From time to time we like to consult with the experts in the field of stock car racing as to their opinions and expertise on subjects of interest. This month, we talked with top shock technical experts and offered some questions and solicited their opinions. Our panel of five shock experts and the companies they support are in alphabetical order: Afco Shocks, Bob McDowell; Integra Shocks, Brian Dougherty; Ohlins Shocks, Christer Loow; Pro Shocks, Jeff Sandt; and QA1 Shocks, Corey Flynn.
1. Overall, we see the average racer becoming more and more educated as to how his/her chassis works in all areas. Share some examples of this that you have seen.
* Afco - Racing schools like RaceWise have been touring the U.S. giving racers a first-hand look into how the mechanics of their chassis actually work. Subjects cover everything from weight distribution and transfer to shock selection. Personal consults are available to help teams properly set up and tune their chassis.
* Integra - The biggest difference we have noticed is the type of questions that are being asked. Instead of just asking "what happens if I add rebound to my left rear shock," racers now ask more detailed questions regarding the interaction between different chassis adjustments. For example: A racer will ask "if I increase my left rear shock rebound to tone my hike down, does that permit me to raise my left bottom four-link rod on the chassis in order to turn on the gas better?"
* Ohlins - When the racer has started adjusting the shocks and noticing the effect it has on the performance at the track, he or she will start working with the adjusters and learning how to adjust them to achieve, for example, more bite or corner-entry speed.
* Pro - No, for the most part they aren't better educated. A few have become better educated but, the vast majority aren't.
* QA1 - On the dirt, I've definitely seen racers make more consistent, educated adjustments to their chassis to compensate for track changes. If the track moves from tacky to dry and then to rubbered up, racers understand what and when to change on the chassis to stay up front. Understanding how the bar angles, tire stagger, and caster and camber changes will effect their chassis is very important, and racers have taken the time to figure it out.
On the asphalt, I've seen racers take the time to plot out their roll center, perform and understand caster and camber curves, and take the time to understand how the chassis will react at its dynamic stages.
2. What are the current trends in racing shock design related to both dirt racing and asphalt racing?
* Afco - We see a two-fold trend, some teams want to have more adjustments in their shock program, while other teams like the ability to bolt on shock packages without the adjustability.
* Integra - Over the past several years, nearly all of the top touring teams have upgraded their shock packages from the "twin-tube" design to the more consistent "mono-tube" design. We have found that most drivers prefer the "feel" they have when running the twin-tube, but need the consistency and reliability that a mono-tube offers. This being said, a base valve is often incorporated into the design of the mono-tube shock which allows for higher compression values without additional gas charge. Because of the many variations in track configurations and surfaces, teams also have stressed the need for shocks that provide a wide range of adjustment on compression and rebound.
* Ohlins - The trend is that the racers are putting higher demand on the performance of the shocks. One way of achieving higher performance is by avoiding the use of a restrictive small-diameter hose to the canister, which hurts the performance of the shock.
* Pro - Currently the only trend relating to both dirt and asphalt is the use of adjustable shocks, both single- and double-adjustable.
* QA1 - On-the-car adjustability is one trend that has really taken off over the past couple of seasons. Having a wide range of rebound adjustment in certain corners is a quick way to help correct an ill-handling race car. Base valve technology is a trend of which we're also happy to be a flagship member. Recently launching a steel rebuildable and revalvable base valve, monotube brings high-dollar technology to a racer on a tight budget. Our trend of racer rebuildable and revalvable is becoming very popular with the tight state of the economy. This feature allows the racer to have less shocks in the trailer but be able to build any valving combination he or she wants.
3. With the trend toward having more adjustment in shocks, have the racers become comfortable with that technology so that they can properly use what is offered?
* Afco - Many teams have taken an active roll in our training sessions and shock schools to enhance their abilities to maximize shocks performance.
* Integra - Although some teams work on their own shocks at the track and in the shop, most still need some guidance as to when and why to make adjustments. At Integra, we not only offer track-side assistance, but individual team training courses are available at our facility in Muskegon, Michigan.
More and more, teams are realizing that there are significant gains that can be obtained from the adjusting and revalving of their shock packages. Integra's goal is to offer teams the most technologically advanced shock, packaged in the most user friendly design. We feel the easier a shock is to understand and adjust, the more likely a team will make the correct adjustments
* Ohlins - Most racers are doing fine adjusting the shocks. Customers who have a shock dyno are keeping up with their shocks. For the customers that do not have one, Ohlins provides very simple setting recommendation sheets to help them. A damper with two efficient, easy-to-understand adjusters is better than four that are less efficient. Three or four adjusters can sometimes add confusion in the setup work.
* Pro - Probably less than 5 percent of the racers are utilizing the dampeners to their fullest advantage.
* QA1 - Racers are really starting to understand how the shock adjustment affects the chassis at a dynamic level. Being able to "tie" the car down in certain corners of the race car allows the racer to get in and off the corner smoother and harder than ever before. The teams that keep good detailed notes of their adjustments are the ones I've seen have a lot of success and fully utilize the technology on a consistent basis.
4. One top Dirt Late Model car builder seems to think the most gains today can be made in proper shock selection from what he has seen. In dirt racing, especially top touring Late Model divisions, do the top teams seem more interested in the high-end shocks than in the past?
* Afco - Yes, Dirt Late Model shock technology has evolved tremendously over the last 5 years. Most top tour teams have shock dynos in their facility or onboard their race haulers, enabling them to fine tune their racing program from track to track.
* Integra - Definitely, we are constantly testing and developing new designs and valve codes to keep up with the demand for better shock absorbers. At Integra, we hold closed test sessions with our top teams two to three times per month during the season.
* Ohlins - Now teams are starting to see that with high-end-adjustable shocks, such as the new Ohlins LMP, they don't have to carry around as many shocks. The shock technology of today is also changing the amount of work teams have to do at the track, by changing the shocks less.
* Pro - Yes, today they would not consider using non-adjustable shocks, but with that being said, the majority of the teams are not utilizing the adjustable shocks to their advantage.
* QA1 - Top touring teams are always going to be after the newest high-end component for racing. In the shock world, I've seen top teams looking for consistent shocks that are non-fading, rebuildable, and revalvable. Being able to offer these teams a product that is race-ready right off the shelf is one aspect that has made our company so successful. Top teams can't afford to be inconsistent, and being able to offer a full product line of shocks, which are 100 percent dyno tested, is a way to ensure their success.
5. With new setups such as the Big Bar and Soft Spring setups now used on asphalt and the more flat-running attitude of the Dirt LMs, have adjustable shocks helped the teams to better tune these setups? Can the shocks of today compliment the popular softer spring setups in both dirt and asphalt?
* Afco - Yes, adjustable shocks can be very convenient in helping a race team dial in its race car but, to achieve ultimate performance, fine tuning of the shim stacks and shock resistance curves is essential.
Yes, it's a particular area we have focused a lot of design time, engineering, and testing.
* Integra - Since there is less spring force to control the motion of the body, the shocks are supplying more force to control this motion. Having adjustability in the shock definitely allows teams to better tune the chassis with these softer spring setups.
* Ohlins - The shocks are playing a big part in the new setups. Today's shocks are giving the mechanical grip that was missing before. Therefore, you don't see the setups that required high wedge and lots of bar angle to get traction.
* Pro - Yes, we have seen an increase in their usage basically for controlling the body and chassis attitude.
* QA1 - As race teams get more and more aggressive with their setup packages, certain shocks can completely compliment them. Having shocks that are revalveable is a huge advantage when working with the popular soft setups of today. These shocks allow you to valve independently, allowing the shocks to not only compliment your spring selection but also your chassis setup.
6. Can shocks be mismatched for a particular type of racing?
* Afco - For maximum performance, the shock type and the resistance curves of the shocks need to compliment the type of race car and the prevailing racing conditions.
* Integra - In general, the vehicle balance is better if all corners utilize the same style of damper. We do have circumstances, such as on an IMCA modified, where we will use a mono-tube shock on the left rear with twin-tube shocks on the remaining corners of the vehicle for additional traction.
* Ohlins - Ohlins' recommendation is that you should stick with one style of damper. Shocks are usually built as a set, so they all work off of each other.
* Pro - They can be, but probably shouldn't be.
* QA1 - Yes! We offer both monotube and twin-tube design shocks. For example, in the very popular Modified and Late Model divisions throughout the U.S., we find a lot of teams mixing and matching these shocks to hit the right setup for the track condition. It's very common to find racers running twin-tubes on the RF, LF, and RR and running a "Traction" mono-tube on the LR.
On the asphalt, you may find a straight twin-tube or mono-tube on the RR and a rebound adjustable shock on the LF and RF to help the car get through the center of the corner and LR rebound adjustable to help the car off the corner. The best thing to do when you're going to mix and match shock styles is to contact the manufacturer about possible suggestions it may have.
7. In both dirt and asphalt racing, the shock can experience extreme limits of travel and force. Which corner for each type of racing gets the most abuse and why?
* Afco - The left rear shock on many hiked-up dirt cars will get a lot of shaft travel as well as high shaft velocities which can harm the shock over time. The right front shock on many dirt cars tends to see a lot of compression travel which can bottom and possibly damage the shock.
The left front shocks on asphalt cars that use the popular Big Bar Soft Spring setup can operate at high temperatures which can cause problems.
* Integra - In Dirt Late Model racing, the right front is without question the shock that gets the most abuse. With the soft right front spring setups being used on today's Dirt Late Models, it's not out of the ordinary for the right front to be bottomed out many times during each race.
On pavement Late Model cars, the front shocks take the most abuse because of the high amounts of rebound being used along with the softer springs when running a bigger sway bar.
* Ohlins - In dirt, I would say the RF, because the cars are so dependent on that to keep the car turning.
* Pro - On asphalt cars, the left front seems to be the most abused shock basically because of the dampening rates used. On the dirt cars, it seems to be the right rear shocks that take the most abuse because of the amount of load on that corner.
* QA1 - For dirt racing we see a lot of abuse on the RF and the LR corners of the car. Usually, this is caused by the large amount of bar angle placed in the LR chassis setup causing a large amount of weight transfer to the RF. While the LR shocks, in this case, are being topped out, the RF is being bottomed out.
On the asphalt, we see both the LF and RF shocks taking a lot of abuse due to the extremely soft springs that are becoming commonplace in this form of racing.
Taking this data, we have developed many new lengths to give the maximum amount of travel your chassis will allow. It's always a good idea to check the amount of travel needed for your chassis and make sure your shocks are not limiting your travel.
8. What maintenance schedule should a team be on in order to help eliminate failures? If it's different for different classes please explain how.
* Afco - Remove shocks weekly, then clean and visually inspect them. Make sure to inspect the shock for bent eyelets, bound up bearings, and interference between shock adjuster knobs and shock mounts. Routine checks for bent shock shafts are another way a team can avoid poor performance.
* Integra - Much like you change the oil, seals, rings, and bearings in a race engine, a shock needs freshening as well. Heat and contamination will break down the seals, bushings, and fluid. Over time, the shims in the shock fatigue from repeated use. To ensure that the shock functions properly when needed, the shock should be rebuilt after every 25-30 races, or after every season.
This is a good rule of thumb for most classes. For those applications where the shock is continually exposed to elevated temperatures or the shock is built with extremely high damping forces, the number of races between freshening the shock should be reduced.
* Ohlins - If a team runs 40-or-so races a year, Ohlins recommends having the shocks serviced at least two to three times per season. If they are running in extremely rough conditions, then have them serviced at least once more.
* Pro - Shocks are much like other components, the better they are maintained the less chance there is of a failure. A shock should be sent in for service at least once a year. We advise to do it every 600-800 laps with our adjustable shocks.
* QA1 - A good maintenance schedule will always benefit you, no matter how good the shock is. I like to check my shocks over after every night of racing. Always make sure they're in the proper working condition and nothing has damaged the shock, limiting its capabilities. One of the nicest features of a racer rebuildable shock is that it's racer serviceable too. Being able to keep fresh oil in the shocks, along with checking the gas pressure, will ensure you're also going to the track with a consistent setup. We feel racing is racing, no matter if you're a top Late Model team or racing in the hobby division at your local track. That's why we offer a complete line of racer rebuildable, revalveable shocks.
9. What typically causes premature failure of a racing shock? I.e., improper mounting (soft springs?), spring contact with shock, crashes, dirt, heat, binding, and so on.
* Afco - All of what you mentioned are common problems that good weekly maintenance can eliminate. It's a good idea to have your shocks dyno'ed after racing on a really rough racetrack.
* Integra - There are many causes of shock failure. One of the biggest causes of failure to a race shock is improper mounting. This can induce a side-load/bending moment into the shock causing premature seal wear, and ultimately can fatigue the shock shaft to a point of failure.
Another failure occurs when the shock is located in a high-temperature environment. The temperature will break down the seal material causing the seal to fail. High temperatures also break down the oil, reducing the lubricity properties, causing premature wear of seals and other internal components.
* Ohlins - The Ohlins dampers have fairly low maintenance needs and will be reliable with only minimal care such as, cleaning the Heim ends, wiping the shaft clean, brushing dirt and debris from the body, and changing the oil regularly.
* Pro - The accumulated heat on full-body cars, especially asphalt cars, is one of a number of things that causes shock failure.
* QA1 - There are hundreds of things that can cause your shocks to fail. I think one of the keys to having a great shock program is in your shop preparation. Take the time to run the shocks through their travel, making sure you have clearance from the frame, springs, and other objects. After the race, try to keep good notes of the shocks' heat and reference the manufacturer for ideal temps. Unfortunately, crashes, dirt, and rubber obstructing the shocks performance is a part of the game, but making sure they're in perfect working condition in the shop will help you avoid any failures.
10. Is there a preferred mounting height for shocks (piston position in the tube) in relation to the amount and direction of travel each shock will experience?
* Afco - In most cases, shock mounting positions are not adjustable. However, it's best to check that you are not bottoming or topping out your shocks for no apparent reasons.
* Integra - A shock is a velocity dependent device. For the most part, it doesn't matter what position it's mounted in. Generally, the shock should be mounted to minimize the number of times it sees full compression and full rebound. In a few cases, however, the shock may be located to act as a limiter in either rebound or compression.
* Ohlins - The Ohlins shocks are designed for good performance throughout the stroke, so the important thing is just to make sure to avoid bottoming or topping out.
* Pro - Yes, but the chassis builders seem to have this under control for each application.
* QA1 - When mounting a shock, I like to check and double-check my stroke length and clearance before leaving the shop. Unfortunately, there isn't a magic number of where one should properly mount his/her shocks. Chassis are different, mounting locations are different, and so on. You want to make sure you're going to have an adequate amount of both compression and rebound stroke for each given corner on of the car. If you're mounting a shock on the left rear of a modified, you'll need to mount the shock to allow for a lot of extension. This extension length can be found by using the travel indicators on the shock's piston rod and also using your knowledge of your chassis. This mounting will change from three-link, four-link, or Z-link styles, so giving a hard number is virtually impossible.
Now, if you're mounting shocks on the front of an Asphalt Late Model, you'll want to make sure you have enough compression stroke to allow the shock to fully compress with out bottoming out.
In both cases, you want to make sure you're fully utilizing the full range of your shock's stroke. You never want to use a shock as a limiter for your chassis. Another thing to keep in mind is shock manufacturers will use different length bodies, which will also affect your mounting height. For example, even though you might be using all 7-inch or 9-inch stroke shocks, you'll need to check the compressed and extended lengths, as they will be different from manufacturer to manufacturer.
We can see where some of the comments differ and many are along the same thought process. It surprised me to learn that some think a small percent of racers are better educated today while some think many are not. I guess it depends on the demographics each expert deals with. All of the comments are informative.
If you have any shock questions about either what you need in a shock package or how to better utilize your existing package, contact your manufacturer's tech consultant and ask questions. That's the only way to learn.