Getting Sprung: Project Corn Star Gets QA1 Coilovers

Corn Star—our resident turbo fourth-gen Camaro—is starting to hit critical mass. In case you haven’t been following along, you can get all the details here. But to sum it up, the car has thus far been converted to E85, received an iron-block 370 from BluePrint Engines, and has been fitted with a Huron Speed turbo kit spinning a Precision Turbo PT7675 CEA Gen II snail. Needless to say, things are getting pretty serious, and for a serious build, we need a serious suspension.

Luckily for us, most of the Camaro’s critical links, including the torque arm, control arms and panhard bar have already been updated to tubular pieces provided by our friends over at BMR. However, the car was still sitting on a set of KYB single-adjustable shocks and Eibach Sportline lowering springs. And while the KYBs and Sportlines have served us well, they aren’t well suited for what is next with Corn Star, so we turned to the specialists at QA1 to help sort the car back out.

Things Get Heavy

Our biggest concern, right out of the gate, was the fact that we ditched the F-body’s aluminum LS1 when we discovered it had a crack in the block. This led us to switch to an iron-block 370 from the guys at BluePrint. And though we selected the iron block for its intrinsic boost-handling capabilities, we also knew that it would require the car to be rebalanced, as we’ve added a substantial amount of weight to the front of the car with not only the engine but the turbo kit as well.

Since we’re far from experts in the field of redistributing a car’s suspension, we turned to someone who was. David Kass of QA1 weighed in on how to get the car back into proper form and, in turn, maximize our car’s capabilities at the track.

“If you remove significant weight from the car, you may need to soften the spring rate, and will have to reset your ride height,” Kass said. “Removing weight from the car without changing the springs will have the same effect as stiffening the spring because there isn’t as much force on them. In the same regard, if you add weight, like with forced induction or adding an iron block, you may need to increase the spring rate. Once again, it comes down to what you are doing with the car. Adding weight to the front of the car may help with drag racing performance because that added weight will compress the springs more which will increase the energy that is being stored in them.”

In essence, adding a little more weight to the front of the car isn’t necessarily as bad as it sounds. While it may slow the car marginally, it also could provide us with better weight transfer coming off the line. Obviously, there is a lot more to it than just getting the springs right. The shocks are a big player in how that weight transfer goes down, and are arguably the biggest factor in our suspension upgrade.

“The shocks are a big consideration in any well-functioning setup. If you increase your spring rate, the adjustments in your valving will most likely need to be changed as well,” Kass said. “In an autocross car, if you increase the spring rate, you can decrease the compression valving but will want to increase the rebound valving. In a drag car, if you increase the spring rate, you may need to decrease the rebound valving because, with the loss of the stored energy, your front end will need more help coming up. With adjustable shocks, you can do all this very easily and quickly. Another consideration is that it really depends on how much weight you add/remove. If you move your battery to the back, or take 20 pounds off the front, that’s not a big enough change to necessitate changing your springs. However, If you make significant changes, you will need to consider changing spring rates.”

Making Adjustments

To give Kass a better idea of what we were working with, we put Project Corn Star on the scales to see where the redistribution of weight had landed us. This is the best possible starting point for the guys at QA1 as many of their recommendations will hinge on where the car’s weight sits and what you want to do with your car. The purpose of our build is primarily drag racing, but QA1 can get you set up for road racing, autocross, or a myriad of other scenarios.

As expected, our Camaro weighed in at 3,635 pounds. Not exactly light, but not too bad considering the car is 100 percent stock as far as the interior goes. We’ve ditched roughly 50 pounds by using BMR’s tubular suspension pieces up front and we also saved some weight by removing the crash bar, though it was replaced with an intercooler. This is roughly 150-180 pounds heavier than the 3,450 that seems to be common for fourth-gen F-bodys—not to mention we have some sound deadening in the car, adding a little extra weight.

This left our car with roughly a 55/45 weight distribution–which is virtually stock. We’d be a little concerned if the car was hitting the autocross course, but with it mostly seeing dragstrip duties there was no need for alarm. After sending our readout to Kass, he recommended that we run a 275-pound spring up front and a 100-pound spring in the rear.

Shocked

Since we wanted a lot of adjustability in the car, we decided to go with QA1’s Pro Coil system which converts our F-body to adjustable coilovers at all four corners. This will allow us to custom tailor Corn Star’s ride height and adjust it fairly easily, depending on how our testing goes.

Each coilover is available in several configurations, all of which feature a lightweight billet aluminum shock with a threaded body for ride height adjustment. They are a simple bolt-on affair that requires no fabrication and come in double adjustable, single adjustable, and Drag R Series. Several springs are offered for the fronts, including the 275-pound spring we chose, as well as a 300- and 325-pound spring. Kass felt that the car wasn’t too far off a standard fourth-gen and thus would benefit from the better weight transference of the lighter spring up front.

At the rear, the story is much the same except the springs’ rates are obviously lighter. However, the coilovers still bolt into the stock locations with no fabrication. And while choosing the Pro Coil system was an easy one, deciding what amount of adjustability we wanted in our system was not. For the answer to that, we once again turned to Kass.

“Double adjustable shocks do have more adjustment capabilities, but are not always the best option,” Kass warned. “It really does depend on the car, and more importantly, the driver. For a lot of normal hotrod street cruiser kinds of cars, a single adjustable shock gives the driver enough adjustability to get the car to ride and handle the way they want, but doesn’t give them the opportunity to have a completely wrong valving combination if they are not the type of person to sit there and really think about what the shock is trying to do as it moves in both directions. Sometimes having too many options can be daunting for some people, so having a shock that gives you enough adjustability without getting too complicated can be valuable. For the guy who really wants to get the most out of his set up, or a car that will be doing different kinds of driving, a double adjustable can’t be beat.”

Clearly, Project Corn Star is well outside the realm of standard performance so we decided to go with the double adjustable to give us the utmost control over our car’s suspension. And what’s more, we have the experts over at QA1 to help get them dialed in. Keep in mind, that’s not just available to us. QA1 is happy to help any of its customers dial in their setups, whether you’re an experienced racer or just a noob looking to have fun.

While single adjustables may take some of the work out of the equation, they can be far from ideal in an advanced setup. “On competition cars, each direction of the shock will have a different job, so being able to control them independently gives you the ability to make sure the car is working best for both conditions,” Kass explained. “In the front of a drag car, the rebound controls how quickly the front end comes up, while the compression valving controls how long the front stays up. In the back, the rebound controls how hard and fast you hit the tire, and the compression valving keeps the wheel from bouncing back, keeping the tire planted. Single adjustable shocks will require you to find the ‘happy medium’ of those conditions. A double adjustable shock will allow you to get the car just right, while a single adjustable shock may leave a little on the table. The more powerful the car, the more important it is to have a shock that can be more specific.”

As you can see here, we ordered our kit with the optional thrust bearings. These sit between the spring and the adjustment collar and make changes down the line much easier, especially when the spring has a decent amount of pre-load.

And since we are expecting to see well over 650 rwhp with Project Corn Star, the need for finite adjustment is exponentially higher, especially if we want to plant any of those ponies. With our springs and shocks picked out, we turned our attention to getting them on the car.

A Spring In Our Step

We chose to start our installation at the rear of the car. It’s the easier of the two ends and doesn’t even require you to remove the wheels. After getting the car up on jack stands, and after making sure the rear suspension was at full droop, we began our install by unbolting the KYB shocks. By unbolting the shocks first, it allowed the rearend to move even further down eliminating the need to use a spring compressor to get our rear coils out.

As you can see here, our car was previously equipped with a set of "drag bags." These airbags allow you to adjust rear ride height and, more importantly, allow you to tailor how hard you hit the rear tire. These, however, are unnecessary with our new set of coilovers.

Once the shocks were unbolted, and with a little more room from the rearend, the coil springs simply slid out. You can see that our car had “drag bags” on it. This is somewhat of a band-aid and allows the car to hit the tire harder coming off the line, making due with the single adjustables. Since we’re going to coilovers, these were discarded along with the springs.

With our springs out of the way, we turned out attention to the shocks. To remove them, we headed to the interior of the car where the top mount sits under the carpet behind the rear seats. To access them, we had to remove the rear speaker panels, sail panel covers, and pull the carpet back. The top of the mount is covered with a foam piece that simply pulls out of the way.

Luckily for us, the rear suspension offers enough droop–once the shocks have been unbolted–to allow us to simply pull the rear springs without the use of a spring compressor.

Once the shock mounts are exposed, it’s only a matter of removing the top nuts and they drop right out. However, if the rod spins inside the shock, you may have to use an adjustable wrench or Vise Grips to keep it from spinning while you loosen the nut. It also may be easier if someone holds them up from beneath to give you better access to hold the rod in place while you loosen the nut.

Pulling the interior out of the car is kind of a pain in the butt, but once the upper shock mount is exposed, it's a simple procedure to remove them.

With all of the old equipment out of the way, it was time to put our rear coilovers together. This was much easier than we anticipated since the adjustable ride height collars allow you to lower the spring far enough to put the upper retainer on the shock without compressing the spring— though you want to be sure to put anti-seize on the shock’s aluminum body so the adjustment collars don’t gall the threads. We also used the optional thrust bearing that sits between the spring and the collar which will allow us to adjust the ride height easier later on. We coated it with a liberal dose of anti-seize to ensure easy adjustment for years to come. It’s a cheap option and well worth it in our book.

With the collar adjusted all the way to the end of the threads, it's simply a matter of coating the thrust bearing with antiseize, slipping the spring over the body and using the retaining collar to lock it all together. Once that's done, you simply adjust the collar until there is pre-load on the spring and the assembly holds itself together.

The rear shock goes together by simply placing the bearing on the adjustable collar first and then slipping the spring over the body. With it fully adjusted to the bottom, the top retainer slides over the rod and butts up again the upper eyelet of the shock. Once this is done, we simply adjusted the collar until there was a decent amount of preload on the spring.

Our rear coilovers assembled and our front ready for their shock mounts.

Once we had our shocks together, it was time to drill our stock lower shock mounts to accept the conversion bracket that will allow us to mount the coilovers. Using the bracket as a template, we simply put the stock shock bolt through the existing hole on the rearend and marked where our upper hole needed to be drilled. Once this was done, we removed the bracket and drilled our hole with a 5/16-inch drill bit. This upper hole is for a bolt that will ensure the new bracket can’t rotate on the single bolt the old shocks were secured with. The shock bolthole may require enlarging as well, which we did with a progressive bit.

Once we had widened our existing lower shock mount bolthole, we used the provided conversion bracket as a template and marked where we would drill our second mounting hole. We then used a 5/16-inch drill bit to drill the new hole on the lower shock mount on the axle.

With the conversion bracket in place, and bolted down by the provided hardware, we were ready to mount our rear coilovers.

Next, we installed the upper mount to the top of the shock and slid the new coilovers into place. The bracket is directional so make sure the smaller end of it faces toward the driveshaft. Here, you’ll definitely want someone to hold the shock in place while you secure the upper nut. And that’s all for the rears. Next, we moved to the front, which is a little more involved.

With the bracket secured to the top of the coilover, it was simply a matter of threading the bolt into the stock mounting location and cinching it down. The upper bracket only fits one way, so be sure to face the narrow end toward the front of the car.

Our coilover in its new home.

At the front, we began by removing our old shock and spring. They come off together as an assembly and we started by first freeing up our lower control arm by disconnecting the upper ball joint. This allows the knuckle to swing down and away from the shock. Once that was done, we unbolted the shock from the lower control arm. Next, we loosened the bolt and nuts that held the shock mount at the top, inside the engine bay. On the driver’s side, this made it necessary to move the brake master cylinder out of the way. We did this by simply removing the nuts at the brake booster and pushing the master cylinder out of the way. This gave us enough room to remove the Torx bolt holding the upper mount as well as the two nuts.

With the upper ball joint disconnected and the bolts removed from the bottom of the shock, we were ready to move under the hood to release the upper shock mount.

Two nuts and two Torx bolts hold the upper mount in. The master cylinder has to be freed from the brake booster and pushed to the side to access the final bolt.

Once the shock mount is free, it allows the whole shock, and the upper control arm, to be removed from the vehicle. After the shock assembly was out of the vehicle, we used a spring compressor to allow us to remove the shock mount without decapitating ourselves. Once the mount was free from the old shock, it was ready to go back on our new set. Again, this is simplified due to the ride height adjustment collar. By adjusting it all the way down, there is no tension on the spring and thus you can reassemble the shock without a compressor.

Once the collar is adjusted to the base of the shock, and the thrust bearing has been lubed and installed, it's simply a matter of sliding the spring over the body and tightening the shock mount with the original hardware. After that, you simply adjust the collar to provide pre-load on the spring, and you're ready to reinstall it.

Again, we installed our adjustable collars and thrust bearing, after dousing both in anti-seize, then the spring. Once they were together, we simply bolted on the upper mount and then adjusted the collars to put tension on the spring. From here, we essentially reversed the disassembly of the suspension and tightened everything down.

With all of the coilovers on, it was time to select our initial settings. Using a measuring tape, we guesstimated a good ride height for the car. You can measure the car beforehand and replicate its stance fairly easily, but since we are going drag racing with the car, we actually didn’t want it sitting as low as before, so we started with conservative measurements first. We dialed in 4 inches from where the spring met the collar and the bottom of the thread on the body. From there, it was simply a matter of getting it back on the ground, letting it settle and seeing where we were at. Once we were satisfied with the ride height, we snugged down the jamb collar using the provided spanner wrenches.

After setting preliminary ride height, we dropped the car back on the ground to see where we're at. Once we let the setup settle, we adjusted our compression and rebound and tightened the jamb collars locking our final ride height in place. With that finished, it was off to the alignment shop.

It’s All In The Settings

With the ride height where we wanted it, it was time to dial in our shocks. QA1 provides suggestions in the installation instructions for general settings that perform well on the car–and with 18 settings of compression and rebound, you have up to 324 possible combinations. For example, they say 12 clicks of compression and 10 clicks of rebound will provide a firm feeling for street driving. This is where we started with our shocks but we will likely dial them down later when we hit the track. We’ll likely leave the compression as is but dial the rebound back substantially. Obviously, at the track you want much lighter settings on rebound to help with weight transfer but decent compression to make sure the nose of the car doesn’t come down too quickly and unload the rear tires. Those are our base settings but will take some time to dial in.

As you can see here, we left Corn Star’s nose in the air a little. This will help us out at the drag strip and keep us from grinding our recirculated wastegate pipe all over the road.

Once we had our preliminary settings dialed in, we took it for a quick spin to make sure everything was in order. Since everything felt and sounded great, we headed to the alignment shop for them to make sure everything was still copasetic. After everything was straightened out, we were good to go.

Honestly, we couldn’t be happier with the setup. With the shocks set at 12 compression and 10 rebound, the car feels crisp yet compliant. It is very similar to our previous setup and drove flawlessly on the street. The great news here is that when we get to the track, we can dial back those rebound settings, race all night, and then dial them back up again for driving Corn Star home.

We couldn’t be happier with our selection and we think we’ll be even happier when we get these bad boys to the track. Stay tuned as we take Project Corn Star to the track and give you even more insight on how to make sure your QA1s are optimized to give you the best bite.

Article Sources

About the author

Chase Christensen

Chase Christensen hails from Salt Lake City, and grew up around high-performance GM vehicles. He took possession of his very first F-body— an ’86 Trans Am— at the age of 13 and has been wrenching ever since.
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