Nope, Nick will get back to you. However, he typically does batch runs for the backing plates as I believe they aren't that cheap to produce as one-off's.

 

I have the 13" M2 brake kit (AP calipers and Alcon rotors) with Ferodo DS3000 pads up front and '99RZ brakes out back with Hawk Green pads. I don't have ducting but I do the the Ntech backing plates. They never showed any signs of brake fade ever. Those DS3000's do dust quite a bit though and shouldn't be used on the street. They ate up my front street rims with dust I could never get off. (GramLight57Pros)

This is with 505 flywheel hp and driving the car at about 90%. My ABS didn't work and I would get lockup if I mashed them.

 

Here's my ducting setup. I have the N-tech backing plates and previously ran the ducts to the R1 lip openings. I could never get the two mated acceptably (and do not have a rapid prototype machine) so I changed it to right side ducting from the unused right oil cooler opening - used a standard plastic 3" duct opening, and the left side ducting from a NACA duct incorporated into my custom fabbed undertray. I don't have temp readings but I feel like I'm getting better airflow than with the previous setup.

 

Here are pictures of my ducts installed with the NTech backing plates, running to the stock R1 lip intakes. I have previously described in another thread how to make the mate pieces for the R1 lip.

I track the car at Thunderhill and Laguna and this has worked so well with the stock calipers and rotors (running Carbotech XP10 pads) that I would recommend anyone with the stock-twin sort of power first duct their stock brakes, and if they still get fade after that, THEN by a BBK. Its a lot cheaper to cool the brakes than it is to make them bigger.

 

Here is my old option...



and my new option...

 

WOW...hardcore. Love to see the finished product! Seems the GTC front is quite popular for track junkies.

 

ok I know its slightly off topic but did anyone notice the adjustable sway bars in the zeckhausen pics? anyone have more info on those?

 

It just occurred to me that you could make stainless steel backing plates that I think would be just as effective as the Titanium, and cheaper. Stainless and Titanium have almost exactly the same thermal conductivity. See

http://www.matweb.com/search/Specifi...assnum=AMETi00

http://www.matweb.com/search/Specifi...assnum=MQ302AA

Any comments on the preference for Titanium? Note the pistons themselves are usually made of stainless, so it isn't the higher melting point.

I bought the Ti backing plates, and have managed to warp one set (oops, ran out of pad towards the end of one session...). Hence the question.

 

I agree with your assesment that stainless should work just as well as Ti, and know several other people in the engineering field who do as well. I think the only reason for using Ti is that is has the "wow" factor that helps sell. This is only really an issue with stock calipers, any upgrade should come with stainless pistons.

 

I agree. I think the SS will get you 95% (pulled that out of you know where) of the way there. I'd go with the SS.
Crispy

 

This is my next project for the stock brakes. I've cooked my Carbotech XP8's and Hawk HT-10's . . .

:-) neil

 

My StopTech rotors already looked like the Mohabe desert before I got to VIR this weekend, and though they're worse now, I'm betting the new ducting allowed them to survive a three day track outing when they wouldn't have otherwise.

This is a PITA to install, but I think it's really worth it.

 

Cool. Make sure to use the orange hose, not the black stuff in the pictures I posted below. The (cheaper) black hose has an inner and outer layer around the spring-wind, and the inner layer can collapse, halting all airflow, while still looking ok from the outside. The orange hose I am currently using is a single layer silicone (so is very flexible).

You also might want to get some temperature sensitive paint and temperature sensitive stickers so you can monitor your temps reliably (a Crispy idea). This is an area where hard data is worth a lot, and I would be very curious to see if your experience is the same as mine.

 

Since type 302 stainless has a lower thermal conductivity than titanium (16.2 vs. 17 W/m-K), it is almost exactly the other way round (Ti is 95.3% as good as 302).


I looked at the stock backing plates, and judging from the magnetism, the smaller, top plate (the one with the arrow) IS already stainless, while the lower appears to be normal steel.

The stock top plate is about .015" thick, the bottom about .025". Each requires a blank of about 4.25"x2.25". Looking on McMaster-Carr, stock numbers 9014K87 and 9014K83 would let you cut out about 10 of each, or enough for 2.5 cars, for a price of around $25.00.

On the other hand, if you really, really have to have Titanium, then Mcmaster-Carr sells a .020" 12"x12" square of that for $57.79. Note it isn't as thick as the .025" base plate in addition to the slightly higher thermal conductivity, so ends up only being about 76% as good at reducing heat to the pistons as the stainless.

 

I think you guys are using the wrong numbers, er scratch that, the wrong material. The shims that I have purchased (and sold) are all Titanium alloys that have small percentages of aluminum and vanadium in them. The thermal conductivity is about 6 W/m-K so about 37% of the stainless numbers you quoted. It was a very noticeable difference when I put them in. Basically, with them, little to no fluid fade, even when the pads are totally cooked. Dunno if you could get that from the stainless or not.

Mcmaster lists the Grade 5 (6%Al/4%V) alloy, 9039K16 at $219.60 for a 12"x12" sheet.

 

You're right, the Grade 5 is a lower thermal conductivity than stainless at 6.7 W/m-K.

http://www.matweb.com/search/Specifi...bassnum=MTP641

Thanks for explaining that.

The backing plates I bought were .020" thick, and McMaster-Carr doesn't sell grade 5 in .020" sheets, but does sell .020" thick pure Titanium (grade 2) sheets. The McMaster Grade 5 you quoted is a sheet .032" thick. So clearly you purchased your Grade 5 from some other vendor....

 

Correct, I was just getting you a part number to some grade 5. I'd have to check again what the ones that I have are for thickness.

From what I've read (and been told) the thickness really isn't that important, that the transfer of heat from the pad backing plate to the titanium and then from the titanium to the pistons is where the shims help. Obviously they still need some strength, so that is also a consideration.

 

I think there is one fundamental aspect you guys are forgetting about. It is NOT so much the conductivity of the SS or Ti that has the largest effect, it is the very small air gap that exists as a result of having the plate between the piston and the pad that has the largest effect. Relative to the metals air is an incredible insulator

Crispy

 

Porsche + FD = Teh Win!!!!

 

Yeah, I think that's what I was trying to say up there.

 

Here is how I understand it:

The transfer of heat from the pad to the fluid runs through a set of thermal resistances in series. If we want to reduce the heat energy transferring to the pistons, we need to increase the thermal resistance of any one of the elements in the sequence pad->pad back->"air"->backing plate->"air"->piston.

The "air" between the piston and the pad is one thermal resistance in the series. We can debate whether it is the "most" important element (I would argue there isn't much air there when the piston is active) but it doesn't matter much since whatever it is, it is there for the stock backing plates as well.

To improve the thermal resistance of any element, you can make it thicker (this does matter - see "L" here http://en.wikipedia.org/wiki/Thermal_conductivity) or you can use a material with a lower thermal conductivity, or you can reduce the area (this latter not really being a realistic option for us).

Thermal conductivity (in this case, lower is better):
Steel = 51.9 W/m-K
Stainless = 16.2
Grade 2 (pure) Ti = 17
Grade 5 Ti = 6.7

I'm going to replace my warped Ti plate with some stainless, as it is cheaper and I have yet to boil the fluid anyway.

 

http://www.awrracing.com/store/produ...products_id=79

Would those fit an FD?

 

Where's the thermal conductivity of the air?
No two surfaces no matter how smooth are ever in perfect contact. The thermal "resistance"of the air, even when very small, will far outweigh the collective resistance of the metal plate. Hence why I submit the delta between using the Ti and the SS will be of little consequence relative to the simple introduction of an air gap when using a backing plate.

FWIW I never had an issue with fluid boiling when using the stock rotors, with Hawk Blue pads and the OEM backing plate combo. I did however generate enough brake heat to crack every set of rotors I used (drilled, slotted, or OEM, made no matter) long before they were close to being worn out.

Note that the OEM setup uses TWO plates. If this is a consideration simply use two SS plates instead of the single Ti plate. Probably cheaper too.
Crispy

 

I would like to second this. I've never boiled my fluid with this setup either, but have cracked my rotors.

 

I agree that the simple introduction of a surface (even a surface between two identical materials - simply cutting one of the elements in two, for example) will act as a thermal resistance - this would be true in a vacuum though, and has to do with the efficiency of transmitting molecular vibration (a.k.a. "heat") across the surface vs. through a homogeneous material. I don't agree it is the most significant element, but whatever. The surfaces are all there in all cases, and if we wish to improve things, we must introduce a beneficial difference.

Another thing to consider with the air theory - I think we can agree that the air layer is mighty thin, and the equations governing heat conduction do indicate that the insulating ability of a given layer is proportional to its thickness. Since the thickness of the air layer is vanishingly small, so too is its insulating ability.

Right on about relative importance of fluid boiling vs. rotor cracking. That's how my rotors die, too. Luckily, rotors are relatively cheap! Crispy, I did take your suggestion about putting temperature sensitive stickers on the sides of the calipers to monitor heat generation. This works like a charm - the one time my duct piping collapsed, that sticker starting registering (around 300 deg F on the outside of the caliper) and that rotor starting getting cracks. If memory serves, you once reported getting up to 500 deg F on the outside of the caliper - that's a little past where I would worry about fluid boiling!

Finally, I bought two thicknesses of stainless, so I could replicate both backing plates (and I did use the Ti plate with the stock "arrow" plate). Since the "arrow" plate is angled, I think it must be there to bias piston pressure so as to promote even pad wear. It is too oddly shaped not to have some design reason for its existence. The stainless sheets from McMaster came today in the mail, and I may try my hand at cutting out the backing plates this weekend.

Anyway, I believe we have beaten this topic to death.... on to other things.