.  Sorry, I don't have better pictures of the front and I can't give you any exact numbers, since this was over 10 years ago and I no longer have it. I'm 99% sure this was still top heavy, but not too much for one person to handle. So, you would want to mount the axis a little higher to fix that.

Thanks, that is considerably more than what I thought it would be, the measurement on the back appears to be about 9" from the top 2 bumper bolt holes to the center of the pivot tube. The front is harder to say but it looks like about 14", would you say that's about right?

 

Also it looks as if the rain gutter of the roof just cleared the center tie holding the front and back pivots secure.

Edited January 1, 2021 by grannyknot

[thisismatt]

The more I think about it, I'm not sure which side was heavier. I did take the trunk lid off after these pics. Clearance to the ground or cross-bar is independent of your axis, so just plan that accordingly

[MikeRL411]

On 1/1/2021 at 7:22 AM, thisismatt said:

Here is where I mounted mine with a completely stripped shell.  Sorry, I don't have better pictures of the front and I can't give you any exact numbers, since this was over 10 years ago and I no longer have it. I'm 99% sure this was still top heavy, but not too much for one person to handle. So, you would want to mount the axis a little higher to fix that.

 

There's got to be an easier way to empty the ash tray.

[thisismatt]

10 minutes ago, MikeRL411 said:

 

There's got to be an easier way to empty the ash tray.

It wasn't that, it was the french fry I dropped down the side of my seat

[grannyknot]

I built each bumper mount pivot bracket at 10", no good, way too bottom heavy, cut them up and settled at 5.5", now it's a bit top heavy  but still manageable.  I think if I had settled at 6.5" it would be a neutral spin.  I can raise the car up a few more inches to clear the roof if I need to but prefer to have  some weight resting on the rain gutter, it makes the whole rig steadier.

 

[docbainey]

shoot, I thought this was a race car topic

[debbheff@gmail.com]

can you really do that to these lightly braced cracker boxes with out causing permanent warps in places you depend on for accurate suspension measurements., reinstalling glass, doors etc to make sure it goes back together straight.  I occasionally watch a tv program where a car is being restored and on a rotisserie and there are numerous braces welded to the body to keep it as straight as when it entered the shop.  I really wouldnt do this to a 510 without some cross and lateral bracing to make sure the body doesnt twist or bend.  Some 510 woiuldn't survive rotesserie without  bracing because to rust issues.  just saying.

[thisismatt]

It's already a unibody...

[Stoffregen Motorsports]

It is a unibody, but the places where the weight rests with the car on the road are very different from where you all are bolting it to the rotisserie. Doubtful this car would suffer from any twisting, sagging or bending caused by that extra amount of leverage, but yes, I would still try to add in some temporary strut supports while on the rotisserie.

 

One easy way to add additional support is by tying the two ends of the rotisserie together with a piece of tubing. The bigger, the better. Some shops even build a truss across between the two end stands. You also have to think about moving the rotisserie around the shop floor. No concrete is poured perfectly flat, so moving around the uneven floor surface can apply extra stress on the shell, which is another reason why adding individual struts or a truss is a good idea.

[grannyknot]

On 1/21/2021 at 5:38 PM, debbheff@gmail.com said:

can you really do that to these lightly braced cracker boxes with out causing permanent warps in places you depend on for accurate suspension measurements., reinstalling glass, doors etc to make sure it goes back together straight.  I occasionally watch a tv program where a car is being restored and on a rotisserie and there are numerous braces welded to the body to keep it as straight as when it entered the shop.  I really wouldnt do this to a 510 without some cross and lateral bracing to make sure the body doesnt twist or bend.  Some 510 woiuldn't survive rotesserie without  bracing because to rust issues.  just saying.

A fully stripped 280z shell weighs 530lbs, I know because I have weighed one,  I won't get a chance to weigh this 510 until it comes off the rotisserie but I'm willing to bet it is going to come in under the weight of a Z. I'll post pics of the weigh in on this thread when it comes off.

But lets call it 500, 250lbs on the front bumper mounts, 250lbs on the rear, an old 2x4 that's been outside for a decade can handle that,  much less a rigid steel unibody.

It's not a Lincoln Continental.

[Stoffregen Motorsports]

I know, you're probably right. I just don't like to risk tweaking a body shell because I didn't think ahead.

[grannyknot]

6 hours ago, Stoffregen Motorsports said:

I know, you're probably right. I just don't like to risk tweaking a body shell because I didn't think ahead.

Now if you had to replace rockers then I can see tacking in some braces to keep the dimensions  perfect, where people get into trouble is trying to do too much at one time.

If major work needs doing then I compartmentalize the removal of metal, one rocker at a time, when that is done then move on to one floor pan, when that is finished move to the other side.

[Stoffregen Motorsports]

Yeah, right now I am planning my attack on the quarter panel, rocker panel and floor replacement on my Sprite race car. Luckily this car already has a cage in it, but I still worry about flex. I am actually going to start with the floor, and leave it out to make the quarter and rocker replacement easier, which produces more risk of flex. The floor will go back in last.

 

On the 510, I would think the top of the trunk opening and the strut towers would flex out, causing the body to sag.

Edited March 13, 2021 by Stoffregen Motorsports

[grannyknot]

I dropped the 510 from the rotisserie today and have some solid  numbers, the car was weighed hanging from the rotisserie mounts at the same place front and back while the other end was suspended by the rotisserie itself.

Front weighed in at 295lbs, rear at 293lbs for 588lbs minus the 80lbs for both stripped doors at 40lbs a piece and 32lbs of rotisserie mounts that were attached when weighed. 

So for a 1973 2dr 510 the stripped shell weighs 476lbs.