I have what I believe is a BMC A-Series rear axle....

Should I expect any backlash (rotational play) in the input shaft?

I would estimate the backlash to be somewhere around 6-7 degrees....Should I be concerned?

|Sounds like an excellent example TBH...!

In all seriousness introduce yourself on 750 Formula and they will be able to give you all the help you need - yes they'll try and persuade you to put a fiat engine in it and go racing with them (tbh that's not actually such a stupid idea anyway as you already have an eligible car ). No other group of people know more about the BMC axle/diff though

[Edited on 26/4/08 by D Beddows]

Good alternative to the english axle Imho. Very much lighter than an english, same width i believe and are capable of taking modest power. The only trouble is finding good examples at the correct diff ratio, especially for bike engines, for a reasonable price. (but if you've already got one that's not much of a worry!)

As mentioned above the 750 formula boys and girls are your best bet. They've been using it for a loooong time...