Originally Posted by
RRR_Products
First off what does a pull bar/torque link do? You have to ask yourself that and keep it simple. We have spring bars out and also urethane biscuits. Now as for what works the best it will depend on how you drive, motor, and tire. Due to the many different sanctions and rules out the classes are very different. In UMP there are cars with over 700hp and soft tire while IMCA there are cars with 400hp and hard tire yet companies advertise there dry slick or tacky track set up which doesn't give you any info for which tire or motor. Truth is there is a huge difference on what you should use. We're simply trying to absorb energy to the rear tires to keep them hooked up and not shock them to break loose. If you're going urethane I would suggest a minimum of 4" stack at a maximum of 1" tall each biscuit. The reason is the life of the biscuit lasts longer. Any and all urethanes should never be compressed more than 33%. 25% or less should be what you shoot for because the biscuits will last longer. As for the larger biscuits that are taller than 1" those that have owned these will say they split. The urethane is traveling so far that it expands outward which causes premature failure and cracking. Also separate your urethane with a washer for every biscuit. There are 5 different types of urethane pucks out right now that are the most popular. The style and height changes how the rates comes in. They are all progressive. Roller skate wheel, cylinders/rod type, cone shaped, 2.25-2.5" tall and bulky, and the taller ones 4" at least I've tested by a certain company that split after 1-2 nights due to the tall height. Then you have coil spring bars. Linear and progressive. Always use a high quality spring for these bars. Spring bars are typically 4lbs heavier at least over a urethane bar. Some like to use a shock for spring bars and some don't but the difference from a urethane bar to a spring bar is the rebound. Spring bars rebound a lot harder than urethane bars. They may store the same energy but releasing that energy they're very much different. The last bar is the spring and urethane bar. These bars typically use a linear spring and then you can adjust when it gets into the urethane biscuit. The biscuit we tested used a 70A durometer puck. The 70 is the most forgiving and getting the timing of the puck is a lot wider window to try and get the sweet spot. The harder the biscuit the smaller the window gets for this adjustment. Too soon on a dry track and you may haze the tires. That sums up most of what I've personally tested and have had drivers feedback to me. If you're wanting a pull bar don't go off of mass marketing which has sold many products. Go with what lasts the longest, easy to maintain, easy to adjust, and in my point of view is engineered the best. But in the end were simply absorbing energy to the rear end.