Cadillac calipers? On my Cobra??? It's more likely than you think

[MB750]

Sorry for the clickbait title... :p

This chapter of my build is taken from the book of SN-95 Mustang enthusiasts. There's a mod where you can graft Brembo calipers designed to be used on the later model Cadillac ATS (with adapter bushings and a rotor spacer, and a little grinding) onto the SN-95 spindles. The Caddy calipers are much better because they're Brembo, they're 4-piston, and they're not floating calipers like the OEM or Cobra brakes.

Have a seat and see how it's done:

https://thefactoryfiveforum.com/attachment.php?attachmentid=178187&d=1673885216

https://thefactoryfiveforum.com/attachment.php?attachmentid=178188&d=1673885216

https://thefactoryfiveforum.com/attachment.php?attachmentid=178189&d=1673885216

This kit is from a guy on Facebook called S&S Engineering. For $175 you get all these bits:

https://thefactoryfiveforum.com/attachment.php?attachmentid=178190&d=1673885216

No, they're not brass bushings. They're anodized steel.

First, use a 7/16" bolt to smack out the old bushings. Trust me, getting them on a press is a PITA with all the weird angles on the caliper surfaces:

https://thefactoryfiveforum.com/attachment.php?attachmentid=178191&d=1673885216

[MB750]

Line up the new bushings. I've put marks for their orientation. They're symmetrical, just use the correct markings:

https://thefactoryfiveforum.com/attachment.php?attachmentid=178192&d=1673885239

Get them started in the vise but don't drive them home yet:

https://thefactoryfiveforum.com/attachment.php?attachmentid=178193&d=1673885239

That new bolt hole is offset, and the caliper casting gets in the way a bit, so bust out your die grinder and take care of business:

https://thefactoryfiveforum.com/attachment.php?attachmentid=178194&d=1673885239

NOW drive them home:

https://thefactoryfiveforum.com/attachment.php?attachmentid=178195&d=1673885239

Calipers done, move onto the car. Make sure the rotor spacer is installed before putting the rotor on:

https://thefactoryfiveforum.com/attachment.php?attachmentid=178196&d=1673885239

[MB750]

The spacer allows perfect alignment:

https://thefactoryfiveforum.com/attachment.php?attachmentid=178198&d=1673885264

https://thefactoryfiveforum.com/attachment.php?attachmentid=178197&d=1673885264

Pretty snug on the back side too, but it clears:

https://thefactoryfiveforum.com/attachment.php?attachmentid=178199&d=1673885264

Pads mount from the top of the caliper now, no more taking everything apart for brake maintenance:

https://thefactoryfiveforum.com/attachment.php?attachmentid=178200&d=1673885264

Done!

https://thefactoryfiveforum.com/attachment.php?attachmentid=178201&d=1673885264

Next step, paint them red and slap on some larger Brembo stickers.

[MB750]

Quick math: I'm all in around $600.

S&S kit was $175
Calipers were around $280 from Amazon
Pad kit was around $30
Rotors from Rockauto were $80

Some people go with those high end floating rotors. I just went with OEM style rotors from a 99 Cobra.

Rotors: RAYBESTOS 66844R here (https://www.amazon.com/dp/B00JGRP8AA?ref=ppx_pop_dt_b_product_details&th=1)
Pads: Power Stop 17-1001 here (https://www.amazon.com/dp/B00JGRP8AA?psc=1&ref=ppx_yo2ov_dt_b_product_details)
Calipers: 172-2777 and 172-2768 here (https://www.amazon.com/dp/B01K8BWCUG?psc=1&ref=ppx_yo2ov_dt_b_product_details)and here (https://www.amazon.com/dp/B01K8BW1YS?psc=1&ref=ppx_yo2ov_dt_b_product_details)
Brembo decal kit here (https://www.amazon.com/dp/B07KSPWHR4?psc=1&ref=ppx_yo2ov_dt_b_product_details)

For the adapter kit, email this guy: ssengineeringllc@gmail.com

[rich grsc]

Nice, but what about the rears? These cars need more rear brakes, not more front brakes.

[J R Jones]

My RV has huge four wheel Brembo's on 13 inch discs and they do not have a Winnebago logo. Pad material is 0.8 thick. It is a Chevy Workhorse chassis.

[MB750]

Nice, but what about the rears? These cars need more rear brakes, not more front brakes.

Until I get down the road a few miles I'll just be sticking with the 38mm OEM calipers that came on the Mustang. It's all upgraded too, brand new bits back there. There's an option to upgrade to 43mm calipers from a Taurus, but I'll make adjustments to the balance bar before putting money into larger calipers.

Honestly, if I can lock up the rear brakes on pavement I can't see a need for more brakes in the rear. Tweaking the balance bar on a "closed course" until I can get even lock up at all four tires is perfect.

[Jeff Kleiner]

Nice, but what about the rears? These cars need more rear brakes, not more front brakes.

Rich took the words right out of my mouth! Now you just have to come up with something for the rear to balance it all out. Not enough rear brake has been the problem on these cars for almost 30 years.

Jeff

[rich grsc]

Until I get down the road a few miles I'll just be sticking with the 38mm OEM calipers that came on the Mustang. It's all upgraded too, brand new bits back there. There's an option to upgrade to 43mm calipers from a Taurus, but I'll make adjustments to the balance bar before putting money into larger calipers.

Honestly, if I can lock up the rear brakes on pavement I can't see a need for more brakes in the rear. Tweaking the balance bar on a "closed course" until I can get even lock up at all four tires is perfect.
The stock front brakes will lock up on pavement, there for I don't understand the need for more front brakes? :confused: You create even more unbalanced braking by better fronts, but doing nothing to the rear. Don't get me wrong, I think that approach for the front brakes are cool, but maybe you should have started with the rear's first? I'm always looking to find more rear braking, but my setup is a bit hard to solve. I have the old style IRS and run pin drive 15' wheels and tires.

[MB750]

You really don't think I can tune it to balanced braking by using the balance bar?

[Gizmosrcool]

Front brakes do 70% of the work. if you have a need to upgrade one or the other, upgrade the front first, and then the rear.

MB750. That is a good option. I plan on 13" mustang in the rear with upgraded drilled and slotted rotors, and upgraded pads. I had not figured out the front yet. That is a good option along with other mustang related brake upgrades. Thx for sharing. Tom

[rich grsc]

I don't know. I don't have any experience with using a balance bar, but doesn't that sorta defeat the purpose of bigger front brakes? The balance bar will apply less front (leverage) pressure, so that more (leverage) pressure is applied on the rear? It might work, but I would be WAY happier to reduce rear braking, that reducing front braking. These cars are ALWAYS short on rear brakes, remember, these are rear weight biased.
Front brakes do 70% of the work. That might be true, on a Mustang, but not on a car that has 55% of the weight on the rear.

[JohnK]

Being able to lock up the brakes is really a poor measure of whether or not brakes are adequate. The stock front and rear brakes are more than capable of locking up. What larger brakes get you is fade resistance and better brake modulation ("feel"). So now you have great modulation on the front, and the rears are basically on/off switches by comparison. That's not really a good setup for confident and repeatable braking. The last thing I want is for my rear brakes to lock up when I'm trying to brake quickly. I want to have a good feel for the point right before both front and rear lock up.

[CraigS]

You really don't think I can tune it to balanced braking by using the balance bar?

You can also swap MCs to a different size if the balance bar doesn't do it. I suspect it won't. BTW I was looking for build specs in your signature line but there are none. Reason I was looking was to see what you are doing in the rear. Solid or IRS? If 2015+ IRS, the stock Mustang calipers are a vast improvement over the older Mustang rear calipers. Before the Q of enough rear brake came up, I was wondering if 2015+ Mustang Performance Package Brembos would fit.

[CraigS]

Being able to lock up the brakes is really a poor measure of whether or not brakes are adequate. The stock front and rear brakes are more than capable of locking up. What larger brakes get you is fade resistance and better brake modulation ("feel"). So now you have great modulation on the front, and the rears are basically on/off switches by comparison. That's not really a good setup for confident and repeatable braking. The last thing I want is for my rear brakes to lock up when I'm trying to brake quickly. I want to have a good feel for the point right before both front and rear lock up.

Well not exactly. Yes the front brakes can lock up. Yes the rears can lock up. BUT.....the problem is that w/ a lot of the brake setups that end up on FFRs there is too much front brake capability. So as brakes are applied harder and harder the fronts lock. What usually happens then? The driver comes off the brake pedal some to try to get the front tires spinning again. Maybe the rears are capable of locking but they never will. The good thing about all this is we can get a perfectly balanced system. Once MCs and calipers are chosen, I start testing w/ the balance bar centered. I test at 40mph and adjust until I get rears locking first. Then I adjust just enough to get the fronts locking first. That good thing I mentioned? Get the balance perfect in good conditions, and any lessor conditions will have the fronts locking earlier.

[rich grsc]

Being able to lock up the brakes is really a poor measure of whether or not brakes are adequate. The stock front and rear brakes are more than capable of locking up. What larger brakes get you is fade resistance and better brake modulation ("feel"). So now you have great modulation on the front, and the rears are basically on/off switches by comparison. That's not really a good setup for confident and repeatable braking. The last thing I want is for my rear brakes to lock up when I'm trying to brake quickly. I want to have a good feel for the point right before both front and rear lock up.
I agree, thats not a requirement I look for. I want all 4 brakes doing the MAXIMUM work they can when hauling down from 120mph

[Skip]

Curious what size wheels will fit?

I checked Rock Auto for a 2016 CTS and the listed rear calipers are shown as having a single 43.18mm piston.

I’m in the process of installing the slightly larger Mustang 11.65 rotors on the rear of my Mk 3 with Thunderbird IRS. The pistons reportedly have a 45.26mm piston. Larger than the CTS with those huge 4-piston calipers?

[JohnK]

Well not exactly. Yes the front brakes can lock up. Yes the rears can lock up. BUT.....the problem is that w/ a lot of the brake setups that end up on FFRs there is too much front brake capability. So as brakes are applied harder and harder the fronts lock. What usually happens then? The driver comes off the brake pedal some to try to get the front tires spinning again. Maybe the rears are capable of locking but they never will. The good thing about all this is we can get a perfectly balanced system. Once MCs and calipers are chosen, I start testing w/ the balance bar centered. I test at 40mph and adjust until I get rears locking first. Then I adjust just enough to get the fronts locking first. That good thing I mentioned? Get the balance perfect in good conditions, and any lessor conditions will have the fronts locking earlier.

Bias adjustment will definitely help, but there is no one single correct front/rear bias. Riding motorcycles in the dirt really helped me understand the effect of weight transfer on traction and braking power. You need to consider what's happening with weight transfer as you brake, and how that affects front/rear bias. If you apply the brakes progressively, weight will shift forward as you apply the brakes, thereby increasing the braking power of the front brakes and reducing the braking power of the rear brakes. If, in contrast, you stab the brakes (panic braking) you now apply maximum braking before weight has transferred and you get a very different braking dynamic. This is why good brake modulation at both ends is critical to maximizing braking potential. Bias adjustment can be optimized for one situation or the other, but by itself cannot always ensure which axle will lock up first.

[Hoooper]

Curious what size wheels will fit?

I checked Rock Auto for a 2016 CTS and the listed rear calipers are shown as having a single 43.18mm piston.

I’m in the process of installing the slightly larger Mustang 11.65 rotors on the rear of my Mk 3 with Thunderbird IRS. The pistons reportedly have a 45.26mm piston. Larger than the CTS with those huge 4-piston calipers?

Youre looking at the wrong caliper, obviously the ones in the pictures are 4 piston not single piston. Theyre 4 pistons, 42mm per piston, or about 3.5x the piston area per caliper of your single piston calipers

[Hoooper]

I have slightly smaller calipers on the front of mine on 13" rotors (9,000mm2 piston area if I remember, compared to your 11,100mm2) and calipers with about 5,100 mm2 piston area on 12.88" rotors on the rear. Your rears are less than half the piston area, and much smaller diameter rotors. I think you are going to find the rears need to be upgraded.

[Ford & Jeep Fan]

Until I get down the road a few miles I'll just be sticking with the 38mm OEM calipers that came on the Mustang. It's all upgraded too, brand new bits back there. There's an option to upgrade to 43mm calipers from a Taurus, but I'll make adjustments to the balance bar before putting money into larger calipers.

Honestly, if I can lock up the rear brakes on pavement I can't see a need for more brakes in the rear. Tweaking the balance bar on a "closed course" until I can get even lock up at all four tires is perfect.

perfectly logical to me.

[Skip]

Youre looking at the wrong caliper, obviously the ones in the pictures are 4 piston not single piston. Theyre 4 pistons, 42mm per piston, or about 3.5x the piston area per caliper of your single piston calipers

I was inarticulate in noting the size of the CTS rear caliper compared to the 4-piston front.

[MB750]

Curious what size wheels will fit?

I checked Rock Auto for a 2016 CTS and the listed rear calipers are shown as having a single 43.18mm piston.

I’m in the process of installing the slightly larger Mustang 11.65 rotors on the rear of my Mk 3 with Thunderbird IRS. The pistons reportedly have a 45.26mm piston. Larger than the CTS with those huge 4-piston calipers?

Skip

I'm pretty sure there's a "Premium" version of the ATS that came with these calipers. Use the link I put in my reply for the exact pieces I bought.

[Dave Tabor]

Sorry for the clickbait title... :p

This chapter of my build is taken from the book of SN-95 Mustang enthusiasts. There's a mod where you can graft Brembo calipers designed to be used on the later model Cadillac ATS (with adapter bushings and a rotor spacer, and a little grinding) onto the SN-95 spindles. The Caddy calipers are much better because they're Brembo, they're 4-piston, and they're not floating calipers like the OEM or Cobra brakes.

Have a seat and see how it's done:



Thank you very much for posting this. I know that GTRich uses a similar setup (with the same calipers in the rear on a solid axle).

I may move to these calipers if my 2000 Cobra R caliper mounting threads ever strip - there does not appear to be a steel insert in them.

Dave
Gen III Coupe #17

[J R Jones]

I don't know. I don't have any experience with using a balance bar, but doesn't that sorta defeat the purpose of bigger front brakes? The balance bar will apply less front (leverage) pressure, so that more (leverage) pressure is applied on the rear? It might work, but I would be WAY happier to reduce rear braking, that reducing front braking. These cars are ALWAYS short on rear brakes, remember, these are rear weight biased.
Front brakes do 70% of the work. That might be true, on a Mustang, but not on a car that has 55% of the weight on the rear.

The 55% weight proportion you reference sounds like scale weights, or the static condition. Dynamics of braking and also accelerating cause weight proportions to shift.
You have seen high performance acceleration lift the front wheels of a car or motorcycle off the ground? What is that front weight?
You may also have seen a "stoppy" typically with a motorcycle where the front brake/tire creates so much stopping force that the rear tire comes off the ground. What is that rear weight?
We had crude (Ford) proportioning valves on our SCCA Production based cars, sometimes with the disc-drum combination. None the less, we engineered the brakes to slide the rears at maximum braking, then dialed the proportioning valve to not slide the rears on maximum braking (for stability). The front brakes are a constant at that point, whether they are good or great.
jim

[MB750]

I appreciate all your replies. So, I've been taking everything into consideration and here's what I'm gonna do:

I'm gonna put it together as-is and beat the tar out of it. Issues will come out in the wash and I'll take care of them as dictated.

No offense, but there's literally thousands of things I could do to make it perfect for bench racing. Ultimately, how it performs during my personal use is what I'm looking at. Since most braking takes place in the front, that's why I went with a larger rotor and more powerful caliper. During tuning I'll get on a gravel road and firmly but slowly apply brake pressure to see what end locks up first, then make balance bar adjustments from there. If I can NEVER lock up the back end, well, then I need to focus more braking power back there somehow. I know I'm not going down gravel roads very much, but it's an easy place to lock up tires for testing.

[MB750]

You can also swap MCs to a different size if the balance bar doesn't do it. I suspect it won't. BTW I was looking for build specs in your signature line but there are none. Reason I was looking was to see what you are doing in the rear. Solid or IRS? If 2015+ IRS, the stock Mustang calipers are a vast improvement over the older Mustang rear calipers. Before the Q of enough rear brake came up, I was wondering if 2015+ Mustang Performance Package Brembos would fit.

To answer your question, OEM Ford solid 8.8 axle from a 95 Mustang GT, 3.27 gears.

Good tip on those IRS Brembos. As an option I could make and adapter plate for my 8.8 to graft them on. Or, maybe something already exists. Thanks!

[phils88gt]

Sorry for the clickbait title... :p

This chapter of my build is taken from the book of SN-95 Mustang enthusiasts. There's a mod where you can graft Brembo calipers designed to be used on the later model Cadillac ATS (with adapter bushings and a rotor spacer, and a little grinding) onto the SN-95 spindles. The Caddy calipers are much better because they're Brembo, they're 4-piston, and they're not floating calipers like the OEM or Cobra brakes.




Ya know I am pretty into the SN95 mustang cars, have several built a few. Raced fox bodies and I hadn't seen this swap. I have seen the C5 corvette calipers but not the ATS. Too bad you didnt weigh them. I make my own wilwood setup and brackets, but since I have an adapter bracket and 2 extra bolts I wonder what is lighter.

Philip

[Gizmosrcool]

A few obserations based on my motorcycle experience. Front vs rear weight does not matter. Weight is weight. The strongest and most effecient is and will be the front brakes. More so than the rear. Newton’s Law of Motion - The object in motion wants to stay in motion. When you are stopping, the vehicle’s weight shifts from the back to the front, and that is when the front brakes do their magic. Rear brakes help. However you do NOT want them to lock up first. Bad things happen when rear brakes lock up. You get squirrely. That is where the ability to adjust bias between the front and back comes in handy. Have a good front braking system and adjust bias where the rears lock after the front.

I hit 8 states and 2800 miles over a week this summer on my touring bike. I used the rear brakes 5-10 times. The front brakes 1000. My bike has twin front disk. The rear has a single. Harley has it figured out.

Given the overall weight of these cars, modern braking components, and a ton of questions and answers on brakes on the forum, the 11"-13" mustang brake system is going to work well for most. Getting the front vs rear bias is the key. My $.02. Tom

[Mark Reynolds]

MB750 That is a very cool upgrade. I am sure you will get the balance figured out.

[J R Jones]

I appreciate all your replies. So, I've been taking everything into consideration and here's what I'm gonna do:

I'm gonna put it together as-is and beat the tar out of it. Issues will come out in the wash and I'll take care of them as dictated.

No offense, but there's literally thousands of things I could do to make it perfect for bench racing. Ultimately, how it performs during my personal use is what I'm looking at. Since most braking takes place in the front, that's why I went with a larger rotor and more powerful caliper. During tuning I'll get on a gravel road and firmly but slowly apply brake pressure to see what end locks up first, then make balance bar adjustments from there. If I can NEVER lock up the back end, well, then I need to focus more braking power back there somehow. I know I'm not going down gravel roads very much, but it's an easy place to lock up tires for testing.

Do not brake test on gravel. It is dangerous and it is almost impossible to recover from a slide. Moreover you will not experience enough deceleration to be valid.
If nothing else you will get very little weight transfer which means the front will always be lighter and the rear heavier than pavement conditions.
BTW in a max braking test the clutch must be disengaged. CraigS has weighed in on this before.
jim

[JDFinley]

Kewl upgrade! Thanks for sharing!

[MB750]

Ya know I am pretty into the SN95 mustang cars, have several built a few. Raced fox bodies and I hadn't seen this swap. I have seen the C5 corvette calipers but not the ATS. Too bad you didnt weigh them. I make my own wilwood setup and brackets, but since I have an adapter bracket and 2 extra bolts I wonder what is lighter.

Philip

Ask and ye shall receive:

https://thefactoryfiveforum.com/attachment.php?attachmentid=178222&d=1673957890

For what it's worth, it's not much over 7 lbs (the max on my food scale). But since you're down to ounces I'm guessing you'd appreciate an accurate measurement.

Don't read into it too much that the caliper maxed out my Weight Watchers scale. ;) It maxes out at 6lb, 9oz and all I have to do is pull up on it just a smidge to register weight.

[MB750]

A few obserations based on my motorcycle experience. Front vs rear weight does not matter. Weight is weight. The strongest and most effecient is and will be the front brakes. More so than the rear. Newton’s Law of Motion - The object in motion wants to stay in motion. When you are stopping, the vehicle’s weight shifts from the back to the front, and that is when the front brakes do their magic. Rear brakes help. However you do NOT want them to lock up first. Bad things happen when rear brakes lock up. You get squirrely. That is where the ability to adjust bias between the front and back comes in handy. Have a good front braking system and adjust bias where the rears lock after the front.

I hit 8 states and 2800 miles over a week this summer on my touring bike. I used the rear brakes 5-10 times. The front brakes 1000. My bike has twin front disk. The rear has a single. Harley has it figured out.

Given the overall weight of these cars, modern braking components, and a ton of questions and answers on brakes on the forum, the 11"-13" mustang brake system is going to work well for most. Getting the front vs rear bias is the key. My $.02. Tom

Like you, I also have a LOT of motorcycle wrenching and building experience. You're exactly correct about weight transfer during braking. It's the reason many motorcycles out there can hoist the rear tire during hard, but controlled, application of the front brake. Also called a "stoppie", it shows just how much weight is transferred to the front tire during braking.

Also correct regarding the rear brake lockup. Many motorcycle accidents have occurred from inexperienced riders hammering the rear brakes in a panic, causing a low side. 90% of the time the only thing I use my rear brake for is what's called trail-braking. Basically for shrugging speed in corners. If you hit the front brake in a fast corner the bike will want to stand up. Drag the rear brake (but DON'T lock it up) and you'll see the bike literally gain composure mid corner. It might even fall towards the apex to allow a tighter exit which allows a faster onset of throttle into a straight.

I know we're not building motorcycles here, but physics doesn't discriminate across mechanical systems. The Cobras might be 45/55 when parked, but as you crank down on the brakes and the nose dives, it just became 70/30 (or thereabouts).

[MB750]

Do not brake test on gravel. It is dangerous and it is almost impossible to recover from a slide. Moreover you will not experience enough deceleration to be valid.
If nothing else you will get very little weight transfer which means the front will always be lighter and the rear heavier than pavement conditions.
BTW in a max braking test the clutch must be disengaged. CraigS has weighed in on this before.
jim

You raise a good point. I just thought of gravel at lower speeds as an easy way to break traction during braking to get an idea where my bias it at. Then I'd take it to a paved "closed course" and do the same thing at mild speeds (around 50). The problem is when on gravel I won't get maximum weight transfer to the front wheels during said braking so it won't be as accurate as on pavement.

Trial and error here. I'll report my findings once I have them.

[weendoggy]

Many SN95 owners are doing this and running 18" wheels as well. Not too sure if any (other than the Cobra R 17's) will fit. Also need to mention the outer edge of the pads need to be beveled or will leave a shoulder during wear.

[Namrups]

Lets not forget about shocks. Your shocks have a compression setting that dictates how fast your shock will compress and a rebound setting that dictates how fast your shock will extend.

The front and rear shocks work together but opposite. When you apply the brakes the weight wants to move forward to the front of the car. Shocks that are set up for a "fast" compression on the front and a "fast" rebound on the rear will allow the car to "nose dive" allowing the weight to transfer to the front wheels making the rear of the car light. Taken to extremes this, in itself, could cause the rear wheels to lock first especially during hard turning or the front wheels to loose traction because of too much weight transfer for the tires causing them to slide.

Conversely, under acceleration, the opposite happens and the weight transfers to the rear wheels causing a "nose up" condition. Think drag racing.

Our DD's are engineered with the proper shock package and in most cases are non-adjustable. Our FF cars are not. The shocks are adjustable. The challenge is to adjust them so that you get enough weight transfer to get the maximum braking force to the front wheels without removing to much weight/braking force on the rear wheels. This "balance" will be different for everyone based on the way we drive. Is it just a street car? Do you use it for autoX? Is it a full blown race car? For a street car the manufactures setting may be best. Minor adjustments may be required for autoX. Race care will adjust this for every different track.

The best way to demonstrate this is with Nascar racing. On larger tracks, that do not have a lot of hard braking or acceleration after the initial start, the nose of the car will drop right to the track surface and stay there giving maximum traction to the front wheels. These shocks have a fast compression but a very slow rebound. On short tracks you will see the nose dive when entering a corner to give maximum grip to the front wheels and a nose up condition coming off the corner giving maximum tracking under acceleration. Both front and rear shocks have a fast compression and rebound setting.

One last note. Springs are for static weight. Think ride height. Shocks are for weight transfer, body roll and ride quality. A very slow moving shock will feel very stiff and harsh. A faster moving shock will feel softer with better ride quality. Street cars are soft and squishy while race cars are stiff and harsh.

[phils88gt]

Ask and ye shall receive

Alright game on. I will weigh all the parts tonight. In your picture there are no pads right? I don't see the pins in the holes so that's why Im assuming that.

[MB750]

Alright game on. I will weigh all the parts tonight. In your picture there are no pads right? I don't see the pins in the holes so that's why Im assuming that.

Correct, no pads nor pins. The only "loose" item on that caliper is the bleeder, which might be half an ounce.

[Avalanche325]

Front brakes do 70% of the work. That might be true, on a Mustang, but not on a car that has 55% of the weight on the rear.

The second you hit the brakes that 55% shifts mostly to the front, which is where that typical "Fronts do 70% of the braking" comes from. You never want more rear braking than front, unless you want to suddenly find yourself going backwards. Rear brakes should never really lock up. The rear tires are your rudders when braking.

[tonywy]

https://shop.wilwood.com/blogs/news/how-does-a-proportioning-valve-work

[Hoooper]

The second you hit the brakes that 55% shifts mostly to the front, which is where that typical "Fronts do 70% of the braking" comes from. You never want more rear braking than front, unless you want to suddenly find yourself going backwards. Rear brakes should never really lock up. The rear tires are your rudders when braking.

70% is a generic, commuter car theory that works for cars that are 50/50 or front heavy. With rear biased cars you dont want 70% front, but you dont want less than 50% either. I have no idea what the right number is for our cars but I would guess something like 60% front as a starting point. The setup in this thread (even ignoring the ~20% extra torque from 13" front rotors vs 10.5" rear rotors) is almost 85% front/15% rear which I think puts it well beyond debate about whether ideal would be even 50% or 70%

[MB750]

70% is a generic, commuter car theory that works for cars that are 50/50 or front heavy. With rear biased cars you dont want 70% front, but you dont want less than 50% either. I have no idea what the right number is for our cars but I would guess something like 60% front as a starting point. The setup in this thread (even ignoring the ~20% extra torque from 13" front rotors vs 10.5" rear rotors) is almost 85% front/15% rear which I think puts it well beyond debate about whether ideal would be even 50% or 70%

The only objection I have with your estimations is that they don't factor in caliper influence on the rotors, only diameter of rotor. I'm running twice the number of pistons than the Cobra setup (with the two-piston calipers). How does that factor in?

Also, where are you getting 85% from? And 60%? For that matter, all your percentages? Braking force isn't measured solely by rotor diameter. If you really want to split hairs, total braking force needs to consider.....

Force applied by your foot, factoring in the moment arm length of the brake lever and additional leverage applied to the master cylinder
Balance bar offset
Size of master cylinder
Size of slave cylinder (caliper)
Number of pistons in slave cylinder
Diameter of each piston in slave cylinder
Surface area of brake pads
Coefficient of friction between brake pads and rotor
Coefficient of friction between your tire and the surface of the road
Type of substrate your tire is on
Rubber compound your tires are constructed of
Pressure of air in tires
etc...

You see how mind-numbing this can get? It's all bench racing. Screw all that mess, I'll just toss on larger rotors and calipers with more pistons. :cool:

[CraigS]

Agreed. The often written F to R of 70-30 is more an illustration of the concept of how weight transfers during braking than it is an actual number. I imagine that auto manufacturer engineers can actually measure it but we can't. The stationary weights we can measure so they can help us figure things out. A lot of times the Fox Mustangs are quoted as having a 55F/45R distribution vs an FFR w/ 45F/55R. Those two sets of numbers help us see that an FFR needs more rear brake than a Mustang did. In the last 10 years more and more FFRs are built w/ something other than Fox takeoff brakes which is a great improvement. One thing to keep in mind is that while the weights are different (3200Fox vs 2300FFR) they still transfer weight forward when braking. It could be that the Mustang starts at 55F/45R and goes to the 70/30 ratio. The FFR starts at 45F/55R so it may end up at 60/40. I agree w/ MB750, "You see how mind-numbing this can get? It's all bench racing. Screw all that mess, I'll just toss on larger rotors and calipers with more pistons." And then test the result and go from there.

[David Williamson]

To add one more item the stock Mustang center of gravity is higher and the car suspension is softer so the weight transfer to the front is greater than on our cars.
Neat mod to use an upgraded stock part that is easily available. Great idea
David W

[Fman]

What a great mod, thanks for sharing. Definitely an upgrade from the GT calipers at a fraction of the cost of the Wilwood kit.

[Hoooper]

The only objection I have with your estimations is that they don't factor in caliper influence on the rotors, only diameter of rotor. I'm running twice the number of pistons than the Cobra setup (with the two-piston calipers). How does that factor in?

Also, where are you getting 85% from? And 60%? For that matter, all your percentages? Braking force isn't measured solely by rotor diameter. If you really want to split hairs, total braking force needs to consider.....

Force applied by your foot, factoring in the moment arm length of the brake lever and additional leverage applied to the master cylinder
Balance bar offset
Size of master cylinder
Size of slave cylinder (caliper)
Number of pistons in slave cylinder
Diameter of each piston in slave cylinder
Surface area of brake pads
Coefficient of friction between brake pads and rotor
Coefficient of friction between your tire and the surface of the road
Type of substrate your tire is on
Rubber compound your tires are constructed of
Pressure of air in tires
etc...

You see how mind-numbing this can get? It's all bench racing. Screw all that mess, I'll just toss on larger rotors and calipers with more pistons. :cool:

Those % are all from just the piston diameter. You have 85% of your total piston diameter in the front, 15% in the rear (assuming stock SN95 rear caliper). If your rotors were the same size, master cylinders are the same size, and the balance bar is set up 50/50 that would make 85% of your braking torque to the front. Since you have bigger rotors in the front its actually worse than that. The number of pistons in the caliper doesnt really change the force (assuming equal piston area) it changes your pad contact area and force distribution so your pads last longer, you can use bigger pads for more fade resistance, etc. You might be able to adjust this to work OK by using the balance bar but the real effect is losing a bunch of the performance you picked up with this nice front brake system to match the under braked rear. I think its a good start and you can obviously use it as a baseline, just think about keeping an eye out for a future rear upgrade.

[GT_Rich]

I also use the Caddy front brakes and I made my own rear brake brackets to use a complimentary Brembo rear caliper. The combo seems to work well together. Here's a thread about it:

https://thefactoryfiveforum.com/showthread.php?41881-New-Custom-Brembo-fixed-caliper-brakes&highlight=brembo

And here's my build thread with more details:
https://thefactoryfiveforum.com/showthread.php?41854-427-SBF-Coupe-R-Build

[MB750]

I also use the Caddy front brakes and I made my own rear brake brackets to use a complimentary Brembo rear caliper. The combo seems to work well together. Here's a thread about it:

https://thefactoryfiveforum.com/showthread.php?41881-New-Custom-Brembo-fixed-caliper-brakes&highlight=brembo

And here's my build thread with more details:
https://thefactoryfiveforum.com/showthread.php?41854-427-SBF-Coupe-R-Build

Thanks for saying something here. I'm glad to see I'm not the only person going down this road.

[Ford & Jeep Fan]

I was a race car parts swap meet last weekend. i saw one part that would be quite helpful is seting ones brake proportioning. It was a dual 0-1500 psi gauge set complete with twin bleeder screws on the back so you could see what the pressure difference.

[phils88gt]

Okay so "tonight" took all week. But regardless I did it:

caliper bracket is 1lb 12.5oz
bolts 5.6 oz
calipers 5lb 4.8oz

total 7lb 6.8oz

On my own car I made the bracket from titanium and used ti hardware as well. This saved over 1lb off the total. 1lb of it was in the mounting bracket alone.

https://photos.app.goo.gl/r7D92MMKhUaeP4rK6