Ask The Experts: Five Mistakes People Make with Their Suspensions


Your suspension is the key to performance for your street to drag car, and over the years, we’ve had numerous conversations with suspension experts on some of the worst choices people can make when adjusting their suspensions, and decided this was valuable information to share, so we reached out to our buddies at BMR to get their opinions on the top five mistakes folks make with their suspensions.

BMR Suspension is an expert suspension manufacturer for everything from street performance, hard-core drag racing, and handling applications with a focus on innovative design, quality construction and affordable prices. Suspension, chassis and drivetrain products are offered for 16 different vehicles, and made in-house at BMR’s manufacturing facility near Tampa, Fl.

Marketing Technician Pete Epple offers up some things to consider when planning a suspension modification.

1. Not Having A Solid Plan


Not having a solid plan for your project can be the death of a project, or cause a lot of unnecessary expense. This is very true when it comes to suspensions systems. The suspension components and settings on a car may differ based on the plan for the project. For example, if a customer wants a car that can turn corners with the best of them and does not care about street manners, the suspension components needed will vary greatly from the guy wanting the best traction at the drag strip. A customer who daily drives his car to and from work will want different components than the customer who only races the car at events, etc.

For BMR, the most common customers are the ones who have street cars that they also race occasionally. This would be considered a “street/strip” car, or a “street/track” car. For those applications, the most popular and best choice is usually components that feature serviceable polyurethane bushings. The poly bushings will limit the NVH increase, while offering a substantial increase in performance and tradition.

True race cars will typically benefit from components that feature spherical bearings or rod ends, and are fully adjustable.

2. Not Having Realistic Goals


The higher the power output, the stronger and more durable the parts need to be. It was once said that cars with over 500hp need to run spherical bearings, but as time has gone by, bushing technology has improved drastically. What we, BMR, typically recommend is polyurethane up to about 700hp on street/strip cars. On a race car, spherical bearings are always recommended.

Customers want their cake, and like to eat it too, while racing. They typically want the highest dyno number, AND a stock-like ride and noise level. This can happen, when you choose a poly bushing, but be warned, bushing failure may occur. Running 700+hp in a heavy street car does not guarantee that you will damage your poly bushings, but it does promise premature failure in comparison to a car making half the horsepower. Bushings and bearings are wearable items, as much as most consumers do not like to hear it, it’s true.

3. Not Knowing What Your NHV/Performance Levels Are


Most people want all the performance and none of the noise. This is difficult to achieve, but it is possible. NVH is defined a noise, vibration, and harshness. You can definitely have the performance without the added NVH, but you have to plan your suspension out and pick the best parts based on what your plans and goals are for your vehicle. Most BMR customers use and are very happy with the performance they gain from our parts with the polyurethane bushings. This is very good because the polyurethane bushings add the least NVH out of all our bushing options. This is because the polyurethane does a good job of absorbing and dispersing the NVH. On the opposite end of the spectrum, you have our rod-ended and spherical bearing suspension components, which offer the best performance, but add the most NVH. The rod-ended parts are solidly mounted to the chassis, which makes the transfer of NVH very easy. We also have another very popular option with our parts that is a happy medium between the polyurethane parts and the rod end parts as far as NVH goes – polyurethane/rod end combination parts. These parts give you the best of both worlds, because they have the rod-ended side on the one end and polyurethane bushings on the other. This design is ideal for many customers because the rod end allows full articulation with minimal bind. On the other side you have a polyurethane bushing that attaches the component to the chassis and absorbs and disperses quite a bit of the added NVH.

In the end you have to figure out what style of suspension components best suit your needs and gives you a blend of performance and NVH that you are comfortable with.

4. Incorrect Installation


Often times, customers who know nothing about suspension or modifying their car attempt to install suspension components. These customers typically have many issues along the way, and often damage suspension components and/or hardware. When a customer does not have much experience installing aftermarket pats on a performance vehicle, we typically recommend select parts that we know may be easier to install. For example, it is much easier to install a fixed length, non-adjustable set of Rear Lower Control arms, than it is to install a set of fully adjustable pieces. Another example is the K-Member and A-Arm system. Customers want the best, so they go for our adjustable A-Arms, but these pieces can be very tricky and difficult to get “right”. At that point, a set of non-adjustable A-Arms is usually the best choice, as they are a “plug and play” solution.

There is no shame in going to a shop and having a professional install your parts. When you do, you know the installation was done correctly and you can drive your car aggressively with confidence that you won’t have issues.

5. Not Servicing Your Suspension


In most cases, suspension components are not “set it and forget it” parts. Bushings or bearings are considered wear items and need to be inspected, serviced, and periodically replaced depending on wear and the amount of use. Bushings and bearings that are serviceable need to be greased on a regular basis. This flushes out old grease along with any dirt or debris that may have found its way into the bushings.

Another aspect of suspension service is the alignment. When adding aftermarket suspension components you don’t always need to have an alignment done. There are really only two situations when an alignment is mandatory. The first would be if you were changing the ride height of the vehicle. The second would be if you had to change the position of the eccentric alignment bolts to install the aftermarket suspension components. If one of these situations apply and you don’t get an alignment done, you will definitely see some negative side effects. The first issue you will notice as soon as you drive the vehicle is that the steering and handling of the car will be unstable and unpredictable. The second, and more long-term issue you will notice is uneven tire wear. With this being said, an alignment is a very important aspect to making your suspension components perform to as high of a level as they possibly can. Over time, imperfections in the roads and general use can affect the alignment, requiring it to be readjusted.

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