Shifting Weight and Steering Straight – BlownZ’s Front Suspension


With Project BlownZ, we are going to try to do something pretty tough. We’re going to attempt to put copious amounts of Procharged horsepower to the ground through some relatively skinny M/T 275mm Drag Radials with a stock-style suspension. It’s not going to be easy,  but we plan to accomplishing this feat by making sure that we are working with the very best stock-style components available, starting with the front suspension.

Nailing a launch at the drag strip all starts with getting the right amount of weight transferred from the front of the car to the back at the exact moment when the rear end needs all the help it can get to plant the tires. That weight transfer all begins in the front suspension set up. It’s a vital task that can make all the difference in how well BlownZ will perform at the strip. So, we went to the experts at Spohn, Afco, PA Racing, Strange, and Mickey Thompson, to help us put together a front suspension combo that can keep things nice and straight through our passes, and help us drop plenty of pounds off the front of the car in the process.

Spohn Front K-Member/Control Arms/Pinto Steering Rack

Here's the basis of our front suspension - the Spohn Performance tubular K-member, chromoly control arms, and Pinto manual steering rack with bumpsteer corrected tie-rods.

We needed a solid foundation for BlownZ’s front suspension; a K-member that could help us drop some weight, gain more alignment adjustability, and still be tough enough to handle the forces that serious drag racing will be putting on it. Based on our prior experiences, we knew that Spohn’s tubular K-Member package with their tubular control arms fit the bill perfectly. The Spohn K-Member is made of 0.120 wall DOM mild steel tubing that weighs 25 pounds less than the stock K-member. “Our k-members are not designed as a ‘drag only’ unit.” says Steve Spohn, owner of Spohn Performance. “We build them to also handle the demands of a daily driven car. We gusset our K-member at every intersection, a total of 20 locations, using 1/8-inch and 3/16-inch steel.”

The Spohn K-member was a breeze to install, and uses all the factory mounting points.

In addition to dropping a good chunk of weight from the front end of the car, Spohn designs their Camaro K-member to open up a ton more room in the engine bay. Anyone who has ever worked on one of these cars will appreciate the fact that Spohn engineers these K-members to give you more room for headers, power adders, and piping. Since we are using a motor plate, we elected to go with the ‘no motor mounts’ option, and freed up even more room on the sides of the engine block.

Our control arms from Spohn are constructed of light-weight chromoly, and we opted for a set of their precision ball joints.

Now we can’t just bolt up those ugly, heavy stamped steel stock control arms to our high-tech K-member, so we also got a set of Spohn’s upper and lower control arms. Both the upper and lower arms are made of 1.25” x .095” wall 4130N chromoly tubing to drop even more weight, and add bullet-proof strength we need at the drag strip. The upper arms have a set of Spohn’s Precision ball joints and have a 3-degree negative angle build in to help lowered cars maintain the correct suspension geometry.

The lower control arms are really where the additional adjustability really comes into play. Spohn tells us, “The lower a-arm alignment slots on our k-member are longer both ways than the factory k-member so you have more front end alignment adjustment available. Also, the rod ends or Del-Sphere pivot joints thread in, so you can change the length of the a-arms for track width changes if you need to.”

Here you can see just how much additional adjustment the alignment slot in the Spohn K-member allows.

In a car drag car like BlownZ, every ounce counts, and we knew there were still more pounds to be dropped from the front end by using one of Spohn’s manual Pinto rack and pinion kits. By ditching the stock power steering pump and all that goes along with it and adding the overall lighter manual rack, we were able to cut a huge 40 pounds of sprung mass. However, since we are using a dry sump oiling system, our pump gets right in the way of the rack. Luckily some billet steering rack brackets from Chris Alston Chassisworks solved our problem in no time and gave us the additional room we needed. Finally, we finished off our steering system with Spohn’s bump-steer corrected tie rod ends to keep the front end geometry right where it needs to be even once we’ve lowered the car.

Spohn 4th Gen Camaro K-Member Kit Features and Benefits

  • Weighs 25  pounds less than stock K-member
  • Direct stock replacement
  • Increased alignment adjustability
  • Strong enough for both racing and daily driving
  • Frees up more room in the engine bay for power adders, headers, and piping

Afco Front Coilover Shocks and Springs

We can control both the ‘attitude’ and ‘altitude’ of the wheelie. -Eric Saffell, Afco Racing

There’s an old racers adage that says “Going up isn’t going out” and since we won’t be using wheelie bars on BlownZ, we have to take that saying to heart. It’s important that the front suspension apply just the right forces at just the right time to minimize the likelihood of a monster wheel-stand, but also have some features built in to help us land safely in the event that one does occur.

In a drag car like BlownZ, the front shocks and springs have a big job to do. It’s up to them to get things moving with the weight transfer process by extending quickly and compressing down slowly. We knew the exact timing of our suspension travel would be anything but a ‘one-size-fits-all’ application, that’s why we went with a set of Afco’s double adjustable coilover shocks, so we could dial them in as we needed.

The Afco Double Adjustable Coilovers will allow us to independently set our compression and rebound according to what's best for track conditions and available traction.

These shocks (PN 3870F-BNC) are a twin tube, shim-stack design with independent settings for the rate of extension as well as rebound and compression. “With the double adjustable shocks we can stiffen up the extension rate and we can control the rate of the wheelie with the dampening curve as well.” says Eric Saffell, Drag Racing Product Specialist with Afco. “We can control both the ‘attitude’ and ‘altitude’ of the wheelie.”

Afco's shocks come with everything we needed to put together our coilovers with the 14-inch chrome springs.

We want to minimize the likelihood of having to ride out and land a big wheelie, but that doesn’t mean that it won’t occasionally happen. If the track conditions are perfect, and those skinny M/T drag radials bite the track just right, we’ve got more than enough power on tap to send BlownZ’s nose reaching for the sky. The problem then becomes landing safely. “BNC Valving was designed to allow the cars to come down soft after a wheelie, so that the front end doesn’t bounce.” says Saffell. “I’ve seen guys crash from this, and the front end geometry can really change. What often happens is the car does a big wheelie, and when it lands the front end will come down so far that the weight is unloaded from the rear end. Then there’s the possibility of a second wheelie once the tires grab again.” Not exactly a good situation to be in, especially considering you can’t steer with the front wheels in the air. “What we like to happen is for the front end to come down, the valving get really aggressive to stop all that mass, and then you can really start feeding in the power and make a clean pass.” Saffell tells us.

Afco's coilovers allowed us to simply bolt in a ton of adjustability in BlownZ's front suspension.

On the spring side of things we are using a 14-inch long chrome coilover spring also from Afco (PN 24275CR), with a rate of just 275-pounds. We went with a longer spring with a lower rate to really help get the front suspension moving. “The main job of the spring in a drag car is just to hold the weight of the car, and it’s the shock’s job is to control weight transfer from a timing perspective.” says Saffell. “But we can also put some stored energy in the front end of a car by choosing a longer spring and a softer shock. You’ve now got a spring with some preload in it and it will explode up when the car is launched, and will help get the weight transfer process get started.”

Afco Twin-Tube Double Adjustable Coilovers and Springs Features and Benefits:

  • Independently control the rate of extension and compression, improving weight transfer
  • Longer 14-inch springs pre-load the front end
  • BNC Valving acts as a safety net for landing wheelies

PA Racing Light-Weight Drop Spindles

To tie our front suspension all together we called up PA Racing for a set of their light weight chromoly drop spindles. We went with these spindles for several reasons, but we’ll start with the big story: weight loss. The PA Racing spindles are significantly lighter than the stock units that our F-body was born with. “They are mainly designed to take weight off of the front end of the car.” said Jason Smith, owner of PA Racing. “That’s one of the biggest problems with the 4th gens is that they are so front heavy. You can save about 60 pounds just by swapping from the stock spindles.”

The biggest advantage to PA Racing's F-body Drop Spindles is that they helped us drop weight off the front of BlownZ.

Next, the built in 2-inch drop allowed us to get the bad-ass drag car stance we were after without having to get our drop from the spring and shock combo. If we lowered the ride height with the shock and spring we would lose upward travel since both the shock and spring would have to be shorter. So, a drop spindle was the right way to achieve a lowered stance and still allow us to take advantage of the longer shock and spring we need for weight transfer. Additionally, the PA Racing spindles have a repositioned steering arm to help further eliminate bumpsteer from the lowered stance.

The built in 2-inch drop of the PA Racing Spindles will give us the stance we are after, while keeping our spring and shock combo nice and long with plenty of travel.

Finally, another huge benefit to PA Racing’s spindles is that they utilize brake kits from 1st Gen Camaros, which ultimately means more cash in our pockets. Smith tells us, “Our spindles are also meant to save you money on brakes since they are set up to use a brake kit from a 1st Gen Camaro instead of 4th Gen brakes. It comes out to be almost $400 cheaper than a 4th Gen brake kit, so that’s money that you can use on something else.”

PA Racing Drop Spindles Benefits and Features:

  • All chromoly construction
  • Pair weighs 60 pounds less than stock
  • 2″ drop gives better stance without lowering springs
  • Repositioned steering arm for reduced bumpsteer
  • Uses 67-69 drag brakes for lower cost

Strange Engineering Drag Brakes

Strange Engineering's Drag Brake Kit for 67-69 Camaros helped us drop weight, gain stopping power, and save some cash at the same time.

Drag brakes are a different animal from the binders in a street application. In a street car, the vast majority of the braking is done with the front, but in a drag car the skinny front tires limit the amount of braking force you can apply to the front. The last thing you want to happen is to lock up the front tires at a buck-fifty going through the traps. So it’s necessary to shift most of the braking force to the rear tires, so the slicks can slow the car down.

Strange incorporates these slots to give the rotor's metal somewhere to expand to when it gets super-heated after hauling down a drag car from 150+ MPH.

The brake kit we used was Strange Engineering’s 4-Piston Drag specific set up (PN B4110WC) for a 67 to 69 Camaros – perfect to use with the PA Racing spindles. The Strange kit uses one piece 11.25-inch slotted rotors made of forged steel. J.C. Cascio from Strange tells us, “Cast-iron is actually better from a wear standpoint, but the forged steel rotor can take the thermal shock of drag racing – going from cold to very hot, very quickly – much better. Cast iron is also very heavy, but that is where you start to see some of the tradeoffs in longevity versus weight.”  The Strange front brakes weigh just 17.5 pounds per side, helping us drop another nice chunk of weight.

Installing the Strange brake kit involved pulling the chomoly wheel studs into the hubs, packing the bearings, and bolting up the billet caliper brackets.

BlownZ’s Front Suspension
 
Spohn Front K-Member with A-Arms – PN 704-AKit
Spohn Pinto Manual Rack and Pinion – PN MR
Spohn Bump-Steer Kit – PN BS-4-MR
Afco Double Adjustable Coilover Shocks – PN 3870F-BNC
Afco Chrome 14″ Springs – PN 24275CR
PA Racing Drop Spindles – 2″ drop, for ’93-’02 F-bodies
Strange Engineering Front Drag Brakes– PN B4110WC
Mickey Thompson Pro-5 Drag Wheels– 15 x 3.5 Front: PN 5351547, 15 x 12 Rear: PN 5125547

No doubt you also noticed the fancy looking slots in the rotors, but they are designed to do more than just look cool. First, the removed material from the disc means less weight. Second, the slots wipe brake dust from the pads and keep the friction surface fresh. And finally, and most importantly, the slots give the rotors somewhere for the material to expand to when it gets super-heated after hauling BlownZ down at the top-end. “If you think of a cross-drilled rotor with a lot of circular holes drilled in it, you can’t really collapse a circle down.” says Casico. “That’s why you get a lot of heat cracks around the holes, because it is trying to crush those circles down. The slots will actually collapse down and will prevent the rotor from warping for a longer period of time.”

The pads we used are Strange’s soft organic compound, since they provide great bite in situations where they are still cold, like staging, but aren’t so aggressive that they will over power the tires when braking after a pass. “It is not a good idea to run a metallic pad on the front of a drag car because it would be too easy to lock up the skinny front tires.” says Cascio. “The metallic pads are a very aggressive, and we run them on the rear of any car going 150 MPH or faster. However, on a car trapping under 150 we recommend using soft all around.”

The calipers in Strange’s kit are forged aluminum, staggered 4-piston units, teamed up with billet aluminum brackets and hubs for a combination of low weight and high strength. As a testament to their effectiveness, these same Strange 4-piston calipers and rotors are the heart of the drag brake kits are standard equipment on the Cobra Jet and COPO Camaros.

Strange Front Drag Brakes Features and Benefits:

  • Forged steel rotors for improved thermal shock resistance and lower weight
  • Slots in rotors give material room to expand when heated quickly
  • Forged aluminum calipers with staggered 4-pistion design for improved pad wear
  • Billet aluminum hubs and brackets for low weight and high strength
  • More common kit for 67-69 Camaro means less cost than 4th Gen kit

 Mickey Thompson Pro-5  Wheels and Drag Tires

For rolling stock, we went with a set of Mickey Thompson's trick 1-piece forged Pro-5 drag wheels.

With the rest of our front suspension in place we knew it was time to get things rolling, literally. So, we called up our friends at Mickey Thompson and ordered a set of their new light weight Pro-5 drag wheels. For the front rolling stock we went with 15 x 3.5 Pro-5 front wheels (PN 5351547) and a set of M/T ET Front tires (PN 3006) with a small contact patch to minimize the rolling resistance and keep the weigh down to a minimum. In the rear of the car, where all our planning is directly aimed, we picked up a set of Pro-5 wheels in 15 x 12 (PN 5125547).

These wheels are as light as they need to be, and as strong as they have to be. -Carl Robinson, Mickey Thompson

To get the “skinny” on our bigs-n-littles we talked with Carl Robinson, the designer at M/T behind the Pro-5. “The Pro-5 drag wheels are a unique forged 1-piece design. We did a 1-piece wheel because it allows us to make it lighter and more robust on a molecular level.” says Robinson. “There are no intersect points, no welds, and no hardware – meaning that we can produce wheels with a much more true lateral and radial runout.”

Up front, the 15 x 3.5 Pro-5 wheels weigh just 7.5 pounds each. The rears feature both Double-D locks for drag radials and pre-drippled dimples for screws if you plan on using slicks.

On the rear wheels, M/T uses an integral, one-piece Double-D Lock for radials, but also has pre-drilled dimples on the back of the wheels if you plan to use wheel screws. Just one benefit of buying your drag wheels from M/T is that they know exactly where to put the screw dimples, since they are the ones who actually make the tires.

The wheels are 15.1 SFI certified, and when we asked Robinson about the weight versus strength dilemma in wheel manufacturing, he laughed and told us, “These wheels are as light as they need to be, and as strong as they have to be.” Sounds good to us.

Final Gear…

Getting all the power from our ProCharged 388ci LSX to the ground effectively at the starting line is a group effort. That effort starts with the front suspension setting everything in motion to get the weight to the rear tires, and getting them planted with just the right amount of force. We’re confident that we’ve put together a serious stock-based front suspension that will help us transfer weight the way we need to, maintain the proper geometry, and even drop more than a few pounds in the process.

Next time, we’ll move to the back of the car and examine the other half of BlownZ’s suspension equation. In the meantime, check out the other BlownZ tech articles here, and stay tuned!

Article Sources

About the author

Clifton Klaverweiden

Clifton has been a car fanatic since his late teens, when he started the restoration of his '67 Camaro. He considers himself a student of automotive science and technology, and particularly loves all things LSX. And, although he has an appreciation for everything, from imports to exotics, his true passion will always be for GM musclecars.
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