Our Hobby stock car awaits a make-over. This car was like many others in this stock chassi
When I learned that my friend, and bank president, for some thirty years needed help setting up his dirt hobby stock car, I jumped at the opportunity. This little project would allow me to apply the technology we preach here in CT to a car with limited adjustment capability. Once we got into the car, I was surprised by our discoveries.
Joe Epton, Jr. from my home town of Ormond Beach, FL, has been dirt racing for six years, starting in the Pure Stock four cylinder division. I have watched him race at Volusia Speedway Park and he is very smooth and calculating, just what I would have expected, but he is in no way slow. With a good car, he can run in the top five in a division that routinely fields 25 or more cars in each race, and has won heat races and features.
Joe is no stranger to stock car racing. His dad was NASCAR's first chief scorer and timer for years starting way back in 1946, and his mom, Juanita "Lightnin'" Epton, started working in the Daytona ticket office in 1958 and is still connected with the speedway.
Before we disassembled the car, we noted that the upper control arm mount had been lowered
His racing career began with racing karts early on, but he soon realized he did not have the financial support to go full-time racing. Later on in life, he decided it was time to just go racing like he had always wanted to do, and he is realizing his dream on the dirt at Volusia. How cool is that? His crew consists of Charley Kinsey as crew chief, Roger Rose, Ron Koch, a local motorsports editor, and Charley, Jr.
The problem with this new car that he had built late last season was that it would not turn well (imagine that), and as a result would push on entry and go loose on exit. There are probably more than a thousand teams in this country that have the same problem. So, I saw an opportunity to jump in there, do an evaluation and try to fix it.
I normally work with late-model teams, often on asphalt and sometimes on dirt. It is a known fact to a small group of individuals that I helped a lot of asphalt teams win races and championships. And as for dirt, back in 1998 I developed a particular different kind of setup that ended up winning both the Dream and the World 100 at Eldora, drawing the wrath of CJ Rayburn whose car was featured in those wins.
Kenny measures the spindle height with the car at ride height. We do this so we can positi
The late-model cars have a lot more leeway in the rules and more opportunity for adjustment in the design than this class. That makes this job more difficult for sure, but also more of a challenge, and I love a good challenge. We will be looking at major issues and finally setting the car up with what has worked for me historically in this class.
The car is a 1985 Monte Carlo and has the metric four-link rear suspension, a stock frame throughout and must use stock type springs in their original positions. Shocks must be mounted in the stock positions and the car must have all stock suspension parts. As in most "stock" classes, teams are allowed to trade stock pieces from other model year cars as long as the brand is the same. This class also runs large Hoosier racing tires all around, where as the street stock classes are only allowed one racing tire on the RF.
The first order of business was to weigh the car on the scales and measure and record the ride heights and the spindle heights for future reference. We wanted to maintain the original ride heights after installing new springs so the geometry would be the same, and we needed to know the spindle height so we could check for proper clearance and make sure there was no bind of the ball joints while the car was on jack stands.
We removed the upper ball joints to get the old springs out of the car. This also allowed
We proceeded to break the car down and remove the springs and shocks to see what we had. To get the front springs out, we had to remove the upper ball joints. This gave us a chance to inspect everything up close. My helper, Kenny Hellyer, was very familiar with the mechanics of these cars and was a definite asset in all of our re-design work.
The first problem we noticed was that the shocks on both sides in the front were rubbing on the inside of the height adjuster that was put into the car not to jack weight, but to create the ride height that was necessary to avoid bottoming out. The rear of the car had legal spring height/weight jacking adjusting bolts.
The shock contact was so bad, that one shock was leaking and both housings were bent severely. These were aftermarket twin tube shocks and still seemed to be working. I tried the standard method of checking them by placing one end on the floor and pushing in from the top. The shocks were so stiff that they barely moved.
Once we removed the shocks, we were surprised to see this damage. The car had height space
I don't know if someone chose really stiff compression numbers, or if the shocks might have been bent, but these units were not helping the situation. On dirt, we must have shocks that will allow the car to run over the holes and bumps and move fairly easily. They must control the springs, but not be so stiff as to cause the tire to skip or bounce.
I inspected the front geometry and noticed that the car builder had used the taller Impala spindles, which reduced the lower control arm angles. He also lowered the upper control arm mounts to gain more angle. Both of these changes are highly recommended for this class. Using taller spindles actually improves both upper and lower arm angles.
The geometry I saw looked a lot like previous cars I have fooled with in the stock classes, and I knew the moment center was close to where it needed to be, at or very near the centerline of the car. Had this work not been done, we could have expected the MC to be somewhere outside the car making the front end overly stiff.
By using Impala spindles, you can increase the upper ball joint height and create more upp
The cambers were not what I would have expected or chosen. The LF was a little less than 1 degree, and the RF was around 5 degrees. This is typical of a car that transfers a lot of load to the RF, as that tire is forced to carry most of the front load and work hard to turn the car. The LF doesn't need camber because it isn't working very hard. We needed to make camber changes to reflect how the front end would work after the re-design.
We reset the cambers to a positive (+) 2.0 on the LF and minus (-) 3.5 at the RF. Once we re-spring the car to allow a more balanced setup, the LF tire will definitely be working harder and take some of the load off of the RF tire. So, we needed more LF camber and less RF camber. Our tire contact patch will be optimal with these changes.Inspection of the caster settings revealed that the RF caster was in the negative range (upper ball joint forward of the lower ball joint) and the left side was positive. That would cause the steering to want to turn right, maybe good for sliding the car through the turns, but we were going to make this car turn well, so I opted for a different plan.
We moved the right upper ball joint back to create about 2 degrees of positive caster that matched the left side caster. This way, the steering would be neutral and the driver could steer both directions without feeling a difference in resistance.
The car had spring adjusters made by AllStar Performance installed in the front end on top
We were a little worried about possible binding of the ball joints with the increased upper control arm angles. So we cycled the spindles beyond what they would see on the track and found we had plenty of clearance. Always check to see if there is any binding or tightness in your suspension while you have the springs and shocks off the car.
Next, we checked out the spring rates that were installed in the car. The fronts were marked as: LF = 1100 lb./in. and the RF = 1200 lb./in. The front springs had a half round of the coil cut off, so the actual rate, although we did not measure them, was obviously higher than they were marked.
The rear springs were: LR = 225 and the RR = 150. The rear had too much spring split, even for a Metric 4-link rear suspension with a high roll center. With the front spring rates being so high, this combination in the rear caused a lot of load to transfer to the RF on entry and through the middle of the turns overloading that tire. That would definitely help cause a push.
We re-used these adjustable height spacers, and after re-setting them for our new spring h
After careful consideration, we installed the following springs: LF = 900, RF = 850, LR = 225, and RR = 175. The front reverse spring split with the softer RF spring helps corner entry and promotes front roll angle, while the reduced spring split in the rear facilitates the high metric moment center while not going too far to help control the rear roll.
Here is a further explanation of this. For a balanced setup, we need for each end of the car to desire to roll to about the same angle in the turns. We have discussed this concept for over four years now in Circle Track. A high moment center reduces the desire to roll, so if we don't soften the RR spring, the rear will be stiff and not allow compliance.
That would overwork the RR tire and cause a loose off, if not totally loose, condition. Running a RR spring that is too soft compared to the LR spring would have the opposite effect. The rear would want to roll over more so than the front and the car would be tight, or tight/loose off. There is an optimum spring split, RR softer, that will keep the car close to a balanced dynamic state and help the car on entry, through the middle and provide more bite off the corners.
The stock upper shock holes in the frame were positioned well outside of the center of the
Because the front shocks were hitting the spring height adjuster, we needed to make a correction. We noticed that the stock hole where the top of the shock was anchored was positioned at the factory well towards the outside edge of the inside of the spring on both sides of the car. With stock shocks and springs, this would be okay for clearance, but with our setup and equipment it was not.
The fix was to create a new "stock" hole farther inward and closer to the center of the spring. We reinforced this new hole by welding a washer on top of the frame. This provided a good bit of spacing between the spring spacer and the shock body.
To make sure we were good with the rules against using front weight jackers, we welded the height adjuster so it wouldn't turn. This made it a spacer rather than a weight jacking device. We also installed a new set of shocks provided by the team that were more inline with what should be used on this type of car.
I reviewed the existing tire sizes versus the tire pressures they had been running. The sizes were LF = 83.75, RF = 83.75, LR = 84.5 and RR = 85.0. This only allowed a 1/2-inch of stagger in the rear, not nearly enough for this track. This would also facilitate a tight car.
Once we had made all of our changes, we weighed the car, set the cross weight and lowered
The tire pressures were: LF = 17psi, RF = 23psi, LR = 15psi and RR = 14psi. The RF was high and the RR was low on pressures. The fix was to try to change the tires around while repressuring the tires so that we could get front and rear stagger.
I traded the RF tire and the LR tires. This put a larger tire at the RF and a smaller tire on the LR. We re-pressured the tires to: LF = 18psi, LR = 16psi, RF = 22psi and RR = 16psi. With those pressures, we now had a front stagger of 1.00 inch and a rear stagger of 1.50 inches.
When we weighed the car before making any changes, the cross weight was at 53 percent. After installing the new springs, changing the front cambers, moving tires around and adjusting tire pressures, we re-set the cross weight at 48.5 percent, or about 75 pounds of left rear weight.
With only 48.2 percent rear weight, the car did not need the 53 percent cross which represented 216 pounds of LR weight. This was yet another reason why this car was way too tight. It was cross weight tight and was driving off the LR tire under acceleration.
Note the placement of lead. I don't like lead placed this far behind the rear end. It caus
Another thing I noticed and corrected was the placement of lead in the rear of the car. The car builder had placed a considerable amount of lead well behind the rear end on the rear hoop that protects the fuel cell. Although fairly common, this tends to act with a cantilever effect and increases the polar moment. Polar moment is defined as a force trying to rotate or swing the rear end to the outside wall during cornering.
Some teams will experience a more neutral car by placing lead behind the rear end, but this is more likely a crutch for a tight car and although it helps the car into and through the turn, it will make the car loose off. It is much better to set up the car correctly and get the front to turn with a balanced spring setup and proper moment center and cambers. That way, you get into and through the turns better and still have more bite off.
It is always a good practice to keep all lead mounted inside the axles. We may decide later on to move it out, but for now we remounted the lead in front of the rear end and high in the car. A higher center of gravity is desirable on dirt cars for dry and slick tracks.
Our lead ended up mounted to a cross bar in front of the fuel cell and high up in the car.
Once we got the springs installed, the tires mounted, the cambers set, the air pressures set and the ride heights and weight distributed like we wanted, we stood back and took a look at the car. It just looked better right away. I've seen lots of hobby stocks, and this one looked like it was ready for the track.
We had to wait until after Speedweeks at VSP was over as the Hobby Stock division races were put on hold. The first chance we got to run the car, Joe noted that this car was now even better than his original Hobby Stock. The difference was that it turned better, which allowed him to maneuver past guys that were hanging it out trying to point the car to get off the corners. And it had much more forward bite than before due to the more straight ahead attitude.
With his smooth and relentless style, this car was just what he wanted. If you prefer to sling the car in sideways, fight to get control and then hope for some semblance of bite off, then you might not want to copy us. Good luck and good racing, now back to the Late Models.