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Stan
Am I missing something here ...?
Using the GTV as an example, you wheel each section into position, bolt it in the bumper mount holes, loosen the locking bolts and jack the car vertically ... maybe 2 or 3 feet and then lock the bolts.
Then what ?
It doesn't appear that you will have enough height to allow the sides of the car to clear the ground and stand and still rotate ... and if you do have the clearance, the weight of the car is not centered at your axis of rotation. Even if you managed to group enough bodies around the car in the correct positions and succeeded in rotating the off-centered weight, at the point that the car was inverted - it will be 8 feet off the ground !!!
On Stan's design the pivot stays still, so when you jack the car up at least 4 feet the pivot will be close to right ... and then the car will be high enough up that it can spin around.

BTW: Be very careful putting shells/cars on to rotisseries ... I ended up dropping my shell when we were putting mine on. Thankfully it landed back on the jack stands AND on the jacking points ... but it was very close to hurting all involved and being seriously damaged.

I'm also amazed that rusty 105 series shells are still strong enough to lift via the bumper mounting holes, but lots of people do it. My car would have stayed on the ground, at least when I started working on it :D.
Pete
 

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Discussion Starter #42
Stan
Am I missing something here ...?
it will be 8 feet off the ground !!!
You're missing something. My theoretical physics is weak, but the height of the axis of rotation is determined by the height of the hubs, which are a fixed height on the base. For my rotisserie, the center point of the hubs are about 38 inches from the ground. If the center of rotation of the car (plus the additional mass of the mounting assembly of the rotisserie) is perfectly aligned to the axis of rotation, the car will spin with only the effort necessary to overcome the friction of the rotating assembly. In my case, the rotating assembly is ball bearings in a wheel hub, so there is little friction. Even if I get the center of rotation off a bit, it should spin, although not as smoothly. finding the center of rotation will take some guess work, but should be somewhere between the line of the bumper and maybe the middle of the grill opening (?) for the x axis, half the weight above, half the weight below that plane. center on the y axis is easy, it's going to be pretty close to the centerline of the car.

I'm sure somebody out there can give a better explaination.
 

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the center point of the hubs are about 38 inches from the ground.
38" from center of hub to ground, minus 31 inches for half the width of the GTV body (62" wide), minus 5" diameter wheel, minus ±.5 inches for the caster bearings, minus 2" for the steel = -.5"

Looks like there may be some interference.

I'm not trying to be critical. I'm just trying to save you extra work down the road if there actually is an interference issue.
 

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Easily fixed ... just put packers between the casters and the pivot frame.

Relax everybody it will work ... or if necessary the pivots will have to be raised, which is only a cut and a weld or 2 away.

BTW: As you have bearings as your pivots Stan, becareful until you have found the correct centre of the car. My car is not corrected centred and I do not have bearings but when it decides it is going to rotate ... it's going to rotate ... best to let it do it instead of fighting it!
Pete
 

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Looking at what you have, you could do what I was talking about...
Figure out what your hub PCD is, and get some old disc brake rotors.
Mount them so that the rotor is sticking back over the frame, and make a bracket that would allow you to put a bolt thru into a hole or holes drilled into the rotor.
Does that make sense?
I would show you pics of mine, but they are in a box somewhere in my storage!
 

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Discussion Starter #47
From the toolman web site (he's the guy who posted the plan).
Restoration Log: January 12, 2005
that's a pretty big buick he has on his rotisserie. He had clearance issues as shadetree suggested, but I suspect his car is a bit wider than mine. I did get the measurement to ground wrong. I'll measure it and post the actual clearance. Proof is in the putting (or is it pudding?). Give me a month and I'll have the car on it.
Stan
 

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Discussion Starter #48
clearance

okay, here are the measurements: vertical distance from the center of the hub to the top of the forward rotisserie frame member is 31.5 inches. in the original blueprint that measurement is 34", but I lost a bit of height by mitering in my horizontal hub mount. If I had welded the mount on top of the vertical frame member, I'm closer to the blueprint spec, but I figured I was putting much smaller cars on this than the buick it was originally intended for. The width of the GTV about 6 inches back from the front edge, which is where it will cross the frame member, is less than 29" (the widest point is further back and won't interfere with anything). I should have about 3" of clearance at the closest point of potential interference. The rotisserie might not work for an american car without some extra height on the mast.

Taking PSK's comments, I will drill through and use a pin to secure the mounting framework to the hub. I don't trust just the friction of the 4 bolts, although they will let me get the height exact before I drill. hopefully a '67 and '71 GTV have the same centers of rotation so the hole works for both.
 
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