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PIcked up a 43mm Varga caliper. This thing looks damn close to an sn95 rear Caliper.

Now to find a moment to pull my rear brake setup apart and test fit. I plan to try to mount it to the sn95 cobra pad bracket.

If anyone has an sn95 Caliper sitting around, it’s ~3.93” from the two machined flats on the Caliper mounting ears.

I’m on kid duty tonight so not sure I can get in garage

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WHat's the spindle mount bolt spacing on the CTS-V caliper? 128MM using M14 bolts?
128mm (eyeballing it with a metric tape measure, since my vernier caliper only goes to 125mm), but the 4-piston Brembos on the 1st gen V are 12mm bolts. The 6-piston calipers on the V2 went to 14mm; that's what I've got on my V1 now.

If anyone has an sn95 Caliper sitting around, it’s ~3.93” from the two machined flats on the Caliper mounting ears.
I get 107mm (4.21") on a new/reman 38mm caliper I've got sitting here. Eyeballing the bolt holes with my vernier caliper the spacing is about 118mm.

i'm more than happy to test fit that front cts-v caliper on my car if you want to ship it over
(can't see your location with this new bs update... i'm in marlborough mass)
I think the bolt spacing is wrong to fit an SN95 spindle - it's 128mm. As far as I can tell the 1st gen CTS-V calipers do not use a mount that you can press out and replace like Mustang5L5 has done during his experimentation with the newer Caddy caliper, so it would not be easy to adjust the bolt spacing.
 

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I get 107mm (4.21") on a new/reman 38mm caliper I've got sitting here. Eyeballing the bolt holes with my vernier caliper the spacing is about 118mm.
I also get 118 mm on the bolt hole spacing.

Promising
 

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Well, looks like there’s a new option in rear brakes for the fox/SN95.

The 38mm and 43mm Varga are the same casting. Same dimensions. Looks like the 38mm is basically a “smaller bore” version of the 43mm.

It bolted right onto my cobra pad bracket.

(Caliper is mounted on wrong side of car)

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So.. anyone want to do a quick brake bias Calc with the 42x4 ATS brembos and the 93-97 taurus 43mm rears?

Now to figure out a proper MC.
 

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So.. anyone want to do a quick brake bias Calc with the 42x4 ATS brembos and the 93-97 taurus 43mm rears?
Using the same effective rotor diameter assumptions I made before, for me the math works out to ~4.7% shift to the rear. That's comparing the 13" rotors and Caddy Brembos up front (with 42mm pistons) + 43mm Varga rear calipers on 11.65" Cobra rear rotors to the stock Cobra setup (38mm version up front front, 38mm Varga in the rear).

If I'm doing the math right, it's about a 24% increase in piston area. I don't know if that means you want a ~24% increase in MC bore? If so, going from 15/16" to 1-1/16" is ~28%. From 1" to 1-1/8" is ~26%.
 

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The Master cylinder will affect the overall pressure most, but not the bias front/rear. That's the combination valve, which has the proportioning valve in it. As the braking forces change at the rotor and caliper, that's when a MC piston size change may be needed.

So a bias change of under 5% may not need any adjustment(CV), but the greater brake forces might need a different MC piston size.

This is where it gets hard to make the final adjustments, picking other parts to restore the balance of forces, front/rear, and total.

Is the combination valve separate in all SN95's, or built into the ABS unit on those with ABS, or do any have the small device in the line below some MC's?

I'm not sure what that thing does, but it was part of the Crown Vic brakes I dealt with converting my 95 CV to ABS. I bought a 97 CV MC, two sets of rear brake lines, the ABS module and lines up to the MC, plus under hood wires to make it happen. It was a bolt in project, besides flaring four line ends at the middle of the car.
 

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Now that i'm at a PC, i can better detail what i observed.

Like said, it appears the 43mm Varga and the 38mm Varga use the same exact casting. The difference is the bore obviously, but it looks like both the 43mm and 38mm have the same outside bore, but the piston diameter is different obviously. Alignment was spot on. The two tabs on the inner pad perfectly aligned wit the notches and the springs on the pads contacted where they need to on the upper pad retainer clip. It was essentially the same caliper...but just 43mm.

Parking brake setup is identical. Same hardware and mounting. Again...same darn caliper, but 43mm piston.

I bolted it to a Cobra pad hanger, but it should also bolt to a GT hanger as well. So the 43mm can be used with the GT's 10.5" rotor or the cobra 11.65".

Now to discuss the master cylinder. As with any slave/master setup, if you change the ratio between the two, you affect the amount of force required on the master to operate the slaves. Go too small and the throw is longer, but effort goes down. Go too big, and the throw shortens but the effort increases.

So, let's use my brake setup. I've run this setup for 10 years and love how it feels for my driving needs. 40.5mm x 2 pistons up front, 38mm rear, and a 1" bore MC with SN95 booster.

But, in calculating out the ratio of slave to master surface area on my vehicle, i get a ratio of 8057mm^2/507mm^2 = 15.8:1.

So, now with the larger ATS brembos and using the 43mm calipers, i get a total surface area of all the pistons of 8446mm^2. Using the next step up of 1 1/16" MC off a 94-95GT, that gives a ratio of 14.7:1. That would be a tad bit fimer than what i'm used to now. If i kept my existing 1" bore MC, it would be 16.6 which would be a little bit softer.

Just to compare to the factory vacuum booster assisted setups
94-98 Cobra - 15.2:1
94-98 GT - 15.8:1
99-04 V6 - 16.6:1

Looks like most of the factory setups run in the 15:1 range. That really means the ideal MC is prob somewhere between the 1" and 1 1/16" bore. To come out with a ratio of 15.5:1 you would need an MC with a bore of 13.2mm/0.520". Unsure if there are any aftermarket MC's in that ballpark.

But then again, 14.7:1 is not that far off from the factory 94-98 Cobra setup at 15.2:1


To sum it all up.

ATS Brembo front calipers on 13" rotors
Rear 11.65" rotors running the Taurus 43mm caliper on Cobra pad hangers
94-95 GT 1 1/16" MC (accepting the firmer pedal)

Brake bias is a 65%/35% split?? That seems pretty light up front with a 4-piston Brembo even with the 43mm rears
 

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Great information on this thread. I really want to upgrade my front calipers to 4 pot units and keep my 17" Saleen reps. I can't quite stomach blowing 1k just for 2300-X calipers. But also do not want to deal with modifying my spindle. I'm looking forward to a full bolt on replacement option.
 

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not sure on the exact numbers although certain that this rear caliper upgrade to the bigger taurus piston design would also help the guys who want to run the GT500 brembo fronts (40/44) or the S197 PRB (dual 43s) with the 14" rotors
 

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Pulled the Caliper off the car to take a better look and 100% confirm it’s a direct swap. I wanted to make sure that inner pad fullseated on the piston. It does.

Red part is cobra pad bracket. Raw unpainted Caliper is the 43mm Varga

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And the 38mm back on the car
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The body around the piston is slightly larger, but it doesn’t appear to be near anything. I haven’t tried to hook up parking brake but looks to be identical setup
 

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I measure right around 41-42mm....but I obviously can’t meaure inside the bore. Given spec online is 42.8mm

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there's a step in the piston right behind what you're measuring
 

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So, let's use my brake setup. I've run this setup for 10 years and love how it feels for my driving needs. 40.5mm x 2 pistons up front, 38mm rear, and a 1" bore MC with SN95 booster.

But, in calculating out the ratio of slave to master surface area on my vehicle, i get a ratio of 8057mm^2/507mm^2 = 15.8:1.

So, now with the larger ATS brembos and using the 43mm calipers, i get a total surface area of all the pistons of 8446mm^2. Using the next step up of 1 1/16" MC off a 94-95GT, that gives a ratio of 14.7:1. That would be a tad bit fimer than what i'm used to now. If i kept my existing 1" bore MC, it would be 16.6 which would be a little bit softer.

Just to compare to the factory vacuum booster assisted setups
94-98 Cobra - 15.2:1
94-98 GT - 15.8:1
99-04 V6 - 16.6:1

Looks like most of the factory setups run in the 15:1 range. That really means the ideal MC is prob somewhere between the 1" and 1 1/16" bore. To come out with a ratio of 15.5:1 you would need an MC with a bore of 13.2mm/0.520". Unsure if there are any aftermarket MC's in that ballpark.

But then again, 14.7:1 is not that far off from the factory 94-98 Cobra setup at 15.2:1
Looks like my math is wrong. 8057mm^2 is incorrect. Of course, the new format won't let me edit my mistake.

Disregard the above post and lets start over.

Lets do a factory 94-98 Cobra setup. 2-piston, 38mm calipers up front, single 38mm rear. Brake bias is 70/30 according to the MM link.

4536mm^2 front calipers + 2268mm^2 rear calipers for a total of 6804mm^2 total surface area.
15/16" bore MC = 445mm^2
Total ratio of 15.2:1.

Now, this proposed ATS/43mm caliper setup. I calculate out a bias of 75%/25%.

5542mm^2 front/2904mm^2 rear for a total of 8846mm^2
1 1/16" bore MC = 572mm^2

with 1 1/16" bore it's 15.5:1
The above assumes pedal geometry remains the same between fox and 94-95 Cobra. That's pretty darn close.


I also ran a brake bias calc and got 75% front/25% rear.

So....
ATS Brembo/13" rotor
Taurus 43mm/11.65" rotor
1 1/16" MC
75/25 bias.

Looks viable. Someone want to check my math?

I'll likely try this setup, but right now my engine is out of the car for an upgrade, and i'm installing an MM k-member setup, so i'll be ironing out those bugs for a while. Changing brakes/MC likely will have to wait.
 

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Man this is some great info! Glad I found the thread as I already purchased the ATS calipers due to a site's "almost bolt on" write up. Mustang5L5 and others, thank you for your dedication to our hobby to figure some of this stuff out for the guys who follow!
 

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Looks like my math is wrong. 8057mm^2 is incorrect. Of course, the new format won't let me edit my mistake.

Disregard the above post and lets start over.

Lets do a factory 94-98 Cobra setup. 2-piston, 38mm calipers up front, single 38mm rear. Brake bias is 70/30 according to the MM link.

4536mm^2 front calipers + 2268mm^2 rear calipers for a total of 6804mm^2 total surface area.
15/16" bore MC = 445mm^2
Total ratio of 15.2:1.

Now, this proposed ATS/43mm caliper setup. I calculate out a bias of 75%/25%.

5542mm^2 front/2904mm^2 rear for a total of 8846mm^2
1 1/16" bore MC = 572mm^2

with 1 1/16" bore it's 15.5:1
The above assumes pedal geometry remains the same between fox and 94-95 Cobra. That's pretty darn close.


I also ran a brake bias calc and got 75% front/25% rear.

So....
ATS Brembo/13" rotor
Taurus 43mm/11.65" rotor
1 1/16" MC
75/25 bias.

Looks viable. Someone want to check my math?

I'll likely try this setup, but right now my engine is out of the car for an upgrade, and i'm installing an MM k-member setup, so i'll be ironing out those bugs for a while. Changing brakes/MC likely will have to wait.
You want to try that new combination, given how much you like your current one? the Corvette C5 front pads are much larger than the Cobra PBR pads, how do those compare to the ATS front caliper pads? is one caliper going to be easier to mount on the Cobra front rotors, or a cut down GT500 rotor, etc? I like the C5 caliper and the pad, and I haven't decided what to do with the rear yet.
 

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I do want to try it. It’s more of a personal challenge to myself of “can I do this properly”

Part of me does want the look of a nice red Brembo Caliper and the white (or black) lettering for that visual “pop”
 

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I like the motivation, and being thorough. I want the basic great brakes with good serviceability, but subtle looks. I like the idea of the caliper with GTC on it, but the color will have to be subtle, darker colored, maybe gold with black.
 

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Looks like my math is wrong. 8057mm^2 is incorrect. Of course, the new format won't let me edit my mistake.

Disregard the above post and lets start over.

Lets do a factory 94-98 Cobra setup. 2-piston, 38mm calipers up front, single 38mm rear. Brake bias is 70/30 according to the MM link.

4536mm^2 front calipers + 2268mm^2 rear calipers for a total of 6804mm^2 total surface area.
15/16" bore MC = 445mm^2
Total ratio of 15.2:1.

Now, this proposed ATS/43mm caliper setup. I calculate out a bias of 75%/25%.

5542mm^2 front/2904mm^2 rear for a total of 8846mm^2
1 1/16" bore MC = 572mm^2

with 1 1/16" bore it's 15.5:1
The above assumes pedal geometry remains the same between fox and 94-95 Cobra. That's pretty darn close.


I also ran a brake bias calc and got 75% front/25% rear.

So....
ATS Brembo/13" rotor
Taurus 43mm/11.65" rotor
1 1/16" MC
75/25 bias.

Looks viable. Someone want to check my math?

I'll likely try this setup, but right now my engine is out of the car for an upgrade, and i'm installing an MM k-member setup, so i'll be ironing out those bugs for a while. Changing brakes/MC likely will have to wait.
First off excellent work trying to correct the bias issue that some of us have been concerned with. I have been told by multiple people it was just like the 00r kit which is BS.

Next I am not following your math. From what I see.

For the stock cobra setup it looks like you calculated the total piston area of both front calipers as you should have. 4 total pistons.

Unless I missed something or I am just plain stupid you only calculated the total piston area for 1 caliper? When I do the math for all 8 pistons (4 per side) I get 11,077 ish. When I calculate 1 caliper or only 4 pistons I get 5542ish like you did. Again I could be plain retarded here as I am just now jumping into this.

One way I could be wrong is that the pistons on the ats calipers are effectively travelling half the distance of the cobra caliper. As you know the cobra caliper has to slide in its bracket to clamp the rotor where the ats would not effectively splitting that distance. Maybe that's why your math looks the way it does?

Please correct me if I am wrong.

Additionally I swore I read somewhere that the pedal ratio changed when ford rolled out the hydroboost setup. This may be corrected though if MM would sell us their adjustable pedal separate that the included in their hydroboost conversion kits.
 
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