Front Brake Upgrade 278mm Discs - Ford Callipers

[Alan Whitaker]

Hi All
It's been the norm in Kit car and some motorsport to put a washer between the caliper and the mount, I say a washer as that does not put a side or twisting force on the bolt, when it comes to thicker spacers it will stress the bolts, nobody knows where the thickness and dia of the spacers becomes a problem but a solid steel or aluminium piece between the caliper and mount will eliminate any twisting or stress on the bolts it links both bolts to the caliper and mount. anything above 2mm and I would make a plate up and that's my 2c on this.

Alan

Alan

[mk1fan]

I can see what you mean about the spacers. In simplistic terms its like trying to push over a cotton bobbin and a margarine tube. Having a one peice spacer would be ideal I agree.

As for bolts. Qbee was reiterating the need for proper hi-ten bolts 10.9 or above as someone had not used them on his car. I think this is relevant to standard or modified brakes.

As I have repeatedly said there is the choice to fit either 58 or 48mm high discs. 48mm being the height of the standard set up. If these are fitted then the callipers can bolt straight to the uprights. Perhaps a hi-ten washer is required.

Fitting 58mm discs moves the disc out / away from the centre line of the car.

[greymrj]

Sorry Stewart but I need to get this clear in my ageing mind! You have fitted 48mm discs and needed 11mm spacer. With 54mm discs you would have needed 1mm spacer. Sorry to be a pain but I genuinely do want to understand, can you clarify the dimensions and exactly what you are measuring because those two sets of figures do not add up in my mind yet.

[mk1fan]

Sorry got my dims the wrong way round. Still abit out of whack from my 'holiday'.

Ford produced the 278 and 283 diameter discs with an overall 'height' of 48mm and 58mm. That is, if you lay the discs on a flat surface they would measure 48 and 58mm high.

The standard S set up uses discs 58mm high. So using 58mm high discs should mean the new callipers bolt directly to the upright. Washers maybe required to take up some tollerance issues - it doesn't take much to build up 1mm.

When TGTVR did his upgrade he had issues sourcing the 273mm 58mm and 273mm 48mm high discs so turned down a set of 283mm to avoid modding the carriers.

To use the 48mm high discs a spacer is required between the carrier and the upright.

[v8s4me]

What would be the effect of having 273mm (solid) discs on the rear and 260mm on the front. If the frontslock up at the moment (260mm) would the larger rears help balance up the breaking, or would all four just lock up?

[mk1fan]

Didn't know 273mm solid discs were available.

[magpies]

Would have thought under heavy braking the front should lock just before rear

[v8s4me]

mk1fan said:

Didn't know 273mm solid discs were available.

Ferodo DDF388

Edited by v8s4me on Tuesday 4th August 23:13

[phillpot]

Solid (Cozzy RWD) or vented (Cozzy 4x4), can't see there being any detectable difference unless you get 'em really cooking, where the better cooling of a vented disc may come into play?



Same pads on both sizes so only advantage is the extra "leverage" of a 10mm radius bigger disc. short of doing some back to back tests (and a set of tyres you don't mind flat spotting) will you ever tell the difference

Edited by phillpot on Tuesday 4th August 23:26

[magpies]

Must admit the ultimate braking probably depends upon the tyres once the car has a decent set of brakes

[phillpot]

If "you" get into a situation where you really have to "slap 'em on" there are so many other factors in play, reaction time, road surface,make of pads, tyres etc. is your choice of disc size going to be the difference between "that was close" or "here's my insurance details"

[v8s4me]

magpies said:

Must admit the ultimate braking probably depends upon the tyres once the car has a decent set of brakes

That's where I'm coming from really. The 260mm fronts already out-brake the tyres (Dunlop Fast Response) so what is the point of going larger on the front? I was wondering if going up a size on the rears would give a bit more stopping power once the fronts had started to slide?

[phillpot]

v8s4me said:

what is the point of going larger on the front?

Bragging rights rites, "mine are bigger than yours"

Edited by phillpot on Wednesday 5th August 10:01

[zombeh]

v8s4me said:

What would be the effect of having 273mm (solid) discs on the rear and 260mm on the front. If the frontslock up at the moment (260mm) would the larger rears help balance up the breaking, or would all four just lock up?

If you want to lock the rears up on a V8 just change down too early (I suspect the v6s aren't *quite* as bad for this)

I found 260mm fronts (with xr4/griff calipers) and the standard 253? rears gave a much better overall balance with the way I drive the car on the road and on track, in theory doing that has actually reduced the braking performance by moving the bias too far forward but I'd rather need a meter or two extra to stop than arrive pointing the wrong way

[v8s4me]

phillpot said:

...Bragging rights rites, "mine are bigger than yours" ...

Yes but my bulge is bigger than yours

[Top Gear TVR]

Mine are 278 front and 273 x 20 ventilated rears. Balance has never been so good and they don't overheat, ever!

[v8s4me]

Top Gear TVR said:

Mine are 278 front and 273 x 20 ventilated rears. Balance has never been so good and they don't overheat, ever!

And you don't have a spacer issue. Clever

[greymrj]

Hi Stewart, could you do me a favour and PM me direct about this issue, I want your advice.

[mk1fan]

Sent an e-mail.

[phillpot]

greymrj said:

Sorry Stewart but I need to get this clear in my ageing mind! You have fitted 48mm discs and needed 11mm spacer. With 54mm discs you would have needed 1mm spacer.

My two'penneth......


"Standard" disc is 58.1mm


So the 278 dia. Scorpio Cosworth disc at 47.5mm needs a 10.5mm spacer to push the caliper further into the wheel.

283 dia. RWD Sierra Cosworth disc at 55mm should need a 3mm (thick washer) spacer.