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Discussion Starter · #1 ·
while pricing out some brake kits (the Endless 6 pot/racing 4 pot kit is what I'm drooling over), it occurred to me that there might be another way other than just doing the fronts - I've seen a fair number of cars with just the fronts done (massive 6 or 8 pot kits) and then the stock 2 pot calipers in the rear. Not only does it look silly, but I imagine braking balance must be way off.

But the economics of it are indisputable - full front and rear kits are damned expensive!

So, seeing as I already have 4 pot calipers (on the front), in just the right size for a big brake kit in the rear, why not just move them rearwards, then just get the 355mm front kit that I want?

the issues that I see:
- will the front discs mount on the rear spindle?
- how hard will it be to fabricate a mounting bracket for the calipers, or might the front bracket be adapted to the rear with some modifications?
- the drum e-brake will be gone, of course, but adding mechanical (cable-actuated) e-brake disc calipers (like the Brembos used on Ferraris) could take care of that. Would need a mounting bracket for those however.
-are stock BNR32 front brakes significantly more powerful than upgraded racing 4pot rear brakes? Hopefully they'd be about the same, to maintain front/rear balance.

any thoughts? thanks!
 

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Although it makes sense to upgrade both front and rears at the same time to keep the bias correct the front discs and calipers are far too big for the rear. You would have to compare disc size, piston size and pad size percentages to front and rear to get an idea of how you're moving away form the standard bias but I doubt that even a huge 6 pot front system would warrant the current GT-R front 4 pots on the back!
 

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Discussion Starter · #3 ·
not if I put 370mm 12pots in front :D
 

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I have AP 6 pots on the front of my R32 and the two pot Brembo's on the back (standard Vspec) almost lock when braking hard due to the weight transfer. So I won't be spending any money upgrading any further.
 

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Indeed, 343mm AP disks with 6-pot calipers and proper cooling with std rear brakes make fro an excellent well balanced track package.

People always want biggest / most expensive etc etc.

Larger disks / calipers not only increase unsprung weight but also increase relative disk velocity at the pad. Neither of which is good.......
 

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Discussion Starter · #8 ·
never seen anything like that, wow. how much bigger of a disc can you run with those offset adapters?

disc velocity at pad. true. never thought of that. you learn something new every day...:)
 

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I'll have a complete set of R34 brakes (front & rear) available in around a months time if you're interested. Mint condition calipers with plenty of life left in the pads and discs. Not as nice as a set of Endless 6-pots obviously, but a cost effective way of upgrading both the front and rear.
 

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Discussion Starter · #11 ·
you're in Yokohama? Close enough to make EMS reasonably priced - PM for sure when you've got your brakes off...what are you upgrading to?? :)
 

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something else worth thinking about is the handbrake ;)

Rob
 

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Discussion Starter · #13 ·
something else worth thinking about is the handbrake ;)

Rob
as stated above, if I did put the fronts in the rear, I'd have to add separate rear cable-actuated e-brake calipers plus brackets. Brembo makes them and they're OEM on Ferraris. Small little things they are, kinda cute actually. Haven't weighed them but they look a lot lighter than a drum e-brake setup, at least on the F430 I saw them on (wheels off of course).

I'll have to look up the sizes, but aren't some big brake rear 4 pot rotors the same size as the stock BNR32 fronts?
 

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Interesting thought as it goes...

Wonder how close the brembo rears are to the sumitomo fronts?

Not that it wouldnt be overkill, just wondered.

Rob
 

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Discussion Starter · #15 ·
Interesting thought as it goes...

Wonder how close the brembo rears are to the sumitomo fronts?

Not that it wouldnt be overkill, just wondered.

Rob
I got the idea by seeing the rear calipers on a few cars at my tuners, particularly the F430 and the Carrera GT - they looked as big as the Sumitomo fronts and are obviously also 4 pot units. Once I saw the Brembo rear disc e-brake calipers, I realized that it might be possible.

However, in order to get fronts powerful enough to balance the Sumitomo 4 pots, I'm sure I'd have to get 19" wheels, and I don't even want to step up to 18"...355mm is therefore my absolute limit.
 

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Discussion Starter · #16 · (Edited)
well, here are some dimensional info:

BNR32 Sumitomo 4 pot fronts, disc 296x32mm
Endless Racing 4 rears (for BNR32), disc 332x30mm (Endless fronts are 355x32mm)

any experts want to chime in on what really makes braking power? If I recall my hydraulics correctly, the pressure of the pistons on the pads will be equal, regardless of the number of pistons. So it seems to me that braking power depends on pad surface area.

are these assumptions correct?
-more pistons allow larger calipers, and therefore more brake pad surface area to be applied to the disc
-larger discs can dissipate heat better
 

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Discussion Starter · #17 ·
Brembo e-brake calipers and brackets run up to $1000US...so much for the economics of this idea :p

it's R33 Brembos for me I guess.
 

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I was writing an article for the Skylines magazine about Brake Tech but as usual with me other things have got in the way of it. Basically putting big brakes on the rear is a waste of time in anything but a proper race car and even then they are not that large. Too big can be down right dangerous for a number of reasons...

Rear locks up too early - golden rules in braking - front MUST ALWAYS lock up first
ABS helps in straight line but can cause other issues while cornering especially if rear brakes are too good
ABS needs reprogramming to work correctly for a big change in disc size
Big discs can affect cooling and heat up suspension components as they are now to near then the manufacturer was expecting etc etc etc

and about 100 other issues.

I think I'll finish the article (that's not a promise John :eek: ).

At the end of the day your tyres are the thing that stops you - the brakes just bleed off the energy. Get yourself some better tyres.
 

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ABS needs reprogramming to work correctly for a big change in disc size
Big discs can affect cooling and heat up suspension components as they are now to near then the manufacturer was expecting etc etc etc
Basically I agree with what you said but these two points are quite interesting.
Why would the ABS need re-programming ? It may be beneficial to do so but I think need may be over-stressing it.
Also, the heat from the brakes can still only really pass through the hub; the conduction through the air couldn't transfer enough heat to affect the suspension (not whilst your moving anyway).
 
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