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All About Leaf Springs

What Is Leaf Springs?

Do you know about a leaf spring? Well, it is a part of the suspension’ system in a number of vehicles. It is made up of numerous thin strips of metal that are known as leaves. They are arranged on top of each other to form a single curved piece. The vehicle’s weight and the bumps are all absorbed by the bending of the leaves and the friction caused between them when they slightly slide over each other. Note that these leaf springs are curved and are often referred to as elliptical springs. The curvature aids the spring absorb the impact.

Where Is Located Leaf Spring?

Generally, a leaf spring is connected to the body or frame of the vehicle at each and every end and the wheel or axle assembly is mounted in the middle of the spring. The spring extends in the same direction along with the vehicle. The attachment points are there on each side in the front and rear. Various suspension designs have a single leaf spring connected at each side that is also known as a traverse spring.

Types of Leaf Springs

Do you know that light commercial vehicles and HGV’S carry heavier loads? Yes, and that’s only possible when they have leaf springs fit. So, only for our precious customers, according to the plates, we have listed here everything you need to know about the types of leaf springs and their uses:

 

  1. Multi Leaf Springs - In this type, the spring is composed of multiple metal plates and these plates are situated on top of each other. Fixed together, these make the operations of the vehicle a lot easier. As you look downwards, you will notice the size of plates getting smaller. Generally, the plates are laid lengthwise for layering. The longest piece located on the top is made up of eyes and hooks to fix the springs well in place. These are widely used for light commercial vehicles and heavy good vehicles. Semi elliptical look is the stacked format that mean that the springs are thicker in the middle.
  2. Mono Leaf Springs - These types can mostly be found in the LCV’s than HGV’s as they are not designed for heavier vehicles. There frame includes a thicker centre, that gradually thins out towards the end. It is similar in structure with the multi leaf system but has no added plates. Earlier, the single leaf spring system was used greatly only until the time when they began breaking on heavier vehicles. Nevertheless, you can still find them and use them, although should not be used in a vehicle that needs protection against a heavy load or the weight of the vehicle itself.

Materials Used For Leaf Springs

In these types, the material that is used is generally a plain carbon steel that contains 0.90 to 1.0% carbon. Note that the leaves present in it are heat treated after the forming procedure. The heat treatment of spring steel products helps acquiring more strength for increased load capacity, range of deflection and enhanced fatigue properties.

Important Features of Leaf Springs

  • Now that we know that the leaf springs are heavily layered, it should be noted that these offer a large amount of support between the wheels, axles and the cars' chassis. Because of their tight knit structure, they can easily bear the heavy vertical loads that are applied to them. They are mostly used in the heavy-duty industries. It can be observed that the vertical loading is also distributed throughout the length of the leaf spring rather than scarcely through a small spring and damper. This helps in creation of concentrated force for larger suspension to be handled.
  • Damping is a highly essential characteristic in a car. In some cases where the suspension is under-damped, the car will tumble and bounce around well after hitting bumps or potholes that are there on the road. Well, this was a primal property in cars that utilized helical springs before the creation of the shock absorber. It is also disadvantageous to cars when driven at any real pace. Due to friction between each plate of steel, vehicle demoing’s became easily tolerable that made the response time after a vertical flex in the suspension much shorter and controllable for the car.
  • These leaf springs have a basic design that involves a cheap production as compared to the early springs and dampers. So, these leaf springs became the go to choose for everyone. Also, the magnolia springs also have a simple design as they use only one leaf spring steel. It is tapered thick in the middle to thin at the edges (referred to as parabolic leaf springs) to distribute the vertical loads evenly. However, this kind of a single leaf framework could only be used on extremely lightweight vehicles because of lack of strength within the bar.

How Do Leaf Springs Work?

  • Love hitting the roads? But wait, is your vehicle bouncing and swaying with heavy weights? Then you should suspect a problem with the suspension of the vehicle. Whenever the vehicle’s suspension gets too rigid and the wheels start bouncing while hitting the roads, there is a problem with the suspension. A good suspension on the other hand, helps in keeping the wheels on the ground. Numerous towers make use of leaf springs to attain stability when they have towed loads to keep the vehicle grounded. Well, leaf springs on larger tow vehicles are one of the earliest forms of suspension. They aren’t really fancy when it comes to their installation as they are simply elongated narrow plates that are connected to the frame of a trailer that rests above or below the trailer’ axle. These leaf springs come in numerous varieties namely: monoolein springs or single leaf springs that often consist of one plate of spring steel. Generally, these are thicker in the middle, while they narrow out towards the end. These don't offer a lot of strength and suspension for towed vehicles. Multiload springs should be used by drivers who tow heavier loads as these contain several leaf springs of different lengths stacked on each other. The short leaf springs are closer to the bottom. These too have the same elliptical shape.
  • Also, these leaf springs have varying ends according to their attachment to the frame. While considering the double-eye leaf springs, you may find the top plate having the longest ends curved into a circle. These ends form two holes, that can be bolted to the bottom side of the trailer's frame while on the other hand, open-eye leaf springs contain only one ‘eye’ or open hole. Generally, the other end of the open eye leaf spring is a hook end or a flat end.
  • Note that only correct installation of leaf springs ensures best suspension for two vehicles. The leaf springs can be located behind the wheel (you won’t be able to see them clearly when they're connected unless you crawl under the trailer). Take off the wheel completely before starting the installation. Now that the wheel has been removed, find a pair of hangers located on either side of the axle. These hangers are small in size and are elongated pieces of metal with holes that hang down from the frame of the trailer. It is only between the holes of these hangers where the eyes of a leaf spring are lined. Make sure you fix them safely with the apt hardware. When the leaf spring is double-eyed, you are likely to notice one hanger with a shackle link.
  • Now that the leaf springs have been bolted into the hangers, next, you should install a pair of U-bolts that is a two horseshoe-shaped metal rods. At times, these leaf springs are over slung (placed over the axle) or underslung (placed underneath the axle). The U-bolts fit around the axle and are fixed to a metal plate that rests against the leaf springs. The U-bolts serve the purpose of keeping the leaf springs flush against the axle so they hold onto the weight of the cargo.
  • Lastly, we advise you to inspect the leaf springs and their accessories for wear and tear as a worn or crooked leaf spring can lead to heavy damage (to a trailer and its contents). Also, while taking leaf springs off, check the shackle links for damage. A round ring of wear matching to the shape of the nut is absolutely fine but if the shape becomes an oval, perform a quick replacement of the shackle link. Properly take care of the leaf springs for safer drives.

Symptoms of Bad Leaf Springs

Here listed are a number of problems that you are likely to notice when the leaf springs are bad:

 

  • You will notice the vehicle leans to one side
  • At times, the vehicle will wander or bottom out
  • Constant spring breakage
  • Noisy springs

Tools Needed for Leaf Springs

There are a number of skilled auto mechanics who have a goal of opening their own car repair shop at some point in their career. But let’s face it; if you want to put up an efficient as well as profit making shop, then you might need much more than mechanical skills. There are a number of tools which you might need to perform the car repairs quickly as well as reliably. Auto repair equipment that you will need to repair your Leaf Springs may include: 

Top Brands for Leaf Spring

If customers trust a brand, then it would make them loyal, and if they are loyal, then they will surely buy more. We are well aware that customers want comfort, cheerfulness as well as satisfaction in their lives and that’s the reason why we offer top quality auto parts brands to our customers. We make sure to provide a positive experience to our consumers from the brands which we are offering so that they can form an opinion that a particular auto parts brand is trustworthy and would give them peace of mind while they are purchasing it for their car. Here we have listed out some top brands for Leaf Springs:

 

Skyjacker Leaf Springs

Hellwig Leaf Springs

Fabtech Leaf Springs

Tuff Country Leaf Springs

Readylift Leaf Springs

Related Parts for Leaf Springs

It is very important to arm yourself with information before you shop any auto part. We are here to help you dive deep into the names of the leaf springs related parts


Total Costs & Repair Times, Effort of Leaf Springs

More than any other kind of failure in a car, there's almost nothing that's quite as heartbreak ingas a completely damaged Leaf Springs Now when we talk about the replacement cost, it might vary a lot even on the same car depending upon its performance, labour cost, brand etc. Mostly, the tentative cost for replacing a leaf spring can be estimated somewhere between $990 to $683 while the labor costs range from $382 to $546. All the prices are exclusive of taxes and fees. Also, as this service requires bigger procedures, so the final bill may vary at times.

How to Change Leaf Spring?

Don’t know where to start from? Well, we have mentioned it all for you. All the information is valid for multiple-leaf springs on rear suspension systems that have two springs fixed longitudinally in regard to the chassis. Usually, numerous leaf springs have plastic spring silencers located in between the spring leaves. When these silencers get damaged, you are likely to hear screeching noises, while you drive on a rough road at low speeds. First, lift the vehicle with a floor jack and support the frame on safety stands so that the rear suspension moves downward, if you want to perform an inspection of the silencers. For removing the silencer, the vehicle weight shouldn't be applied. Well, damaged shackle bushings, brackets and mounts lead to excess chassis lateral movement and rattling noises. When the normal vehicle weight is resting on the springs, a pry bar should be inserted between the rear outer end of the spring and the frame and downward pressure should be applied on the bar. Next, observe the rear shackle for any movement. Remove the shackle bushings, brackets, or mounts if in case there is any movement in the shackle. Similarly, follow this process to check the front bushing in the main leaf as a worn out or damaged spring centre bolt enables the rear axle assembly to move rearward on one side. This movement can lead to changes in the rear wheel tracking that results in handling issues, tire deterioration and a fall in directional stability. Broken rear springs also tend to decrease the curb riding height. Also, spring replacement is quite essential if the springs are damaged. Still not there? Follow these instructions:

 

Step 1 - Lift the vehicle

 

  • All you got to do is park the vehicle in a flat solid surface area as this helps in giving the vehicle stability by reducing the risk of an accident. Ensure that the vehicle is not leaning to the side as rolling is a more common issue because at times an improperly lifted car can tip over.
  • Next, utilize a pair of wheel chocks that are wedges that fit under tires to prevent the vehicle from rolling. Note that, wedge 1 of the chocks is located under the front side of the tire. After that, wedge the other chock behind that same tire. Uplift the rear wheels using a floor jack. Crank the jack till the tires are approximately 7.6 cm off the ground. Then put these jack stands in front of the back tires. Place the stands in front of the back wheels (2.5 cm). Make sure that the car’s frame is able to rest on the top side of the stands while keeping the jack stands on the same height. Try pushing the car to see if it is stable before moving on to the removal of the leaf springs. If the vehicle is unstable, lower it onto the jack stands by lowering the floor jack. Check the position of the jack to make sure they are under the vehicle’s frame. 

Step 2 - Remove the old springs

 

  • Firstly, wear safety glasses to protect eyes from all the dust. To loosen the parts, sprinkle some spring’s nuts and bolts in oil to prevent any damage while removal. You can use penetrating oil such as WD-40. The leaf springs are elongated, flat, and slightly curved metal strips that extend across the length of the tire. Next, remove the bolts from the shock pads using a ratchet wrench (triangular mounting bracket right next to leaf spring). Generally, it is on the axle and is bolted to a bar that is connected to the car’s underside. The ratchet wrench should be used to turn the bolts counter clockwise for removing the bracket. Register the location of all the parts. Then loosen the U- bolts for removal. These can be found above the shock absorber bracket, hanging off the axle. Twist and turn the nuts counter clockwise to drop the bracket off the bolts. Then slide it. These are horse shaped, so they are easy to locate. Then unscrew the eyelet bolts on the spring’ ends by turning them counter clockwise to slide them off the leaf spring. Then, repeat this to disconnect the bolts on the spring’s back end. Now that you have removed the bolts, make sure that the leaf springs don’t fall. Repeat the steps to remove the other leaf spring that is situated next to the opposite wheel. 

Step 3 - Install the new springs

 

  • Place the new leaf spring under the mounting brackets in the way that it looks like a U with the lowest point in the middle. Ensure, to see that it spans across the tire and reaches the mounting brackets at both ends. Then, screw the leaf spring to the front bracket using a ratchet wrench. The leaf spring is mounted in the lowest point of the bracket and hangs down underneath the car. Then slide the eyelet bolt into the bracket and spring by changing the nut and twisting it clockwise. Place the bolt in a way that the car’s head points towards the car’ centre. This will help in preventing the bolt from popping out in case it loosens. Connect the spring to the rear bracket by simply fitting the other end of the spring in the square-shaped bracket at the back end of the wheel. Change the eye bolts and nuts and tighten them until the spring is suspended in the right position. Next, install the U-bolts and shock pad. For that hang the U-bolts over the axle (1 on each side of the spring). Slide the shock pad brackets onto the ends of the bolts. Place the nuts underneath the pads and tighten them to finish securing the parts. Then you need to loosely tighten the nuts for now to ensure that the other parts are placed correctly. Tighten the nuts later, if you do this. Properly put the other leaf spring to the opposite tire. The you should repeat these steps in order to install the replacement spring on the other tire. Place the spring in the brackets and then screw them in place. Ensure that they are screwed tightly so that the spring doesn’t wobble while touching. In case, the pieces seem loose or rattle when the vehicle is driven, readjust the bolts as soon as possible. Finally, remove the floor jacks by using a floor jack to lift the vehicle off of the jack stands. Slide the stands out from under the vehicle, if they are clear. Lower the floor jack to put the car on the ground with its new installed leaf springs. 
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John Framigllia
Technical Writer
Our technical writer is known for simplifying automotive parts and services. Intuitive with various vehicles and manufacturers, he knows how to simplify complicated problems.