are the stub axles made of any special steel as i want to to make some so i can fit mx5 hubs to the spitfire stubaxle thanks in advance

Good question Instinctive answer would be: Seriously unlikely :-)
I'm eventually doing similar. There are a variety of aftermarket stub axles from the Bespoke Triumph stockists and even Caterham itself... Likely pricey but worth trying to glean a little knowledge from?
Beyond the axle to fit the new hubs.. what about the Caliper mounts? Given any though to that yet?

going to make brackets fit fit brembo 4 pots with 285mm discs

You want to start with Vitesse/GT6 parts rather than Herald/Spitfire the stub axle is a larger dia and the caliper mounting brackets are bolt on.
The GT6 also had bigger brakes.

Because they were used on so many racers mounting bells for big competition discs should still be easily available also aluminium hubs that can be drilled to any pcd.

My guess would be that they are not ordinary mild steel - more likely to be EN16 or similar .

thanks for the replies i dont want to use gt6 as they cost a fortune for large vented ones i want the mx5 hubs as they are 100pcd and then i can use clio cup discs which are only £60 a pair for drilled & grooved

Admirable sentiments... Once into the Mazda bits you are technological leagues beyond what Triumph even fantasized about.
But the Drilled part of your Brake desires suggests you really aren't fully aware of what you are up to... yet.
Lots of Reading & Researching is strongly indicated before you can go further.

[Edited on 12/11/11 by Bare]

I Think what British Trident is getting at is that you can use a standard Vitesse/GT6 stub (read that as readily available) with an un-drilled GT6 hub.

This setup would have bearings all-ready matched up, and you could then drill the hub to suit the MX5 PCD, and then use any disc/caliper combination you desire.

And as noted already I too would avoid drilled discs, grooved to act as a pad de-glazer yes but drilled no.

[Edited on 12/11/2011 by Hector.Brocklebank]

this is along the lines of what i was thinking but these are for rx7 hubs. mx5 would be pretty much the same


















top: original Triumph spindle. bottom: new adaptor spindle to accomodate Mazda brakes.

http://www.canleyclassics.com/?xhtml=xhtml/product/catkit3.html&xsl=product.xsl

obviously not a cheap option, but seems a good idea (ie pilfer it!)
Saying that, with very little lathework (open the bore up by less than 1mm, or machine the hub to do the same job) you can fit citroen xantia discs to the GT6 or Spitfire hubs.

thanks for the link but a those prices no thanks (i want locost)
i can get the stubaxles made for £40 per pair & get mx5 hubs from scrappy for tenner
the other bonus is i am using mx5 rear uprights on the back so everything will be the same

[Edited on 12/11/11 by geordielad]

EN16 possibly(but brittle), EN8 more likely.

Cheers,
Nev.