Brake Upgrade

[JAGR33]

Jack, who on here is still running just front AP CP5555s? snowflake has rears as far a i know... how do they go at Sandown?

I can't think of anyone that just runs the AP CP5555s on the front, actually STOCKGTR (Nick) on these forums runs AP fronts with standard rears, although he hasn't been on the track for a while, maybe shoot him a PM for his opinion...

Will be good to see your car out on the track!!!!

[djr81]

I bought mine through Unique Autosports, was about $8.4k for the whole kit, so 5k for the fronts sounds about right...

Check here: http://www.nismo.com.au/pricelists/pricelist_gtrbrakes.htm

Although the kit comes with Ferodo DS2500 pads for the front, if you ask nicely I'm sure John at UAS will chuck in the Ferodo DS3000's instead....

DS2500 are good for the street, but with your car you'll need the DS3000's....

Noice. Some questions:

Which rotor diameter did you get (365mm?)

What wheel rim diameter are you running?

What sort of piston area are those things running at the front & rear?

[Beer Baron]

man, johnny's brake page is a dangerous place to browse! god he has some nice brakes there. I want one of each.

[maccattack]

I run a 17" rim for track work - I suppose I should look at changing size to 18's to accommodate larger rotors? Thoughts!!

[Roy]

Well, personally, i think 355 is on the money. You are better running a ticker rotor then larger diameter rotor. At 355 you can still run 17" rims and tyres. Although if you find you are heating up 17" semis too quickly then that is another reason what you may want to move to 18" rims/tyres.

But as far as braking and handling goes, i would think 355mm x 36 is the ideal rotor size. Next to that 355x32. But 365x32 wotn be any heavier really then the 355x36.

[Ronin 09]

Well, personally, i think 355 is on the money. You are better running a ticker rotor then larger diameter rotor. At 355 you can still run 17" rims and tyres. Although if you find you are heating up 17" semis too quickly then that is another reason what you may want to move to 18" rims/tyres.

But as far as braking and handling goes, i would think 355mm x 36 is the ideal rotor size. Next to that 355x32. But 365x32 wotn be any heavier really then the 355x36.

yes but a 355 you may struggle to get under a 17" with good clearance (unless it's a Te37 or similar)

furthermore a 36mm rotor takes longer to get the pads up to temp

[ferni]

Noice. Some questions:

Which rotor diameter did you get (365mm?)

What wheel rim diameter are you running?

What sort of piston area are those things running at the front & rear?

Yeah they are 365mm up front.

He runs 18"x 10.5" CE28 on track and 18x10.5" LMGT4 for street....

Not sure about piston area sorry...

[JAGR33]

I run a 17" rim for track work - I suppose I should look at changing size to 18's to accommodate larger rotors? Thoughts!!

Definetly!!! 17's will not accomodate for 355mm rotors, and if they do there will be fark all clearance between the rim and the caliper.

Also 18's you will be able to go wider aswell, and run atleast a 265 wide tyre = more grip....

[JAGR33]

Yeah they are 365mm up front.

He runs 18"x 10.5" CE28 on track and 18x10.5" LMGT4 for street....

Not sure about piston area sorry...

Correct, although not sure on what piston diameter the Alcons run..

Roy (the brake expert!!!) reckons they have a larger piston diameter than the AP CP5555 calipers... I don't have concrete evidence...

[Ronin 09]

Correct, although not sure on what piston diameter the Alcons run..

Roy (the brake expert!!!) reckons they have a larger piston diameter than the AP CP5555 calipers... I don't have concrete evidence...

how about this - you give me your car, i take the calipers off, and measure them.

i give you your car back.

deal?

[sav man]

Jack, who on here is still running just front AP CP5555s? snowflake has rears as far a i know... how do they go at Sandown?

I don't have AP CP5555's, but i've got Porsche/Brembo 6 pot's on 355x32 rotors with stock rears. I do have Hawk blue pad on the rear, but they are bog stock appart form that (not even slotted rotors).

Edited September 24, 2007 by sav man

[Roy]

Well ppl are fitting 355mm rotors with the bulky Brembo F50 caliper under a 17" wheel, (GTR offset) so since it is one of the bulkier and more rigid calipers gettign around?!?! Though yes, you are left with stuff all clearance to the inner wheel.

AP CP5555 calipers have the following piston sizes: 27mm x 2 / 31.8mm x 2 / 38.1mm x 2

Alcon Monobloc 6 piston calipers piston sizes : 30.2mm x 2 / 34.9mm x 2 / 41.3mm x 2 (i have also seen a data sheet saying the largest pistons are 38.1mm which makes more sense then the 41.3mm)

So as you can see the Alcons have a lot larger piston area then the APs

[R32 TT]

Ok, I've got to get in on this because I want to know what you guys think about how all this alters the brake balance front to rear and what you have done about it?

ie, you go put a massive set of brakes on the front, and yes - now they don't fade, you always have brakes etc. All good.

But do guys check your stopping distances before and after? Or is it just not making that much difference..?

Do you have any adjustment to sort this out?

Technically, it should be making your stopping distances longer since the rear brake will be proportionally less effective.. so by the time your fronts are at maximum braking force, your rears are only doing 50% of their potential braking... (numbers for example only ...you get what I mean...)

[JAGR33]

Well ppl are fitting 355mm rotors with the bulky Brembo F50 caliper under a 17" wheel, (GTR offset) so since it is one of the bulkier and more rigid calipers gettign around?!?! Though yes, you are left with stuff all clearance to the inner wheel.

AP CP5555 calipers have the following piston sizes: 27mm x 2 / 31.8mm x 2 / 38.1mm x 2

Alcon Monobloc 6 piston calipers piston sizes : 30.2mm x 2 / 34.9mm x 2 / 41.3mm x 2 (i have also seen a data sheet saying the largest pistons are 38.1mm which makes more sense then the 41.3mm)

So as you can see the Alcons have a lot larger piston area then the APs

I told you, he IS THE MASTER!!!!

[Ronin 09]

Well ppl are fitting 355mm rotors with the bulky Brembo F50 caliper under a 17" wheel, (GTR offset) so since it is one of the bulkier and more rigid calipers gettign around?!?! Though yes, you are left with stuff all clearance to the inner wheel.

AP CP5555 calipers have the following piston sizes: 27mm x 2 / 31.8mm x 2 / 38.1mm x 2

Alcon Monobloc 6 piston calipers piston sizes : 30.2mm x 2 / 34.9mm x 2 / 41.3mm x 2 (i have also seen a data sheet saying the largest pistons are 38.1mm which makes more sense then the 41.3mm)

So as you can see the Alcons have a lot larger piston area then the APs

you freaking brake nerd-alert

[Swiper the Fox]

Has anyone successfully made a bracket and sourced a rotor to offset the STD brake caliper.

Im looking for a budget upgrade.

[Ronin 09]

Has anyone successfully made a bracket and sourced a rotor to offset the STD brake caliper.

Im looking for a budget upgrade.

there's a japanese kit that offsets the std gtr32 sumitomo to a 324 (around that) Supra JZA-80 rotor...

will have a look around for it - it's in one of the HyperREV GTR publications

[djr81]

Ok, I've got to get in on this because I want to know what you guys think about how all this alters the brake balance front to rear and what you have done about it?

ie, you go put a massive set of brakes on the front, and yes - now they don't fade, you always have brakes etc. All good.

But do guys check your stopping distances before and after? Or is it just not making that much difference..?

Do you have any adjustment to sort this out?

Technically, it should be making your stopping distances longer since the rear brake will be proportionally less effective.. so by the time your fronts are at maximum braking force, your rears are only doing 50% of their potential braking... (numbers for example only ...you get what I mean...)

There are three parameters for the brakes (Assuming you have no external balancer).

1. Piston size. The larger the piston area in the calliper the greater the bias toward that end.

2. Rotor diameter. The larger the rotor diameter the greater the bias toward that end.

3. Brake pad friction coefficient. The higher the brake pad friction coefficient the greater the bias toward that end.

A new set of brakes SHOULDN'T massively change your stopping distances on a once off basis, unless you are running very sticky tyres that is. What it will do is stop you well time & again.

The frustration I get is that very few of the suppliers will quote you piston areas (or clearances for the rims) & all of them assure you their particular setup will be balanced nicely. So they offer you a larger rotor with a unchanged piston area for the fronts & then tell you the balance will be fine.

So either it doesn't matter or they are full of shit. I haven't made up my mind on that, but I suspect the latter.....

Edited September 25, 2007 by djr81

[Roy]

There are three parameters for the brakes (Assuming you have no external balancer).

1. Piston size. The smaller the piston area in the calliper the greater the bias toward that end.

Is that right? Brake bias is the ratio of brakign torque front to rear. So if you increase the piston diameters at the front then you are increasing the front brakign torque whereby increasing the front bias.

Now pedal travel is a different thing...we are talkign brake bias arent we ???

[djr81]

Yeah sorry, upside down Miss Jane.

You need to team a larger rotor with a smaller piston area for the smae brake bias.

I fixed the first post. Need to engage the brain before the keyboard.