Ask the Experts: Five Things You Should Know About Your Suspension

suspension

BMR Suspension Marketing Technician Pete Epple is back to offer some expert advice on suspensions after telling us about the mistakes people typically make with their suspensions (read here). This time, it’s five things you absolutely must know about your suspension to most effectively modify it for street or track performance.

1. Know Where Your Suspensions Parts Come From

suspension

Oftentimes, people see inexpensive suspension components for sale on automotive website and think they are getting a great deal. What people don’t realize is that you absolutely get what you pay for, and in some cases, inexpensive does mean cheap. Parts made oversees using sub-quality materials with questionable manufacturing processes can be extremely inconsistent, causing alignment and suspension geometry issues. This can make for an extremely unpleasant experience when it comes to installation and how these parts work on the vehicle. BMR Suspension doesn’t want you to have issues due to poor manufacturing with subpar materials.

All BMR products are proudly designated, tested, and manufactured in the U.S.A, in our Central Florida facility. We cut, bend, notch, drill, and mill our tubular components from American-made DOM and chrome-moly steel. Every part is fixture-welded to maintain consistent quality. We beadblast our parts then powdercoat them on our own powdercoating line. We then assemble and package the products in our assembly department. By manufacturing our products in-house, BMR can control the quality at every stage of the manufacturing process.

2. Know What Materials Are Used to Build The Components

suspension

Whether it’s bushing materials or tubing, the materials used to build suspension components is critical to longevity of the parts. Parts made with sub-par materials will be prone to failure, rust, or the deflection the components are designed to prevent.

BMR uses quite a few different high-quality materials to build our parts. It mostly depends on what the part is designed for and what the intended use is. For our bushings we use either polyurethane or Delrin for the material. For the majority of our parts, we use polyurethane bushings and we will get into the reasoning for that later on. We also manufacture quite a few CNC-machined billet aluminum parts for items that need to hold a very tight tolerance.

As far as fabricated parts go, we use three different kinds of steel. For all of our boxed suspension components we use ERW (electric resistance welding) steel because it is really the only boxed tubing option available. For the majority of our tubular suspension components we use DOM (drawn over mandrel) steel, which is the highest quality mild steel available. We really like the DOM steel because it has certain characteristics that make it a great material to use for suspension components that see regular street use. DOM steel holds very tight tolerance and has no welded seam. so it is very easy for us to work with, plus the finished product looks great. Another thing that makes the DOM steel very appealing for us to use is that it has very good fatigue characteristics. It holds up very well under regular street use and when blunt force is applied to the metal, it will bend rather than break.

suspension

The other type of tubular steel we use for some of our suspension components is Chrome-moly steel. The main benefit of the Chrome-moly steel over the other types of steel we use is its strength. Due to the extra strength of the Chrome-moly steel, you are able to use thinner wall tubing, which in turn will save a decent bit of weight depending on the amount of tubing used in the component. Now there is some give and take with the Chrome-moly steel. The added strength of the steel makes the steel more brittle, so it doesn’t hold up as well as the ERW and DOM steel does to regular street use. When a blunt force is applied to the Chrome-moly steel it is more likely to crack or break than bend like the ERW and DOM steel does. This is why you mainly see the Chrome-moly steel used on more race-oriented products. With that being said, there are definitely certain suspension components where you can use the Chrome-moly steel on the street. It just comes down to what kind of load/force the component sees.

No matter where you buy you suspension components from, be sure you get components from a quality company that uses quality materials.

3. Know About the Construction of the Components (Welding Types, Coatings, Etc.)

suspension

Quality construction is huge in terms of the fitment, correct geometry, and the strength of any suspension component. Whether it’s MIG or TIG welded, every BMR component is fixture welded to ensure the perfect fitment every time. This is a major part of building a consistent quality component.

Once the parts are fabricated, they get coated. BMR powder coats the majority of its components, giving you an incredibly durable, yet good looking finish that will hold up even in the harshest conditions. Every part is beadblasted to remove any oil, dirt, or debris, ensuring the surface is clean and ready for coating. All parts are either coated in black hammertone or red. Painted parts are not as durable and scratch easier, letting rust form and damage the finish and the steel beneath.

4. Know What Bushing Material is Used

suspension

There are quite a few differences between rubber and polyurethane bushings, and the rod ends and spherical bearings. Polyurethane bushings are more suited towards cars that are daily driven and don’t see extreme horsepower numbers. This material is harder than the rubber used in factory bushing, so performance is significantly increased. For more race-oriented applications, rod ends or spherical bearings are recommended. The polyurethane bushings offer a better ride quality and less NVH than the rod ends do because they are made out of a softer material. The major downfalls to the polyurethane bushings is that they don’t articulate very well under extreme horsepower applications. The rod ends and bearings are more suited to high horsepower applications and cars that see extreme use. The rod ends articulate freely so there is minimal to no bind in any working situation. The rod ends can really take anything you can throw at them but the major downfall to the rod ends is that they tend to transfer NVH into the vehicle.

Determining what parts will work best for you can really be a tough decision. It really comes down to what kind of driving you plan on doing with the vehicle and what kind of power the vehicle will be making. The rule of thumb is that parts with the polyurethane bushings work better for daily driven vehicles that make moderate power and the rod ended parts work better for vehicles that will see some track use and make more extreme power.

5. Know What Testing Goes Into the Parts

suspension

When BMR test parts, it all starts with a basic design. Once the design is approved, we build prototypes. Once we have prototype parts, testing begins. The parts are installed on multiple vehicles to account for any manufacturing tolerances in the car. At this point we may make changes to bushings or bushing saddles, but any changes are usually very minor at this point. We primarily build suspension parts for the street performance segment of the automotive aftermarket, so that’s where our dynamic testing begins. Once we have a baseline on the stock vehicle (including NVH levels, photos, video, track times, vehicle feel, etc.) we reevaluate every aspect of the suspension component and its impact on the car for each part tested in the baseline. We will spend anywhere from 250-2500 miles on the street ensuring the parts are durable, quiet, and deliver the gains they are designed for. Once this is complete, parts that do not need to be track tested are ready to be released, and parts that need testing in more controlled environments are taken to the track. Our testing process relies heavily on video footage of the parts in their natural environment being pushed as hard as possible. Once the parts pass this stage of testing they are ready to be released. This allows us to offer street and track tested parts that will perform flawlessly at any level.

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