Often, when jacking up cars, owners complain about not knowing the correct jack spots. More often than not, you may end up using the pinch weld to lift your vehicle. However, that is not advisable as it can damage your vehicle’s structural integrity. In this article, we answer questions like “what is a pinch weld” and “how to jack your car safely.”
Primarily, a pinch weld is an area at the front of the car where different metal components are welded together. It is the process of attaching the outer frame of the vehicle to the vehicle’s inner body. Pinch welding involves the part that forms the structure of the windscreen and windows.
Pinch welding proves much more economical and efficient than the traditional method of bolting together different parts of the vehicle’s structure. Because concealing it requires a substantial amount of money and can significantly raise the cost of the car, most car manufacturers just leave it exposed.
How to Create Pinch Welds
To create a pinch weld, you join two pieces of metal by placing them on top of each other. You then run a high voltage current through them to melt that material and create weld joints.
Also known as spot welding, the material sheets do not join all the way through. Instead, you apply adhesive to areas between the spots and then reheat the setup. The additional energy melts the adhesive and covers up the space between the welds.
Pinch welds not only form the frame for the windscreen but also run throughout the body of the car. They join the internal structure to the outer body to develop a protective covering. They run along the length of the car, from the rear wheel to the front, and under the doors. They are what form the lower chassis of the vehicle. There are three different types of pinch welds. Let’s have a look at all three of them. They are as follows:
- L shaped
- Flat shaped
- Z shaped
L shaped
The L shaped pinch weld is the most common pinch weld that you’ll see in most vehicles. It is the one that is found running under the length of the vehicle. To create this type of weld, you need two sheets of metal. One sheet out of the two has to be L shaped, which means that it has to bend at 90 degrees, while the other sheet must have a flat or horizontal portion.
You need to place the two sheets side by side and join them using the spot welding technique. Finish the procedure by applying adhesive, and the result will be an L shaped joint. The little flap of metal you see running along the length of the car is a result of this technique.
Flat shaped
The procedure that welders use to create this joint is the same as the procedure that’s required for a standard pinch weld. In this technique, you join two continuous horizontal sheets of metal. You use this technique to add a protective covering to the vehicle’s machinery.
Z shaped
The Z shaped pinch weld is essentially two L shaped Pinch welds joined together. There is one diagonal metal sheet that has an L shaped joint at the top and one at the bottom. You will find this type of joint on the top front of the car. It creates the structure for the windscreen and the windows. By adding a urethane bead on the diagonal surface, you add the structure needed to support the glass.
Pinches found at the top are not as susceptible to harm as the ones found at the bottom. When it comes to the pinch welds found at the bottom of the car, you may accidentally damage the weld joints, especially if you do not use a jack that is designed to lift your vehicle from the factory jacking points.
Where Should You Jack your Vehicle from?
After a while, the metal of the vehicle loses its strength and begins to cave in to pressure quickly. This happens due to corrosion and wear and tear. Jacking up your car becomes significantly tricky in such a situation, as the metal caves instead of providing support. There are several measures you can take to avoid such damage to your car.
Change the Jack Stand Points
We understand that you’re probably comfortable and familiar with specific jack points on your vehicle. As per human nature, you will always refer back to the same points. However, switching jack stand locations is a smart move. Doing so ensures that you don’t end up weakening the structure of your vehicle over time.
You can view the factory approved jack points from the owner’s manual. There will be gaps in the car’s underside that are structurally more sound than the pinch welds. We suggest that you use these for routine checkups and tire changes.
For garage work that requires the vehicle to be elevated for an extended amount of time, you can use a solid area on the car’s chassis. The ideal jacking location is in the middle of the front subframe (just behind the undertray) and the differential.
Use the Correct Jack
Most cars come with specially designed jacking points nowadays. Even then, it is relatively easy to end up with a distorted structure if you use the wrong type of jack. You should instead use a jack that features a special jack pad. The pad distributes the weight of the vehicle evenly across the weld.
With the right jack, you can avoid creating sensitive pressure points that can weaken the welds. With the right jack, we also suggest that you avoid using the factory demarked jack points very often. You should only use them to lift the car from one side.
For extensive repair work, you should use a garage lift or a floor jack hooked to a solid section on the chassis of the vehicle. For your day to day repair work, and routine procedures like a changing a tire, use one of the following jack pads.
The Rennstand by Safe Jack
The Rennstand is a revolutionary piece of equipment. It features interchangeable jack pads that work with all vehicles. The stand allows you to distribute the weight in the right spots to ensure minimal to no damage to the structural integrity of the car.
Universal Pinch Weld Rennstand Jack Pad
If you don’t want to go through the hassle of choosing a jack pad as per the make and specifications of your car, then you can opt for Rennstand’s universal pad instead. It works with all vehicles unless there is a significant difference in the design of the vehicle.
Safe Jack’s pads are also available as per the specifications of various other cars. If the universal pad doesn’t work for you, then you can search for one made for your vehicle specifically, like:
- Porsche Macan Rennstand Jack Pad
- Ford/Honda Rennstand Jack Pad
Which Part of the Pinch Weld is the Strongest?
If you look closely at the weld, you will notice a small mark on it. Companies place that mark to help you identify where to place a scissor jack. The marked part is considered to be the strongest part of the pinch weld.
However, not all cars have the mark, and many people hook up their jacks on either side of the pinch. Depending upon the use and the material of the vehicle, this may or may not be the best strategy. The pinch weld overall is just not meant to be used as the hookup point for the jack stand, regardless of how strong it may be.
How to Straighten Pinch Welds?
To straighten a bent pinch weld, you need to slowly bring the lip back to its original position. You can do this by using duckbilled vice grips. We suggest you first heat the rim before you start to curve it. Starting the process without effectively heating the metal can result in the metal cracking if you put it under too much stress.
Once you straighten out the fender, let it cool down a bit. Then, using the vice grip, straighten it out little by little. You will need to repeat this process multiple times. Apply a little bit of heat, let it cool, and then straighten it a little. After straightening it, have the metal cool down a little before you hammer out the slight curves and bends.
To finish up the process, use a blow torch and a cooling air fan at the same time. Doing so strengthens the metal and leaves it looking brand new.
How to Avoid Bending the Pinch Welds?
You can avoid the bending of the weld through two simple steps. Either use a jack pad to ensure equal weight distribution on the body of the car. If you don’t have the correct pad for the make and model of your particular vehicle, then use a wooden block or a piece of rubber to avoid overstressing one specific spot.
If you ignore these simple steps and let the lip fold over, it can cause multiple problems in the future. The folded-over metal accumulates water, which can eventually cause it to corrode.