BMR's Ultimate F-Body Suspension Guide

mark@lsxtv · #1 (**permalink**) 01-09-2010, 01:20 PM

The F-Body is one of the most popular platforms in the history of automotive performance. With that popularity comes a huge selection of suspension parts that makes picking the right ones for your car a real challenge. One of the leaders in F-Body suspension is BMR, but even they have a HUGE selection of different components for the platform. Now we will help you make your decision a little easier - not only will we show you the difference between street, street/strip, and race BMR suspension setups, but you can follow along as we give you helpful tips for your own project install.

We produced two full complete videos that go along with this article.

Front Suspension Video:

Rear Suspension Video:

Not only do you want to upgrade your suspension with high performance parts, but you want them to be more durable than stock as well. For this article, BMR Fabrication sent us a "pallet full" of suspension components, with everything from street oriented components to their hardcore 8-second capable race suspension. “We are going on our eleventh year of building F-body suspension parts, and we started with shock tower braces and lower control arms”, explained Lee Spicher, BMR Technical Manager. Needless to say, BMR has come a long way in those 11 years, but even they can't magically build a set of components that will work for every application. Before you get started, you'll need to ﬁgure out what type of F-Body you are building.

How Will You Use Your F-Body?

The biggest challenge when selecting components is being honest with yourself about your vehicle's intended use. There is no quicker way to end up with a poorly handling car than to install racing suspension components on a street car. “You always want to try to feel out the customer on recommending components. Initial response is to over-modify, but you should start with one or two nonadjustable pieces to see how the car reacts first,” Lee says.

While everybody loves the idea of installing race parts on their street car, racing-oriented torque arms and suspension components equipped with rod ends produce a miserable experience in real-world conditions when it comes to noise and harshness of ride. Race cars do not see street duty, and if they do, it is less than 10% of their total use.

How do we define them... here's how we tried...

Street Car - One that spends 90% of its time being driven on the highway and local roads. It rarely sees the drag strip, and when it does, it is usually raced with the same street radials that it drives on.

Street/Strip Car - In an F-Body, it is one that spends somewhere around 50% of its time on the street and 50% of its time on the drag strip. Slicks or drag radials are typically swapped over at the race track. With a street/strip application, you can begin to use more aggressive parts that will provide greater track performance.

Strip Only Car - The name says it all. This will be an application that may only see street travel on its way to the track or it may be one that is trailered. Maximum performance can be achieved without the worry of an ill-handing car or the excessive noise and vibration that comes with rod ends coupled with stiff bushings.

We are going to cover three key areas of upgrading your suspension:

The front suspension, featuring the K-member upper and lower control arms.
The rear suspension, featuring the rear control arms and panhard bar.
The torque arm, a suspension part designed to absorb rear axle torque reactions.

The BMR K-member weighs nearly 1/2 the weight as the factory unit.

BMR’s Front Suspension Options: Up to 31 Pounds Saved

BMR K-Member

The biggest weight savings you can achieve from BMR’s line-up is the tubular K-member. The stock behemoth stamped steel version weighs in at a hefty 49 pounds and contains way more metal then you really need. Not only is the tubular K-member a direct replacement, but it doesn’t require any vehicle modiﬁcations. Believe it or not, this K-member is 24 pounds lighter than stock. It provides additional clearance for larger headers, and it allows for increased camber (1/2”) adjustment, which is great for lowered cars that are looking to dial out some negative camber. Whether you’ve got a street or race car, an aftermarket K-member is a great place to start as a foundation.

Larger diameter tubing to increase durability. Equally at home on the street, road course, or drag strip.
Nearly half the weight of a stock K-member.
Additional 1/4" of A-arm adjustability provides up to 4 degrees of additional camber adjustment.
Works with stock A-arms or any aftermarket A-arms.

Part Numbers:

KM001 - Without motor mounts. For use with factory power rack mounts.
KM001-1 - Without motor mounts. For use with BMR manual rack-n-pinion.
KM014 - Turbo style high-clearance K-member without motor mounts. For use with factory power rack mounts.
KM014-1 - Turbo style high-clearance K-member without motor mounts. For use with BMR manual rack-n-pinion.

Front K-member Removal

A tubular K-member is the most difficult suspension component of all to install. Think of it as being equivalent to your hip bone; the K-member supports your entire engine. Keep in mind that it will require jack stands during installation in order to properly support it. Unless you enjoy driving your car with the steering wheel turned in one direction, be sure to center and lock your steering wheel prior to removing any parts. Next, remove the power steering lines that feed into the rack, steering shaft joint, bolts that hold the rack to the K-member, and the rod end bolts that are attached to the control arms.

The K-member mounts directly into the factory mounting holes without any fabrication.

Moving outside to the control arms, start by removing the ABS sensor plug from the spindle and the fasteners that hold the wiring to the control arm. There are two bolts that hold the control arms to the K-member, sway bar end link, two strut bolts, and the control arm ball joint. If you plan on reusing the stock ball joints, we recommend using a pry bar between the control arm and the spindle rather than a ball joint separator that may damage the joint. There are brake line bolts that secure the lines to the side of the K-member that require removal. At the same time, be sure to remove any wiring harness that route around or attach to the K-member.

Removal is now getting close! It’s time to support the engine with jack stands on solid points, and NOT on the oil pan. With the engine securely supported, access the single bolt on each side of the engine that holds the engine mount brackets to the rubber mount. With the K-member now supported by a jack, remove the two bolts on each side that hold the K-member to the front frame rails. The K-member should now easily drop out of the car. Follow in reverse order on the tubular counterpart and everything will bolt into their corresponding areas.

Front Control Arm Selection

If you have ever worked on your car, you know exactly how pathetic the stock, stamped, steel upper control arms are; they may even bend if you look at them wrong! The stock pieces also use bushings that are designed for slight flex, which helps to eliminate vibrations through your suspension components.

BMR offers their upper control arms in two different options - either polyurethane equipped or adjustable that use rod ends. The polyurethane bushings provide a good ride on the street, whereas the adjustable control arms provide adjustable suspension geometry along with the use of mechanical rod ends. Those rod ends don't retain any rubber and are all metal, therefore they will be more noisy.

Upper Control Arms

New greasable ball joints
1.25" DOM tubing with 3/16" ball joint mount
Includes new high quality bolt-in upper ball joints
Low deflection polyurethane mounting bushings
3 degree improved ball joint angle for lowered cars
Adjustable version allows additional alignment adjustability utilizing chrome moly, teflon lined XR series QA1 rod ends

Applications:

Street - Street/Strip - Strip - Part number AA001 Non-Adjustable
Street/Strip - Strip - Part number AA004 Adjustable

Paper thin, stamped steel stock arms on the right and DOM tubular BMR arms on the left.

The BMR upper control arms that we selected were the non-adjustable versions that fit directly into the OEM upper mount.

The benefit of the adjustable versions is their ability to adjust for camber, helping dial in for alignment and track conditions. Overall, the upper control arms do not weigh much less than stock, but they are significantly stronger and less prone to deflection under hard driving conditions. According to BMR, they have hundreds of drag racers using the standard poly-bushing arms in 9 and even 8-second cars.

The polyurethane mounts are much more durable than the OEM versions.

Front Lower Control Arm Options

Out with the heavy lower control arms and in with the new tubulars! The BMR lower control arms come in only one version with a poly front mount and an adjustable rod end on the back side. The reasoning behind this is the ability to adjust positive and negative castor for adjusting your overall track. “Keeping the one mounting point poly helps us reduce the natural vehicle harmonics of the car and keeps everything quieter,” Lee says. We noted a 3.5 pound drop in the weight of each lower control arm, helping to decrease spring weight. Also, the lower arms are a direct fit that come with new ball joints and maintain all stock mounting points, including the sway bar mount.

The upper A-arm installation is simple. There are four bolts that hold the strut and control arms to the car that can be removed from the engine compartment. That same control arm mounting plate is simply swapped to the BMR arm that also comes with new ball joints. With the adjustable versions, replicate the stock length of each side of the A-arm to maintain stock angle until you are able to visit an alignment shop.

Front Lower Control Arms

Weight loss of 3.5 pounds over the factory A-arms.
Direct bolt-in, no vehicle modifications required.
Manufactured from seamless DOM tubing.
All plates are CNC lasered and formed for exacting manufacturing tolerances.
Includes new high quality press fit lower ball joints already installed.
Free-moving greasable polyurethane bushings.
Provides additional castor adjustment with the QA1 XR series rod end in rear of A-arm.
Works with factory and all aftermarket K-members.

Applications:

Street - Street/Strip - Strip - Part number AA002

One part number fills all the lower control arm needs.

The control arms come with a shock mounting plate and bolt in without any modifications. They also work with the OEM K-member.

For installation, two mounting bolts and a ball joint is all it takes to get the arms off. Be careful when removing the forward control arm bolt, though, as we experienced slight interference with the rack and opted to loosen the rack in order to remove it. If you are doing the lower control arms with a K-member installation, install the lower control arms before installing the rack. With the adjustable uppers and lowers, this will give you the ability to adjust your front suspension in castor, camber, and toe.

We opted for the single adjustable rear lower arms that feature a hiem/poly joint combination.

Rear Lower Control Arm and Panhard Options

Upgrading your rear control arms is made easy with BMR because they have a wide variety of street, street/strip, and full race control arms. They have 7 models total, and they are available in both adjustable and non-adjustable versions. The stock control arms are weak, and the stock rubber bushings encourage this little problem called wheel hop. So even if you’ve got a street car, upgraded control arms need to be the first thing on your list. “We always try to recommend the lower control arms as their first piece and the relocation brackets if the budget allows,” Lee says.

Let’s start by taking a look at the BMR street-oriented control arms which feature low deﬂection polyurethane bushings and are available in both adjustable and ﬁxed length versions. Their boxed street control arm is the cheapest in the BMR line and looks like a reinforced version of your stock arm, only with much stronger poly bushings. The next step is their tubular style street bars that are offered in standard DOM steel and stronger chrome moly. Both of these come with full poly mounts.

Rear Control Arms

The heavy duty boxed control arms are fabricated from 1.5" x 3" rectangular tubing.
The non-adjustable tubular control arms are fabricated from 1.625" x .120" DOM tubing or in the optional 1.625" x .083" 4130 chrome moly option.
The "On-Car" adjustable versions are made from 1.25" x .095" 4130 chrome moly tubing. These control arms use custom 3/4" heavy duty chrome moly double adjusters for the street version and HD XR series QA1 rod ends with stainless spacers for the race version. Both models can be adjusted "on-car".
Xtreme Control Arms are made from 4130 chrome molly tubing and feature large 1-1/8" double adjusters. Arms are adjustable in length up to 1/2" in either direction.
Billet arms are CNCed 6061 T6 aluminum that are 2” x 2.5” in design. They feature thicker bushings for increased durability.

Applications:

Street - Street/Strip - Part number BCA001 Boxed Arms, Part number MTCA001, and Part number TCA001 Tubular

Street/Strip - Strip - Part number TCA004 Poly/Rod, Part number MTCA002 adjustable, and Part number XCA001 Xtreme Arm

Strip - Part number MTCA003 Double Rod End

The rod end is adjustable on the car and is solid fixed.

The last step in the non-adjustable street control arms are their billet versions. These are by far the beefiest lower control arms offered by BMR and are made from solid 6061 T6 aluminum with full poly mounts. Lee remarked, “The billet rear control fully captures the bushings so you don’t have a bushing welded onto the end, which helps with strength.”

BMR does offer adjustable versions of their chrome moly full poly bar, called their On Car Adjustable Control arm and their Xtreme Control Arm. “The adjustable rear control arms are designed for changing wheel base and comes in handy when doing rear end swaps on centering your rear wheels,” Lee states. These street arms will give you 1/2” of adjustability in either direction and are both made from chrome moly, though the Xtreme version comes with a larger 1-1/8” adjuster.

A quick, two bolt installation is all that is needed to install the rear control arms.

The remaining two rear control arms are better suited for street/strip and full race applications. The first bar is their combination poly and rod end control arm that is also adjustable at the rod end. For the full race version, BMR offers the control arm in a full rod end combination. The rod ends that BMR uses are heavy duty QA1 Teflon lined units. Installation of the control arms are straight forward and take little time. be sure to support the rear end with jack stands on each side before removing the two bolts on each arm.

It should be noted that any of these control arms can also be used with BMR’s bolt-on relocation brackets, athough BMR highly recommends welding the top part of the brackets to eliminate any movement. They reposition the instant center of your rear suspension by altering the lower control arm angle for increased traction.

Pandard Rod

Panhard Rod Options

Manufactured from seamless DOM tubing or chrome moly option for lighter weight.
Fully Tig welded construction.
Uses low deflection greasable polyurethane bushings and a QA1 Teflon lined rod ends.
Less deflection than the factory panhard rod, helping keep the rear centered in vehicle.
Custom CNC machined 4130 chrome molly adjuster for precision on car adjustment.

Applications:

Street - Poly Part number PHR001 Standard, Part number MPHR001 chrome moly non-adjustable
Street/Strip -Poly Part number PHR002 Standard, Part number MPHR001 chrome moly center adjustable
Strip - Part number MPHR003 chrome moly double adjustable with rod ends

F-bodies come equipped with a panhard rod that assists the torque arm in controlling rear end movement. The panhard rod locates the rear end side to side in the chassis and provides the rear end alignment of the tires relevant to the centerline of the car. This is important because a deﬂecting panhard rod will steer the car, creating a dangerous handling condition in a high-powered vehicle. However, just like the control arms, panhard rods do transmit vibration and road noise to the F-bodies' unibody structure, so bushing choice is very important.

BMR offers a selection of panhard bars that mirror their control arms offerings. They have a full poly mount rod that is nonadjustable and is offered in DOM or chrome moly options. The same bar is also offered with a built-in adjuster for setting your rear end track. For you street/strip guys, there is an adjustable panhard that comes with a poly/rod end combination in DOM only. Their full race version has double rod ends that are adjustable on both ends.

Installation of the panhard is a simple two bolt process. Start with setting your adjustable rod to the stock length and then adjust accordingly.

Installation of a panhard rod is a simple bolt-in affair, with the adjustable versions featuring left hand and right hand threads to allow on-car adjustment. Follow our advice on control arms to pick your panhard bar. Whether you go with poly, poly/rod end combinations, or just a full race rod end version, make sure it matches your selection of control arms. Remember that if you have a lowered car, or plan to adjust the ride height, an adjustable panhard bar is a requirement because the panhard bar will alter rear end position as ride height changes.

The Final Stop - Getting Torquey... The Torque Arm

No part on your suspension takes more abuse under hard acceleration than your torque arm. That is because this component absorbs all of the rear axle torque and applies it to the chassis. When you upgrade your engine beyond the factory power rating, the ﬂexible stamped torque arm deﬂects and dissolves the power rather than applying it to the chassis.

Not only does it reduce the efﬁciency of your power increase, but Lee says, “For a guy that is around the 400 horsepower mark, this is the best upgrade to help his car launch better.” No decision is more important to your F-Body than selecting the correct torque arm and setting it up correctly.

Full Length Torque Arm

Less flex over factory stamped steel torque arm.
Manufactured from seamless DOM tubing or chrome moly.
Direct bolt-in, no modifications required.
All plates are CNC lasered and formed for exacting manufacturing tolerances.
Includes new low deflection polyurethane transmission mount bushing.
Comes equipped with integrated adjuster for adjusting pinion angle quickly (adjustable version).
Clears all factory and aftermarket exhaust systems.
Works with factory rear end as well as all aftermarket rear housing assemblies.

Relocated Torque Arm Additions

Multiple bolt holes for precise and easy on-car adjustment of torque arm.
Clears all factory and aftermarket exhaust systems.
Takes the load off of the tail shaft of the transmission housing and directly applies it to the chassis for increased performance.

Applications:

Street - Part number TA002 non-adjustable
Street/Strip - Part number TA001 DOM, Part number MTA001 chrome moly adjustable
Strip - Part number TPU001 Universal Trak Pak, Part number XTA001 Xtreme Torque arm

The BMR street series of torque arms are a direct fit that also include a poly front bushing.

Torque Arms for the Street

Let’s start by taking a look at BMR’s stock replacement style torque arms. They are made with upgraded MIG welded tubing with heavy duty mounting plates, and they are designed to bolt directly to the factory torque arm using all factory mounting locations. These low-deﬂection poly front bushings are available in both adjustable and non-adjustable versions. The non-adjustable is suitable for stock height vehicles by incorporating the -2 degrees of pinion angle directly into the bar. The adjustable torque arm is better for lowered vehicles that require more adjustment or for suspension gurus that are looking to fine tune their own setup.

Stock replacement arms are great for many different applications, from stock-type cars all the way to 10-second street/strip cars. The weakness in a stock-replacement torque arm is the nature and design of the front OEM mount. At some point, the power applied to the transmission mount can cause failures.

Torque Arms for Hardcore, Straight Line Racing

The Track Pak and Xtreme Torque arm are shorter and require welding of a closer mounting point bar.

BMR also offers the Trak Pak torque arm that is designed for drag racing and not for street or road handling cars. This helps locate the torque arm at a better spot, the chassis, which then takes the load off of the transmission housing. “Having the torque arm further back is going to make the car react a lot quicker and pushes the tire down harder,” Lee says. It also moves the instant center rearward for greater weight transfer. However, the Trak Pak does require welding and professional installation due to this cross-brace. The Trak Pak is made from DOM Mandrel tubing.

If you are truly a serious racer and have a drag strip only F-body, the B-M-R Xtreme Torque arm is an upgrade from the Trak Pak and is designated for racers looking for 9-second or even 8-second elapsed times. Made from TIG welded chrome moly, it features a gusseted rear mounting bracket, solid 4130-rod eyes, and a fully reinforced front mount. It even includes an integrated driveshaft loop. As you can see, picking a torque arm for your F-Body is no different than choosing a camshaft. Bigger may seem better, but often it results in a poor experience for the car driver. Pick the right part for your true intended use, and you’ll be much happier.

Gripping Better and Weighing Less in no Time!

The F-Body is one of the best chassis platforms because of the variety of suspension parts and chassis components available. However, variety means confusion to many enthusiasts and racers. The key to building a good suspension platform is picking the right shop to do the work and picking the right suspension components to match your combination.

Discuss all of the options with a performance suspension company like BMR Fabrication before making any ﬁrm decisions. Remember, it only takes a few bad decisions to turn your street car into a miserable ride. However, with a properly matched set of suspension parts - whether you have a street car, a street/strip car, or a full on 7-second drag car - you’ll be having fun and sailing into the winners circle!

Source:

BMR Fabrication
Web: www.bmrfabrication.com
Phone: (813) 986-9302

Wookieman · #2 (**permalink**) 01-15-2010, 09:11 AM

I have the BMR control arms and rear relocation brackets on my 1996 T/A and they work great. I have been debating about putting the K-Member, but after seeing the weight savings and how easy to install (my motor out for the 383 build) I think i need to make this upgrade.