Your thoughts on roll oversteer please

[John Bonnett]

With the big seven axle even with one shackle immobilised, carefully balanced wheels, stiff front spring and dampers I could not eliminate wheel patter unless I set the car up so that it understeered horrendously. With and Ulster type axle I did not have the same issues and could get superb light responsive cornering once the springs and dampers were sorted as already mentioned.

John, The front firewall bulkhead area of my car contains a series of interconnected closed boxes, these to my mind are light and stiff they tie into the floor which in turn closes the boxes formed by the chassis rails and under tray. I have limited myself by wanting to retain the appearance of something recognisably Austin, so mine not exactly monocoque but utilising an element of that thinking. Which is why the visible part of the fire wall is extremely Nippy inspired, and the overall body shape echoes both Ulster and Speedy, I tried to creatively think of it as what Austin might have done had they continued more in the Ulster vein with the LWB chassis. I will post some more pictures on the build thread rather than clog up this one.

Some more detail photos would be very helpful Ian; thank you. Just a couple more questions if I may please?

Did you use for 20 gauge mild steel for the channel sections riveted to the chassis for boxing and mounts for the stressed floor?
What thickness aluminium for the bulkhead and did you weld it?

Thank you

John

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Hi John,

Rollsteer is not confined to the rear axle only .
the front axel does the same only the roll puts the axel into under steer
I will try and explain if you look at the front of the car and imagine a horizontal line going from front to back starting from were the gooseneck  bolts to the spring , if the radius  ball bolted to the cross member was mounted on that line, as the chassis rolls the axel would stay at a right angle to that line.
But the Ball is mounted about 4 inches below so that it moves in an arc so that if the chassis rolls to the right the ball moves to the Left and because the radius arms are attached they pull the axel back on the right hand side and forward on the left  putting the axel into under steer.
This is why the front suspension is tightened  to reduce roll
The only thing I would do differently is stiffen the leafs of the spring and use the dampers as dampers
but I under stand why the do it because its much quicker
I would also do the same on the rear

Colin
Tinopai NZ

Yes I can understand that Colin. A bit like a Panhard rod that moves through too big an arc. So I would imagine that it isn't possible to have a car with compliant suspension (comfortable ride) that will behave well on the road.