AP Brakes

[Mjpmark]

Guys

Can anyone tell me if the standard factory supplied AP Brake Kit can accept a larger Brake Disc?
If so how large and what else would be required?

Thanks

Mark

[GTWayne]

I have 362mm discs with six pot AP's on the GTW and that is the largest you will get to fit inside an 18" rim. I reckon you could use this size disc with the standard four pot caliper but you would obviously need to fabricate new brackets to fit the caliper to the upright.

[Gulf -LS2]

ive got 385mm in my 18's..... only 4 pots though

[GTWayne]

^^^ I forgot, the original split rims can accommodate a larger disc, 362mm is the max that can be fitted inside my magnesium Dymags
It is worth bearing in mind that using only a larger disc is fairly unproductive in increasing the effectiveness of your brakes, it may aid cooling a little but a larger pad area is what is really needed to improve efficiency

Forgot to mention the added weight of the larger disc X 4, it all adds up although a meaningful improvement in braking efficiency would more than compensate I guess.

Edited by GTWayne on Saturday 8th August 23:14

[San Diego GTR]

So did you notice any meaningful improvement in stopping effectiveness with the 6 pots vs 4?
Thanks,
Paul

[GTWayne]

I have only ever known the car with six pot calipers as they were fitted from new. Interestingly enough, I have heard two individual owners slate the standard brakes and they both had Mitsubishi Evo's before the GTR, strange 'eh?
I think pad material plays a very large part with regards to the feel you get from an non servo assisted car with a 40/60 front to rear weight split. Another area worth exploring with regards to pedal feel is possibly using a smaller master cylinder; the pedal will move nearer the floor but feel will improve. My brakes do feel a little wooden but they sure do stop the car

[GTRCLIVE]

Don't play with Cylinder size, but you can play with the Pedal ratio, that helps with feel. But they will always be hard when cold, and takes some getting used to.

[GTWayne]

GTRCLIVE said:

...Don't play with Cylinder size...

Why not?

[GTRMikie]

GTWayne said:

using only a larger disc is fairly unproductive in increasing the effectiveness of your brakes

Edited by GTWayne on Saturday 8th August 23:14

Surely it is much easier to stop a rotating disc if you grab it near the circumference rather than near the centre, so wouldn't a larger disc give better braking? ( I know that on a classic mini, the 8.4" discs give much better stopping power than the 7.5's)

[GTWayne]

^^^ Good point Mike, it may well technically be the right way to go, or at least a step forward as opposed to standing still, but more pad swept area on a standard disc will still give a better brake. After all, it's not like the standard size disc is small is it?

[srreck]

I tryed to fit the Ultima 4 pot on new 362mm discs. It doesn't work. The radious of the caliper doesn't match the radious of the disc. I was reading the AP's manual and maximun disc diameter for the 4 pot is 330 x 32mm. You will need the 6 pot units.

[ezakimak]

http://www.roymech.co.uk/Useful_Tables/Drive/Axial...

clutch theory?

consider the condition as Ri approaches Ro

Edited by ezakimak on Monday 10th August 09:57

[GTWayne]

srreck said:

...maximun disc diameter for the 4 pot is 330 x 32mm...

That is strange as GulfLS2 states above that he has 385mm discs ( I presume he has standard four pot calipers )
Gulf, please elaborate?

[Rusti Evo]

I have just started testing the Pagid RS 29 pads and have done 1 trackday and some road miles.

The bite is improved a bit and maybe a tad more feel. Will report back when the smaller master cylinders are fitted.

Didn't use my favourite Carbotech pads as their performance without a servo was uncertain. Also didn't use the DS3000 as they would have trashed the wheels.

[srreck]

GTWayne said:

srreck said:

...maximun disc diameter for the 4 pot is 330 x 32mm...

That is strange as GulfLS2 states above that he has 385mm discs ( I presume he has standard four pot calipers )
Gulf, please elaborate?

My comments are concerning the CP5000 series. May be bigger 4 pot that can manage a 385 disc....(very tight I think).

[Mjpmark]

Ap have just confirmed that a max of 330mm disc will fit nothing more.

[Gulf -LS2]

GTWayne said:

srreck said:

...maximun disc diameter for the 4 pot is 330 x 32mm...

That is strange as GulfLS2 states above that he has 385mm discs ( I presume he has standard four pot calipers )
Gulf, please elaborate?

A bit misleading on my part im sorry.....

I have custom made Hi Spec brakes with 4 pots and 385mm discs

[Mjpmark]

Kyle, it looks like sticking with the 4 pot AP's, unless i upgrade the whole kit to Ap's 6 pot or the larger Hi-Spec kit, other than the standard AP discs looking tiny im probably best off sticking with them.

I'd be best to plough the money into the Supercharger. Agreed?

[Gulf -LS2]

Mjpmark said:

Kyle, it looks like sticking with the 4 pot AP's, unless i upgrade the whole kit to Ap's 6 pot or the larger Hi-Spec kit, other than the standard AP discs looking tiny im probably best off sticking with them.

I'd be best to plough the money into the Supercharger. Agreed?

they work well mate!!! they just look like metro discs on your Ultima!!

[Rusti Evo]

Sorry for butting in with my comments on pads I should have explained fully.

As I see it the factory standard setup provides the fastest decellerating road car on the planet so I don't need more brakes. What I'm trying to do is to improve on the wooden dead pedal. With a bit more bite and some normal feel to the pedal it would take a hell of a track driver to need more than the standard 4 pots. (that driver certainly isn't me...........)