Discussion
My week for daft queries. At full lock (worse on "rights"), and at low speed (not tried full lock at high speed yet), there is a shudder from front wheels feeding back through steering.
I can't detect any wear or play in ball joints or suspension generally so assume it's either a tracking problem (and therefore something to address) or yet another "characteristic" of the design (and therefore nothing to worry about). Tyres sem to be wearing reasonably evenly (although driver's front is slightly more worn than passenger's), so your views welcome...
(Do get an impression of the steered wheels trying to follow different tracks)
V8??...just four TL1000s zip-tied together, innit!?
I can't detect any wear or play in ball joints or suspension generally so assume it's either a tracking problem (and therefore something to address) or yet another "characteristic" of the design (and therefore nothing to worry about). Tyres sem to be wearing reasonably evenly (although driver's front is slightly more worn than passenger's), so your views welcome...
(Do get an impression of the steered wheels trying to follow different tracks)
V8??...just four TL1000s zip-tied together, innit!?
Steering geometry is a suprisingly complex issue.
When a car is steered around a corner, the inside wheel will describe an arc of shorter radius than the outside wheel. In order for both tyres to be tangential with the arc they are describing, the steer angle of the inside wheel must be different (more steer) from that of the outside wheel.
The bloke that realised this was called Ackermann, and he was interested in stopping carriage wheels from making a mess of nice gravel drives. If steering geometry is set up to make the wheel always point tangentially to their direction of motion, the geometry is described as 'Ackermann' (or 'Full Ackermann).
Most hatchbacks/cars tend to have steering geometries near to Ackermann so that they can drive around supermarket car parks.
In order for a tyre to develop lateral forces, it must be moving in a direction at an angle to the direction which it is pointed. Hence when you turn the wheel, you generate lateral forces that rotate the car. This angle is called the 'slip angle'.
When slip angles are taken into account, the ideal geometry at low steer angles (typical of racing or driving at high speed) may be to have only a small Ackermann effect. Real race cars sometimes have 'parallel' steering (no Ackermann at all), or even 'reverse Ackermann'. This can make them absolute b*******s to move around the pits, as the front tyres are fighting each other.
It sounds to me like the TVR has less 'Ackermann' than you would expect from the average shopping trolley/hatch. This is probably to improve high speed handling.
Edited by MEMSDesign on Tuesday 22 January 09:59
When a car is steered around a corner, the inside wheel will describe an arc of shorter radius than the outside wheel. In order for both tyres to be tangential with the arc they are describing, the steer angle of the inside wheel must be different (more steer) from that of the outside wheel.
The bloke that realised this was called Ackermann, and he was interested in stopping carriage wheels from making a mess of nice gravel drives. If steering geometry is set up to make the wheel always point tangentially to their direction of motion, the geometry is described as 'Ackermann' (or 'Full Ackermann).
Most hatchbacks/cars tend to have steering geometries near to Ackermann so that they can drive around supermarket car parks.
In order for a tyre to develop lateral forces, it must be moving in a direction at an angle to the direction which it is pointed. Hence when you turn the wheel, you generate lateral forces that rotate the car. This angle is called the 'slip angle'.
When slip angles are taken into account, the ideal geometry at low steer angles (typical of racing or driving at high speed) may be to have only a small Ackermann effect. Real race cars sometimes have 'parallel' steering (no Ackermann at all), or even 'reverse Ackermann'. This can make them absolute b*******s to move around the pits, as the front tyres are fighting each other.
It sounds to me like the TVR has less 'Ackermann' than you would expect from the average shopping trolley/hatch. This is probably to improve high speed handling.
Edited by MEMSDesign on Tuesday 22 January 09:59
quote:
Went straight the Amazon to get it, but it is £78!!!
Blimey
You could try 'Tune to Win' by Carrol Smith. He's an american, but he does know his stuff, and the book is cheaper. Or you could try a library for a copy of Millikan, and then be naughty and use a photocopier (not that I'd ever do anything like that).
You have no worries there - 99% of us wouldn't be able to pick holes in it! It would make interesting reading so go ahead and stick it in the files folder. Certainly I have always wondered what effect camber and castor have on steering, if you add in Ackerman which I had never thought about (although I have heard the expression) it is totally mind boggling! 
Rich...
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