Installing ATS Brembos on the Cobra.

[03HP]

Below is a picture from the maximum motorsports website showing all the different brake bias percentages. I trust their math.

You're basically telling me the ATS calipers with 13 inch (cobra) rear rotors have a better bias than the 00R Brembos that have smaller pistons.

View attachment 1802201

That is not what I am saying. My calculator has ATS front/Cobra rear at 72.7% and Cobra R front/Cobra rear at 69.3%. The data I have found says the ATS calipers have a taller pad than the Cobra R calipers so on the same 13" rotors, they have a slightly smaller effective rotor radius. But, the much larger pistons overcome that and result in the ATS calipers having a higher front bias than Cobra R calipers.

I definitely trust Maximum Motorsports' numbers too; they're the experts. I was unaware of this chart!

A slight difference in determining the effective radius and piston diameter could result in the slight discrepancies between their numbers and mine. My calculator does effective radius = rotor diameter / 2 - pad height / 2. This assumes the pad is perfectly at the edge of the rotor (it isn't), that I have decent values for pad heights (found online), and that the caliper pistons are in the middle of the pad. Ideally, the effective radius is from the center of the rotor to center of the caliper piston but I have no reasonable way to get that data.

A few comparisons between MM's results and mine:

front	rear	MM	me	delta
04 Cobra	04 Cobra	72.6	72.6	0.0
04 Cobra	04 GT	74.9	74.9	0.0
Cobra R	04 Cobra	69.6	69.3	-0.3
Cobra R	04 GT	72.0	71.7	-0.3
04 GT	04 GT	72.8	74.1	+1.3
98 GT	04 GT	75.7	75.4	-0.3
98 Cobra	04 Cobra	70.0	70.3	+0.3
98 Cobra	04 GT	72.5	72.7	-0.2

It looks like my calculator is working right, but some of my source data may be slightly off. Very small changes to the data can account for the differences in calculated front bias %.

If anyone has better effective radius and piston diameter data, or if you see a bug in my code, please let me know!

Note: edited chart after getting improved data in my calculator!

 

[Blkkbgt]

...

 

[03HP]

I was able to update this calculator (SN-95 Mustang Brake Bias Calculator) to get more accurate results after talking with @Blkkbgt and reading some old posts by Jack from Maximum Motorsports. Optimal bias seems to be in the 69-71% range (Terminators are 72.6% from the factory). Here is a table of the front bias % data from the calculator for the ATS/XTS Brembos this thread is about (note that GT & Baer rotors are thinner and only meant for SRA cars):

ATS %	XTS %	rear caliper	rear rotor
63.4	65.5	Taurus	13-14 GT500
64.4	66.4	Taurus	Baer 13.25"
64.9	66.9	Taurus	FTBR 13"
67.7	69.6	Taurus	Cobra
68.8	70.7	Mustang	13-14 GT500
69.8	71.6	Mustang	Baer 13.25"
70.2	72.0	Mustang	FTBR 13"
70.2	72.1	Taurus	GT
72.7	74.5	Mustang	Cobra
75.0	76.7	Mustang	GT

I recommend looking at the calculator itself; it will always be up-to-date with the most accurate data I can get.

To the best of my knowledge, moving from the 03-04 Cobra front calipers to ATS front calipers will only move your front bias by +0.1%! Changes could be made to get it in that 69-71% range, but it is nearly the same bias as factory.

However, moving from 03-04 Cobra front calipers to XTS front calipers (and 14" rotors) moves the front bias by +1.9%. Changes should probably be made to get the bias closer to stock or into the 69-71% range.

 

[Blkkbgt]

Finally got the tires mounted and half of them on the car. I have it back in the air so I can flush the brake fluid, gotta get ready for that next track weekend!

Do you have any pics of the barrel and spoke clearance?

I don’t know what you posted above because the pictures are broken.

Asking because I am pretty set on a set of Apex 18x9.5 wheels for my car.

 

[Blkkbgt]

Bringing this one back up yet again to take a shot in the dark.

Does anyone know how the ATS calipers compare dimensionally to the 2000 Cobra R Brembos?

I can find a template for the 2000 R calipers but not the ATS for some reason.

 

[lowranger96]

Bringing this one back up yet again to take a shot in the dark.

Does anyone know how the ATS calipers compare dimensionally to the 2000 Cobra R Brembos?

I can find a template for the 2000 R calipers but not the ATS for some reason.

I’ve had both in my hands and test fit a wheel that wasn’t fitting on the cobra R setup with an ATS. They are both about the same dimension width wise, cobra r is slightly smaller in terms of body since the fluid passages are internal on the ATS compared to cobra R.

 

[Blkkbgt]

I’ve had both in my hands and test fit a wheel that wasn’t fitting on the cobra R setup with an ATS. They are both about the same dimension width wise, cobra r is slightly smaller in terms of body since the fluid passages are internal on the ATS compared to cobra R.

Would you say the ATS is slightly smaller width wise?

From what I can find on the net and my own measurements the ATS seems to be about 5mm smaller giving just a little more spoke clearance.

 

[lowranger96]

Would you say the ATS is slightly smaller width wise?

From what I can find on the net and my own measurements the ATS seems to be about 5mm smaller giving just a little more spoke clearance.

IIRC it’s slightly smaller but wasn’t enough of a difference for the wheels I was testing.

 

[IllCobra]

Bringing this one back up yet again to take a shot in the dark.

Does anyone know how the ATS calipers compare dimensionally to the 2000 Cobra R Brembos?

I can find a template for the 2000 R calipers but not the ATS for some reason.

I would think the 2000 R calipers would be slightly smaller considering that the ATS caliper uses (4) 42mm pistons vs (2) 36mm pistons and (2) 40mm pistons for the 2000 R.

 

[gilby959798]

Do you have any pics of the barrel and spoke clearance?

I don’t know what you posted above because the pictures are broken.

Asking because I am pretty set on a set of Apex 18x9.5 wheels for my car.

Let me know if this works... Sorry broke the car on track and haven't wanted to look at it since.

 

[lowranger96]

I would think the 2000 R calipers would be slightly smaller considering that the ATS caliper uses (4) 42mm pistons vs (2) 36mm pistons and (2) 40mm pistons for the 2000 R.

That logic is tough to apply since cobra calipers are externally the same size with two different piston sizes between the rears and also the 38mm vs 40mm rear calipers. Most of the fitment tightness for the ATS calipers is caliper face to the inside of wheel and in that area they are virtually the same. The cobra R may offer some extra clearance to the barrel of the wheel though

 

[Mustang5L5]

The '00 R brembos have the same clearance issues as the ATS stuff. Putting 2 pistons on the outside of the caliper requires space regardless.

They clear the typical Ford 17x9's but need spacers for 17x8 wheels.

Really the only 17x8 that is going to clear a LOT of 4/6 pot calipers is going to be the 1998 Cobra wheel. TONS of clearance due to the aggressive curve design of the spokes. It was actually what Ford used as a full size spare for the '00 R.

More reason why the 1998 Cobra wheel is the best SN95 wheel Ford ever made


Edit: I'm talking about OE Ford SN95 wheels only here.

 

[gilby959798]

There's plenty of room. I'll get more pics when I can get to the car

 

[Blkkbgt]

I THINK I've figured out what is causing the parking break issues on the Taurus calipers.

This is basically the stackup of components for the parking brake mechanism. What's important note is the notch in the lever and the pin.

Here is what I found comparing the notch in the levers side by side

It's very hard to tell but those notches are not cut the same.

I THINK the pin is not being allowed to drop back into the notch after the parking brake is used.

Another thing that could be happening is the screw may be of lower quality in the reman Taurus calipers. They could be galling inside the piston and binding up. I am no metallurgest but they do seem to be a different metal and feel cheap.

With all that said I have decided to stick with rebuilding my old calipers. Messing with the Taurus pieces isn't worth the potential consequences even if I rebuild them.

 

[Mustang5L5]

The problem with identifying the root cause is the average joe just doesn't have the skillset required "repair" them, not should they even have to.

I still havr the original cardone 43mm I use to test fit this way back in the day. I should pull that apart and see how it's constructed.

Wou;d be interesting to pull apart some calipers from other manufacturers as well to compare, and maybe even a junkyard Ford OE caliper.

If anything, it might be worth at least sending a note to cardone saying "Hey, your calipers are locking up and causing accidents because...."


BTW, these calipers are still available from Ford. Motorcraft BRC15RM is the left. I don't have the right one handy. Remans.

 

[Blkkbgt]

The problem with identifying the root cause is the average joe just doesn't have the skillset required "repair" them, not should they even have to.

I posted what I found because I always want to know the cause of the failure. I thought someone else may be interested in the information.

 

[Mustang5L5]

I posted what I found because I always want to know the cause of the failure. I thought someone else may be interested in the information.

Sorry, didn't mean that to come off sounding like we don't appreciate the info. I'm glad someone decided to look further into it.

I'm disappointed in general at the failure rate for these calipers, especially considering i put the word out there that these fit. It bugs me to see that these calipers may have contributed to folks losing their car in a wreck because they may or may not be poorly manufactured.

 

[Blkkbgt]

Sorry, didn't mean that to come off sounding like we don't appreciate the info. I'm glad someone decided to look further into it.

I'm disappointed in general at the failure rate for these calipers, especially considering i put the word out there that these fit. It bugs me to see that these calipers may have contributed to folks losing their car in a wreck because they may or may not be poorly manufactured.

I didn't take it that way, no apology necessary. I was simply explaining why I posted what I found.

 

[muscleatsrice]

I’m sure it’s been said in here somewhere, but do these clear the factory wheels?

 

[Mustang5L5]

Factory 17x9's? Yes
Factory 17x8's no, except for the 1998 cobra wheel.