Tony Posted November 15, 2007 Report Share Posted November 15, 2007 As we know the rule for Ackerman is a negative gain accentuated on the inner wheel. Theory> Well for certain motorsports a positive Ackerman gain would be beneficial....... Sports like Drifting are a prime example and gain an advantage if the outer wheel had an accentuated Ackerman during weight transition, F1 tested the theory some years ago and now use a positive Ackerman So i have a theory ..... Since the accentuation is the disparity born from the steering pivotal points, normally agitated by the track rod-end then simply reversing the position of the end would reverse which wheel is accentuated.... Stay with me on this..... If the rotational pivotal axis is reversed by fitting the track rod end nose down rather than nose up then the curvature pivotal displacement will be positive? But we have a problem...... By moving the location the radius of the wishbone and the steering arm are no longer uniform.... As the suspension compresses the steering arm (now disproportionate) to the axis will "bump steer". It is feasible to re-locate the steering rack to belay bump steer but this would destroy my easy option to modify Ackerman the cheap way Since this is only a theory any advice would be welcomed Quote Link to comment Share on other sites More sharing options...
Mat Posted November 16, 2007 Report Share Posted November 16, 2007 you know you have always got a test bed to work on. ...all sounds very good, lets hope your able to put your theory into some form of practice Quote Link to comment Share on other sites More sharing options...
Tony Posted November 16, 2007 Author Report Share Posted November 16, 2007 you know you have always got a test bed to work on. ...all sounds very good, lets hope your able to put your theory into some form of practice Cheers mat, i was going to ask if you were up to some research...... I think a positive Ackerman would be a valuable tool for drift during weight transfer. Quote Link to comment Share on other sites More sharing options...
Fundamental Posted December 4, 2007 Report Share Posted December 4, 2007 could you explain a bit more Tony, i just want to make sure i am getting it right .. Main benifit during weight transfer would be NOT to have a bump steer, and during rapid transfer have more grip, basically keeping car more in control in rapid and often transfers, as drift is not Formula 1 driving theory with as smooth as possible lines having transfering weight smoothly. If i got it wrong please correct me, just need to understand! Quote Link to comment Share on other sites More sharing options...
Tony Posted December 4, 2007 Author Report Share Posted December 4, 2007 could you explain a bit more Tony, i just want to make sure i am getting it right .. Main benifit during weight transfer would be NOT to have a bump steer, and during rapid transfer have more grip, basically keeping car more in control in rapid and often transfers, as drift is not Formula 1 driving theory with as smooth as possible lines having transfering weight smoothly. If i got it wrong please correct me, just need to understand! Bump steer issues should have been dealt with way before this suggestion. Objective is to have the transient weight on the outer wheel allowing more control during the continuation of the drift. Most drivers complain the steering reaction is numb between transitions.. If the dominant wheel is also the one holding the Acherman at the point of transfer then the steering reaction will be incredibly reactive. Rotational/polar centres and indeed Geometric positions could become much less complicated if the dependence on extreme Geometry angles can be relaxed..... And save the tyres! You are correct that the F1 chassis requires a smooth transition but F1 and Drift are very detached.... Nevertheless the technology can be manipulated Quote Link to comment Share on other sites More sharing options...
Fundamental Posted December 5, 2007 Report Share Posted December 5, 2007 I gave a good thought about all this,correct me if im wrong. As i understand, we move track rod end more towards the center of the wheel as with this gaining positive Ackerman, but steering rack assy would be an issue as it will be under strain, and at the same time if we reloctae steering rack for a bit, then we are were we begun roughly? I hope i didnt get it wrong. And then i wonder what if we try to put HICAS kind of connection in the rod end, wouldnt that theoritically do the job? But the problem again is, that it is a verry sensitive joint against dirt and dust. Quote Link to comment Share on other sites More sharing options...
Tony Posted December 6, 2007 Author Report Share Posted December 6, 2007 I gave a good thought about all this,correct me if im wrong. As i understand, we move track rod end more towards the center of the wheel as with this gaining positive Ackerman, but steering rack assy would be an issue as it will be under strain, and at the same time if we reloctae steering rack for a bit, then we are were we begun roughly? I hope i didnt get it wrong. And then i wonder what if we try to put HICAS kind of connection in the rod end, wouldnt that theoritically do the job? But the problem again is, that it is a verry sensitive joint against dirt and dust. What is the HICAS connection rod? Quote Link to comment Share on other sites More sharing options...
Mat Posted December 6, 2007 Report Share Posted December 6, 2007 HICAS is the rear wheel steer componenets on some of the bigger nissan's Quote Link to comment Share on other sites More sharing options...
Fundamental Posted December 7, 2007 Report Share Posted December 7, 2007 Yes you are correct i didnt quite express myself right, hicas would not be the correct name in this case ! The joint i mean looks something like this at the end of the rod, not just a ball joint like it is, but a joint like pillowball joint to reduce slop.. Something like this http://www.speedstar.ca/product%20photos/J...2000%20(46).jpg Quote Link to comment Share on other sites More sharing options...
Sam@TDi Posted December 7, 2007 Report Share Posted December 7, 2007 Way ahead of you Quote Link to comment Share on other sites More sharing options...
Fundamental Posted December 7, 2007 Report Share Posted December 7, 2007 Way ahead of you Chasing up and following in your footsteps Quote Link to comment Share on other sites More sharing options...
Tony Posted December 7, 2007 Author Report Share Posted December 7, 2007 Way ahead of you Care to share Quote Link to comment Share on other sites More sharing options...
Fundamental Posted December 7, 2007 Report Share Posted December 7, 2007 http://www.wheels-inmotion.co.uk/forum/ind...p?showtopic=949 I think this is what Sam meant Quote Link to comment Share on other sites More sharing options...
Tony Posted December 7, 2007 Author Report Share Posted December 7, 2007 <a href="http://www.wheels-inmotion.co.uk/forum/ind...p?showtopic=949" target="_blank">http://www.wheels-inmotion.co.uk/forum/ind...p?showtopic=949</a> I think this is what Sam meant Odd...... That link doesn't work?..... can you copy/past again please. Quote Link to comment Share on other sites More sharing options...
Fundamental Posted December 7, 2007 Report Share Posted December 7, 2007 http://www.wheels-inmotion.co.uk/forum/ind...p?showtopic=949 Quote Link to comment Share on other sites More sharing options...
Tony Posted December 7, 2007 Author Report Share Posted December 7, 2007 This is more relevant to controlling bump-steer though?.... For TOOT we need a for/aft design..... In the old days i used to simply bend the inner steering arm for the rods that raced the ovals.... This gave a great TOOT but it was negative i want positive for the Driftys. Quote Link to comment Share on other sites More sharing options...
Fundamental Posted December 7, 2007 Report Share Posted December 7, 2007 Yes, this was my mistake for a bit in understanding this topic, that's why Sam pointed that out! I'm just a learner, starting from a scratch few years ago and slowly picking up bits by bits! Now i have a place and material to try experiment as well as some skill in driving. One thing is driving sideways and just understanding something is not correct with the car, the other already is driving sideways and understanding WHAT is not correct and what has to be done to to get things better, thats what i am aiming for Quote Link to comment Share on other sites More sharing options...
Sam@TDi Posted December 7, 2007 Report Share Posted December 7, 2007 I think that Kaspar was pointing out that the toe in on bump characteristic from my bump steer mod is doing the same thing as positive ackermann, basically producing an artificially high amount of slip angle on the out side front wheel. The main reason that the F1 cars employ positive Ackerman is because they have zero body roll (in order for the aero to work) and therefore can't take advantage of the kinematic geometry changes that body roll can bring with it. Quote Link to comment Share on other sites More sharing options...
Tony Posted December 7, 2007 Author Report Share Posted December 7, 2007 I think that Kaspar was pointing out that the toe in on bump characteristic from my bump steer mod is doing the same thing as positive ackermann, basically producing an artificially high amount of slip angle on the out side front wheel. The main reason that the F1 cars employ positive Ackerman is because they have zero body roll (in order for the aero to work) and therefore can't take advantage of the kinematic geometry changes that body roll can bring with it. Interesting.... My thoughts were no where near your explanation.... I need to re-vamp my assertion of positive achermann for Drift. Your method is much simpler than mine but i'm not sure the results would be aggressive enough to solely use "bump gains" during transition... I'm looking for three degrees on the outer wheel In addition the Drift chassis are incredibly rigid as you know so again bump-steer seems less of a friend toward my end goal. Did you manage to measure what gains the Type R had before the mod?..... Reason i ask is that the R has such long steering arms i am surprised the radii is in conflict with the suspensions kinematic conditions. Also why not use track rod ends that allow perpendicular adjustment of the main through pin.... Same thing commonly used on cars like 200sx once lowered. Quote Link to comment Share on other sites More sharing options...
Sam@TDi Posted December 7, 2007 Report Share Posted December 7, 2007 I agree Tony, please don't get me wrong I think your absolutely barking up the right tree here Quote Link to comment Share on other sites More sharing options...
Fundamental Posted December 7, 2007 Report Share Posted December 7, 2007 Snow has melted, our new project 300zx is finished, its cold, but dry, just done suggested setups. Time to take it for a spin and get some feels of new setup Quote Link to comment Share on other sites More sharing options...
Tony Posted December 7, 2007 Author Report Share Posted December 7, 2007 Snow has melted, our new project 300zx is finished, its cold, but dry, just done suggested setups. Time to take it for a spin and get some feels of new setup Without giving to much away, what areas are you looking to improve? Quote Link to comment Share on other sites More sharing options...
Mat Posted December 7, 2007 Report Share Posted December 7, 2007 i need to look at improving steering lock firstly!! Quote Link to comment Share on other sites More sharing options...
Tony Posted December 7, 2007 Author Report Share Posted December 7, 2007 i need to look at improving steering lock firstly!! I disagree... You have 41 degrees on the inner with a TOOT value of 1 degree 20' (stock positions).... If the inner exceeds the lock angle by another degree or so then the lock angle will "lock"... Basically the car will retain the lock position and you the driver will need to influence the recovery..... This is bad news for Drift in my opinion. I confess i have seen some "impressive" lock angles on some Drift cars over the years, but i feel they are barking up the right tree for the wrong reasons. As a really crude example the London taxi has a lock of 62 degrees on the inner.... It turns on a pin but needs a steering wheel the size of Devon to pull the steering back. Modern PAS versions use non-politically correct calibration positions to aid the steering.... This could not be transported to a Drift calibration. Trust me Mat.... Positive ackermann will work despite the lack of body roll.... My theory is based on transition and polar centre. Quote Link to comment Share on other sites More sharing options...
Fundamental Posted December 7, 2007 Report Share Posted December 7, 2007 Snow has melted, our new project 300zx is finished, its cold, but dry, just done suggested setups. Time to take it for a spin and get some feels of new setup Without giving to much away, what areas are you looking to improve? Modified steering as suggested here, want to see if it does any good. Mechanic spent half day to give this a try, i will post some pictures later of work done! Quote Link to comment Share on other sites More sharing options...
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