With the new year came a new project car that is tailored toward our Blue Oval fans, our 2005 Mustang GT. In our introductory segment, we detailed that our Mineral Grey Three-Valve-powered Mustang has a goal of eventually transforming into a 10-second street/strip driven machine.
Keeping in the spirit of budget-minded modifications, to help us achieve our long-term goal, we needed a long-term solution for the car in its current form. This entailed us to momentarily think outside of our budget-minded mentality in order to save that money in the long run, as we’ve detailed below later in this segment.
It’s important to look at what someone is doing with their car today; but we always ask them–what’s the end-goal for the car?—David Kass, QA1
Throughout this feature, it’s important to keep in mind that what we are doing today will ultimately be for the better of tomorrow. Some of the modifications may not make sense now, and their full potential is yet to be realized; so stick around as the folks involved teach us how to fully utilize our suspension, wheels and tires both now and later.
Keeping Up The Suspense
OK, we won’t keep dragging our feet on this one. Here’s what we got – basically every component we chose is double-adjustable, save for a few. Most components use a mixture of street-friendly polyurethane mounts and not-so street-friendly spherical bushings, but there’s a good reason for that, as we’ve detailed below.
The Full Suspension List
- QA1 ’05-’14 Front Pro Double-Adjustable Coilover Strut System w/ Sway Bar Bracket (PN HD605S-12200)
- QA1 ’05-’14 Double-Adjustable 708 Aluminum Stocker Star Rear Shocks (PN TD708)
- QA1 ’05-’14 Bump Steer Kit (PN BAX105)
- QA1 ’05-’14 Caster Camber Plates (PN CC105MU)
- UPR ’05-’14 Adjustable Rear Spring Mount Kit (PN 2007-101)
- UPR ’05-’14 Pro Street Double-Adjustable Upper Control Arm & Mount (PN 2001-110)
- UPR ’05-’14 Pro Street Chromoly Double-Adjustable Lower Control Arms (PN 2002-16)
- UPR ’05-’14 Lower Control Arm Relocation Bracket Kit (PN 2018)
- UPR ’05-’14 Pro Street Double-Adjustable Panhard Bar (PN 2021-02)
- UPR ’05-’14 Chromoly Panhard Bar Brace (PN 2020-01)
- UPR ’05-’14 Spherical Differential Housing Bushing (PN 2003-88-05)
“The biggest motivator for us to recommend the double-adjustable suspension on this project, versus the single-adjustable, was that the goal for the car in the near future was to build a quick car,” David Kass, Customer Service Manager for QA1 told us. “With the double-adjustable suspension, you’re building a foundation that you can do more with later.”
David said that the QA1’s single-adjustable version of shocks and struts would have been great for what we are trying to accomplish today.
However, as soon as we try to take the next competitive edge at the car, tuning ability is where it will begin to become the dividing line between how well the car is going to perform, or not perform.
“When someone is riding the fence on whether they want a double- or a single-adjustable style of suspension, we always ask them—what’s the end-goal for the car?” Dave explained. “It’s important to look at what someone is doing with their car today; but what gets so expensive about this hobby is when you repeatedly upgrade the same components over and over. We see it all of the time–people over the years upgrade from a single-adjustable to a double-adjustable—and they end up spending two to three times the money they originally wanted to.
“If it’s in the cards (or in the budget), and you know the car is going to progress to that performance level–it’s best to try and purchase that component up front. And while it may cost a little more today – you may not use it to its full potential today, but it’s going to be there tomorrow when you eventually need it,” he concluded.
Installing The Complete Package
Installing the whole package was a pretty straightforward endeavor, minus having to burn the old differential housing bushing out of place in favor of the new spherical version from UPR. Other than that, it’s a 95-percent bolt-on affair, save for welding the rear spring adjusters to the spring perch. No cutting or permanent modification necessary here, and everything mounts in the factory locations.
We also asked Sharad Raldiris of UPR Products about the advantages and disadvantages of utilizing double-adjustable suspension components. “In regard to double-adjustable rear lower control arms, these components are not used to adjust pinion angle. Pinion angle is adjusted by adjusting the upper control arm’s angle,” he said.
So why would enthusiasts want to use double-adjustable lower control arms then? “Most enthusiasts choose a set of double-adjustable lower control arms because they’re making so much power that spherical bushings are the only option,” Sharad explained. “However, with that said, even if a car is only 400 horsepower at the wheels, and the car is raced avidly, it’s nice to have a solid bushing for the added durability.”
To circle back to pinion angle, this is where the double-adjustable upper control arm comes into place. To keep things short and sweet for this section, the definition of pinion angle is the difference between the driveshaft angle and the pinion angle on the differential. Older iterations of the Mustang [Fox, SN95 and New Edge] all used a four-link 8.8-inch rearend, but our ’05-plus S197 uses a slightly different setup.
“Throughout the entire process of upgrading a car’s suspension, it’s important to keep in mind that Ford designed these vehicles with comfort in mind–as well as to meet noise, harshness and vibration standards,” Sharad explained. “The reason why Ford uses super-plush, soft rubber bushings, is because they’re absorbent. It makes the car smoother and quieter, and it appeals to a larger audience.
“Even launching on the street, those crazy soft bushings cause that unmistakable wheel hop. More-so when you’re at the track, and you actually have enough traction to apply a load. What you’re feeling is the reaction to the soft rubber bushings–and you immediately find the weaknesses.”
“When it comes to getting the pinion angle just right, the goal is to minimize vibration, and to make the system work more efficiently,” Sharad elaborated. “If an enthusiast is having an issue with traction during the initial launch, adjusting the pinion angle won’t fix it. Measure it from the driveshaft to the rear end, and adjust it to a -2 or -3 pinion angle when using polyurethane bushings on the S197 chassis.”
Lastly in our discussion with UPR, Sharad informed us of a few common misconceptions regarding suspension and correcting geometry angles. In regard to pinion angle, making adjustments to it will not yield more traction or faster passes. Sort of a PSA, but bare with us. In our discussion, he explained that the S197 platform can hook very well when lowered.
We mentioned earlier in the article that we utilized QA1’s caster camber plates on our suspension build. One of the reasons why is because, if we ever decide to lower the car further, we can adjust the alignment further than just your normal toe settings. As their name suggests, the caster camber plates allow for adjustments in both caster and camber alignment settings.
This is not only crucial for daily driving, but also lowering your vehicle. Anytime an adjustment is made to the suspension system, an alignment is highly suggested to correct any suspension geometry issues, as well as wheel and tire issues.
The Final Countdown
The final piece of the pie was our Race Star Dark Star wheels and Mickey Thompson tires. Because our ’05 Mustang GT is equipped with a manual transmission, our friend Carl Robinson of Race Star Industries (formerly with M/T) recommended a bias ply rear tire for our application.
Along with those ET Street R bias ply tires, he also recommended a matching set of 15×10-inch Race Star wheels for the rear.
For the front, we went with a set of M/T Sportsman S/R radial tires, paired with a set of 92 Dark Star 17×4.5-inch wheels. Because we plan to run a larger-than-stock front brake assembly in the near future, Carl recommended the larger diameter for the front wheels and tires.
“The bias ply tire is far more suitable to the clutch style (manual) transmission,” Carl explained. “Without going into the gritty details, there is a significant difference between a clutch vs. converter in the delivery of power through your drivetrain. The bias ply construction is far more forgiving, and is more able to absorb the shock delivered by the clutch, versus the torque multiplication of a converter.
“These were things were learned through trial and error–and there remains those who are convinced they can make a radial work better than a bias ply using a clutch–jury is still out. But, as technology expands, so does the opportunity to make the radial/clutch combo outperform the auto/radial combo,” he concluded.
In our baseline segment on the factory suspension, wheels and tires, we were able to accomplish a novice pass of 9.259 at 79.16 mph down the eighth-mile, accompanied by a 2.313 60-foot time. We detailed that, while we’re certainly not professional drivers, there was plenty of room for improvement according to those numbers.
You may not use it to its full potential today, but it’s going to be there tomorrow when you eventually need it. – David Kass, QA1
Our factory 3.55 gear ratio had virtually changed to a 3.42 (according to using a quick online calculator), fundamentally leaving our underpowered, under-geared Three-Valve in worse shape.
We knew opting for a larger tire size currently wasn’t the most ideal way for us to take advantage of our naturally aspirated application. However, following the regiment of our budget-minded build that we mentioned in the last segment, we really weren’t looking forward to purchasing tires twice–so we opted for the larger tire now.
As our friend David Kass of QA1 said earlier, “You may not use it to its full potential today, but it’s going to be there tomorrow when you eventually need it.”
Out at the strip, we calculated about four hours total of trial and error testing. On a naturally aspirated combination like ours where there isn’t a ton of power being made, while equipped with a larger tire, we found it to be very difficult to get the tires to spin just enough to rollout a decent 60-foot time. Because of the larger diameter tires being on the car, it was essentially dead hooking all the way up until a 5,000 rpm clutch-dump – where we were finally able to garnish enough wheel spin to make the suspension begin to work.
We started the day with rear tire pressure around 18 PSI, but found that between 15 and 17 PSI was the magic number for us. Remember, you’ll have to continually check tire pressure after each run, as it will continually increase after each pass you make.
All said and done, after dialing in the tire pressure on the rear, we found that in our case, the adjustable suspension really worked best using QA1 and UPR’s recommendations. For the double-adjustable shocks and struts, we cranked the fronts up to 12 clicks on the compression, and left the rebound at zero. For the rear, we left compression at full soft (zero), and we set the rebound at four clicks. For the double-adjustable lower control arms and the upper control arm, we set our pinion angle to -2 degrees, centered the axle in the wheel well, then left the arms in the middle portion of the relocation brackets so that the arms would be parallel to the ground at full rest.
Because of the larger diameter tires coupled with a lack of power, we weren’t surprised at the end of the night when we matched our initial e.t., but surpassed our original 60-foot either. As we said earlier, our 60-foot really needed some attention first. After that, it’s all uphill from there.
Now the question begs, how can the larger tires benefit us in a forced-induction application?
“You’ll grow into this tire, and the whole combination, through gear ratio,” Carl elaborated. “What I mean by that, is that a 28-inch tire is a bit taller than the stock 27-inch size; so right off the bat, you’ve effected the final drive ratio unfavorably. You’ll need to gear up appropriately for a higher horsepower combination. Making more power and torque, while working your way up the RPM range, will further the need for additional mechanical advantage, due to the torque curve modification.
“What you’ll find is related to the tire, you’ll evolve in tire pressure as well. The goal today [in natural aspiration form] is to run as much air pressure as possible, given the conditions and ambient temps. When trying to wring-out every thousandth from your car, you can’t be stuck on one level of air pressure and keep improving your performance,” Carl concluded.
If you’re in the market for wheels, tires and suspension for your street/strip application like ours, hit up our friends at QA1, UPR Products, Mickey Thompson Tires & Wheels and Race Star Industries for the ultimate in traction for the street and the strip.