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This has been a hot topic lately. Many many thanks to Alan H. (SVT_Alan) and Jojomofo21 for helping me with the info on this install. Alan posted a how to up on Facebook and he sent it to me since I am not on groups. This whole thing can be done for well under $500 and depending on what options for under $400. Great upgrade over the stock Floating 2 Pistons. The ATS is 4 Piston and just look much better in my opinion.

A.jpg

I am posting parts I did and hopefully help others.

**RockAuto 5% coupon code expires 7/28/19: 110511239104454439 ****

Parts needed:
2013-2018 Cadillac ATS Brembo Brake Calipers PN: 172-2777 and 172-2768. ($121.79/each)
2. 4 Flanged 10.9 M14x2.0x40mm Bolts. ($7.59 for 5)
3. Brake Pads for the J55 brake kit for 2013-2018 Caddy ATS. I installed Power Stop Z23-1001. ($40.99)
4. A HSS 9/16 or 14mm drill bit. (had one)
5. A rat's tail file (had one)
Optional Parts
6. New Cobra rotors if you want to replace yours while out. I installed AR8144/8145XPR. ($89.98/pr)
7. Also Optional is the Stop-Tech 950-61001 comes with correct Banjo bolts. SS lines are one of the best improvements you can do to your brake system so I highly recommend it. ($55.43)
8. Brake Fluid for bleeding the brakes (~$9)
9. Caliper paint (~$8)

B.jpg

The parts can be purchased at many places. The calipers can be purchased at Rockauto.com, Amazon.com, SummitRacing.com along with many others. Depending on your state tax laws and shipping prices as to who has the best price. The bolts and drill bit can be bought from McMaster-Carr. Brake pads and rotors can be bought anywhere but when I bought them the best price was Rockauto for the Powerstop Rotors. Best price we found on the Stop-Tech SS lines was PartsGeek.com. Also you can always find a coupon for 5% off at rock auto. Not a lot but it is something.

The biggest part of this mod is machining .075" off the back of the Brembo mounting tabs where they bolt to the spindle. This is very important as it helps center the rotor. They need to be flush so don't use a grinder.

C.jpg

This is also a good time to paint or powder coat your calipers and put on a logo if you want. Cadillac is printed on there so it can easily be skuffed up and painted over.

D.jpg

Next we get to the car. Put the car on a lift or jack-stands and remove the wheels, brake calipers, rotors, and brake lines if you are replacing those.

Once everything is removed you need to take the drill bit and is drill out the two holes on the spindle. The new bolts will just barely slide in. Next you want to take the rat's tail file and file the two holes towards each other. You want to file a little bit and then put the calipers up and see if you can screw the bolts in by hand. If not file a little bit more off.

E.jpg

The Brake pads are a little too tall. You will have to grind 6mm off the top so they sit even with the rotor. We marked 6mm from top of pad all the way across the top and then used an air grinder to make quick work of it. It is VERY messy and don't breath the brake dust. I think Alan used a Belt grinder and his came out way better than mine. So that is another option.


Once you get the Caliper to mount all the way remove them. Now is time to put the rotors on and bolt the caliper back on. With the Brembos calipers full bolted down you drop the pads down the back and slide a pin in to hold the pads in place and then put the metal clip in and slide the other pin in through the pad holders and push the other side of the clip down.


At any point you can install the new brake lines. They make a bit of a mess so make sure you have a drip pan to catch the mess.
Once all the parts are back in place mount the wheels and bleed the brake system.
Enjoy and Good Luck!

I will continue to edit and update this hoping to help others.
 

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Discussion Starter #2
Here is how the Calipers look from the factory:

A.jpg

Here is the weight difference between the two:

B.jpg

The Stock and Brembo side by side:

C.jpg

Between rim spoke and caliper:

D.jpg

When Bleeding don’t forget to bleed the master cylinder:

E.jpg
 

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I've seen this mod picking up steam in the FB Groups and a few IG pages. These calipers are very cheap on Ebay, as i picked up one for $50 just to check out.


I had a few ideas about different rotors that i haven't had a chance to play with. Mostly, i was looking for a way to mount these calipers without the need to shave the pads down 6mm or machine the flange (not that that's a big deal).

Corvette Z51/J55 rotors are 13.4" vs the cobra 13.1 rotors. Problem is, of course, the bolt pattern is different than the mustang. Solution would be a 2-peice rotor. Mustang hats, with corvette rings. Of course, this is expensive, but you gain a 1.25" thick rotor with a slight diameter increase and no need to cut pads each time you burn through a set (such as in road racing)

Of course, no idea if the mounting ears still need to be machined to center the caliper on the thicker rotor. I'm assuming the 0.075" needed to center the rotor may not be needed with the wider rotor. Again...would need to try it out.


I have Corvette C6 calipers on my car with the Baer specific brackets. In the past, we experimented with a cut-down GT500 14" rotor that fit VERY well on the caliper (nice and centered) and gave us a nice heavy 1.25" thick rotor. Never did anything beyond some test fits though. The GT500 14" rotors were dirt cheap (under $50) and machining was about $100 each rotor. Cheaper than the 2-piece rotors.


Low on my list of things to do right now though as my light fox doesn't need much braking power, but i'm curious about the swap in general
 

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Discussion Starter #4
I've seen this mod picking up steam in the FB Groups and a few IG pages. These calipers are very cheap on Ebay, as i picked up one for $50 just to check out.


I had a few ideas about different rotors that i haven't had a chance to play with. Mostly, i was looking for a way to mount these calipers without the need to shave the pads down 6mm or machine the flange (not that that's a big deal).

Corvette Z51 rotors are 13.4" vs the cobra 13.1 rotors. Problem is, of course, the bolt pattern is different than the mustang. Solution would be a 2-peice rotor. Mustang hats, with corvette rings. Of course, this is expensive, but you gain a 1.25" thick rotor with a slight diameter increase and no need to cut pads each time you burn through a set (such as in road racing)

Of course, no idea if the mounting ears still need to be machined to center the caliper on the thicker rotor. I'm assuming the 0.075" needed to center the rotor may not be needed with the wider rotor. Again...would need to try it out.


I have Corvette C6 calipers on my car with the Baer specific brackets. In the past, we experimented with a cut-down GT500 14" rotor that fit VERY well on the caliper (nice and centered) and gave us a nice heavy 1.25" thick rotor. Never did anything beyond some test fits though. The GT500 14" rotors were dirt cheap (under $50) and machining was about $100 each rotor. Cheaper than the 2-piece rotors.


Low on my list of things to do right now though as my light fox doesn't need much braking power, but i'm curious about the swap in general

Ya I did the install a few months ago and was wondering if there was a rotor out there that would give ya extra radius over the stock 03-04s. if you ever dive into new rotor setups and find one that works let us know.
 

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if you ever dive into new rotor setups and find one that works let us know.
Will do. Z51 13.4" rotors are actually pretty cheap. I was going to just buy one for $20 or so and do a backyard redrill of the bolt pattern and mock it all up on a spare set of spindles i have to see it redrilling those rotors would be a good option to get a larger, and thicker rotor on there.

I'll update if i get around to trying it out
 

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Corvette Z51 rotors are 13.4" vs the cobra 13.1 rotors. Problem is, of course, the bolt pattern is different than the mustang. Solution would be a 2-peice rotor. Mustang hats, with corvette rings. Of course, this is expensive, but you gain a 1.25" thick rotor with a slight diameter increase and no need to cut pads each time you burn through a set (such as in road racing)
The other problem is that the hat height of the Corvette rotor is 1.9" - 2.0". The 03/04 Cobra hat height is 1.7".
 

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The other problem is that the hat height of the Corvette rotor is 1.9" - 2.0". The 03/04 Cobra hat height is 1.7".
Good point and thanks for mentioning that.

So that moves the rotor inboard. I wonder if a small spacer would make up for that? You gain 0.075" by not machining the caliper mounting ears. Looks like you need about ~0.1-0.2" of a spacer.
 

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Well, if you were going to make a spacer, then you could start looking at another option. Have a look at the Power Stop JBR1529XPR. It is the right mounting pattern and is 13.4". Hat height is 2.2". You would have to make up a lot of space. I already have extended studs so that's OK.

Just food for thought.
 

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Well, if you were going to make a spacer, then you could start looking at another option. Have a look at the Power Stop JBR1529XPR. It is the right mounting pattern and is 13.4". Hat height is 2.2". You would have to make up a lot of space. I already have extended studs so that's OK.

Just food for thought.
Not sure i want to sandwich a spacer between the hub and hat though. At least with the Z51 rotor, that small ~.2 spacer can go between spindle and mounting flange.

My goal is to tryand minimize as much modification as possible to perform this swap. Of course, i realize the spindle itself needs to be modified, but i was thinking of machining the spindle and installing offset bushings. I need to see if the narrower offset of GM caliper can be consumed when i ream the holes in the spindle to 14mm. I'll cross this bridge later with a spare set of spindles i have.


I ordered a Z51/J55 rotor off rockauto for $38/shipped just for test fit purposes. I'll machine the bolt pattern to Sn95 specs, and see if this rotor will work.

I'll update when i make progress, but fair warning is i have a busy summer and may not get to it for some time.
 

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At least with the Z51 rotor, that small ~.2 spacer can go between spindle and mounting flange.
OK. I am tracking with you now. Yes, that would be much easier and better than spacing the rotor back out 0.5" for the rotor I posted. hadn't though about just spacing back the caliper. Much better solution. I guess you could get pretty close doing the 5x114.3 freehand. I wonder if I can get one of my friends to create a drawing and have the holes punched out on the CNC. The only thing that worries me about freehand is that it wouldn't be concentric
 

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At least with the Z51 rotor, that small ~.2 spacer can go between spindle and mounting flange.
OK. I am tracking with you now. Yes, that would be much easier and better than spacing the rotor back out 0.5" for the rotor I posted. hadn't though about just spacing back the caliper. Much better solution. I guess you could get pretty close doing the 5x114.3 freehand. I wonder if I can get one of my friends to create a drawing and have the holes punched out on the CNC. The only thing that worries me about freehand is that it wouldn't be concentric
I've got access to a CNC. I was going to do it freehand just for the sake of mocking it all up, but I might as well do it right.

I have seen templates available as well.
 

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I picked up a C6 j55 rotor. Seems the closest in proportion although the thicker rotor gives less wiggle room.

Not here til next week and then I leave on vacation...so hang tight.
 

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I just went out to do some measurements. As far as I can tell, on my 03, there is no way to backspace for the C7 hat height. I think the only way that works is by shimming under the hat to bring it back out.

I think with the C6, you might be able to get away with milling the mounting tabs on the caliper. So, 0.1" to make up for the hat and another .075" to make up for centering. I don't know how thick the mounting tabs on the ATS caliper are. But 0.175" off could be worrisome if there isn't enough material.
 

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Discussion Starter #17
how did you do the cobra emblem
I designed the lettering and then my wife user her Cricut to cut it out of Oracle 651 Vinyl.
 

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Saw one guy was using a 11-14 Mustang GT rotor.

13.2" diameter, correct lug pattern, caliper needed to be milled a touch more due to deeper hat.

He also drilled and installed bushings into the caliper and then redilled M12 threading so that the spindle is unmodified. A little bit of work to get that done.
 

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Broke out some parts to do a little measuring and some CAD work. Trying to figure out what combo will give the best combo of off-the-shelf parts with as little mods as possible. I'm aware of the flak this swap is getting on the road racing forums.

Anyway, my $50 auto recycler Caliper and a spare 96+ spindle. I need to swap to the 96+ spindle when I swap on my mm kmember, so I need to ream the tie rod holes anyway for the bolt through kit.

But, I'd rather not modify the spindle.

If you look at the Caliper, there's a steel insert pressed into the aluminum body of the Caliper. Since these are threaded for 14mm bolts, I wonder if I could model up and machine an insert that is drilled for 12mm bolts, and offset 0.5mm inboard. I can then press the new insert in and have a purely bolt on Caliper.

From what I find...the GM spacing is 1mm narrower than SN95.

Of course, still trying to see if there's a better rotor to use. I have a j55 rotor arriving tomorrow, but thinking it might be worth it to check out a 11-14GT 13.2" rotor.

My car is purely a street car, so I'd prob be fine just redrilling the spindles...but I feel there's a "better" way. I'd like to use off the shelf pads and rotors and not have to mill the Caliper down at all.
 

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