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
Having a goal of achieving a 10-second quarter-mile e.t. might sound easier than you’d think, but it actually takes a lot more than just having some serious horsepower. The S197 platform is far more advanced than the Fox/SN-95/New Edge generation of Mustangs it replaced, and the folks atQA1,UPR Products,Mickey Thompson Tires & Wheels, and Race Star Industries are here to help us dial in our ’05 Mustang GT both in bone-stock and modified iterations.
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 (PNHD605S-12200)
QA1 ’05-’14 Double-Adjustable 708 Aluminum Stocker Star Rear Shocks (PNTD708)
Without a doubt, we could have fully relied on strictly polyurethane bushings throughout, and a non-adjustable (or even single-adjustable) suspension setup; but having that adjustability is going to help us work smarter, not harder, to achieve that 10-second e.t. goal.
“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.
David Kass of QA1 also said he has seen folks equipped with QA1's single-adjustable components run all the way into the 8s on occasion. However, these folks know their cars aren’t dialed in to their full potential either. While he said the single-adjustable shocks are a fantastic setup, after a certain point, they begin to lose the benefit of adjustability by growing out of them–and that’s where the double-adjustable units come in. Our double-adjustable units allow for adjusting each shock and strut's compression and rebound independently, with each travel direction having more than 18 different settings. Safe to say, there's more than enough compression and rebound combinations to custom tailor your experience driving on the street, and enough precision for the strip.
Installing The Complete Package
The rear suspension upgrade requires you to remove the rear seats to access the fasteners for the upper link mount. It’s up to you if you want to replace them when all is said and done!
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.
As you can see, the factory 12- year-old, 70,000-plus mile suspension is looking pretty worn from the outside. There were no visible leaks from the rear shocks, but driving this Mustang on the street everyday told another story.
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.”
Removing the old and worn factory components in favor of replacing them with our new UPR and QA1 components.
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.
Out with the old, in with the new! Burn the upper factory upper diff bushing out with a torch and replace it with UPR’s spherical unit. Be sure to put thread sealer on the retaining nuts.
“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.”
Comparing the old stamped steel upper control arm (left) to the new UPR component (right) immediately reveals the massive differences between the two. Going from the old, soft and worn factory rubber bushings to the new billet aluminum spacers and polyurethane ones makes a world of a difference – both in a street and a performance setting. Having a double-adjustable unit like this one from UPR makes adjusting your pinion angle as easy as a few turns of a nut.
We can only imagine how much longer those soft, old and cracked rubber bushings would have lasted during hard launches at the strip. The factory stamped steel lower control arm is notorious for flexing under heavy load. Another added benefit of our new double-adjustable lower control arms from UPR is its strength. The chromoly tubing is much thicker than the factory unit, and the new arms feature bulletproof like strength due to a larger tubular wall-thickness in the construction.
“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.”
Remember when we mentioned welding? For the new UPR rear coilover setup, the mount itself needs to be welded to the spring perch. Not a hard task by any means, but definitely one you'll want to take on only if you know how to weld. Then again, it's hard to mess things up when you're using a unit like our Miller one. To adjust the springs for lowering or raising the vehicle, you'll want to thread the adjuster up or down to your liking, then lock it in place using the locking rings below the adjuster. Since we daily drive our Mustang on factory wheels and tires for now, we left our Mustang just slightly lower than the factory ride height, just to clean up some of that nasty wheel gap left over from the factory.
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.
“Low cars can work, if they’re setup to work properly at that ride height,” Sharad said. “There’s not a reason why someone can’t make their car hook when lowered, but there are factors involved (such as instant center, anti squat and others we’ve discussed here) that need to be taken into account.” Sharad concluded.
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 components installed, and the full suspension in all of its glory. Our double-adjustable Panhard bar helps to center the rear axle after the vehicle has been lowered beyond the factory ride height – a must for any lowered Mustang. The Panhard bar brace helps to keep the Panhard bar from shifting side-to-side during acceleration and cornering, while adding additional support to the body as well. It’s extremely important (and in our eyes, necessary) for lateral grip. The purpose of a Panhard bar is a bit more complicated, but that’s the short answer.
The Final Countdown
We finally made it to the strip, but not before some trial and error testing.
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.
"On the '05 and up Mustang, there is a bracket holding the sway bar in place that interferes with the inner barrel of a 15x10-inch rear wheel. A simple bracket kit from Race Star solves the problem," Carl Robinsion of Race Star Industries explained.
“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.
Even with what little horsepower we have from the factory, we were still able to get our bone-stock, underpowered and overweight Three-Valve to transfer weight quite nicely, thanks to all of the new suspension components.
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
When we got on the horn with M/T, we originally opted for a slightly larger than stock tire size (28-inches versus the factory 27-inch size). We knew we would essentially change our effective gear ratio, which ultimately affected us on our naturally aspirated iteration.
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.”
From the right lane: We were able to improve our 60-foot by nearly three tenths of a second with the new suspension.
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.