Lotus Alloy Wheels fit to Hub
Posted: Mon Feb 23, 2009 7:27 pm
I have just made some measurements to my new +2 alloy front wheels (as fitted to S130 versions).
When placed on each hub with no centre nut fitted there is no detectable play from the 5 dogs in the hub and the holes in the wheel. I then looked at the gap between the threaded centre shaft of the hub and the inside hole edge of the wheel.
I measures a worst case difference of 9 thou on the NS hub and 14 thou on the OS hub (UK RHD)
A wheel/tyre combination weighs 12 kg. For each thou of centre offset you get an out of balance moment of 0.001 x 6,000 each side. This is roughly equivalent to a 2 gram balance weight at 6.5 inches from the centre. As the centre wheel nut is tightened up when the wheel is fitted, the dogs will prevent the wheel from centreing.
So as tyres are balanced on the centre hole, there is a likely 18 gram out of balance condition on the NS, and a whopping 28 grams on the OS!
My solution is to bore out the 5 holes in the wheels by 10 thou, giving me a float of 20 thou. If you have balance problems, measure that centre gap with feeler gauges and see for yourself.
Dave Chapman
When placed on each hub with no centre nut fitted there is no detectable play from the 5 dogs in the hub and the holes in the wheel. I then looked at the gap between the threaded centre shaft of the hub and the inside hole edge of the wheel.
I measures a worst case difference of 9 thou on the NS hub and 14 thou on the OS hub (UK RHD)
A wheel/tyre combination weighs 12 kg. For each thou of centre offset you get an out of balance moment of 0.001 x 6,000 each side. This is roughly equivalent to a 2 gram balance weight at 6.5 inches from the centre. As the centre wheel nut is tightened up when the wheel is fitted, the dogs will prevent the wheel from centreing.
So as tyres are balanced on the centre hole, there is a likely 18 gram out of balance condition on the NS, and a whopping 28 grams on the OS!
My solution is to bore out the 5 holes in the wheels by 10 thou, giving me a float of 20 thou. If you have balance problems, measure that centre gap with feeler gauges and see for yourself.
Dave Chapman