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The Bose system seems to be a fully active system. Not sure I'd want to trust the long term reliability of such a system when compared against say a simple spring and orifice damper. The MR system is intriguing. Some dampers contain a motor that controls the size of the orifice within the damper. But this approach doesn't offer real time control of the dampers characteristics. On the MR damper it seems that they have used a fluid whose viscosity can be controled by an applied magnetic field. I haven't got the feintest idea just how usefull such real time control would be for road use, though at least it should fail safe when the electrics plays up.

I wonder what would happen if you(roger or Tony that is) were to phone them up and ask what they do for the money... They may be happy to explain what kinematic toe is and how it works/matters/ cost £150

I don't understand the question. So can't possibly answer

this lot www.performancetrends.com have a piece of software that allows the simulation and visualization of suspension systems. There software has time limited demo modes.

http://users.bigpond.net.au/lachlan/tech/rosejoint.html okay so its a modification to the control arms but I guess its similar in principle.

is the wear pattern repeated at equal intervals all the way around the circumference?

I'm no expert but I know that ALL GREEN does not mean ALL GOOD. Symmetry between left and right is probably more important than having everything green. It doesn't seem like a good idea to have both rear wheels pointing to the right. When Tony gets here I hope he will explain what 'Steer Ahead' means. Also if you do go elsewhere ask for a full geometry check and a full printout. There is really no excuse for just giving you the bare minimum of camber and toe measurements. ======================= Regarding price of the rear track control arm; are you a member of any car clubs?

Curious... has the inner rod actually broken or has it 'just' fallen out of a socket in the top cover? have to cut open the top cover to see how the inner rod is connected to the top bit (LOL there's a song in there somewhere #The damper rods connected to the knuckle joint....#) The damper supresses the inherent resonance in the spring mass system. So as long as you avoid driving at just the right speed over a bumpy road the wheels ought to stay in contact with the road. Could be fun, in an old banger that is. Theoretically even small bumps will get a damperless car airborn if you get the speed and bump pitch just right, I say theoretically because I have no personal experience but some mad fool must have tried it.

When the springs are removed do they return to their correct shape? If they do then as far as the spring is concerned the collapse is the correct behaviour. Maybe not what the customer wants but the spring doesn't care about that

Would you agree with the placement of 'F' X+F Y+F Z+F as a resultant dynamic position.... and indeed moment so say the Governor I'll give a couple of responses. Mostly because I'm not quite sure where you are comming from with the desire to say X+F 1) I don't think any of my profs would have been happy about my playing fast and loose with the seperate ideas of position and force. When you try to solve problems in statics involving position and deflection you work exclusively with the forces. The positional information is incorporated into the force diagrams because force has magnitude, direction and a point of action. This point of action is the whole XYZ thing. These force diagrams always form a closed path as there can be no 'resultant' in a static system. Even though the overall aim of such diagrams is a zero the sizes and directions of the forces are instructive. Used to predict deflection and component failure. 2) Hooke's law.There is a well known relationship between Force and extension (position). Indeed since there are no physical materials that are infinately stiff. Hooke's law always applies, its just that often many of the deflections of the components that form a cars steering system can be ignored. Some of these ignored deflections have important implications such as the choice of toe-in over toe-out. But I dont have the experience or expertise to understand how these ignored deflections influence the behaviour of a car. They usually show up in the dynamics (where time T is involved). Shimmy is the only one that springs to mind. If I ponder a bit more I may think of a third response to the 'X+F' Force is important I can see why you want to include it as the unspoken fourth dimension. But I'm not sure where you are taking me. I hope the ride wont be too harsh (more dynamics *grin* )

Yep Very helpfull group

There are three HSVs and two VXRs in the car club I belong too. I don't know if its possible to get comparative data from them. Most if not all the comments on the quality of Vauxhall main dealer competence would be unprintable.

Waves his engineering degree. Maths rulz down wiv spellin. X, Y, and Z and you are firmly in the realm of statics. Add in change ie time and you are into the much harder subject of dynamics. The math for dynamics gets hairy very fast. To make it worse real systems are non-linear. Very awkward stuff where one plus one does not make two At this point you end up reaching for a big super computer. Even then you have to build the damn thing cos the real world just doesn't seem to want to agree with the output of the computer models. Thats where experience and expertise comes in. So no I wouldn't have picked F but then the whole topic of dynamics is enough to bring me and my computer out in a sweat!

slip ratio = (speed of roadwheel/ vehicle speed) -1. +ve slip = accelerating. -ve slip = decelerating. I found a reference that indicates that ABS systems work by calculating the rate of change of wheel speed. If this is the case, then ABS wont operate under the rolling turn in the first post, as this is a steady state condition. Using rate of change of wheel speed would make my earlier statement that ABS has a target slip as part of its control strategy incorrect. There is an optimum slip for both braking and accelerating but the ABS doesn't have to care about optimum slip to function. The same isn't true for TCS though. The book indicates that Traction Control is more complex than ABS and that the control system has to adapt its target slip values to different road conditions and to allow for the negative effect that slip has on cornering. (negative unless your aim is drifting that is). One of the strategies used by the TCS designers to cope with different raod conditions is a driver selectable off switch LOL. [bTW How do I post pictures? I could then post the graph showing how friction varies with slip from the book] reference : An introduction to modern vehicle design editor Julian Happian-smith. chapter 11: control systems in automobiles. graphs taken from Chowanietx and Jurgen 1995)

these figures are from a couple of years ago... All numbers a before left before right then === the after figures for left and right F CAMBER -1o 02' -1o 08' ==== -0o 58' -1o18' F CASTER 4o 19' 4o 50' ==== 4o 19' 4o 50' F TOE 5.0mm -8.4mm ==== 1.0mm 0.7mm F SET BACK left 0o 13' ==== left: 0o 15' INC ANGLE 13o 25' 13o 52' ==== 13o 29' 13o 42' SAI 14o 27' 15o 00' ==== 14o 27' 15o 00' R CAMBER -1o 37' -1o 46' ==== -1o 34' -1o 46' R TOE 2.0mm 0.4mm ==== 1.5mm 1.0mm R SET BACK right 0o 07' ==== right 0o 03' THRUST LINE right 0o 07' ==== right 0o 03' I don't know what the correct figures for caster SAI KPI should be. The printout did indicate that the Caster angle was out of spec both before and after adjustment. I am suspicious of the CAMBER figures as they did not check either the fuel level in the tank or use any weights in the car. Something that I was later told should have been done. I have to locate another geometry shop and get the car remeasured. So here I am engaged ina crash course on geometry LOL. A little knowledge may be dangerous but no knowledge is far worse. The car is a 24V 3.0 Senator 1994.

I suspected that the garage muppets had taken the car out for a "spin" and hit the nearside wheel on an obstruction in the road. The garage of course denied it and the extra miles on the clock were my imagination too They also denied that the car pulled left when the steering was released claiming that that was all down to road camber. I stopped using that garage shortly afterwards. Some time later whilst underneath the car changing oil and filters I noticed a shiny ring around the bolt that holds the cross member to the chassis. I took the car to a local geometry shop who gave me a printout showing set back which when I asked what does it mean they didn't have a clue! They adjusted the toe on the front, didn't adjust the rear thrust line and charged me money. MORE DISILLUSIONMENT. So I borrowed some optical allignment kit and reset the rear thrust and toe then set the front alignment to the rear. Car still pulled left but at least tyre wear was okay. Since that time I've hid an obstruction in the road whilst trying to avoid the lorry comming down the middle of a country lane. Unrelated to this I've also had to replace the front wishbones (old rubber bushes = MOT fail) and I'm getting edge wear on the front tyres. So the car needs fixing once again. I'd like it to be done properly this time. So here I am.

argh too ....much...... information On my Senator the front crossmember /cradle isn't square. I think its about 5mm set back on the nearside. Car pulls to the left The standard pinch bolts don't allow for camber adjustment, some friends have modified their cars to allow adjustment though I think the tinkering is reserved for the Lotus Carlton's which have much more expensive tyres. The topic of alignment comes up every now and then, but none of us knows of a decent shop that is trustworthy. I suspect that the Lotus boys would be quite happy to trek some hundred miles to ensure that their cars are just right. There is quite a market out there for a decent geometry allignment shop.

Correct... well done... the -20' and +20' rear toe displaces the cars centre line (Thrust angle) so the driver needs to compensate through the steering position to manufacturer a new thrust position. One more example then we will move on to modifications.... Example: This car is camber/castor/toe adjustable Front Camber nsf -45'........ osf -40' Castor nsf +5d 59'....osf +6d 13' Toe.......nsf 0.............osf 0 KPI/SJI.nsf 4d 40'.......osf 7d 27' Included angle.... you can maths that one Rear Camber nsr... -1d 10'....osr -1d 25' Toe.......nsr 0...............osr 0 Thrust..0 Clue: Remember the parallelograms and there is no point trying to triangulate since the car is naturally adjustable. So indeed a bit more difficult but can you suggest whats happening to this car when driven? Answer: This example is difficult so i am not surprised it went unanswered but if you want the wim logo then it's school time From the above example the only visible disparity is the KPI (King Pin Inclination) This angle is very misunderstood so conveniently ignored but vital to diagnostics...... So what is it?.. The KPI is the inclination of the front lower swivel pin, it exists in three planes (vertical, perpendicular, longitudinal) and is the recipient of the upper parallelogram of the cars weight. What is hard to understand about this angle is it's measured position ver force... Since the angle is measured in a 3D plane then true vertical would read as 0 KPI as the pin is declined the measured angle increases but is reactive influence decreases... The longitudinal position is due to the mechanical castor trail by design. So in the example above the nsf has 4d 40' inclination and the osf 7d 27' inclination, as explained this then suggests the nsf pin is more inclined than the osf so supporting more weight from the upper parallelogram of the vehicle.... Agreed? To the consequence.... By design the inclination is compressed pushing back down the cars weight, but both the front King Pins want to be at rest, this resting opportunity is available through the steering rack turning the front wheels until both pins share the same inclination..... So in answer to this example the car is pulling to the left and by the drivers defensive reaction the steering position is right hand down. An area to note is the fact this example is 'multiple adjust' Geometrically so in essence this masks the real reason why the KPI has this disparity....most times it's soley due to a bend at the wishbone, most times the bend would take the camber with it... unless it's been adjusted correcting the angle?.... Now the shop are wondering why is the car pulling?..... We know Will the 3 degree difference in included angle change the scrub radius enough to cause the car to pull under breaking? Hmm fully adjustable geometry is that a curse or a blessing. To adjust anything other than toe on the Senator requires the use of an engine lift so that the front cross member can be loosened and moved. Makes fixing the geometry a pain once it is wrong. None of the local alignment /geometry shops are willing to do anything other than the manufacturer adjustable toe. Which does nothing for the underlying problem. BTW how is adjustable castor implemented?

Isn't the target slip for both ABS and Traction control about 20%? If your vehicles track is 1.4 metres then this would imply that the turning circle has to be less than 16metres before either the ABS or the TC would consider the "slip" needs correcting. I've just realized that I don't know what the minimum turning circle is for my car! I wouldn't be surprised if it was similar to 16m. Which means that even on full lock the TC and ABS systems wont be fooled. Not that it has TC. I think that the ABS system on my car doesn't operate below 5mph but I'm not certain of this. If this is common practice then this is another strategy that the control unit has to avoid operating during manoevering.

I'm going to ignore the wide-band lambdas .My car's ecu, like many, would make no use of the extra information about the exhaust gas composition. The difference between wide band and standard isn't that great anyway. Last time I looked at the data sheets that is. Normal lambdas are 'simple' switching devices. They tell if the exhaust is too rich or too lean. If just the right amount of air is mixed with the fuel and burnt then it is theoretically possible for all the exhaust gasses to consist of just C02 and water. In practice the combustion is incomplete so cats are added to perform the final burn and keep the exhaust gasses clean. Too much fuel in the exhaust is bad for the cats and too much air is wastefull as air takes energy to push through the engine. The ecu uses the lambda sensor primarily to ensure that the mixture going into the cats can be completely burnt. Its an emmisions control device. The 14.7:1 stoichometric point is neither the best for power (slightly rich) nor best for fuel economy (slightly lean) but it is best for the cats. Cats penalise fuel economy, and though they clean the exhaust gasses, ultimately the Carbon load is increased by their presence. Lambdas do wear out: when they do the switching response time slows down. The ecu gets confused as it doesn't know the lambda is slow and emmisions and drivability suffer. A simple test for an ageing lambda is to hold the car at 2000 rpm in neutral. Keep your foot absolutely still and the engine revs should be similarly stable. if they hunt up and down slowly then its time for a new lambda sensor. So is there any point in changing a working lambda sensor for a more expensive wide band one? I doubt it.

I'm new to this, other than knowing that there is something wrong with my cars setup but that the local garages don't know how to fix it. So from the picture.... Steering wheel looks to be straight. Suspension looks unloaded Perspective makes judging the tyre's direction difficult. It could be straight ahead. So:- the car just went airborne and is about to land with a bump?