Tracking settings in mm
Discussion
Hello
Have recently acquired a '98 Griff 500 and am in process of getting to grips with the car. Front tyres show some signs of uneven wear so I want to check the tracking.
Had a search in the forums but can only find the tracking settings in degrees, however my tracking tool (used FACOM with projectors) works in mm. Does anyone have the metric settings or the correct way to convert settings in degrees to mm.
Cheers
Philip
Have recently acquired a '98 Griff 500 and am in process of getting to grips with the car. Front tyres show some signs of uneven wear so I want to check the tracking.
Had a search in the forums but can only find the tracking settings in degrees, however my tracking tool (used FACOM with projectors) works in mm. Does anyone have the metric settings or the correct way to convert settings in degrees to mm.
Cheers
Philip
Hi
if the wheels are 15 inch, they are about 400mm across the wheel (for the sake of arguement). To get the figure in mm, =sin(angle)*400*2. 20 minutes of toe in (60 minutes per degree), is 4.6mm. In this case measured as the difference from measurement across the back of the rim to the front of the rim, across the car. Most TVR garages go for no toe in, I would go for 3 to 5mm.
Nic
if the wheels are 15 inch, they are about 400mm across the wheel (for the sake of arguement). To get the figure in mm, =sin(angle)*400*2. 20 minutes of toe in (60 minutes per degree), is 4.6mm. In this case measured as the difference from measurement across the back of the rim to the front of the rim, across the car. Most TVR garages go for no toe in, I would go for 3 to 5mm.
Nic
Toe-in measured in mm is normally measured at the tread not the rim. It's also usual to give the total difference between front and rear of the wheels i.e. the total toe-in on both sides.
When toe-in is measured in degrees it is common to quote the angle between the wheel and the centerline of the car - this is only half the total toe-in angle. So you need to make sure you're comparing like with like.
The easiest way to convert from mm to degrees is to use the '1 in 60' rule. For small angles, a 1mm arc 60mm from the center represents one degree. So in practical terms, if the diameter of the tyre is roughly 600 mm then a 10mm difference between the front/rear distances represents 1 degree of toe-in.
When toe-in is measured in degrees it is common to quote the angle between the wheel and the centerline of the car - this is only half the total toe-in angle. So you need to make sure you're comparing like with like.
The easiest way to convert from mm to degrees is to use the '1 in 60' rule. For small angles, a 1mm arc 60mm from the center represents one degree. So in practical terms, if the diameter of the tyre is roughly 600 mm then a 10mm difference between the front/rear distances represents 1 degree of toe-in.
Reading this just confirms the doubts I have about taking the car ANYWHERE and expecting them to get it right. So many variables and so many people with different approaches to one issue.
Is it different depending on the type of shox? Ride height? Bushes? Tyres?
Philipo - "Front tyres show some signs of uneven wear so I want to check the tracking." Whenever I have been for tracking to be reset AFTER the wear has become visbly uneven, the nice men in the tyre selling shop always say it cant be done once the tread is wearing uneven - "you need new tyres, mate" is the reply.
Is that true?
PS And you have a tracking setting machine at home?!!
>> Edited by shadowfax on Monday 6th March 21:08
Is it different depending on the type of shox? Ride height? Bushes? Tyres?
Philipo - "Front tyres show some signs of uneven wear so I want to check the tracking." Whenever I have been for tracking to be reset AFTER the wear has become visbly uneven, the nice men in the tyre selling shop always say it cant be done once the tread is wearing uneven - "you need new tyres, mate" is the reply.
Is that true?
PS And you have a tracking setting machine at home?!!
>> Edited by shadowfax on Monday 6th March 21:08
Adjusting the settings is very much part of the tuning process. Adjusting the toe can trade turn in for stability and can also result in different wear patterns. The toe is also often affected by camber and othe suspension settings so if anything is done to the car , probably with the exception of simple rebushing but even then it is worth a quick check, the geometry should be checked. For most people, the factory settings are fine and a good place to start. However it is easy to get into geometry hell where the search for the magic settings becomes dominant when in fact, other aspects such as driver style comes into play and what works for A doesn't for B. Like all suspension work, it is a process of establishing what is not right, why it is happening and then correcting it and finally testing.
And yes I have the camber/caster gauges/ and toe in stuff at home as well.
And yes I have the camber/caster gauges/ and toe in stuff at home as well.
Well, my driving style is no more demanding than the next enthusiast's I'd say, and the wear on the front left outer is not due to me turning one way with more vigour than the other, I'm sure.
It's down to basic tracking needing setting and or left wishbone / shocker issues. Await opinion of my mechanic on that.
Meantime, my local ATS man, who will supply & fit the sp9000 all round next week, says he can sort out the tracking / geometry for all four wheels if he has the right settings.
Can anybody kindly advise what info I should give him?
It's down to basic tracking needing setting and or left wishbone / shocker issues. Await opinion of my mechanic on that.
Meantime, my local ATS man, who will supply & fit the sp9000 all round next week, says he can sort out the tracking / geometry for all four wheels if he has the right settings.
Can anybody kindly advise what info I should give him?
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