G4 / D2 8 Piston Brakes - The Diffinitive Review

[tacker]

I have been shown a pic with red hot rotors on my car by a bystander and his camera phone.

[Sydneykid]

Under hard driving on the street you feel a bit more confident but in reality you are traction limited long before the brakes run into problems even with a quality standard sized setup, so it's not really possible to experience anything extra the G4 kit might give you.

I think it worth emphasizing this point, the tyres are the limiting factor in braking performance in most Skylines, not the brakes themselves. If maintained properly, the standard 4 spot front and 2 spot rear brakes are more than capable of outbraking the best/biggest road tyres you can buy.

cheers

[Laurence]

As far as multipiston theory goes... I always thought it was to give greater leverage on the rotor for the same diameter of rotor. In a racing series brake diameter is limited by wheel size or regulation. You can run bigger rotors by running low profile calipers but also the further out you put the pad the more leverage it has.

Anyway just a theory I made up, so feel free to ignore it. I drew something in MS-paint using the pad on my laptop but then gave up cause it was too hard. Anyway just based on Torque = Force x Length it made sense to me.

[Roy]

Thats partly it. The other is a longer pad means more surface area of pad which helps with lower pad temperatures meaning less need for craxy high temp pads. Also the fact that the narrower pad means for a given rotor diam you have a shallower pad which allows you to run a narrower steel rotor with larger alloy hat reducing unspring weight. Also the larger pads means you have less localised heating of the rotor which at high temps can help with the onset of rotor warping. Then you have the more even pad wear...there are a whole bunch of reasons. If i wasnt drunk i could think up some more

[Sydneykid]

I had the opportunity to look at a set of these last week and I was surprised at how small the mounting hardware is. Grossly undersized in my opinion, flex just waiting to happen. Bolts coming loose is a telling symptom of that problem.

Cheers

Gary

[phunky_monkey]

Does anyone have the measurements of these calipers, or a spec sheet?

The design is a knock off of an AP from memory, if I can't get the measurements, does anyone know which caliper they copied?

Cheers

Dane

[skylinekid]

ok well if u guys have only ever heard of these g4 brake calipers coming loose ive seen worse.

r33 gtst here where i live fraser coast has a set of alcon 8 pots front and 6 pot rears. it was driving along behind him and the right rear suddenly locked up solid flat spotting the good ol nankang lol. now like i said alcon like 8 grand of brake front and back and one of the bolts thats hold the caliper to the original bracket had come out and the whole caliper flicked up hitting his 19inch chrome wheels. i couldnt help but laugh at the time cuz all he did was take the caliper off put a set of vice grips on the line and drive it home. either way moral of the story never blame the equipment until proven guilty. and yes loctite always comes in handy.....

now im not saying u didnt do a good job at tightening ur bolts either ok so dont have a go lol.

[Lunatikk]

Does anyone have the measurements of these calipers, or a spec sheet?

The design is a knock off of an AP from memory, if I can't get the measurements, does anyone know which caliper they copied?

Cheers

Dane

I've got a pair of Monobloc 8-piston Brembo's & before they went on the car I put them on the bench side-by-side with a pair of the D2's. From memory they were pretty much identical as per the piston spacings & overall dimensions etc although the pics of the G4's at the start of this thread appear to have a large leading piston & 3 small trailing pistons whereas my Brembo's are staggered big-small big-small.

The other big difference apart from the monobloc construction vs the 2-piece construction of the D2/G4's was where the D2's use on single pad per side, my Brembo's use 2 pads per side with the ability to "quick change" the pads out thru the top so they are effectively 2 sets of 4-piston calipers sharing a common body & hydraulic circuit.

They def seem to be a "knock-off" but whether they copied Brembo directly with regard to the piston specs or copied the AP's which in turn copied the Brembo's (but went to a single pad to avoid patent-infringement etc), I don't know.

[Ronin 09]

doesn't AP own Brembo or the other way around?

[R34GTFOUR]

like everyone else said, great write up

just wondering since your running just the front setup, have you noticed any brake bias at all?

[Roy]

...whereas my Brembo's are staggered big-small big-small.

... my Brembo's use 2 pads per side with the ability to "quick change" the pads out thru the top so they are effectively 2 sets of 4-piston calipers sharing a common body & hydraulic circuit.

Thats why your caliper does the big small, big smal differential piston sizes, because as you noted you effectively have two 4 piston calipers in one with you running the two pads. If the caliper only used 2 pads, one each side you would expect the traditional small leading and larger trailing pistons

[Duncan]

I have these on the stagea with standard master cylinder and standard rears - no sign of bias problems. they are very small pistons

[boostdq]

So the big question. How do these compare to R33/34 GTR brembos - or similar braking setup for around the same price?

[Duncan]

I upgraded to these from the 33/34 brembos. the brembos are rubbish for such a heavy car with so much go. the g4s are 21mm bigger slotted discs, calipers are bigger and lighter, and the pads are about 20% bigger too. No comparison

[Roy]

Yeh, thats why i am using S13 brakes now on my car

[SLY33]

Great write up, thanks for taking the time!

Guys are the stock GTR brembo's really that bad?? Most people say the stock 33GTSt calipers are much underestimated, and the GTR brembos have got to be a yard ahead of those surely?

Im planning a top end brake upgrade for my GTR and conveniently upgrade my GTS-t with the old brembos front and rear at the same time.

[Roy]

The OE GTR Brembos are pretty good calipers. Problem is when people ask the money they do for them. Its the whole supply and demand thing. There are some other attractive options when you are looking to pay $1600 odd for front calipers with used rotors and pads.

And as far as OE Brembos the Nissan caliper is behind most others fitted to EVOs, STIs, Jags etc

[tacker]

the G4 can take a AP 6pot pad as i got some from from a guy in the BTCC.

As far as i can tell they are a thing of beauty for the money got 2000 kms out of the last set of rotors and its a track only car. I was more than please as they lasted the same amount of kms as my mates RBA 5000 on my mates EVO track car

[phunky_monkey]

Yeh, thats why i am using S13 brakes now on my car

Haha nice Troy. Top brakes, the old S13's

[Abo Bob]

I just wanted to post somewhere in here that I have now had the opportunity to use the "race" pads that Just Jap sell for the G4's. I have standard rear brakes with BEndix Ultimates in there and find that not only is there no bias issues, I have fixed a bias issue that I believe the car has from factory. I was regularly cooking rear rotors and pads before but now it all runs fine. Lap times are down and the car stops amazingly. I was regularly braking far too early due to being used to the standard setup. With the addition of good tyres and these brakes I knocked 3 seconds off my previous pb at Wakie.