Confusion over Fiesta ST caliper upgrade

[Fenderer]

I know this has been covered many times on here but all my searching just seems to generate more confusion.. Hoping someone can clarify.

I'm looking to upgrade my front brakes with the popular Fiesta ST calipers option but there's seems to be conflicting advice on here about whether the Sierra Cosworth (2wd) 283mm discs will work with these and fit within the standard 15" alloys, or whether they will need machining down to 279mm. Also whether spacers are required between the upright and caliper. I don't really want to go the machined down disc route mainly because I don't know anyone locally that will do it without charging me an arm and a leg but using spacers on the caliper brackets would be OK. I'm also not that keen on the idea of minimal clearance between the caliper and wheel and spacers on the wheel itself.

Can someone clarify exactly what's needed and whether it will work without any machining?

Thanks!

[N7GTX]

I fitted ST discs to my Chim.

They were 300mm diameter, 4 stud, min thickness 22mm, height 45mm. The ST caliper has one 54mm diameter piston.

So I fitted Mondeo Mk3 calipers which have one 60mm piston. The front discs on a Mondeo 3 diesel/estate or 2.5v6, are 300mm, min thickness 26mm, height 52mm, but cannot be used as they are 5 stud (unless you have upgraded the hubs).

I do not know the min thickness and height of the 283mm Cosworth discs. If they are close to the ST ones then they will probably be good. Fitting the 300mm disc was very tight on standard size wheels. The calipers were all but touching the rims. So I fitted 5mm spacers (cheap on eBay) and the problem was solved. The only other modification was very slightly enlarging the holes in the hub to take the slightly thicker Mondeo carrier bolts.
I went to a scrappy for the Mondeo calipers and their brackets. I kept the brackets but got Pagid calipers on exchange from Euro Car Parts. I also did the rears with larger discs/calipers but it involved some modification to make the handbrake work. I did a full write up some 4 years or so ago as I'd fitted a turbo.

[TVR Stef]

I've done just this upgrade a few years ago, and it worked fine.

I used the Fiesta ST calipers and the Sierra Cosworth 283mm discs and there is plenty of clearance within the standard 15" wheels. The only spacer that is needed is about 2-3mm (I just used thick washers) for the calipers, when I removed the standard calipers they also had a space but much bigger.

Just tried to get a pic but too dark and cramped in the garage to get a good shot.

[Fenderer]

Brilliant thanks TVRStef, that helps a lot.

Thanks N7GTX too. I did consider the Mondeo route too but I just think the Fiesta ST option will be a better fit for the standard wheels.

[TVR Stef]

Not a problem, I mainly went the ST route as the calipers were easier (and cheaper) to get hold of. Don't forget to get the carriers as well!

Managed to get a few photos this morning, hope they help.





Spacer required to centre caliper to disc:

[Fenderer]

Brilliant, thanks for the photos. They really help a lot. All looks really good.