Can I Dangle My Car in the Air from the Quick Jacks Alone?

[patrickt]

Originally Posted by Buzz

:lol: :lol: :lol:

O ye of little faith. And on Good Friday of all days.


Here are some progress pics. As you can see, I drilled the hole and have it put together. Here's how it will appear after I mount it back on the car. I still have to cut, debur and chamfer that hefty bolt that is about an inch too long. Remember, it just unscrews, so it's there when you want it and gone when you don't. The trick to getting that hole cut perfectly was to use a cobalt bit and cutting fluid. Shortening the Grade 8 bolt shouldn't take long, but that can wait 'til tomorrow.

[1795]

Looking nice Patrick. You've got thinking about moving from the straps to the eyes. I will have to see how that would work with the FIA having the quick jacks reversed. Want to make sure that the heavy metal eye would not be able to hit the bodywork and cause damage, as mine have to be on both ends at all times.

[patrickt]

Originally Posted by 1795

Looking nice Patrick. You've got thinking about moving from the straps to the eyes. I will have to see how that would work with the FIA having the quick jacks reversed. Want to make sure that the heavy metal eye would not be able to hit the bodywork and cause damage, as mine have to be on both ends at all times.

If you have 3/4" between the back of the quick jack and the body of the car then you have enough room for the Grade 8 Flange Bolt and two threads coming out from it. Plus, when you don't want to see it you just unscrew it and stick in this nice rubber plug to make the hole invisible.

[tomshep]

What about drilling a hole in the actual quick jack just above where the lift rod would go and put the red ring directly in the quick jack? You already have a vertical plane for the ring. From a front view you wouldn't see the hole. Sideways there would be a small hole visible. Most wouldn't even notice the small hole.

Tom

[xb-60]

Originally Posted by patrickt

Patrick - Where's Ellie?

[patrickt]

Originally Posted by tomshep

What about drilling a hole in the actual quick jack just above where the lift rod would go and put the red ring directly in the quick jack? You already have a vertical plane for the ring. From a front view you wouldn't see the hole. Sideways there would be a small hole visible. Most wouldn't even notice the small hole.

Tom

Yes, that would work. The ring will hang a little lower, but that might actually be easier to drill -- and I would bet the weld would easily hold up on the quick jack itself. You wouldn't have to cut and chamfer the Grade 8 bolt either (which I will do today).

Originally Posted by xb-60

Patrick - Where's Ellie?

Ellie will help me on the final install.

[patrickt]

Ellie did a spectacular job of cutting, deburring, chamfering, and restoring that all important last thread so that it's easily screwable in by hand. She said she will be rewarding herself with a steak bone and nap in the sun later today.





And now you see her, now you don't...

[patrickt]

Bob, if I sleeve the frame boss and aluminum round tube, at the red arrow, with 4130 Chromoly round tube, maybe the upper connection as well, even though the boss is shorter, think I can get a 90 degree recovery tow drag on my hook across pavement without ripping it all apart?

[KDubU]

Looks nice and beefy. Only on one side? Perhaps I missed the whole engineering piece on pulling up on a flat bed but prefer two straps even length to the one tow cable on the flatbed but that is me. I still really like this tow hook and agree go beefy or go home. You do NOT want a failure.

[1795]

The engineers covered this in earlier posts. Puling from both quickjacks creates bending force that pulls the quickjacks towards each other.

[Argess]

Doesn't a flatbed have the winch in the center, so the pull won't be straight if that's the case. Gets worse the farther up the flatbed you are. Honestly, I never really noticed if a flatbed winch can be moved laterally.

And any side load would be doubled with only one strap....

Also, there will be a twisting torque on the whole car when you pull it from one side, so there will be side-loads even if it is a straight pull. If the whole business is beefy enough, everything will be OK.

But is it? Patrick's ERA looks different than my older one, if I remember correctly. I wouldn't trust the threaded rods in mine for this purpose as I think they would bend quite easily.

Mind you, Patrick is committed now as he's drilled the hole, so he might as well try it and see what happens.

[patrickt]

Originally Posted by Argess

Mind you, Patrick is committed now as he's drilled the hole, so he might as well try it and see what happens.

Patrick is waiting for Bob P. to opine on sleeving the frame bosses and aluminum round tube, but he's already ordered the 4130 Chromoly thick-walled round tube and shaft collars to beef up the lateral strength anyway.

[1795]

Originally Posted by Argess

Doesn't a flatbed have the winch in the center, so the pull won't be straight if that's the case. Gets worse the farther up the flatbed you are. Honestly, I never really noticed if a flatbed winch can be moved laterally.

And any side load would be doubled with only one strap....

Also, there will be a twisting torque on the whole car when you pull it from one side, so there will be side-loads even if it is a straight pull. If the whole business is beefy enough, everything will be OK.

But is it? Patrick's ERA looks different than my older one, if I remember correctly. I wouldn't trust the threaded rods in mine for this purpose as I think they would bend quite easily.

Mind you, Patrick is committed now as he's drilled the hole, so he might as well try it and see what happens.

Good point about the winch typical being in the center. When I installed the winch on my trailer it was offset to the side that the strap was attached to the quick jack, so it is more of a straight line pull.

[patrickt]

Originally Posted by 1795

Good point about the winch typical being in the center. When I installed the winch on my trailer it was offset to the side that the strap was attached to the quick jack, so it is more of a straight line pull.

Wait a minute, this is just high school trig. You know, the horizontal and vertical components of a force that acts at an angle measured from the x-axis? I asked Ellie and she says that if the quick jack tow hook is one foot away from the exact middle of the car, and the tow winch is lined up with the exact middle of the car, and the winch is ten feet away from the car, the angle is just over 5 degrees to that quick jack hook from the winch. The sine of 5 degrees is about .087, so if the winch is pulling a thousand pounds worth of force to get the car up the ramp, you've got 87 pounds pulling sideways on that hook. That ain't much. Ellie says she can muster up that amount of force with one paw and that we're dumb for having to ask a dog to solve a simple trig problem.

[rodneym]

Yes.
Indeed, Ellie is the smartest one here

[patrickt]

Beefing up the horizontal strength of the linkage. Here is the before picture:



And here is the upgrade. The sleeve around the lower boss and aluminum tube is 4130 Chromoly, with a wall thickness of .120", just measure it, cut it, grind it at an angle for a perfect fit, and tap it on to the boss for a snug press fit. I used an ID of .76", as the aluminum tube is .75" and the boss was a few thousandths above that. With the grommets out you can test for any lateral play with the aluminum tube and threaded rod installed -- if you did it right there will be next to none.



To get to the bottom linkage ERA was kind enough to include a removable plug in the fender well.



Part two will be the replacement of the threaded rods, nut, and acorns with Grade 8 stuff. Then, not only can I dangle her from a crane, but I can drag her sideways across asphalt without ripping the front end off.

[patrickt]

This part's easy. The advantage of using this double ended stud is that I get 40% more strength from the increased tensile stress area, since it's not threaded, over all thread. This little gem has 120,000 psi yield strength, for those sideways pulls. Plus I'll trim it down so the quick jack is actually on the shank, instead of the threads, for increased shear strength. The acorn, stover nut, and washer are all Grade 8. And that's the heavy-up.

[Jerry Clayton]

Its no stronger than the weakest point----------sooooooooo???????????????

[Buzz]

Patrick is nothing if not determined. Nice work. I'm just waiting for the field test video.

[xb-60]

Originally Posted by Buzz

.....I'm just waiting for the field test video.

Me too.
Three pages in now Patrick. Time to to test the prototype, otherwise it's all hot air.
After all, the question was asked..."Can I Dangle My Car in the Air from the Quick Jacks Alone?"

Cheers!
Glen