Use of Metro Hubs
There seems to be much confusion over the use of Metro hubs on the Mini.
Here are some comments on the subject.
The post-1984 Metro uses a different size top ball joint, which has a larger taper and will not fit the Mini upper arm. This can be solved by fitting a pre 1984 Metro top joint.
Although this will allow you to physically fit the hubs, the Metro suspension geometry is different to the Mini. This means that there will be enormous amounts of positive camber (the wheels will lean out at the top).
Some people (including high profile magazines) have suggested that fitting longer lower arms will get the wheel to the correct position. This may, indeed, get the wheel to somewhere near its original camber angle. But, this is taking a very simplistic view of suspension design. There is far more to it than just getting the wheel to the right angle in the static state. Suspension is, by its very nature, a dynamic device. It is important that the wheel behaves correctly throughout its motion. By using Metro hubs with longer lower arms, the ‘kingpin’ axis is still not the same as the original Mini. This means that, when the wheel is steered or the suspension is operated, it will move in a different manner to the way it should.
There is little point in getting into the technical details of what actually happens to the wheel, but it is fair to say that it won’t be as Issigonis intended it to be!
Our view is that the use of Metro hubs and longer lower arms should be avoided. If you do insist on using vented discs and 4 pot calipers, then start with Mini disc brake hubs. You can then build up the Metro vented discs, drive flanges and calipers without wrecking the excellent suspension geometry of your Mini. It works very well in standard form, why mess with it?