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| Bump Steer and Ackerman https://setup.teamxray.com/xsetup/legacy/viewtopic.php?f=8&t=13483 |
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| Author: | Nathan Wilson [ Mon Apr 22, 2013 17:39:48 ] |
| Post subject: | Bump Steer and Ackerman |
Can somebody please clear something up please. please correct anything that is wrong. i think i understand that the straighter your steering links are the more ackerman affect you have (Dynamic toe out). So on a T4 the less bump steer shims and the less ackerman shims you have the more ackerman effect you get as the arms are straighter. The T3 set up book states that for low grip you would want more ackerman effect and for high grip less ackerman effect. So to get more steering in general would you go for more ackerman (More dynamic toe out) or less ackerman (more parallel steering) Thanks |
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| Author: | DaleBurr [ Mon Apr 22, 2013 18:12:08 ] |
| Post subject: | Re: Bump Steer and Ackerman |
Okay, so there are two adjustments there; they are separate, and do different things. Ackerman is caused by steering lock, and is the difference in angle between the inside and outside wheel. Even sat on the bench, when you turn the steering the car has ackerman. On the T4 adding spacers to the bellcrank reduces ackerman. This gives less turn-in, but more steering through the corner, and generally feels more aggressive. Bump-steer is generally undesirable as it makes the car unstable over bumps. However by adding bump-steer we also get roll-steer, which can be desirable as it increases steering through the corner. The harder you drive the car, the more steering you get. On the T4 adding spacers between the steering link and the hub increases roll-steer (or bump-steer if you prefer). This gives more steering, especially mid-corner where maximum roll is achieved. So in low-grip conditions if you're short of rear grip, you could remove bump-steer spacers, as this will reduce the steering and make the car easier to drive. The T4 seems to work well with 2mm bumpsteer spacing in all the conditions I've ran it so far outdoors, from low to medium grip. What you do with the ackerman depends on the balance through the corner. But I've only ever seen between 0mm and 1mm of ackerman spacing on the T4, which isn't going to make a night-and-day difference, so I'd leave it at 1mm and look at other settings if you're short of grip. |
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