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As we direct our Project Silver Bullet towards better dragstrip performance we need to increase traction at the starting line. A key to maximizing starting line traction is proper location of the instant center of our rear axle. To adjust this appropriately we turned to BMR Suspension for a set of their lower control arm relocation brackets. We also had BMR send us one of their bolt on drive-shaft loops so as we continue to run faster ETs with our car, we can remain legal and safe at the track.
Both the BMR lower control arm relocation brackets, and driveshaft loop offer easy bolt-on installation with no need for special tools.
Getting Centered
The BMR rear lower control arm relocation brackets, part number CAB005 are constructed from 3/16-inch CNC laser cut steel. These brackets feature three mounting points for fine tuning the rear suspension. This allows us to compensate for lower ride height and also get the car launching better off the starting line. Installing the control arm in a downward angle (at the axle bracket) will hit the tires harder on the launch. While this sounds good in theory, hitting a drag radial too hard will result in wheel spin. Though we have to say, in bolt-on form, these brackets have been as fast as a 1.1 60-ft time at the dragstrip on other BMR customer cars.
With our lower control arms disconnected from the axle housing we put the BMR relocation brackets in place, and tightened the bolts by hand. With three mounting positions for the rear lower control arm, the BMR relocation brackets can help compensate for spring height changes or aftermarket control arm lengths to get instant center where it's supposed to be for better launches.With our relocation brackets in place we tightened the bracket mounting bolts at the housing.
The brackets offer a simple bolt-on installation, requiring removing only the mounting bolt at the axle on each control arm and the panhard bar mounting bolt on the driver side of the axle. Installation can be done with basic hand tools either on a lift, or the garage floor with the help of jack-stands and a floor jack. Total installation time is about an hour if working on the floor, less than that if you have access to a lift.
The relocation brackets are installed using the factory mounting points and allow owners to select from three new positions to mount the lower control arm. We chose the middle position
Safe Shaft
Go fast enough at the drag strip and you’ll eventually be required to have a driveshaft safety loop on your car. Before the tech officials throw us out, we decided now would be a good time to install one of BMR’s driveshaft safety loops, part number DSL017.
Top Row: Left: With the transmission supported we removed the cross-member. Center: We placed the top strap of the safety loop over the driveshaft. Right: BMR provides this bracket to space the transmission mount appropriately with the new parts. Bottom Row: Left: Next to go in is the main structure of the safety loop. Center: We then installed the factory cross-member back into place. Right: Last we installed the bolts to connect the top strap to the main structure of the safety loop.
The BMR driveshaft loop for 2011 and newer is made from 1/4-inch steel plate to meet NHRA safety regulations, and BMR also provides Grade 8 hardware for attaching it. Perhaps the coolest features is that it mounts using the factory transmission cross member mounting locations. This means there’s no drilling or welding involved, making for a very clean installation that can be easily undone later without leaving behind unsightly holes.
The BMR driveshaft safety loop provides us with a NHRA legal driveshaft retention device in case of a u-joint or driveshaft component failure.
The BMR driveshaft loop can be installed using hand tools, also on the garage floor or on a lift. This might take a little more time if you’re doing it on laying on your back since the transmission cross-member has to be removed, however it’s still about a one hour installation.
On the Track
Back at the track with Silver Bullet, we proceeded to do a little testing. Our blower belt was slipping during our test session, however we were able to net a best 60-foot time of 1.54 on our way to a 6.88 at 102.3 eighth-mile time slip. Our previous best 60-foot had been a 1.58, so we’ve definitely seen an improvement. Once we get the belt slip issue figured out, and then start adding more power it’ll be nice to know we can rely on our BMR lower control arm brackets to help us hook up, and do so without getting kicked out of the track for a safety violation thanks to our BMR driveshaft safety loop.
