My $600 Big Brake Kit

[JRitt]

Okay...we got a chance to look at the numbers. I'm still not 100% clear on the actual piston sizes you guys figured out on the calipers being used, so we ran all three scenarios. The disc was held constant at the 317mm diameter. We took a an educated guess on effective radius (which basically means where the center line of the piston is clamping on the disc).

If the piston sizes are 4x30mm or 4x26mm, the bias is way off. That's what caught my eye when I first read the thread. You'd be going from what we calculate as a roughly 67% front bias to a low 50% front bias. I'd definitely say to steer clear of doing such a swap. I would expect longer stopping distances than stock, as well as potential ABS issues.

If the piston sizes are 4x40.45mm (which is the number that was provided later in the thread and sounds more likely given the car from which they're sourced), then yes, the front bias is within a couple % of stock as eikond calculated. I would not expect any issues with ABS integration, etc.

If that's the case, you just have to look at all of the other variables that go along with the swap to see if it makes sense for your needs and goals (as described above).

[JRitt]

A couple of further points for consideration:

Pads
The OEM front BRZ pad is what Ferodo calls an FCP1639 with the following dimensions (in mm):
137.5 x 50.1 x 17.6

The 300ZX front caliper under discussion uses a smaller pad, which is the FCP986:
119.3 x 49.5 x 14.5
So this one is about 20mm shorter and 2mm thinner. The 300ZX is a little more square though. The 300ZX is going to have a slightly lower overall pad volume and heat capacity, and provides the pistons with less insulation from heat due to the thinner thickness.

Also for reference (and this is an important one), the OEM FT86 pad in Ferodo's top racing pad compound (DS1.11) retails for $250.82. The DS1.11 in the 300ZX shape is $445.37...that's a $200 difference in price on every pad change! So you're going to have less pad material at a considerably higher price. I'm not sure what the pricing structure is for other manufacturers, but it's something to look into, particularly if you were thinking about tracking this setup. The real bugger is figuring out if that larger disc is going to net you any better of a pad wear rate vs. a stock pad on a stock disc, despite the pad having lower overall volume and thickness. Putting a number to that is darn near impossible with so many factors involved.

Discs
Even though the discs do provide a larger heat sink, they aren't providing any greater efficiency (which is one of the primary functions of the disc in a purposefully designed BBK). If you buy a Centric 120.xx blank disc, it's still going to be a pillar vane disc that doesn't necessarily pump much air (see my previous long post above on heat transfer and evacuation). You also don't gain any of the benefits of an aluminum hat with regards to heat transfer or weight reduction.

As eikond mentioned above, you do still have a small net weight loss on the corner, although that is going to be offset by having substantially more rotational mass in the disc (which means it takes more energy/power to accelerate that larger disc vs. an OEM FT86 disc).

An easier pad change is a clear plus. Cosmetics would depend on the condition of the calipers you get your hands on and what you do with them (shave the Nissan off, paint them, etc. as eikond plans to do). If they're beat up from use or sitting in a junkyard, need new seals, etc. the rebuild would add a bit more cost as well.

Overall though, I have to commend eikond for creatively digging into the project and exploring new options.

[eikond]

Originally Posted by JRitt

Okay...we got a chance to look at the numbers. I'm still not 100% clear on the actual piston sizes you guys figured out on the calipers being used, so we ran all three scenarios.

If the piston sizes are 4x40.45mm (which is the number that was provided later in the thread and sounds more likely given the car from which they're sourced), then yes, the front bias is within a couple % of stock as eikond calculated. I would not expect any issues with ABS integration, etc.

This is the case.. 4 x 40.45mm. I've found this data in multiple sources online as well as an eyeball with an unexact tape measure in my own garage.

Interesting point on the pad costs.. I hadn't considered this. I did a quick check on the project Mu NS400 pads and found them to be about $100 for Z32 and about $90 for BRZ. Interesting that Ferrodo is such a big difference.. This will probably be luck of the draw.. but something to consider before making any change.

[finch1750]

Originally Posted by JRitt

A couple of further points for consideration:

Pads
The OEM front BRZ pad is what Ferodo calls an FCP1639 with the following dimensions (in mm):
137.5 x 50.1 x 17.6

The 300ZX front caliper under discussion uses a smaller pad, which is the FCP986:
119.3 x 49.5 x 14.5
So this one is about 20mm shorter and 2mm thinner. The 300ZX is a little more square though. The 300ZX is going to have a slightly lower overall pad volume and heat capacity, and provides the pistons with less insulation from heat due to the thinner thickness.

Also for reference (and this is an important one), the OEM FT86 pad in Ferodo's top racing pad compound (DS1.11) retails for $250.82. The DS1.11 in the 300ZX shape is $445.37...that's a $200 difference in price on every pad change! So you're going to have less pad material at a considerably higher price. I'm not sure what the pricing structure is for other manufacturers, but it's something to look into, particularly if you were thinking about tracking this setup. The real bugger is figuring out if that larger disc is going to net you any better of a pad wear rate vs. a stock pad on a stock disc, despite the pad having lower overall volume and thickness. Putting a number to that is darn near impossible with so many factors involved.

Discs
Even though the discs do provide a larger heat sink, they aren't providing any greater efficiency (which is one of the primary functions of the disc in a purposefully designed BBK). If you buy a Centric 120.xx blank disc, it's still going to be a pillar vane disc that doesn't necessarily pump much air (see my previous long post above on heat transfer and evacuation). You also don't gain any of the benefits of an aluminum hat with regards to heat transfer or weight reduction.

As eikond mentioned above, you do still have a small net weight loss on the corner, although that is going to be offset by having substantially more rotational mass in the disc (which means it takes more energy/power to accelerate that larger disc vs. an OEM FT86 disc).

An easier pad change is a clear plus. Cosmetics would depend on the condition of the calipers you get your hands on and what you do with them (shave the Nissan off, paint them, etc. as eikond plans to do). If they're beat up from use or sitting in a junkyard, need new seals, etc. the rebuild would add a bit more cost as well.

Overall though, I have to commend eikond for creatively digging into the project and exploring new options.

Originally Posted by eikond

This is the case.. 4 x 40.45mm. I've found this data in multiple sources online as well as an eyeball with an unexact tape measure in my own garage.

Interesting point on the pad costs.. I hadn't considered this. I did a quick check on the project Mu NS400 pads and found them to be about $100 for Z32 and about $90 for BRZ. Interesting that Ferrodo is such a big difference.. This will probably be luck of the draw.. but something to consider before making any change.

Just to give more info. The pricing is very manufacturer dependant it appears. I looked at the pad choices I would choose from and found this (straight from Winmax and Mackin Industries websites).


Project Mu HC+800

Nissan/Subaru 4pot/2pot:
Front - $133
Rear - $89

FRS/BRZ (stock)
Front - $174
Rear - $145

Winmax W3

Nissan/Subaru 4pot/2pot:
Front - $145
Rear - $145

FRS/BRZ (stock)
Front - $145
Rear - $145

So as you can see Project Mu is actually significantly cheaper while Winmax is the same price. These are fairly common brake pads used on non-Brembo Skylines (R32,33, and 34), Mitsubishi 3000GT, and basically any Subaru with a 4/2 pot set-up that isn't Brembo.

[mav1178]

Originally Posted by finch1750

So as you can see Project Mu is actually significantly cheaper while Winmax is the same price. These are fairly common brake pads used on non-Brembo Skylines (R32,33, and 34), Mitsubishi 3000GT, and basically any Subaru with a 4/2 pot set-up that isn't Brembo.

Virtually every Japanese factory 4-pot made by Sumitomo uses this pad.

Also found on S14/15 Silvia K's/Spec-R, among other cars.

-alex

[eikond]

Just to continue the process of sharing information.. here is a look at the difference in size of the rotors from Stock OEM blank to Stock Leg GT Blank.





Jritt is correct about adding weight to the rotating assembly.. but I can't help but wonder if these do have more cooling capacity than he thinks.. Look at the width.. so much more space in the center cooling channels.. that has to move more air and help cool them better.

[Fett4Real]

But its not a FWD car....how much of an issue is adding weight to the front wheels theres less overall weight up front...

[eikond]

Originally Posted by Fett4Real

But its not a FWD car....how much of an issue is adding weight to the front wheels theres less overall weight up front...

This brake setup actually reduces weight to the front of the car..
The calipers are 6.1 lbs each vs. 14.1 lbs for stock.
The rotors (OEM Leg GT blanks) are 22lbs vs. 17lbs.

So the net weight loss is 6 lbs. The problem with this is that the lost weight is in non-rotating mass, while the weight gain is in rotating mass.. so it may have a detrimental affect to acceleration feel. I doubt it would be very noticeable, but I think from a pure math perspective, that weight is detrimental.

Some day when I'm rich I'll upgrade to set of lightweight 2 piece rotors and then I'll have a lot lower weight and better cooling, etc.. But that's another $800 or so?

[Fett4Real]

Originally Posted by eikond

This brake setup actually reduces weight to the front of the car..
The calipers are 6.1 lbs each vs. 14.1 lbs for stock.
The rotors (OEM Leg GT blanks) are 22lbs vs. 17lbs.

So the net weight loss is 6 lbs. The problem with this is that the lost weight is in non-rotating mass, while the weight gain is in rotating mass.. so it may have a detrimental affect to acceleration feel. I doubt it would be very noticeable, but I think from a pure math perspective, that weight is detrimental.

Some day when I'm rich I'll upgrade to set of lightweight 2 piece rotors and then I'll have a lot lower weight and better cooling, etc.. But that's another $800 or so?

COULD be made up in the wheel...but again its not FWD so I really dont see the "feel" thing making it into the equation. However hes not running a light wheel at all...

[eikond]

Originally Posted by Fett4Real

COULD be made up in the wheel...but again its not FWD so I really dont see the "feel" thing making it into the equation. However hes not running a light wheel at all...

I see your point I think.. You are saying that the impact of increased rotational mass is less impactful since these are on the front wheels of a rear-whee-drive car.

Also it should be noted that running lighter wheels would/could offset the weight gain from these rotors.


Just an FYI.. I picked up another set of these calipers from a salvage yard. They were $35 each plus shipping.. so $85 overall. The rebuild kits run about $20. Here's an instruction guide on rebuilding them:
http://www.nicoclub.com/archives/reb...-calipers.html

I should re-title my thread.. $500 Big Brake Kit

[P@ul]

Originally Posted by mav1178

Virtually every Japanese factory 4-pot made by Sumitomo uses this pad.

Also found on S14/15 Silvia K's/Spec-R, among other cars.

-alex

If you really want to have fun with this, the 94 + 3000GT Twin Turbo also came with these Sumitomo calipers.

40.4x2 + 42.8x2 piston setup in the front (From: Stealth 316)
38.1x2 piston setup in the rear

I don't know how the caliper bolts are spaced, but it's food for thought.

94TT Centric reman calipers for $220 + $100 core charge (From: 3SX)

[mav1178]

https://www.google.com/search?q=sumitomo+4-pot
https://www.google.com/search?q=sumitomo+4+piston

there's a lot out there.

-alex

[mike the snake]

I'm going tomorrow to see if I can find a set of these calipers.

The ability to change pads by simply pulling some pins is a big win for me.

[JRitt]

Originally Posted by eikond

Jritt is correct about adding weight to the rotating assembly.. but I can't help but wonder if these do have more cooling capacity than he thinks.. Look at the width.. so much more space in the center cooling channels.. that has to move more air and help cool them better.

The LGT disc will definitely have superior cooling vs. the OEM BRZ. I have no doubt of that at all. They have a considerably bigger air gap and far greater surface area. I was talking efficiency. An OEM-style blank will never have the efficiency of a good aftermarket design. You can make the air gap two inches wide, but if the vanes aren't shaped properly you're going to have a lot of turbulence relative to a design built specifically to move air. That's why a considerably smaller racing disc can run much cooler than a larger OEM-style disc.

With big brake kits, most of the kits on the market go about the same thing via two different routes. First would be the brute force method. This is typically the method employed by street BBK's. That means BIG disc and big pads. You use mass to combat heat. The second method would be efficient designs. That is the method used in racing. You use advanced technology and materials to address the heat issue at a far lower size/mass. As in every field, advanced technology is more expensive.

10-4 on the pad pricing info. Ferodo is the main brand we sell, so those are the prices I checked.