dirtydiesel Posted January 31, 2013 Share Posted January 31, 2013 Does anyone KNOW what angle the Ackermann is set at on a range rover classic? Verify able sources or direct measurements only please. Quote Link to comment Share on other sites More sharing options...
dirtydiesel Posted January 31, 2013 Author Share Posted January 31, 2013 Mmmm... the silence is deafening! Google came up empty as well. So I've been and measured a early rrc front axle, it came out at 10.1° Quote Link to comment Share on other sites More sharing options...
rick Posted February 1, 2013 Share Posted February 1, 2013 Mmmm... the silence is deafening!Google came up empty as well. So I've been and measured a early rrc front axle, it came out at 10.1° And where does that let the intersection point fall in relation to the wheelbase ? (classic ackerman dictates the theoretical intersection point continuing from the angle of the steering arms being the centreline of the rear axle) I've always assumed coiler front ends had their ackerman based on the 100" wheelbase and they used the same angle arms across all colier models (it's the same swivel housing isn't it across models of the same vintage ? I've never checked the part #) If that's the case, the 110" and 127" wheelbases have increased ackerman, which IMO isn't a bad thing at all as I'm a great believer in increased toe out on turns. Quote Link to comment Share on other sites More sharing options...
rick Posted February 1, 2013 Share Posted February 1, 2013 DP Quote Link to comment Share on other sites More sharing options...
dirtydiesel Posted February 1, 2013 Author Share Posted February 1, 2013 It puts the designed in ackermann wheelbase at 144 inches Quote Link to comment Share on other sites More sharing options...
Daan Posted February 1, 2013 Share Posted February 1, 2013 Mmmm... the silence is deafening!Google came up empty as well. So I've been and measured a early rrc front axle, it came out at 10.1° I reckon that the ackerman is designed for a 100 inch, to work at fast corners, were you want about 50 per cent of ackerman. Daan Quote Link to comment Share on other sites More sharing options...
dirtydiesel Posted February 1, 2013 Author Share Posted February 1, 2013 I reckon that the ackerman is designed for a 100 inch, to work at fast corners, were you want about 50 per cent of ackerman.Daan I wondered it it was set that way to induce oversteer, to counteract understeer from the permamnant 4wd and the lsd center diff the first classics had. Quote Link to comment Share on other sites More sharing options...
Daan Posted February 1, 2013 Share Posted February 1, 2013 I think it is more that you aim at a controlled 4 wheel drift, so that the rear wheels effectively steer a bit. In reality, i dont think it matter much, with the c of g that high, most of the load will be on te outside wheel, so the inner wheel wont do much, regardless of what position it is in. I think.. Daan Quote Link to comment Share on other sites More sharing options...
mmgemini Posted February 1, 2013 Share Posted February 1, 2013 The late great Colin Chapman described the Ackerman principle of steering as "The greatest fraud ever perpetuated in the history of automible design" Make of that what you will. That would be said IIRC before the Range Rover was on the market. Quote Link to comment Share on other sites More sharing options...
bill van snorkle Posted February 2, 2013 Share Posted February 2, 2013 An excerpt from a book titled 'New Directions in suspension Design' by Colin Campbel. "Ackerman arranged his steering layout to give a slightly greater steering angle to the inner wheel than the outer. With the trackrod behind the axle the steering arms are inclined inwards so that their projected lines converge to meet at the centre of the rear axle. If on neglects the effect of slip angle (as Ackerman obviously did) the car will have a turning centre on eny corner which is in line with the rear axle centreline. When slip occurrs at the four contact patches the turning centre will move forward, the extent of this movement depending on the relative slip angles at front and rear wheels. Not all designers adopt the original Ackerman layout.Some use an intersection point behind the rear axle,others use parrallel steering arms. There is some logic in adopting negative (reverse) Ackerman angles, ie,one where the intersection point lies ahead of the front wheels. High cornering forces create roll and create greater slip angles from the outer wheels than the inner. The original Ackerman layout, designed to give a greater angle to the inner wheel is therefore based on a false premise." I'd assume that large section offroad tyres on relatively small diameter wheel rims will have significantly greater slip angles than the lower profile high performance road tyres that Colin Campbels book focusses on, so IMO reverse Ackerman linkage makes even more sense for the kind of vehicles we operate. Bill. Quote Link to comment Share on other sites More sharing options...
Mo Murphy Posted February 2, 2013 Share Posted February 2, 2013 Well I know what an ackermann angle is now. Doubt I'll ever have a use for it though Mo Quote Link to comment Share on other sites More sharing options...
Daan Posted February 2, 2013 Share Posted February 2, 2013 Another one to consider is castor. More big castor results in rolling on camber for cornering, which is a big help for grip. Dan, I saw you are putting on 10 degrees on your G axles, which is a lot, but I think it will help when cornering, even with the diff locked. Daan Quote Link to comment Share on other sites More sharing options...
rick Posted February 2, 2013 Share Posted February 2, 2013 The late great Colin Chapman described the Ackerman principle of steering as"The greatest fraud ever perpetuated in the history of automible design" Make of that what you will. That would be said IIRC before the Range Rover was on the market. And he was wrong. Chapman and the entire British race car building industry didn't believe in toe-out either. Carroll Smith in his excellent series of Prepare to Win, Tune To Win, Engineer to Win, etc took Chapman to task over that and reckoned he missed some tuning potential. Plenty of us have played with ackerman over the years, I've used anti-ackerman as postulated by Chapman all the way through to having the intersection point as much at 2/3 the wheelbase on a race car, and almost always running ackerman helps turn in and negate understeer, particularly in low speed corners. In very high speed stuff it can be detrimental by having too much scrub, but steering angles are tiny when turning in at 130mph anyway and it was handy if you had a lose at that speed. One car I had used anti-ackerman as standard and it was an absolute bitch to push around the pits, the front tyres would just scrub, you would need three goes to get into a garage where another car with the same lock would steer straight in. Change the ackerman plates to zero, then 'classic' and it became easier and easier to manoeuvre when pushing. I think that example is more relevant to us than anything relating to high speed use. Quote Link to comment Share on other sites More sharing options...
rick Posted February 2, 2013 Share Posted February 2, 2013 Another one to consider is castor. More big castor results in rolling on camber for cornering, which is a big help for grip. Dan, I saw you are putting on 10 degrees on your G axles, which is a lot, but I think it will help when cornering, even with the diff locked.Daan Yep, I'm a great believer in lots of castor. It increases directional stability and as you mention, rolls camber onto the outside wheel as the steering angle increases. The downside is it makes the steering heavier, which isn't a problem with power steering. Having said that, I've been too lazy to slot my balls Quote Link to comment Share on other sites More sharing options...
bill van snorkle Posted April 8, 2013 Share Posted April 8, 2013 I'm temporarily bumping this thread because some of the tech relates to discussion on a couple of other current threads. Quote Link to comment Share on other sites More sharing options...
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