Every scissor jack I've had that came with a car has a space to fit around the pinch weld jacking point when changing a tire, however our new Corolla scissor jack has a flat surface contact point that seems like it would bend the pinch weld when raising the car. Once it's "deformed" or flattened is that just how it's designed to be? Just seemed odd to me.
Scissor jacks and pinch welds
- Thread starter Corollaman
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They sell a puck that has a slot in it for that. I have one but use it for gunsmithing.
It's exactly like the picture posted above. The pinch weld jack point does have a slight bend to it, maybe a few millimeters so maybe that's the way it's designed.
RoadDukie, A gun barrel sits nicely in the slot. Keeps it from rolling around while pushing a sight or pin. They are kind of a soft plastic that doesn't mar the bluing.
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Interesting it would come that way from the factory. I do think that modern shops today now have flat surfaces on their lift arms, by default (look at Costco), not the jaws of yesterday. Most likely those pinch welds will be flattened over time by techs who don't use or maybe their shop lost or do not have the adapters. It's not something they really worry about.
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Most likely lack of anything bending is because you've always taken the time to lift things correctly. this just isn't the case out in the real world imho. There are tons and tons of images online showing the "seam" to be bent across various makes and models. Because adapters avoid the seam and let the surfaces around the seam, bear the weight (as should any factor scissor jack but apparently not necessarily). Even a flat pad doesn't really do that, but it's rubber.
Pinch welds are for roadside tire changes. Look in a shop manual for your vehicle and you will see lift points. Lift points are for maintenance lifting, regular lifting. There is a difference between jacking and lifting.
I never use pinch welds for maintenance lifting.
I never use pinch welds for maintenance lifting.
My Toyota has floor jack points center front and back. I put the jack stands under the pinch welds. Is that wrong? There is nothing in the manual that shows otherwise - only the place to put the floor jack, and the pinch weld to use the tire jack?
I ALWAYS use pinch welds on my 2-post. Two potentially notable differences are 1) the lift pad is longer than most scissor jack pads and 2) there is a rubber cover which provides a bit of cushion
I've never seen pinch weld damage from doing so. Escapes, Nissans, Kias, Toyota cars, tons of Subarus.
The exception was KL Cherokees where the lift point is buried UP in plastic cladding (dumbest design EVAR), where I machined custom adapters.
Also a '64 Falcon made me nervous and I used my adapters there
The way I see it, if the manufacturer says a given location can withstand ~25% (many variables, I know) of the vehicle's weight on the roadside, no reason four points can't withstand 100% of the vehicle's weight on the lift.
I have yet to observe damage. I've seen Subarus damaged where they clearly high-centered and came down on the pinch weld.
I've never seen pinch weld damage from doing so. Escapes, Nissans, Kias, Toyota cars, tons of Subarus.
The exception was KL Cherokees where the lift point is buried UP in plastic cladding (dumbest design EVAR), where I machined custom adapters.
Also a '64 Falcon made me nervous and I used my adapters there
The way I see it, if the manufacturer says a given location can withstand ~25% (many variables, I know) of the vehicle's weight on the roadside, no reason four points can't withstand 100% of the vehicle's weight on the lift.
I have yet to observe damage. I've seen Subarus damaged where they clearly high-centered and came down on the pinch weld.
Yeah well that's why I only brought my old car in for service ONCE. I jack it up under the front subframe and where the rear trailing arm is attached to the body. Those don't bend, and are in easy reach.
Once flattened the factory jack doesn't fit anymore.
That part was definitely better on Hyundais, the pinch welds never flattened.
I am pretty sure big Crescent wrenches were designed to straighten out bent pinch welds.
f355spider
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there are dozens of pucks used in gunsmithing, depending on the gun type.
some are "universal"
https://www.amazon.com/Wheeler-Non-Marring-Construction-Gunsmithing-Maintenance/dp/B0047WKF84
When you wrote "new Corolla", do you mean factory new or just new to you, and are you certain that it has the correct factory jack?
No, the pinch rail is not supposed to just get deformed or flattened. If it were meant to be flat, it would have started out that way. Is it possible that the jack is meant to be positioned right next to the pinch weld rather than under it?
The picture Rand posted, does not appear to me to show a scissor jack with a flat saddle, it shows it going up on one side and presumably also on the other side around the pinch weld, which means that the recess in the middle should be as deep as the pinch weld vertical size.
For a roadside tire change you could be lifting 50% of the car's weight or even more. You're only lifting one corner, unevenly, and will note the diagonally opposite spring actually compressing because of the weight shift.
A mechanic's lift grabs every corner nearly simultaneously so there won't be a weight shift. Also the pads are generally larger than the inch or so given by the cheesy scissor jack.
I think Toyota just found a cheaper supplier of their jack, they only care that it barely works.
Most pinch welds that I've seen fold, have been folded by Redneck Joe using a trolley jack in his dirt driveway and having a pebble prevent the jack from properly rolling underneath as its saddle arcs up and towards the operator.
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