01-04-2016, 10:30 AM
So since the old post was lost on the previous forum I'll do this again since it was requested.
First, this will be written in as simple a way as I can so that you can understand how your car's suspension works in general. There is a lot more information available out there, but also a lot of MISS-information, so think about the things you read online and if you have questions feel free to ask.
Also, the wheel alignment suggestions given in this thread are just that - suggestions. You are welcome (and encouraged) to ask questions or make suggestions.
OK, so let's start at the beginning.......
Tyre -> Suspension -> Vehicle body
The way your car rides (comfort) and turns (handling behavior and grip) is determined by the grip generated by your tyres as well as how these forces gets transferred to your vehicles' body.
Tyres:
Tyres are the most important thing on your car.
Let this sink in before you read further......
Tyres are the most important thing on your car.
I'm not going into a whole load of detail here, the important things to note are:
Tyre width - generally speaking a wider tyre will provide more grip (side force) than a narrow tyre, but a wider tyre provides more drag (air resistance as well as rolling resistance). A wider tyre provides a larger contact patch with the road.
Tyre contact patch - this is the area of the tyre that touches the road at any time. The tyre is able to generate a side force that actually allows your vehicle to turn by deforming this contact patch. As it gets distorted the contact patch changes, but the tyre tries to regain its natural shape which generates the side force that allows the car to turn. Why am I talking about contact patch? The tyre behavior is directly affected by the next point....
The larger the contact patch, the more resistance the tyre has to turning - thus the heavier your steering becomes.
Tyre sidewall - generally a high sidewall provides a more comfortable ride since the sidewall works like suspension - absorbing bumps in the road. The drawback of high sidewalls is because it allows for more flex it responds slower to changes in the contact patch. It also handles slight alignment issues better since it can flex more than a lower profile.
OK, so what does this mean?
I mention the above to try to help you understand that how you setup your suspension and how it works is greatly influenced by your tyre choice. This should also be kept in mind when you look at the suspension setup of the mini considering it was designed to use high profile 10" tyres.
Suspension:
This will be a short summary - more info is available on the internet.
Camber - Camber is the vertical angle of the wheel and tyre relative to the vehicle body.
Neutral camber provides the biggest contact patch and the least amount of external forces due to a deformed contact patch.
Negative camber provides better tyre performance during cornering since the outside tyre's contact patch works in a better "shape" as the tyre is running almost vertical. The contact patch is smaller due to the camber and the deformed contact patch (from running on a side of the tyre) actually generates a side force as the tyre tries to get itself upright.
Positive camber - no use in this discussion, makes for easy steering but poor tyre performance in straight and cornering.
Caster - This is the angle around which the hub rotates around the vertical plane.
Positive caster - Provides steering self centering (the steering returns to the straight ahead), which provides stability at speed. Positive camber makes your steering heavier. Positive camber provides a certain amount of camber gain - this means that as the wheels are turned it sits at a camber angle that is more negative than when it was in the straight ahead position.
Neutral caster - Provides no self centering, provides no stability. Makes for light steering. Has no camber gain.
Negative caster - No use in this discussion and not suitable for vehicles.
Toe angle - This is the angle of the wheel/tyre in the horizontal plane - the front of the tyres being further apart than the rear of the tyre is toe out and vice versa.
Front suspension - Toe out provides better turn in and allows for better traction on a front wheel drive car since the wheels pull the car forward and due to the play in the suspension effectively runs parallel or with no toe angle, thus providing the best grip. Excessive toe out will increase tyre wear.
Toe in provides more stability but sluggish turning response and increased tyre wear.
No toe angle is the best for tyre wear, but the toe angle changes as the front wheels are the driven wheels as per the above.
Mini setup:
The stock mini setup is as follows (need to update this with specifics as per the manuals)
Front:
Camber: 0 degrees
Caster: about 3 degrees
Toe out: 1 degree
Rear:
Camber: Positive
Toe in: lots....
When fitting 13" wheels and tyres with stiff sidewalls the biggest issue is the rear suspension, in my opinion. The stiff sidewalls mean very poor road contact. Also since the tyres do not see the load they should to generate any heat to get to proper operating temperature it results in a very loose rear end (I experienced this first hand with my car)
So bearing in mind how the mini struggles to get heat into the tyres and how the tyre dynamics change from 10" to 13" a lot of changes can be made.
I have been running a fairly aggressive alignment setup on my car for a while now, it does not provide a whole lot of straight line grip and tyre wear is increased a lot - however since my 1100 is not a powerhouse it works well for me. I also like the fact that the tendency for the rear end to become loose of lock up under braking is reduced to the change in the contact patches front and rear.
I should also state here that I am running 13x6 wheels, meaning my sidewalls are not stretched on the tyres.
My car's alignment:
Front:
Camber: -1.5 degrees
Caster: 4.5 degrees
Toe out: 1 degree (I think, might be 0.5)
Rear:
Camber: 0 degrees
Toe in: 0 degrees
These are very aggressive settings, and not what I would suggest as a starting point.
I will also be changing these at the next alignment session to decrease the camber a bit as it is just too much. In the wet the braking performance is too poor to be safe.
My suggested start for a car with 13 inch wheels and tyres:
Front:
Camber: -0.5 degrees
Caster: 4 degrees
Toe out: stock (think it is around 1 degree, but will check)
Rear:
Camber: 0 degrees or very slight negative.
Toe in: stock (need to check and update)
My suggested start for a car with 10 inch wheels and tyres:
Front:
Camber: -0.5 to -1 degrees
Caster: 4 degrees
Toe out: stock (think it is around 1 degree, but will check)
Rear:
Camber: 0 to -0.2 degrees
Toe in: stock (need to check and update)
It would be great if guys with experience running adjustable setups with 10inch wheels would provide some insight.
As per what I stated at the start, these are just my suggestions based on my experience with a road car. The racing guys will run very different setups to this.
First, this will be written in as simple a way as I can so that you can understand how your car's suspension works in general. There is a lot more information available out there, but also a lot of MISS-information, so think about the things you read online and if you have questions feel free to ask.
Also, the wheel alignment suggestions given in this thread are just that - suggestions. You are welcome (and encouraged) to ask questions or make suggestions.
OK, so let's start at the beginning.......
Tyre -> Suspension -> Vehicle body
The way your car rides (comfort) and turns (handling behavior and grip) is determined by the grip generated by your tyres as well as how these forces gets transferred to your vehicles' body.
Tyres:
Tyres are the most important thing on your car.
Let this sink in before you read further......
Tyres are the most important thing on your car.
I'm not going into a whole load of detail here, the important things to note are:
Tyre width - generally speaking a wider tyre will provide more grip (side force) than a narrow tyre, but a wider tyre provides more drag (air resistance as well as rolling resistance). A wider tyre provides a larger contact patch with the road.
Tyre contact patch - this is the area of the tyre that touches the road at any time. The tyre is able to generate a side force that actually allows your vehicle to turn by deforming this contact patch. As it gets distorted the contact patch changes, but the tyre tries to regain its natural shape which generates the side force that allows the car to turn. Why am I talking about contact patch? The tyre behavior is directly affected by the next point....
The larger the contact patch, the more resistance the tyre has to turning - thus the heavier your steering becomes.
Tyre sidewall - generally a high sidewall provides a more comfortable ride since the sidewall works like suspension - absorbing bumps in the road. The drawback of high sidewalls is because it allows for more flex it responds slower to changes in the contact patch. It also handles slight alignment issues better since it can flex more than a lower profile.
OK, so what does this mean?
I mention the above to try to help you understand that how you setup your suspension and how it works is greatly influenced by your tyre choice. This should also be kept in mind when you look at the suspension setup of the mini considering it was designed to use high profile 10" tyres.
Suspension:
This will be a short summary - more info is available on the internet.
Camber - Camber is the vertical angle of the wheel and tyre relative to the vehicle body.
Neutral camber provides the biggest contact patch and the least amount of external forces due to a deformed contact patch.
Negative camber provides better tyre performance during cornering since the outside tyre's contact patch works in a better "shape" as the tyre is running almost vertical. The contact patch is smaller due to the camber and the deformed contact patch (from running on a side of the tyre) actually generates a side force as the tyre tries to get itself upright.
Positive camber - no use in this discussion, makes for easy steering but poor tyre performance in straight and cornering.
Caster - This is the angle around which the hub rotates around the vertical plane.
Positive caster - Provides steering self centering (the steering returns to the straight ahead), which provides stability at speed. Positive camber makes your steering heavier. Positive camber provides a certain amount of camber gain - this means that as the wheels are turned it sits at a camber angle that is more negative than when it was in the straight ahead position.
Neutral caster - Provides no self centering, provides no stability. Makes for light steering. Has no camber gain.
Negative caster - No use in this discussion and not suitable for vehicles.
Toe angle - This is the angle of the wheel/tyre in the horizontal plane - the front of the tyres being further apart than the rear of the tyre is toe out and vice versa.
Front suspension - Toe out provides better turn in and allows for better traction on a front wheel drive car since the wheels pull the car forward and due to the play in the suspension effectively runs parallel or with no toe angle, thus providing the best grip. Excessive toe out will increase tyre wear.
Toe in provides more stability but sluggish turning response and increased tyre wear.
No toe angle is the best for tyre wear, but the toe angle changes as the front wheels are the driven wheels as per the above.
Mini setup:
The stock mini setup is as follows (need to update this with specifics as per the manuals)
Front:
Camber: 0 degrees
Caster: about 3 degrees
Toe out: 1 degree
Rear:
Camber: Positive
Toe in: lots....
When fitting 13" wheels and tyres with stiff sidewalls the biggest issue is the rear suspension, in my opinion. The stiff sidewalls mean very poor road contact. Also since the tyres do not see the load they should to generate any heat to get to proper operating temperature it results in a very loose rear end (I experienced this first hand with my car)
So bearing in mind how the mini struggles to get heat into the tyres and how the tyre dynamics change from 10" to 13" a lot of changes can be made.
I have been running a fairly aggressive alignment setup on my car for a while now, it does not provide a whole lot of straight line grip and tyre wear is increased a lot - however since my 1100 is not a powerhouse it works well for me. I also like the fact that the tendency for the rear end to become loose of lock up under braking is reduced to the change in the contact patches front and rear.
I should also state here that I am running 13x6 wheels, meaning my sidewalls are not stretched on the tyres.
My car's alignment:
Front:
Camber: -1.5 degrees
Caster: 4.5 degrees
Toe out: 1 degree (I think, might be 0.5)
Rear:
Camber: 0 degrees
Toe in: 0 degrees
These are very aggressive settings, and not what I would suggest as a starting point.
I will also be changing these at the next alignment session to decrease the camber a bit as it is just too much. In the wet the braking performance is too poor to be safe.
My suggested start for a car with 13 inch wheels and tyres:
Front:
Camber: -0.5 degrees
Caster: 4 degrees
Toe out: stock (think it is around 1 degree, but will check)
Rear:
Camber: 0 degrees or very slight negative.
Toe in: stock (need to check and update)
My suggested start for a car with 10 inch wheels and tyres:
Front:
Camber: -0.5 to -1 degrees
Caster: 4 degrees
Toe out: stock (think it is around 1 degree, but will check)
Rear:
Camber: 0 to -0.2 degrees
Toe in: stock (need to check and update)
It would be great if guys with experience running adjustable setups with 10inch wheels would provide some insight.
As per what I stated at the start, these are just my suggestions based on my experience with a road car. The racing guys will run very different setups to this.
I'm only here to LOL and +1
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