Garage lifts and pinch welds

[NissanMaxima]

Hi all;
Is it common practice for shops (dealerships, brake places, tire places etc) to lift a car using only the very bottom of the pinch welds? Most of the shops I've been to use what I believe is called a four pole lift system where each of the metal pads at the ends of the arms have "cutouts" around the perimeter. They simply place the metal pads on the bottoms of the pinch weld and lift the car. Some had hard rubber pads incorporated on top of the metal pads that are pretty much all gouged up with slices in them. Other places like Discount Tire seem to have these mini-lifts that have supports on either side of the lift that basically contacts the entire pinch weld area from right behind the front tire to right in front of the rear tire.

Either way, contact seems to be exclusively made on the bottom of the pinch weld areas rather than wrapping around and further contacting the rocker areas on either side of the pinch welds. I've read some posts on BITOG where folks here buy or make "pucks" with a groove down the center to use on their hydraulic floor jacks. Why aren't shops using these? Is it acceptable to only exclusively contact the bottom of the pinch welds?

I was thinking about this when getting an estimate for some new tires at Discount Tire. That's where I noticed their mini lifts contact almost all of the pinch weld area (but still only on the bottom). I suppose this way at least contacts almost the entire length to spread out the weight.

The factory service manual for my Maxima shows an accessory for garages that looks like a professional version of the pucks folks describe here. It looks like a device meant to be used at shops but the parts folks could find no trace of it in their system and the service writer or even mechanics had no clue about them.

 

[KrisZ]

In my opinion, it doesnt matter as long as the lifting method doesnt damage the pinch welds or the rocker panels.
The lifts without rubber pads installed could scrape the lip of the pinch weld to bare metal and accelerate rust, even when the pinch weld itself is not bent or visibly damaged otherwise.

 

[kschachn]

Are you saying they flatten over the pinch weld? If so then that is an incredibly poor business practice.

Years ago a shop did that to my old Mazda 626, and I never knew it until one night I tried to change a flat tire and the adapter on the jack wouldn't fit over the damaged weld. If that shop is bending over the weld then it can crack or prevent the area from being properly utilized in the future. On all of my cars when you have to remove the suspension crossmember (such as when removing the transmission) you must support the car on the pinch weld area. I certainly don't want to find it damaged at that time.

 

[NissanMaxima]

No, I'm not saying they bend over the pinch weld, but what I've seen at least on the four pole lifts, is the metal contact pads on the ends of the arms are sort of a cup or dish shape. Around the perimeter, they sort of have cutouts and the practice seems to be to place position the pads so the pinch welds align within the cutouts (working from memory here!). I always ask if they at least have some sort of rubber pads to use or if they are incorporated into the metal pads to avoid the very thing you mentioned - scraping off the paint and promoting future rust) It is curious that the jack (at least on my 2015) Corolla, seems to actually wrap around the pinch weld. I've never used it so I can't say for sure if it also then contacts the rocker on either side of the pinch weld to help support the weight. So I don't know if that is simply a safety design so it is not simply setting on the very bottom the weld, or it is meant to actually help support the weight via contacting both the bottom of the pinch weld AND the sides of the rocker. It would seem to me that contacting either side of the pinch weld area would help prevent pinch weld damage, but like I said, every shop I've been to (when I'm forced to have work done I can't do myself) seems to lift the car exclusively by contacting the very bottom 1/8" of so of the pinch welds often citing that is the strongest part of the car.

 

[Hall]

Look at the jack in the trunk of your car. That's what those pinch welds were designed for. Factory manuals will often specify a special 'adapter' that a shop can use on their hoists to then use these same pinch welds safely and without bending them. I'll bet you Nissan dealers don't even use 'em though unless almost all models use the same (which you'd hope is the case !).... Depending on the unique design, you can't expect a shop to have the right adapter for every variety of cars either.

 

[JoelB]

Pinch welds are different heights and widths on different cars. If you're implying a lifting device should contact the bottom of the pinch weld and touch the rocker then you would need custom inserts for every single car. A flat pad is universal.

Alternatively if you are implying that it's better to not lift on the pinch weld at all and only on the rocker, I can't see that being the case. The pinch weld is 2 pieces of metal stuck together, where a rocker is likely just a single metal skin.

 

[WhizkidTN]

OP, that's a very good question! I have the "pucks" w/slits that I use for my floor jacks and the QuickJack system but I never noticed what the tire shop I use actually does (FireStone). I assumed that with the four point lifts, they picked some frame member to lift and not use the pinch welds at all but IDK.

 

[Chris142]

The better lifts have a flat plate about 6inches across with a rubber pad on it. Those wont fold the pinch weld over.

 

[eljefino]

When you jack your car on its pinch weld, you're lifting half the car!

Imagine, you're lifting the RR. The LR and RF wheels won't change their weight much, and the car will pivot on them. But the LF strut will actually compress!

(Assume 50/50 weight distribution and no sway bars.)

Lift all 4 corners of your car simultaneously with a shop lift, and you've got less weight on those pinch welds than you yourself can do.

Also, typically, the front arms are still so long the mechanic will chuck them under the firewall, maybe on the rear-most part of the subframe, probably on the "Frame rails" that are built into most unibodies so the engine stays under the car in a serious front-end collision. Since this is only a couple feet forward of the center of gravity, the engine will pry down on the front, lifting the rear.

That all said, the pucks that came with my quick-jack are very soft, almost too soft.

 

[AC1DD]

This has always been a problem in my case these shops do NOT properly set the lifts to make sure that the pads (usually metal) are resting on the correct part of the pinch weld, which of course seriously damages the area usually crushing the rocker panel.

It's disgusting that one of the most elemental parts of a mechanics job is to know how to life a vehicle properly, but most in the USA never do. I've personally had the problem with a well known chain shop CRUSHING the pinch weld and rocker panel of my VW when the arrows for lift pad placement embossed CLEARLY on the rocker panel. Sick of incompetent and careless mechanics and shops.

 

[clinebarger]

Originally Posted by NissanMaxima

Is it common practice for shops (dealerships, brake places, tire places etc) to lift a car using only the very bottom of the pinch welds?


Yes it is. If lifted in the correct locations.....Causes no damage to to the pinch welds. Lift points are usually marked in some way.

Tire shops are usually the ones that carelessly throw a jack under one corner of the car & mangle the pinch weld, It's hard to do much damage with a 2-post swing arm lift.

Profit margins are slim in auto repair, Owners are not going to spend money on adapters that get lost/stolen just to protect some paint on your pinch welds.

 

[RayCJ]

You absolutely want to use rubber/neoprene pads as shown... The pads deform slightly and the weight at the lifting point is distributed evenly around the contact area. Also, since that area is very prone to rust, the pads protect the paint and keep it from peeling and chipping off.

... yet another reason that I'll try to do my own car repairs until I'm too old to drive!


Ray

 

[nobb]

I've tried cutting slits into hockey pucks and they never last more than a dozen lifts. Need to make these adapters out of a high density/durable plastic.

 

[clinebarger]

Try using them without cutting slits, They last a good while when used with a 2-post swing arm lift......Used them on show cars all the time.

 

[LeakySeals]

No mention of the year Maxima. Each is different. But I have a rusty 03. And I use my 3 ton jack with a 4in long 2x4 just inside of the pinch weld on the flat part of the unibody. It's strong there. My other daily driver Chevrolet classic is the same way. Spread out the weight with a piece of wood just inside of the pinch weld on the unibody. No issues. I made pucks, bought them online. And came to the conclusion they don't even use the pinch weld solely. They are compressing and putting most of the weight in the same area I put a 2 x 4. if you really look at the puck, the pinch weld is fitting into the slot that's been cut in the puck. The rest of the puck is coming in contact with the body. Why I decided to just use a 2 x 4 in that location. IMO the pinch welds are made for a specific device. the scissor jack that comes with car. If you look in most manuals it makes no reference to any other device to be used on the pinch weld other than the supplied jack.

 

[JTK]

There's always a risk a shop is going to damage them. More so for the DIY as said above, when you're trying to lift from just one corner. One was beat up badly on our Quest that I didn't notice until a few weeks after we bought it used. I've tried slotted rubber pucks like in the pic above. Also purchased a fancier slotted aluminum disk style one. Neither will fit all pinch welds. Best I've found and bought online for around $12 shipped is this floor jack adapter. I lined the top with self adhesive felt pads.

 

[RayCJ]

Originally Posted by LeakySeals
No mention of the year Maxima. Each is different. But I have a rusty 03. And I use my 3 ton jack with a 4in long 2x4 just inside of the pinch weld on the flat part of the unibody. It's strong there. My other daily driver Chevrolet classic is the same way. Spread out the weight with a piece of wood just inside of the pinch weld on the unibody. No issues. I made pucks, bought them online. And came to the conclusion they don't even use the pinch weld solely. They are compressing and putting most of the weight in the same area I put a 2 x 4. if you really look at the puck, the pinch weld is fitting into the slot that's been cut in the puck. The rest of the puck is coming in contact with the body. Why I decided to just use a 2 x 4 in that location. IMO the pinch welds are made for a specific device. the scissor jack that comes with car. If you look in most manuals it makes no reference to any other device to be used on the pinch weld other than the supplied jack.


Yep, agree! When I purchased some rubber pads for my floor jacks, the original slot was not as deep as the slot in the scissor jack that came with the car. I happen to have a machine mill using a 1/4" bit, made the slot a little deeper. The tweak seems to work for all five family vehicles. I've used those rubber pads countless times in the last 4-5 years and they're fine.