Cadillac ATS Brembo calipers

Mattpal

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So I have a Fox with sn95 disk brakes. I came across a post that a guys was selling front GM Brembo calipers claiming will bolt on to the spindles. Anyone hear of this? Do this? Use 13” cobra rotors with 17” wheels min. I know can use a gt500 set up but I love the idea of keeping my 17” wheels
 
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Mustang5L5

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Yes, Cadillac ATS brembos. They are dirt cheap...even new

IMG_4937.PNG



I've been searching for a used pair. Missed a couple that sold on eBay for $100/pair. I'm running corvette calipers now but wouldn't mind the Brembos

My understanding is the Spindle needs to be redrilled as GM uses a 14mm bolt while the spindle is drilled for Fords 12mm bolts. Also the bolt spacing is 1mm or so narrower.

Eventually I'll get to it. I'll repaint the calipers in a more traditional brembo livery
 
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Mattpal

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Oct 27, 2018
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Yes, Cadillac ATS brembos. They are dirt cheap...even new

IMG_4937.PNG



I've been searching for a used pair. Missed a couple that sold on eBay for $100/pair. I'm running corvette calipers now but wouldn't mind the Brembos

My understanding is the Spindle needs to be redrilled as GM uses a 14mm bolt while the spindle is drilled for Fords 12mm bolts. Also the bolt spacing is 1mm or so narrower.

Eventually I'll get to it. I'll repaint the calipers in a more traditional brembo livery
So basically drilling out for the difference in bolt size it will open up the spacing so they bolt up?
 

Mattpal

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i saw the same post, isn't the guy asking $600 plus shipping? seems like a decent deal.
$700 plus shipping but yes. I’m actually more concerned about home much it of a direct install they are. What if I want to go back to “stock” calipers. Are spindles that screwed up
 

Mustang5L5

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$700 plus shipping but yes. I’m actually more concerned about home much it of a direct install they are. What if I want to go back to “stock” calipers. Are spindles that screwed up
Not screwed up, but pretty much a one way deal. No going back.

Edit: unless he's welded and drilled the Caliper for Sn95 spindles. Link to post? I haven't exactly done this yet myself so only speaking to what I know from this experience

I need to get my hands on a set. I keep missing awesome deals. Those brembos are all over eBay dirt cheap

IMG_0399.JPG
 
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Mustang5L5

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Found the post.

IMG_4989.PNG


Looks like he's welding the mounting flange and then redrilling for sn95 spindle mounting.

These are also the same ATS casting.
 

Mattpal

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Found the post.

IMG_4989.PNG


Looks like he's welding the mounting flange and then redrilling for sn95 spindle mounting.

These are also the same ATS casting.
Not same guy. But same setup. Minus the “corvette “caliper. The post I saw didn’t say what they were from. Just said gm calipers
 

Mustang5L5

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Ok, dug into this and got some parts.

Not a bolt on swap, as claimed incorrectly. The road racing forums are giving flak on this mod.

To get them to fit Cobra 13.1 rotors, you need to open up the spindle mounting holes to 14mm and slot them about 0.5mm towards each other. You also need to mill off about 0.075" off the mounting face of the mount ears.

Then you need to remove about 8mm of the pad material because the rotor diameter needs to be about 13.4" vs the smaller cobra rotors.

So...some work needs to be done.

I think there is a better way. The calipers have steel inserts so they will mount a variety of spindles. My thought it to machine up a new insert with a m12 threaded hole offset 0.5mm to match up to the SN95 spindle spacing

IMG_5435.JPG

IMG_5436.JPG

IMG_5437.JPG

IMG_5438.JPG


You can see in the bolt hole, that if you go to a smaller m12 bolt that th sn95 use, you do have room to offset them inward, and perhaps upward as well to sit the Caliper lower and cover the cobra rotor better

I also think there's a better rotor to use too. I refuse to slot my spindle or shave brake pads. Needs to be bolt on or nothing at all.

I bought that Caliper for $50, so I'm definitely curious about doing this swap "correctly"
 
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Mattpal

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Ok, dug into this and got some parts.

Not a bolt on swap, as claimed incorrectly. The road racing forums are giving flak on this mod.

To get them to fit Cobra 13.1 rotors, you need to open up the spindle mounting holes to 14mm and slot them about 0.5mm towards each other. You also need to mill off about 0.075" off the mounting face of the mount ears.

Then you need to remove about 8mm of the pad material because the rotor diameter needs to be about 13.4" vs the smaller cobra rotors.

So...some work needs to be done.

I think there is a better way. The calipers have steel inserts so they will mount a variety of spindles. My thought it to machine up a new insert with a m12 threaded hole offset 0.5mm to match up to the SN95 spindle spacing

IMG_5435.JPG

IMG_5436.JPG

IMG_5437.JPG

IMG_5438.JPG


You can see in the bolt hole, that if you go to a smaller m12 bolt that th sn95 use, you do have room to offset them inward, and perhaps upward as well to sit the Caliper lower and cover the cobra rotor better

I also think there's a better rotor to use too. I refuse to slot my spindle or shave brake pads. Needs to be bolt on or nothing at all.

I bought that Caliper for $50, so I'm definitely curious about doing this swap "correctly"
I got a set of them also and wanting to do the mod. Little hesitant on drilling out the spindles to be honest. Curious to see what you come up with
 

Mustang5L5

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Picked up a corvette j55 rotor off rockauto for $28 to play with.

This is 13.4" x 1.25" so it hopefully will eliminate the need to shave pads.

Rotor does fit in the brembo rotor slot, and the hub diameter seems to match the sn95 hub.

Need to redrill for sn95 lug spacing.

IMG_5444.JPG
 

Mustang5L5

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So I played around a bit on a bench to see if there was a better way to make this fit. Unfortunately, I think what I've found is causing me to lose interest in this swap.

The ATS and base c7 better that also uses this casting uses a 12.6" rotor. As a result, the Caliper is design with that radius in mind.

You can see what I mean here with the ATS pad on the 13.4 rotor.
IMG_5463.JPG


The Cobra 13.1 and vette C6 j55 13.4 rotor have a larger radius. So the Caliper hits the front and rear on the rotor as you try and lower the Caliper into the rotor before the pad area fully covers the rotor face.

Here's with the 13.4 rotor
IMG_5461.JPG


With the cobra 13.1 rotor, you do have room but it requires moving the Caliper down about 8mm or so. That requires major surgery on the spindle.

IMG_5465.JPG


Since I'm a sucker for making things fit correctly, I'm going to abandon this as I don't see how to make a Caliper made for a 12.6" rotor accept a 13.1 rotor and have full pad contact without overhang.

I am not modifying the spindle, nor shaving pads.

I now have a $50 paperweight
 
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Mustang5L5

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I like the paperweight idea. Clean it, paint it and give it a useful new life.
Gonna still poke around a bit on this one. Not giving up yet, just less enthusiastic about it.


I actually bought the other caliper from the recycler for $50/shipped as well. So i'm into this for $100. The 12.6" rotor diameter is a hurdle, but I'm not giving up yet.
 
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Mustang5L5

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Playing around a little bit more.

Popped the steel inserts out. Very easy to do. You can see the caliper has a mating cup that the insert is pressed into.

IMG_5531.JPG

IMG_5527.JPG
 

Mustang5L5

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With those now out how close is the mounting?

I need to make and reinstall an insert. The caliper alone doesn't have the proper support.

It's off 2mm. 128mm spacing vs the SN95's 130mm. My plan is to machine up a insert with a 1mm offset. Since i'm going from M14 bolts to M12 bolts, I have the room.

I need to model a few more things up in CAD (caliper flange, SN95 flange) and play with the orientation a bit to make sure this idea will work