Scat Pack 4 piston Brembo calipers and rotors

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75slant6 said:
...run Hellcat widebody wheels on it.
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If you end up running 20" HC wheels, you could also run the 6 piston setup using these plates. The 4 piston Scat Pack setup and at least the 15.4" 6 piston HC brakes interchange as both models use the same spindles on the LX/LC cars. Mopar changed the HC brakes to a 15.7" rotor recently, but I can't remember if the caliper changed as well, or if the spindle did. So not sure if those would bolt up.
 
DionR said:
Sweet! First I've seen of anything on that project. What front suspension is that? Or is that not your project, just visuals for what your goal is?

In regards to the bolt pattern, here is some info I found while doing this swap. Not definitive, but interesting.

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I should break out a new rotor and get everything bolted up and the F14 wheel slipped on. Curious to see how the new rotors match up to the studs on the hub.
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I found the pictures of that Dart on fb. The post said it was the personal project of one of SRT’s head designers.

I’ll have to check out that link when I get off work this evening.
 
Another idea on how to do this if someone had access to a milling machine.

1P Caliper Adapter v2 Top.png


1P Caliper Adapter v2 Bottom.png


Needs some refinement, specifically to remove the pointy remnants. It was just a quick sketch to see if it even looked feasible.

3D printing one to see how well it bolts up.
 
Surprisingly, Xometry quoted me $85 each for the above CNC part out of 6061-T6. Better than I expected.
 
Ear mount calipers are a royal pain. It is so much easier to use radial mount calipers. The mounts are super simple to make and they are very strong. All of the higher end cars use radial mount calipers so there is a really big supply to pick from.

DSC_1148 (Large).JPG
 
Here is the Baer 6S on a Mopar knuckle. The radial mount bracket is very simple to design and build and it is very strong. I don't recommend messing around with ear mount calipers. The spacing rarely works and bracket usually ends up oddly shaped and too weak to handle the stress of multiple high speed stops.

6S_mount.jpg
 
AndyF said:
Ear mount calipers are a royal pain. It is so much easier to use radial mount calipers. The mounts are super simple to make and they are very strong.
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AndyF said:
The radial mount bracket is very simple to design and build and it is very strong.
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I agree the radial mount calipers are much easier to get located correctly both at the circumference and centered over the rotor thickness. But I'm not sure I agree they are simple or easy for someone without their own machine shop to make. I can't imagine trying to build something like you show in your second picture with a drill press and a grinder. :D

Even with the advent of online machine shops, it still isn't a cheap option. I've got a single '03 Viper rear caliper I messed with and 3 years ago it was going to be $125-$175 per bracket to get a couple of brackets machined from Xometry. I don't know what it would cost now, but the bracket for the ear mount caliper was $85 each last week. Not necessarily an apples to apples comparison as I don't remember what material the radial mount bracket was quoted as.

I will add that the ear mount bracket above was a breeze to get the caliper located correctly once I got the holes located. Not sure on the "oddly shaped and too weak" criteria though.

AndyF said:
All of the higher end cars use radial mount calipers so there is a really big supply to pick from.
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There might be a good supply, but they aren't cheap. At the same time I was looking at the radial mount bracket for the Viper caliper I have, it was about $300 for another remanufactured caliper to make a pair while the Scat Pack calipers were about $240 for a pair. And a pair of Mustang GT Brembo's were about $260 a pair. Right now the only source is used as far as I know. BTW, the one I have is brand new, never even had brake fluid in it.

I know there is a "Viper tax" so anything with Viper in the name is going to be more expensive, but generally there is a tax for all high end cars as well. Either way, I did look around and couldn't find anything that was reasonably price and had pistons big enough to be usable.

Funny thing was, last week RockAuto had Scat Pack calipers for $18 for one side and $57 for the other. But those are gone now. At the same time you can still get reman's for as low as $121 each and they list new ones for $158 each while a single match for my Viper caliper is going for $330-$725 on eBay right now.

The thing that really opened things up for me is the option for laser cutting flat plates from online sources. The cost for all the plates for the Scat Pack calipers (both sides!) was less than a single radial mount bracket, and I went way overboard with the plating. Bare, I could buy 2 complete sets for less than 1 radial mount bracket.

I've got 5/8" of steel supporting the caliper, 3/8" on one side and 1/4" on the other, so I think it is plenty strong. And not cantilevered like the failed aluminum bracket I referenced at the beginning of the thread. If I had drilled the threads out of the spindle, I could have used any thickness I wanted on backside of the spindle.

The only drawback I can see is that using off the shelf flat plate thicknesses means the caliper will need some shimming to get it centered over the rotor. In this case the calculated shim thickness is 0.0547" which is more than I would have liked. This what you are saying in that an ear mount caliper spacing is not the best, I agree. But I have to point out that at least all of the big dollar kits that I have looked at that use radial mount calipers include instructions for shimming the caliper bracket to get the caliper centered over the rotor. So I'm not sure the radial mount calipers really fix that.

If I was marketing this and trying to make this setup the absolute best it could be, I would drill out the threads in the spindle, make the outside plate 5/16" or 3/8" and get a single cut done on a mill to make the thickness of the plate where the ears mount match what is needed. Best guess, the outside plate would be maybe $50 each from Xometry while the rest of the plates might be $60 (bare) from SendCutSend. So $160 for a set of brackets to mount a pair of $300 Brembo calipers. Not back in my mind. Certainly the low end of the fix caliper market, but a reasonable path for someone budget minded like me.
 
Here's another way to side step the offset issue on ear mount calipers; build your own spindle.

sindle-a-png.png


:rofl:
 
A little bitty bit off topic but anyone tried using Autodesk Fusion 360? How does it compare to CAD. My son is using it for 3D printing. These programs are crazy expensive so I might just have to wait until we can get him into a STEM program and get an educational license.
 
go-fish said:
A little bitty bit off topic but anyone tried using Autodesk Fusion 360? How does it compare to CAD. My son is using it for 3D printing. These programs are crazy expensive so I might just have to wait until we can get him into a STEM program and get an educational license.
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The image of the spindle I posted just a bit ago and the machined bracket from last week is from Fusion 360. Not real experienced in it, but I am getting better.

I usually do my layouts in 2D and then loft them in 360 so I can export an stl file for 3D printing. Haven't done any real modelling in it though.
 
I design everything using a MasterCAM Draft license that I bought 20 years ago for $99. I've never upgraded to 3D. Most of my parts are 2.5D since I rarely do anything that is truly 3D. The radial mount parts are so much stiffer that you can make them out of aluminum. Aluminum is much faster to machine so the cost is much lower.
Here is a picture of the Viper kit that I used to sell. The rotors were off a Mercedes S class, the calipers were from a Viper and the brackets were made from aluminum. They were basically just some aluminum bar stock with some holes drilled and tapped in them. This was all designed in MasterCAM 2D and made by local machine shops. The brackets didn't cost me much to have made, maybe $40 each.

AR189 (Medium).jpg
 
In regards to ear mount calipers being difficult to make work, here are layouts for a Scat Pack caliper and a '07-14 GT500 caliper with a 13" rotor. I don't believe here is a way either could be done.

50998386411_553181a9b7_z.jpg


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The only way I could make either of these ear mount calipers work was to step up to a 14" or 14.2" rotor. But that removes the 17" wheel option, 18" only.

So Andy, you are right that there are issues that ear mount calipers cause, no argument. And a radial mount can be easily made to work with a 13" rotor.
 
When I was selling brake kits I found that the Mopar market size dropped rapidly as the wheel size got larger. Almost everyone would use a 15 inch wheel but only a few people would upgrade to a 17 inch wheel and almost nobody would go larger than 17 inches. So if you design a brake kit that requires a 18 inch wheel you are locking out about 99% of the Mopar crowd. Which might be okay if you're only looking to sell a few kits a year.
I eventually gave up on even the 13 inch rotor kits since I just couldn't convince Mopar guys to upgrade to 17 inch rims. They just refuse to do it so I stopped trying to sell big brake kits.
 
AndyF said:
When I was selling brake kits I found that the Mopar market size dropped rapidly as the wheel size got larger. Almost everyone would use a 15 inch wheel but only a few people would upgrade to a 17 inch wheel and almost nobody would go larger than 17 inches. So if you design a brake kit that requires a 18 inch wheel you are locking out about 99% of the Mopar crowd. Which might be okay if you're only looking to sell a few kits a year.
I eventually gave up on even the 13 inch rotor kits since I just couldn't convince Mopar guys to upgrade to 17 inch rims. They just refuse to do it so I stopped trying to sell big brake kits.
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Yep, I see that. And honestly when I first looked at the idea of using an SP or GT caliper and discovered I couldn't stay with 17" wheels, I dropped it. And it sat for close to 2 years before I looked at it again and decided I was ok with 18" wheels. I like the proportions of 18" wheels but it's a fine line getting some sidewall without the tire getting too big. Which is one of the reasons I doubt I will ever go above 18".

I do think people are more and more open to 17" and 18" wheels though. If for not other reason than the options for a decent 15" tire is basically nill for anything that might want to carve canyon roads. And you almost have to step up to a 17" wheel if you want to run a 245 tire or bigger in the front unless you want flairs. At the same time, I was on board with 17" rims and 13" rotors pretty early so I could be looking at things with rose colored glasses.

In regards to this setup, I'm not locking anyone out of buying a kit because I don't have any intentions of selling anything. Sure, it would be nice to do something like this for a living, but I'm not excited by the headache nor do I think I could support myself. So I do this for the fun of it and if it helps someone I am glad.
 
AndyF said:
Here is a picture of the Viper kit that I used to sell. The rotors were off a Mercedes S class, the calipers were from a Viper and the brackets were made from aluminum. They were basically just some aluminum bar stock with some holes drilled and tapped in them. This was all designed in MasterCAM 2D and made by local machine shops. The brackets didn't cost me much to have made, maybe $40 each.

View attachment 1716231206
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Out of curiosity, I worked up a bracket to fit the same Mercedes rotors as above but with my hubs (cut down rotors) to mount the Viper caliper I have.

Using a 2"x1.25" bar, 6061-T6 material and machining done by Xometry which includes tapping 2 of the holes, the quote came out to $131.24 each if I get them machined in the USA and $88.29 if I get them machined internationally. I could save a little if had the holes just drilled and tapped the holes myself, which might be necessary as it appears they are limited in the available thread pitches.

Not an apples to apples comparison as my hub doesn't put the rotor out as far as yours so my bar stock might be smaller, but I have more meat around the holes that might be unnecessary. Either way, a bunch more than $40 each.

I shutter to think what it would cost to have them do the below bracket.

6s_mount-jpg.jpg
 
Yeah, if you only make two parts it is expensive.
I looked up the numbers in my BOM from back when I was building those kits and the Viper brackets were $30 each. The brackets that I used to sell to mount Wilwoods on 11.75 rotors were $35 each. Those were three dimensional parts carved from steel but the machinist had a cool way of hogging the material away that saved a lot of time.

I never built in very high volumes, I usually ran 20 or 30 parts at a time. It is a balancing act. You have to give the machine shop enough business to make it profitable for them without killing yourself with inventory. 30 brackets would be 15 kits and $1000 check to the shop. But the kits sold for $150 so you double your money on every batch.

AR000 (Medium).jpg
 
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AndyF said:
Yeah, if you only make two parts it is expensive.
I looked up the numbers in my BOM from back when I was building those kits and the Viper brackets were $30 each. The brackets that I used to sell to mount Wilwoods on 11.75 rotors were $35 each. Those were three dimensional parts carved from steel but the machinist had a cool way of hogging the material away that saved a lot of time.

I never built in very high volumes, I usually ran 20 or 30 parts at a time. It is a balancing act. You have to give the machine shop enough business to make it profitable for them without killing yourself with inventory. 30 brackets would be 15 kits and $1000 check to the shop. But the kits sold for $150 so you double your money on every batch.

View attachment 1716231684
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Sure enough, quantity makes a huge difference. 30 brackets would be $41.25 or $21.30 each depending on where I had them machined. $639 for 15 pairs machined internationally isn't that big of an investment, better than I expected.

But....I'm not willing to buy 15 sets and have them sit on the shelf for 5+ years.

Regardless, I didn't do any of this so I could market a kit. I did it for me and because of what I wanted (and could afford). Which means the cost of brackets for the Viper calipers would be $265.

FYI, money no object I would be rocking 2 piece rotors and Viper calipers. No question. :D
 
When I make custom parts for my car I order 10 rather than one. Then I sell the other 9 parts and get my part for free. If you do inside a business everything you spend on car parts is considered R&D so it is tax deductible and you get a tax credit.
 
AndyF said:
Yeah, if you only make two parts it is expensive.
I looked up the numbers in my BOM from back when I was building those kits and the Viper brackets were $30 each. The brackets that I used to sell to mount Wilwoods on 11.75 rotors were $35 each. Those were three dimensional parts carved from steel but the machinist had a cool way of hogging the material away that saved a lot of time.

I never built in very high volumes, I usually ran 20 or 30 parts at a time. It is a balancing act. You have to give the machine shop enough business to make it profitable for them without killing yourself with inventory. 30 brackets would be 15 kits and $1000 check to the shop. But the kits sold for $150 so you double your money on every batch.

View attachment 1716231684
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You don't still have a set of those laying around do you?
 
AndyF said:
I design everything using a MasterCAM Draft license that I bought 20 years ago for $99. I've never upgraded to 3D. Most of my parts are 2.5D since I rarely do anything that is truly 3D. The radial mount parts are so much stiffer that you can make them out of aluminum. Aluminum is much faster to machine so the cost is much lower.
Here is a picture of the Viper kit that I used to sell. The rotors were off a Mercedes S class, the calipers were from a Viper and the brackets were made from aluminum. They were basically just some aluminum bar stock with some holes drilled and tapped in them. This was all designed in MasterCAM 2D and made by local machine shops. The brackets didn't cost me much to have made, maybe $40 each.

View attachment 1716231206
Click to expand...
To use these rotors you had to make the custom hub? I was planning on using a cut down stock hub but I'm having a hard time finding the center register size for these. Also, Did you re-drill the 112mm bolt pattern?
 
bjkadron said:
To use these rotors you had to make the custom hub? I was planning on using a cut down stock hub but I'm having a hard time finding the center register size for these. Also, Did you re-drill the 112mm bolt pattern?
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I've used stock hubs as well as hubs from Baer and Doctor Diff. I've also had custom hubs made. Just all depends on the circumstances.
The Mercedes rotors were modified slightly to fit on a 5 on 4.5 BC hub.
 
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