Dirt Late Model Newsletter
SHOCK DYNO TESTING SERVICE
November 1, 2010 through January 31, 2021
Now that the racing season is over, this is the ideal time to start preparing for next season. Many of our customers send all their shocks in to be dynoed at this time of the year, so that they can be checked after a long season of racing. To urge all of our customers to check the condition of their shocks before next season, we are reducing the cost for shock dyno service on any A.R.S. shock to $5 per shock until January 31, 2021. This reduced shock dyno offer will give you a chance to evaluate the condition of your shocks after a season of racing and at the same time review any new valving combinations. When sending your shocks to us for service, please enclose a note with return address, phone number, and a brief description of what you would like done to your shocks. A shock maintenance form is available from our website. After shocks are dynoed, we can call you with the results and discuss the outcome of your shocks or any new shock combinations. Many customers send all their shocks to us during this special dyno offer, so send your shocks in as early as possible to avoid any delays in preparing for next season.
The 4” top (extended load) spring on the left rear preloader has been changed to a 4” x 050 lbs. spring. Softening this spring has created more traction on corner exit. The original stiffer top spring would break traction on slick conditions. The 4” x 50 lbs. (#3204×050) spring will allow the extended load to be between 50 lbs. and 150 lbs. The 20” x 50 lbs. spring on the preloader has not changed just the extended load spring.
Right front bump spring
The double bump spring has been a big gain this year. This combination allows you to compress the right front and make it turn but not bottom out the cross member. The driver will have a lot more confidence in driving the chassis harder if the rate in the right front spring package limits the travel instead of hitting the cross member and skating up the track.
Right rear double spring combination
The double right rear spring combination is nothing new, but a lot of racers don’t know how good it works on a dry slick track. The less right rear load and the harder the compound tire the better it works. When the right rear radius rods drive the frame up it unloads the right rear spring. Which in turn dramatically reduces the load on the right rear tire. This is good for heavy tracks but kills the side bite and forward traction on dry slick tracks. The lighter secondary spring keeps loaded when the main spring becomes unloaded. Now that front suspensions don’t raise up like the chassis of the past right rear grip is more important than ever.
There are a couple of things that need to be addressed in the left front shock dampening. The rebound holds cross weight in the chassis which creates forward bite. Too much rebound pulls the tire off the ground and makes the chassis push mid-corner to exit. The rebound dampening requirements change on a short tight corner track versus a fast sweeping corner track.
The compression on the left front is adjusted for corner entry. If the chassis is tight on corner entry, you need to soften the compression. When the track dries out and your chassis gets free on entry you stiffen the compression. After we dyno your shock, we will send you dyno sheets showing your complete adjustment range. We will mark your dyno sheets showing you how you need to adjust your shocks to accommodate changing track conditions.
The right front is possibly the most important shock on the car. The rebound dampening in this shock controls the chassis attitude throughout the corner. Too much rebound hurts forward bite, and too little rebound unloads this corner creating a push condition. It is important to have enough low speed rebound to hold attitude but not too much high speed that it makes this corner too rigid.
The low speed compression needs to be soft enough to allow the chassis to get down on corner entry and enough high speed to keep the chassis from slamming the bump stop on corner entry. We have built special pistons just for the right front shock to accomplish these requirements.
This corner is very critical on shock and body lengths for different chassis builders. The right front shock body needs to hit the bump stop at the right time and rate. We can set the bump stop and spring load for you with our spring smasher while we are servicing your shocks.
The right rear shocks have a new valve curve (T/C) that creates more traction than ever before but still creates enough high speed control to run the cushion. This has always been the challenge to provide both of these requirements. The rebound range allows you to soften the rebound enough for heavy track conditions, and then stiffen the rebound for maximum traction. We lock in the compression dampening and adjust the gas pressure for heavy to dry/slick tracks. After we dyno your right rear shock we will send you dyno sheets showing your complete adjustment range. We adjust this shock more than any shock on the car to accommodate changing track conditions.
We now change the right rear spring load more than ever. The standard is a 225 spring with spring rubbers or many customers prefer the double spring (inner & outer) combination for dry slick conditions. Whatever your spring combination is you need to stay on top of your load numbers as track conditions change throughout the night to create the correct balance.
The left rear (behind) shock and spring combination has become more critical than ever before with the requirements on this corner of the race car. It is necessary to have a soft ride height rate so the chassis sets down to get the spoiler thru tech. Then have the correct extended rate to provide maximum traction. We can create this spring combination with the spring pre-loader. Every chassis manufacturer has different heights and load requirements. We can create a good combination for you regardless of the brand of chassis that you are racing.
The left rear(front) or (top) shock provide enough extended rate to hold the left rear up and make sure the left rear corner does not fall down and let the chassis lose the rear steer. A fine balance of compression dampening and gas pressure provides this combination. This shock’s main function is to hold the left rear corner up under deceleration or part throttle conditions. It does not provide traction except to keep the left rear bars in the correct angle which creates traction. This shock is very critical in making sure you have the correct combination to develop maximum traction. Some racers remove this shock on dry slick conditions but you must have enough L.R. back extended rate to make this work.
The secret to this unit is to have a stiff rate for instant traction but create enough travel (3-1/2”to 4”) to make the torque arm pick up the chassis and plant the tires in the track. If you have less than 3” of travel, your chassis will not have maximum traction. We create this combination with the P/D fifth coil assembly. The 1st inch of travel is the stiffest rate with the 2nd and 3rd inch of travel getting softer for maximum travel. We have been running this unit for years, but it is high maintenance and if it is not clean it will not work. We have just built new sliding floaters that are more dirt and dust friendly. When this unit is set correctly and it moves freely there is nothing better for the 5th coil. We can update all old units with these new floaters and make this unit much more reliable.
All chassis builders are making the frames stiffer and out of better tubing to make cars more repeatable throughout the season. This makes the shock dampening and spring rates (load rates) even more critical.