Swiftmini
Automotive
- May 25, 2007
- 7
Hi All, My name is Kev and iam new to the forum and also fairly new to chassis and suspension design.
Here is what iam stuck with:
About a year ago i started investigation into a beam axle that was made for a classic mini by Don Loughlin of aldon automotive, the axle was for David Vizards mini and was featured in one of his books 'how to modify your mini'.
Basically the reasons behind fitting a beam axle onto a mini are:- Wheel attitude with the road, weight transfer and lowering the overall weight of the car.
When a mini rolls during cornering the wheels assume an angle equal to the roll angle. With a beam the wheels in theory have no choice to stay vertical, although weight transfer and tyre flex mess things up pretty well. The flexure problems can be helped by adding static -VE camber to try and keep the wheel vertical.
Ok all this is probably boring you but...
What iam mostly interested in is finding out why Don and David vizard placed the rear roll centre at 14-15 inch above ground level.
The Aldon/Vizard axles
Apparently this axle has the same geometry as the one below, but very different mounting arrangement.
Looking at the last pic i can now see that the X for the roll centre is right in the middle of the panard rod that runs across the top. In this case i think i can easily do the roll centre calculations.
But what i have also noticed is that because of the way the axle is linked into the chassis, it would have to twist to move throughout bump and droop. Under braking this may have an anti-dive affect, i'm not sure.
If some one can explain a few simple questions for me i would be very happy.
1. What are the effects of a roll centre that is really high at the rear?
2. What are the effects of a making the roll axis steeper (when higher at the back)?
3. The book said that the change completley transformed handling in the wet. How?
Thanks in advance.
Kevin lee
Here is what iam stuck with:
About a year ago i started investigation into a beam axle that was made for a classic mini by Don Loughlin of aldon automotive, the axle was for David Vizards mini and was featured in one of his books 'how to modify your mini'.
Basically the reasons behind fitting a beam axle onto a mini are:- Wheel attitude with the road, weight transfer and lowering the overall weight of the car.
When a mini rolls during cornering the wheels assume an angle equal to the roll angle. With a beam the wheels in theory have no choice to stay vertical, although weight transfer and tyre flex mess things up pretty well. The flexure problems can be helped by adding static -VE camber to try and keep the wheel vertical.
Ok all this is probably boring you but...
What iam mostly interested in is finding out why Don and David vizard placed the rear roll centre at 14-15 inch above ground level.
The Aldon/Vizard axles
Apparently this axle has the same geometry as the one below, but very different mounting arrangement.
Looking at the last pic i can now see that the X for the roll centre is right in the middle of the panard rod that runs across the top. In this case i think i can easily do the roll centre calculations.
But what i have also noticed is that because of the way the axle is linked into the chassis, it would have to twist to move throughout bump and droop. Under braking this may have an anti-dive affect, i'm not sure.
If some one can explain a few simple questions for me i would be very happy.
1. What are the effects of a roll centre that is really high at the rear?
2. What are the effects of a making the roll axis steeper (when higher at the back)?
3. The book said that the change completley transformed handling in the wet. How?
Thanks in advance.
Kevin lee
