MoPar Brake Upgrade Options?

IF this package existed, would anyone be interested in it?

  • YES!

    Votes: 4 30.8%
  • Maybe... How much?

    Votes: 8 61.5%
  • Nope

    Votes: 0 0.0%
  • This already exists you bonehead!

    Votes: 1 7.7%

  • Total voters
    13
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D_Matheson

Matheson Sports Car
Joined
Feb 13, 2018
Messages
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Reaction score
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Location
Jonesborough, TN
Hello everyone! This is my first forum post (besides my introduction), and I really just have a question for you all. I've done a lot of research about what's available out there for bolt on front brake upgrades, and it looks like there's:
  1. the B/E body upgrade for drum cars
  2. the KH 4 pot upgrade (seen this on a some vintage racers)
  3. and a few different Wilwood kits ranging from $650-$1000.
I actually have the B/E kit for my 64 Cuda, and boy are they heavy! The KH calipers seem like a solid upgrade from the big single pistons, but it's still older tech. And the Wilwoods can be expensive.

As a community, how would a cheaper 4 pot brake upgrade that still fits behind 15" wheels be received? The upgraded parts, aside from the hub and caliper bracket (which would essentially be the whole kit), could all be sourced from any national auto-parts store, would be relatively cheap, have a substantial aftermarket support network in place for easy further upgrades, and be on par with Wilwood kits in performance. IF this package existed, would anyone be interested in it, or are most happy with the current options? Also, if this kit already exists please point me in that direction!

-Dave
 
Hi Dave. Looks like you have put some thought into this. If comparing to a Wilwood pkg., then you should list out the prices of all the pieces needed to cobble a front disc brake upgrade. I'm sure parts availability and prices may vary by location, but listing what you've found would be helpful. Thanks.
 
I had wilwood on my charger and they were very good, but recently did a Dr Diff conversion on my road runner. For the money you can't beat the Dr Diff kit.
 
I like the 4 piston KH calipers and I just picked up a light weight strange master cylinder to add on.

20180606_210949.jpg
 
As someone who is finishing up the process of finishing the equivalent of the Dr.Diff stage 2 kit from used/rebuilt/junkyard parts AND wanting to convert to LBP. I am only ending up saving about $40 overall (but I got a boosted master cylinder) and losing ALOT of hours doing so. If I would do it all again I would either go full modern to Wilwood (can't go wrong, and they have dual bolt patterns on the hubs aka SBP and LBP, just lots of $$), or to keep it original style to get replacement parts easier which is the route i preferred, Dr.Diff can't be beat. Definitely just starting with his kits when I help my father rebuild his '70 cuda. The K/H is really only a good option if you want to stay at SBP.
Good Luck with your build!
 
Mostly everything on the K Frame is Doctor Diff. And all the brake parts too.

20170704_220758.jpg
 
Hi Dave. Looks like you have put some thought into this. If comparing to a Wilwood pkg., then you should list out the prices of all the pieces needed to cobble a front disc brake upgrade. I'm sure parts availability and prices may vary by location, but listing what you've found would be helpful. Thanks.

Thanks for the input Disarray! And to respond to what everyone else said, I had never heard of Dr Diff, but it looks like I had almost the exactly the same idea as what he implemented with the stage 3 and 4 kits. The only difference in what I want to do is to use what I believe is a much higher performance caliper than a stage 3 kit that is still something you could get replaced at a parts store.
I plan to use a caliper set from a 2006-2007 WRX (not STI). I know that these calipers are the highest quality and performance as many people in the rally community still replace even brand new 2018 WRX calipers with these for racing and rally. Only the 2006-2007 cars had these 4 piston fronts and 2 piston rears. There are many pad options for these ranging from $10 all the way to full race compounds.
The other nice thing about planning to use these calipers is that they are direct bolt on replacements with other WRX calipers that are cheaper. Though those calipers aren't as high performance, they would be perfect for a budget setup.
So the design would be configurable for lower budgets up to full race/autocross setups.
The rotors would be sourced from a 2004 (and similar model years) 350Z with the standard brakes (non Brembo). These are a 5x4.5 bolt pattern and there are options for these ranging from cheap $20 rotors up to full racing spec. Again, configurable to your needs and budget.
A proposed kit would only include the necessary machined pieces and adapters. It would also include a detailed list of compatible parts for the assembler to pick and choose from based on needs and budget. Go to Rock Auto or your favorite store and order the rest - including the replacement bearings and dust seal which will be OEM items for your spindle.
I'm still in the design phase, but I plan on making a system for my 64 Barracuda (#RallyCuda on instagram). I'll make a new thread when I finally get around to doing this. I'm pretty sure the torture test of Rally racing will either show the strength of the components or that I have no idea what I'm doing. :realcrazy:
 
Can you make the calipers compatible with the mopar 11.75 rotors that fit the stock big ball joint spindles?
 
Can you make the calipers compatible with the mopar 11.75 rotors that fit the stock big ball joint spindles?
Would depend on rotor thickness, but I can't see why not. I'm going to order a caliper soon to measure and finish my CAD model. I'll check on that.
 
Can you make the calipers compatible with the mopar 11.75 rotors that fit the stock big ball joint spindles?

I'm running this rotor right now using calipers from a '79 New Yorker. Just wanted to add that to show there ARE people to actually use this rotor.
 
I have the 11.75 rotors with tall brackets on my dart using the original 73 slider type calipers. There's not alot of pad choices EBC makes 3 compounds and there's regular parts store grade pads and that's it.
 
What I would really like a 13 or 14 inch disk brake kit that uses my '73 and up spindles. The only choice really is Doctor Diff's kit, which isn't a bad choice actually.
 
C-body 11.75" rotors are 1.25" thick.
I'm running a pair of '73 Chrysler discs on my daily driven '73 Dart.

I've run Hawks Racing pads and EBC Yellow Stuff pads which were I nice improvement.

Currently I'm also using the C-body calipers as well but definitly would like to switch to a lighter caliper soon. But its combined piston-diameter has to be the same of pref. larger then 2.75" to be an actual upgrade for me.
 
Alright everyone, I've been hard at work on this kit for my project car, and I wanted to let you all see it to get some opinions. I designed the kit with the components I described before: 2006 WRX calipers, 2004 350Z rotors, large bearing A body spindles, with custom components to hold it all together. I was also able to complete FEA analysis on the new hub to optimize thicknesses and confirm that it is stronger than the stock spindle (so it should never fail before the spindle does).
Let me know what you guys think. I'll go ahead and say this about fitments too, the calipers will most likely not fit under rallye wheels since from what I've heard even 15" rallyes use 14" centers. The kit pushes the wheel out at least .4" on each side which is unavoidable due to caliper mounting restrictions. And, wheels with flat spokes (limited brake clearance) might also have fitment issues. A spacer could take car of that, but it also increse the stress in the spindle and pushes the wheel out further.
If you want a really detailed discription of the design process head on over to my build log here. Theres a lot of good images and better detail on the finite element analysis.
MSC_Rally Cuda_Assy1.PNG
MSC_Rally Cuda_Assy3.PNG
MSC_Rally Cuda_Assy6.PNG
MSC_Rally Cuda_ExplView1.PNG
MSC_Rally Cuda_ExplView2.PNG
MSC_Rally Cuda_StressCalcs1.PNG
MSC_Rally Cuda_StressCalcs3.PNG
 
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Nice work.
Personally, I think the last thing an A-body needs (for looks) is more wheel offset to the outside. Especially with wider than stock tires, the fender lip comes into play very quickly. Even more so on the later 70+ A bodies.

I think I would try to 'rotate' the caliper away a bit from the spindle more so it can be positioned deeper and more beside the spindle. With an evenly deeper discrotor, the wheel itself will be positioned further back too, which would look good again.
 
What I would really like a 13 or 14 inch disk brake kit that uses my '73 and up spindles. The only choice really is Doctor Diff's kit, which isn't a bad choice actually.

That stuff has existed for at least 10 years if not more. I think I did my first 13 inch front brake kit back around the year 2000. I have 13 inch Baer rotors on one car with Porsche calipers. The other car has 13 inch Baer rotors with Viper calipers. Both cars use FMJ knuckles.
DSC_1148 (Large).JPG
 
Here the car is on the ground. You can just see the 13 inch rotor inside the wheel. The wheels are 17 inch to clear the rotor. What I found out years ago was that most Mopar guys wouldn't put a 17 inch rim on their car so there was no way to fit a 13 inch rotor. That might be changing a bit now. I put 17 inch rims on my car almost 30 years ago. I think I bought these rims in 1992. Back in those days there were not very many classic Mopars with 17 inch rims on them.
DSC_2399 (Large).jpeg
 
Alright everyone, I've been hard at work on this kit for my project car, and I wanted to let you all see it to get some opinions. I designed the kit with the components I described before: 2006 WRX calipers, 2004 350Z rotors, large bearing A body spindles, with custom components to hold it all together. I was also able to complete FEA analysis on the new hub to optimize thicknesses and confirm that it is stronger than the stock spindle (so it should never fail before the spindle does).
Let me know what you guys think. I'll go ahead and say this about fitments too, the calipers will most likely not fit under rallye wheels since from what I've heard even 15" rallyes use 14" centers. The kit pushes the wheel out at least .4" on each side which is unavoidable due to caliper mounting restrictions. And, wheels with flat spokes (limited brake clearance) might also have fitment issues. A spacer could take car of that, but it also increse the stress in the spindle and pushes the wheel out further.
If you want a really detailed discription of the design process head on over to my build log here. Theres a lot of good images and better detail on the finite element analysis. View attachment 1715201332 View attachment 1715201333 View attachment 1715201334 View attachment 1715201335 View attachment 1715201336 View attachment 1715201337 View attachment 1715201338

What material are you going to use for the hub? I used to make custom hubs from aluminum but I found that it was difficult to get the correct bearing crush. You need to be able to retain the wheels bearings when the hub gets hot so it takes a lot of crush. I eventually switched to steel for my custom hubs just for that reason but Cass uses aluminum and so does Baer. Rather than reinventing the wheel you might buy a set of hubs from either Cass or Baer and then work from there. Trying to fit good brakes inside of a 15 inch rim is a bit hopeless. Cheapest and most effective setup inside a 15 inch rim would be to use a 11.75 x 1.25 rotor and a set of big calipers. Maybe 6 piston Wilwood or something like that.
 
So...your basically trying to reinvent the scarebird kit?
 
That stuff has existed for at least 10 years if not more. I think I did my first 13 inch front brake kit back around the year 2000. I have 13 inch Baer rotors on one car with Porsche calipers. The other car has 13 inch Baer rotors with Viper calipers. Both cars use FMJ knuckles.
View attachment 1715201793

I know you made a kit or caliper adapters or something? But wasn't it for drum spindles? I have a '74 with disc spindles. I'm also running 18's too. I guess I don't have enough grey hair to be opposed to large diameter wheels. ;)
 
Thanks you all for you interest an input. I've been thinking about some responses and investigating your ideas.

Nice work.
Personally, I think the last thing an A-body needs (for looks) is more wheel offset to the outside. Especially with wider than stock tires, the fender lip comes into play very quickly. Even more so on the later 70+ A bodies.

I think I would try to 'rotate' the caliper away a bit from the spindle more so it can be positioned deeper and more beside the spindle. With an evenly deeper discrotor, the wheel itself will be positioned further back too, which would look good again.

Thanks for the compliment! I went into my model to investigate your idea further, and with this caliper it really is not possible to push the caliper itself back any further. Of course I'd like to as well, but the caliper mount face is designed the bolt from the back side, meaning that I can't move the caliper to the other side of the mounting bracket. The spindle is designed to mount to the front side, so I can't move it to the other side either. A machined piece could move the caliper bracket back in theory, but the biggest issue I run into when locating the caliper is that the top mount wants to hit the upper ball joint upright. If you rotate the caliper downward until it clears, its basically vertical - the maximum I'd mount it. BUT at that point the bottom caliper mount interferes with the ball joint mount area on the spindle. If you move it on until it clears the caliper is sitting at the bottom of the wheel - not good.
It was honestly more difficult to find a position for this caliper that I was hoping.

It's worth noting that without the spacer, the track width actually decreases .2" overall. The spacer is there to give more spoke clearance. I guess it's a trade off. You can have spoke clearance and a wider track, or you can have a narrow track and smaller spoke clearance. BUT, the 2002-2005 WRX calipers have exactly the same mounting pattern and dimensions, but they are 2 piston sliding calipers instead of the 4 pots. They would require much less spoke clearance meaning you wouldn't need a spacer quite so big. At that point, but kit would basically be the same as a Dr Diff stage 3 with cobra brakes, but with WRX calipers and 350Z rotors.

What material are you going to use for the hub? I used to make custom hubs from aluminum but I found that it was difficult to get the correct bearing crush. You need to be able to retain the wheels bearings when the hub gets hot so it takes a lot of crush. I eventually switched to steel for my custom hubs just for that reason but Cass uses aluminum and so does Baer. Rather than reinventing the wheel you might buy a set of hubs from either Cass or Baer and then work from there. Trying to fit good brakes inside of a 15 inch rim is a bit hopeless. Cheapest and most effective setup inside a 15 inch rim would be to use a 11.75 x 1.25 rotor and a set of big calipers. Maybe 6 piston Wilwood or something like that.

I'm planning to use AISI 1045 steel. Aluminum would be nice, but the ultimate tensile strength of 1045 is almost twice that of 6061 t6 from what I can find; also, the yield strength is a little higher on 1045.
Other hubs are specifically designed to work with specific caliper and rotor combos. I want to have hubs that are specifically designed for this application without compromise.
I don't think it's hopeless!
Finally, I really like your Wilwood idea in hindsight. Looking at it again and really digging into their product catalog, I see now that they have some calipers that would most likely be easier to mount that would fit on the rest of the stock A-body disk equipment. No hub or rotors required. If I hadn't already bought these calipers and rotors, I'd probably move that way instead!

So...your basically trying to reinvent the scarebird kit?

I've never heard of Scarebird, but it appears that their aim is to provide the cheapest means of getting disk brakes on a vintage car. Of course that's better than no disk brakes, but I don't think I'm after the stopping power of a 1990 Chevy Celebrity on a race car.

Anyway, thanks again for all your comments. And, AndyF, that's a FINE looking kit you built. I hope mine looks half that nice.
 
I know you made a kit or caliper adapters or something? But wasn't it for drum spindles? I have a '74 with disc spindles. I'm also running 18's too. I guess I don't have enough grey hair to be opposed to large diameter wheels. ;)

I built some kits for drum knuckles a long time ago but eventually I switched everything over to the late model disc knuckle. I found that the late model FMJ was the best knuckle to use for big brake kits. If you use radial mount calipers then the bracket kit is fairly simple to make.
Builder_3.jpg
 
What I would really like a 13 or 14 inch disk brake kit that uses my '73 and up spindles. The only choice really is Doctor Diff's kit, which isn't a bad choice actually.

Baer sells a bunch of different brake kits for the Mopar disc knuckle. Doctor Diff is also a Baer dealer. I don't know if there is anyone at Baer these days who understands Mopar vehicles but it is worth a call to talk to them. I've used Baer stuff on a lot of different conversions so the stuff exists, but they don't really advertise it much. Here is a shot showing a 13 inch Baer kit on a '68 Valiant. (engine is a 427 incher. That car would go 160 mph!)
install.jpg
 
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