“Round Two. Fight!” rang in our minds as we pushed onto the second round of testing our 2020 Ford Mustang GT500. Unlike the Street Fighter video game where pushing buttons to release random kicks and punches works, we’ve decided to take a formulated approach to produce results. In this round we focus on our suspension and tire package to hopefully improve from our last outing.
Our last round of testing involved us running on stock tires at stock power levels. Unfortunately the power of the supercharged 5.2L Predator engine was above what the track conditions could handle. A pedal fest emerged on our first pass and a scary wheel hop on the next. This resulted in us throwing in the towel for the night. Even barring these rough circumstances James Lawrence was able to crack off a 7.68 at 98.94. A decent time considering the track surface was not much better than a slightly prepped street.
We had planned on immediately adding power enhancing products after our baseline runs, but afterwards realized the chassis needed our attention more. We knew adding more power would only amplify the problem. It wasn’t a lack of power, but a lack of proper chassis setup holding us back. We decided to focus on chassis tuning rather than engine. On the agenda was BMR Suspension and a set of Forgeline wheels wrapped in Mickey Thompson ET Street R Drag Radials.
Our Shelby GT500 Goals
At this point I remind everyone of our goals for our 2020 Mustang GT500. While Lawrence has raced and won the NMCA series, this car will not be a test bed for building the fastest GT500 on the planet. We plan to keep this build a simple bolt on affair. These products will showcase what modifications help and by how much. These products are intended for the GT500 owners who enjoy the car’s performance, but also like the creature comforts Ford has provided. We also want these aftermarket products to fit 100% with no permanent modifications. This allows owners to revert back to stock with no trouble. With that in mind we are continuing to improve the chassis, but also take noise, vibration and harshness (NVH) into consideration with every move.
Our first step of making this production beast track ready was to address the suspension. The 760 horsepower power plant combined with poor track surface required a call to the good people of BMR Suspension. We discussed the issues we had and their team suggested specific parts to rectify them. Within a few days the solution arrived in the form of tubular powder coated red parts. Our mission for this round is to reduce wheel hop and wheel spin experienced in our baseline testing.
Cradle of Flex
We knew we had to attack the wheel hop first. On our last pass, wheel hop caused the torque management to kick on and kill any chance of a good ET. While electronics saved our parts this time, wheel hop has the potential to cause major drivetrain damage. Damaged parts are never fun, so we decided to reduce it as best we could. To understand what parts we need, we first need to diagnose what caused the wheel hop. In the case of the S550 the major problem is cradle movement.
Cradle Bushing Lock Kit
]The cradle under load can move in multiple directions. The stock cradle bushings were built with NVH in mind, not performance. Unfortunately that means it does not appreciate the amount of power being thrown at it from a dig. Thankfully BMR has a solution with their IRS cradle bushing lock kit. The kit utilizes a set of lockout rings and locating washer to secure the cradle. It is also 100% bolt on with no modifications needed.
The way the lockout kit works is the billet aluminum upper bushing lockout rings capture the inner bushing sleeve and the outer lip of the bushing. The lower bushing location washers capture the bottom portion of the bushing’s inner sleeve. This captures both parts of the bushings inner sleeves and nearly eliminates any movement.
What’s great about the lockout kit is its ability to be installed with simple hand tools as no modifications are required. It is a 100% bolt on affair using existing boltholes and hardware. The lockout retains creature comforts as little to no increase in NVH was witnessed. The lockout removes 80-90% of cradle movement!
BMR Differential Bushing Inserts
Since we were already this far into the chassis we decided to install BMR differential bushing inserts. Even though our Mustang’s rubber is new, it is still prone to break down from exposure, road salts and other harsh environments. Simply put, stock rubber can’t compete with the likes of polyurethane inserts. The new bushings double as an increase in stability and preventative maintenance.
BMR IRS Support Brace
To complete our suspension overhaul we added a BMR IRS support brace. The BMR brace has more connecting points limiting the subframe movement. This will aid in preventing wheel spin and in turn wheel hop. Aside from having a practical usage, it also provides some awesome underbody color and looks. This product is not permanent, nor does it add any NVH, so going back to collector status is a few bolts away.
No Action Without Traction
Next on our shortlist was to attack the loss of traction. While throwing some stickies on the stock wheels might have worked, the unfortunate truth is the stock 20” wheels are too large to also provide good sidewall. The lower profile tires will result in less bite and more spin. We decided to go with a set of Forgeline wheels. Forgeline has been paramount in the road and drag racing world for years now. They produce extremely strong wheels that are also light and allow for large braking setups like found on our GT500.
For this GT500 we decided to run a set of Forgeline GS1R wheels wrapped in Mickey Thompson ET Street R. The GS1R wheels are crafted from a single forging of 6061-T6 aluminum. We wanted to maintain the correct attitude on the front and stuck with a 20” wheel that was 8.5 inches wide. On the rear we dropped two inches off the diameter while remaining 11” wide. We decided to take it a step further and run a beadlock setup. This will allow us to prevent tire slip on the wheel while keeping the bead seated at high speed. Overkill? Maybe, but wheels are crucial in building a performance vehicle.
So after we performed all these modifications it was time to see where we stand. Drag strips offer little to no consistency, but for our testing purposes we headed back to the same track. As with last time, our first pass was our quickest and fastest. Instead of trusting prep we left at idle and the GT500 blasted down the eighth to the tune of 7.2 at 102 MPH. This is almost half a second faster and picked up over 3 mph on the top end. These are huge gains for any drag racer. On a properly prepared surface these gains would be exponentially better.
Now that the frustrating experience of chassis wheel hop or spin has been reduced we can start our transition into making more power! The struggle will no longer be chassis related, but a restraint against our horsepower loving shop. I know I’ll constantly check back to the drawing board in hopes “bolt ons and e85” has been replaced with “larger blower and nitrous”. Sadly though that is not our goal with this build. So get ready for next week as we swap pulleys, add a few bolt ons and bring on the corn juice to this amazing GT500.