Yes another Brake Upgrade Thread Vented front + drums

[PrincePaul]

Hello Guys,

 

since last weekend I´m owning a 280z which will be fully restored and therefore I`ll change every component that was/is in contact with fluids or has orings inside. Especially the brake system. So when buying new parts I also could just spend a little more and get "better" parts.

So the idea came up for a brake upgrade. I was reading a lot of threads about rear disc conversion in a couple of forums together with the problems that go along with it (brake bias, not for this stress designed axels etc.) Together with the fact that I`m out of germany and its not that easy to get it road legal with a disc brake where normally a drum sits.

I was deciding to leave the stock drums and just get new pads, hardware and wheel cylinders for the back. In the front I`d like to install a vented disc setup. That this setup works well was backed by the nissan competition catalog were as far as my understanding goes they installed a 4 piston caliper with 41,3 mm dia (FIA MK63 brake) a vented disc and changed the rear drum wheel cylinders to 13/16". Nothing else was touched - is that right? So stock proportion valve, stock 7/8 master.

My problem is I can`t find anybody who did this swap before due to the fact that everybody goes straight to a rear disc conversion which I don`t wanna do.

 

So seems that two upgrades would be possible for me. The vented S12-8 from a 88 L4 4runner with vented discs (couldn`t find a kit online) with two 43 and two 34 mm dia pistons in each caliper which seems to work good with a rear disc setup. Or the S12-W conversion with four 43 mm dia pistons.

If you go through the other threads a lot of people say that the S12-W is really heavy but I couldn`t find any numbers. Wheel clearance wise the S12-8 vented should also be better than the S12-W.

 

So what we know is that the original nissan upgrade works well. To check the bias change I was trying to do some calculations based off the premises you don`t change pad compound, leave the rear drum alone (besides the piston dia on the FIA brake). So as these values would be all the same you can remove them from the calculations - right?

Question is only by how much a little bit bigger padarea would make a difference and also a couple mm bigger dia disc would make a difference.

What I did is not the REAL brake bias but I guess its a good starting point to only compare these three systems to each other. Or what do you think?

So the FIA Brakes are 4 piston with 41,3 mm dia the rear drum cylinder are 13/16" so 20,6375 mm dia. So in total you`ve 8 pistons up front which combined have 10717,168mm² while the backs are two pistons each side so four in total with 2676,048 mm² together.

S12W are 43 mm dia and stock 280z rear drum cylinder are 7/8 so 22,225 mm dia. Same number of pistons so up front 11617,608 mm² and rear 3103,584 mm².

S12-8 vented has 4 pistons 43 and 4 with 34 mm that makes 9440,484 mm² plus the same in the rear like one above with 3103,584 mm²

 

That makes a 80/20 distribution with the MK63 FIA brakes

and 78,9/21,1 with the S12W and stock drums

75/25 with S12-8 vented

 

Mounting points are the same so you don`t have different leaver. Considering you run the same pad compounds. Which have almost the same dimensions as well. You also should have the same pressure because they are not changing the master. Which I probably would due to the necessity of more fluid - so a 15/16 master would probably go in.

 

Seems that the S12W is a pretty close call compared to the original vented upgrade with MK63 and 13/16" rear drum cylinders. What do you think?

A manual willwood proportion valve (the black one) could also get rid of that 1% difference and would remove a tiny bit line clutter in the engine bay.

 

 

Is someone running that setup and has some rekomendations or experience? Because you can talk and calculate a lot, but when it is not even noticeable in the end...IDK.

 

The car will go down the performance road, so upgraded suspension, wider wheels, overfender, around 200 HP (hopefully) etc.

 

BTW out of jdmjunkies.ch:

MK63 Solid disk type including brake-pads: 4.300 Kgs
Standard two pot OEM including brake-pads: 4.445 Kgs

what I found on an other side is 3,8 kg for the vented MK63 without pads - not really comparable.

And I did`t find anything about the S12W or vented S12-8...

 

Thanks for your help, much appreciated

[siteunseen]

Here's some Toyota fronts in a kit.  He also has vented rotors.

https://zcardepot.com/all-products/brakes/front-big-brake-caliper-upgrade-toyota-4-piston-kit

https://zcardepot.com/all-products/brakes/front-sport-big-brake-kit-vented-rotor-toyota-caliper

I put stock calipers and vented rotors on mine as well as all new rear hardware and aluminum drums.  Stops very well. 

 

Edited March 15, 2018 by siteunseen

[PrincePaul]

Thats the Kit I was thinking of:

https://zcardepot.com/all-products/brakes/front-brakes/front-big-brake-kit-toyota-caliper-240z-260z-280z

 

But the don`t offer the vented S12-8. But seems that the s12w with drums is a good bias system, isn`t it?`Where are the people running this setup?

On hybrid Z there is also no one

[munters]

I went with the vented toyota and drums. (I didnt pass the swiss inspection with 4 discs)as you mentionned. I changed also to 15/16 MC and a 280z brake booster the rest i kept stock. Passed Inspection and bias is spot on all 4 wheels block at the same time.

[siteunseen]

I use a parachute on mine.  Kidding, 

[gnosez]

If you are keeping the drums you can install a prop valve as long as you remove the stock one. You could also consider upgrading your shoe compound (Carbotech is a good source or Porterfield).

Not a fan of cross-drilled rotors as the hot gas is trapped by the pads on both sides of the caliper. Slotted rotors solve this issue by having slots longer than the pads themselves.

I have run the vented rotors with the S12-W Toyo calipers and drums for nearly 10 years on the 240 race car with good results. I moved to rear discs to get great results (jury is out on that until the car sees a track)

 

Edited March 16, 2018 by gnosez

[PrincePaul]

On 15.3.2018 at 9:42 PM, munters said:

I went with the vented toyota and drums. 

Nice, good to here. May I ask which vented toyota upgrade you installed? S12-8 or S12W?

 

 

Thanks for the input @gnosez so than I´m buying that as well  yeah I was thinking of this willwood valve:

http://www.wilwood.com/MasterCylinders/MasterCylinderProd.aspx?itemno=260-11179

 

Because I could get rid of the original proportion valve (I don`t have to rebuild it) and this divider block on the left side of the car. I`m planning on fabricating all new brake lines anyway so I could integrate it straight away.

Disc will be normal plane vented ones. Not drilled, dimpled no slots. Thats best for the german TÜV inspection because like stock, best price and I will probably not go over their limit anyway.

 

What do you say about the extra weight? probably not even noticeable with new suspension, bushings and swaybars?

 

Have a nice weekend.

Edited March 16, 2018 by PrincePaul

[gnosez]

SW/12 with no slots or holes rotors. Those I had cyro and REM treated.

Edited March 17, 2018 by gnosez

[munters]

I went as well with the S12W not drilled not slotted.

(btw i would not pass with a prop valve in Switzerland) Steel braded hoses i had to take off. (Again no way to pass inspection)

[PrincePaul]

Alright, I `ll go down that route, too.

Probably the exact same situation with the german TÜV. So have to hide the prop valve or build a "heatshield" around it

 

Thanks for your feedback. Helped my a lot.

[Chickenman]

One thing that is very important with calculating piston area. With Fixed caliper you only Calculate one side of the Piston volume ( if switching from floating Calipers ) . This is VERY important when comparing Piston values between sliding calipers and Fixed calipers. It is very important to stay as close to the Piston Area of the original design ( front and rear ) otherwise you will end up with balance issues and possibly pedal travel issue.

Here is a handy Piston Area calculator. IMPORTANT. For floating calipers multiply the resulting value by 2 with this particular calculator. 

https://brakepower.com/help_abc_27_PAC_t.htm

Edit. WilWood also has a handy chart. 

http://www.wilwood.com/TechTip/TechCaliperTip.aspx

Edited March 18, 2018 by Chickenman

[Chickenman]

For rear shoes, go with some of the Carbon Racing shoes. Carbo Tech makes some good ones. The MSA Carbon shoes may be good. I personally haven't tried them.

Back in the 70's we could get some pretty good semi metallic shoes or Velve-Touch sintered Metallic. I use Nissan " Green Stuff " on my race 240's. Great shoes, but a bit hard for the street. 

Most of the Retail available brake shoes for our cars are junk these days.