![\"Blaine](\"http:\/\/performancetrends.com\/images\/Customer%20Stuff\/Blaine%20Launching%20w%20PTI%20Decal.jpg\" "\\"Blaine")
<\/a>On his next outing, Blaine almost jumped to the other lane when he got on the brakes at the end of the pass.\u00a0 Something had really changed in the suspension.\u00a0 Luckily Blaine\u2019s engineering mind brought him to our Suspension Analyzer<\/a> as the proper tool to solve this problem.<\/p>\n The first step was to see what the problem was.\u00a0 Was it some severe caster change from before, a bump steer problem, camber change, etc?\u00a0 Blaine made the measurements of his McPherson strut suspension and modeled its motion in the Suspension Analyzer.\u00a0 What popped up as a problem was the severe bump steer, or that the tire\u2019s toe in changes dramatically as the suspension goes through dive and rebound.\u00a0 This would have caused the steering instability as Blaine went from accelerating (rebound or spring extension) to braking (dive or spring compression).\u00a0 See Figure 2 for visual of what Blaine’s bump steer looked like.\u00a0 It shows the tires severely toeing out with 3\u201d of front end dive.<\/p>\n <\/p>\n Because Blaine has the Drag Race Datamite<\/a> v4.1 and the new DataMite<\/a> 4 data logger with shock travel sensors, he knows exactly how much spring travel he\u2019s getting when this happens.\u00a0 The graph of a typical run with the shock sensors show shock travel going from 2\u201d of rebound to 0.4\u201d of dive.\u00a0 See Figure 3 of DataMite 4 shock travel data.<\/p>\n <\/p>\n When Blaine saw this, he confirmed it by checking toe on the actual car as he jacked it up and watched the tires toe out significantly.\u00a0 Now, how to fix it?<\/p>\n This is where the real advantage of using the Suspension Analyzer comes in.\u00a0 You can try many different modifications manually and instantly see how the Toe Gain changes.\u00a0 (Toe Gain is the amount of toe change you get from a standard 1\u201d of dive, where Bump Steer is the amount Toe changes for most any amount of suspension travel.)\u00a0 Anything which reduces Toe Gain will also reduce Bump Steer.\u00a0 Modifications which typically affect Bump Steer are relocating either end of the tie rods, either on the spindle or the rack.\u00a0 So Blaine tried moving the rack around and moving the tie rod attachments on the spindle.<\/p>\n There is also an automatic Optimize feature in the Suspension Analyzer which lets the program try hundreds of combinations of modifications to check for some improvement you are looking for.\u00a0 Figure 4 shows what the Optimize feature came up with for a better rack location.\u00a0 Blaine could easily move the rack back about 1.5\u201d, so that was what was done with the rack.\u00a0 The same can be done in Optimize by moving the left or right Tie Rod Ends to find better (lower) bump steer.<\/p>\n <\/p>\n Figure 5 shows where you can see Toe Gain.\u00a0 This number instantly changes as you relocate any suspension mounting point.\u00a0 It shows on the right how Toe Gain has been reduced considerably when the Tie Rod mount on the Spindle is raised.\u00a0 Compared to the left at the original position, it is about 4 times better (smaller).<\/p>\n Not all modifications the program would suggest were easily obtainable.\u00a0 What Blaine came up with is moving the rack back about 1.5\u201d and raising the tie rod on the spindle by about 2\u201d. \u00a0 (Figures 6 and 7.)\u00a0 This dramatically improved the bump steer, as shown by the graph of Toe In vs Dive for the 2 conditions, Baseline and Fixed.\u00a0 See Figure 8.<\/p>\n <\/p>\n<\/a><\/a><\/a><\/a><\/a><\/a>