4 piston brembos, Master cylinder, proportioning valve confusion.

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1973dartswinger

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Hey all, got myself an interesting (well interesting to me) brake set up. The car that is going to be built is a 73 swinger. Hdk front suspension with a narrowed ford 8.8 in the rear. I’ve managed to get brackets to run four piston brembos front and rear off a new Camaro, and 13.5 corvette rotors. The car is an original front disc brake car, manual brakes. I’m looking to go to power brakes but the more I read and look up the more I confuse myself. I’m currently in the process of making list of what I need to buy and accumulating parts for the car but I’m lost on what I’ll need as far as master cylinder and proportioning valves. Hopefully I can get some things cleared up here.
The first product that I thought would work is this link here:
1962-74 Mopar Black Out Series Power Brake Booster Kit, Wilwood Master Cylinder
My issue with this, is I can’t find any real world experience with them, I’m not sure if it even fits the car with out needing to modify stuff, and it’s pretty costly.

The second option I saw was this here :
Right Stuff G800110: Brake Booster/Master Cylinder Combo Mopar - JEGS

In my mind this should bolt right up, and then I would just need some sort of proportioning valve but not sure what style. The issue I see with this is wondering if the bore size would be good enough for the size calipers I will be running.

The third option I saw is this:
Mopar Dual Power Brake Booster Kit, 1-1/8" Master & Disc/Disc Valve

This seems like it would be a home run and that it would bolt right up, and run four wheel disc brakes. But I couldn’t find any real life experience from it either. Or I just suck at searching.

Lastly from Dr diff he has the following products:
Bendix Style Dual Diaphragm Booster for Mopars

Mopar 1 Piece Distribution Block

Adjustable Proportioning Valve

What’s your guys opinions and thoughts? I’m open for any suggestions and other products you guys think might work best. I’m kind of lost with what would be best to run at this point

Thanks a lot.
Mike.

IMG_1138.jpeg
 
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Honestly, with brakes that powerful in an A-body I wouldn't even bother running a power booster. I've had manual front discs on my Duster forever and never wished I had power assist.
 
Try without the booster first, save some $$$ can add later.
I would suggest dealing with Dr.Diff for advice and parts, starting with a 15/16 master cylinder I use in Mopar builds.
Good luck .

Brakes :: Components

Category listing of parts sold by DoctorDiff.
www.doctordiff.com www.doctordiff.com
 
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Uhhh....



MopaR&D said:
Honestly, with brakes that powerful in an A-body I wouldn't even bother running a power booster. I've had manual front discs on my Duster forever and never wished I had power assist.
Click to expand...

inertia said:
Try without the booster first, save some $$$ can add later.
I would suggest dealing with Dr.Diff for advice and parts, starting with a 15/16 master cylinder I use in Mopar builds.
Good luck .

[/URL]
Click to expand...
UNboosted master cylinders are often a poor choice for a 4 wheel disc arrangement because the calipers need more force than the driver can provide. The booster makes it possible.
I have tried 4 different master cylinder sizes when I've tried to make a manual MC work with 4 wheel discs. All of them gave an hard pedal with far too little braking force. I just couldn't press the pedal hard enough to slow the car in a rapid and safe manner.
Also, 4 wheel disc systems should NOT need a proportioning valve. The caliper piston count and sizing is what should determine the proportioning.
You want the fronts to have double the surface area of the rear. In short, a 2 to 1 ratio in brake force front to rear.
 
furyus2 said:
I second talking to Dr Diff. Good guy, very smart.
Click to expand...
Good luck getting through. Since Covid, the man seems to be email only. Maybe he lost some employees or something but I've had no luck with calls.
He is good at responding to emails.
Years back, the guy would talk my ear off to the point where I wondered how he had so much time to talk to me.
 
Kern Dog said:
Uhhh....






UNboosted master cylinders are often a poor choice for a 4 wheel disc arrangement because the calipers need more force than the driver can provide. The booster makes it possible.
I have tried 4 different master cylinder sizes when I've tried to make a manual MC work with 4 wheel discs. All of them gave an hard pedal with far too little braking force. I just couldn't press the pedal hard enough to slow the car in a rapid and safe manner.
Also, 4 wheel disc systems should NOT need a proportioning valve. The caliper piston count and sizing is what should determine the proportioning.
You want the fronts to have double the surface area of the rear. In short, a 2 to 1 ratio in brake force front to rear.
Click to expand...
Lol. Uhhh
I don't put boosters on racecars, use 4 whl discs, that will lock up sticky slicks, - and run lap after lap after lap .
 
Advising a member with a street car using your experience that applies to a race car is an apples and oranges issue.
Race cars use custom everything. You can make the brake pedal ratio whatever you want. Stock based street cars use mostly stock equipment.
I measured mine and was surprised to be around 6.6 to 1. It still wasn't enough.
 
Kern Dog said:
Advising a member with a street car using your experience that applies to a race car is an apples and oranges issue.
Race cars use custom everything. You can make the brake pedal ratio whatever you want. Stock based street cars use mostly stock equipment.
I measured mine and was surprised to be around 6.6 to 1. It still wasn't enough.
Click to expand...

I'm telling him what I run on my son's dart, my foster son's dart, and what I have put on past Darts, Camaros, Challengers . . . some 4 whl disc, - beside my experience with 4 whl discs with 7 inch slicks.
Last weekend, - off to the strip .
But I certainly recommend Cass, he is hard to get hold of by phone.

Note No Slapper bars, - they hook .lol

IMG_20230713_154548_248.jpg


IMG_20230713_154743_569.jpg
 
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Kern Dog said:
Advising a member with a street car using your experience that applies to a race car is an apples and oranges issue.
Race cars use custom everything. You can make the brake pedal ratio whatever you want. Stock based street cars use mostly stock equipment.
I measured mine and was surprised to be around 6.6 to 1. It still wasn't enough.
Click to expand...

I would also add that there are finned aluminum (no name displayed) 4 piston calipers in varying puck sizes that are used on many imports, for $20 to $80 each on VW, Mazda, Toyota, Nissan, at the junkyard.
OP, if you can return those calipers, keep the decal, lol !
 
1973dartswinger said:
Hey all, got myself an interesting (well interesting to me) brake set up. The car that is going to be built is a 73 swinger. Hdk front suspension with a narrowed ford 8.8 in the rear. I’ve managed to get brackets to run four piston brembos front and rear off a new Camaro, and 13.5 corvette rotors. The car is an original front disc brake car, manual brakes. I’m looking to go to power brakes but the more I read and look up the more I confuse myself. I’m currently in the process of making list of what I need to buy and accumulating parts for the car but I’m lost on what I’ll need as far as master cylinder and proportioning valves. Hopefully I can get some things cleared up here.
The first product that I thought would work is this link here:
1962-74 Mopar Black Out Series Power Brake Booster Kit, Wilwood Master Cylinder
My issue with this, is I can’t find any real world experience with them, I’m not sure if it even fits the car with out needing to modify stuff, and it’s pretty costly.

The second option I saw was this here :
Right Stuff G800110: Brake Booster/Master Cylinder Combo Mopar - JEGS

In my mind this should bolt right up, and then I would just need some sort of proportioning valve but not sure what style. The issue I see with this is wondering if the bore size would be good enough for the size calipers I will be running.

The third option I saw is this:
Mopar Dual Power Brake Booster Kit, 1-1/8" Master & Disc/Disc Valve

This seems like it would be a home run and that it would bolt right up, and run four wheel disc brakes. But I couldn’t find any real life experience from it either. Or I just suck at searching.

Lastly from Dr diff he has the following products:
Bendix Style Dual Diaphragm Booster for Mopars

Mopar 1 Piece Distribution Block

Adjustable Proportioning Valve

What’s your guys opinions and thoughts? I’m open for any suggestions and other products you guys think might work best. I’m kind of lost with what would be best to run at this point

Thanks a lot.
Mike.

View attachment 1716127483
Click to expand...

Curious if those calipers have emergency brake provisions ?
Can't see from pix .
 
Kern Dog said:
Uhhh....






UNboosted master cylinders are often a poor choice for a 4 wheel disc arrangement because the calipers need more force than the driver can provide. The booster makes it possible.
I have tried 4 different master cylinder sizes when I've tried to make a manual MC work with 4 wheel discs. All of them gave an hard pedal with far too little braking force. I just couldn't press the pedal hard enough to slow the car in a rapid and safe manner.
Also, 4 wheel disc systems should NOT need a proportioning valve. The caliper piston count and sizing is what should determine the proportioning.
You want the fronts to have double the surface area of the rear. In short, a 2 to 1 ratio in brake force front to rear.
Click to expand...

I think I remember your thread about your issues, it's the red Charger with the Cobra brakes right? In that case I agree you need more pedal force than manual brakes can provide. However when I looked into it while debating whether to get the Cobra kit or Mopar-based discs with 11.75" rotors and bigger calipers for my '70 Duster it turns out the total caliper piston area of the Cobras is almost half of the Mopars. I know there are other factors involved but that's a significant difference and is likely a contributor to why you had trouble locking up your wheels (in addition to a heavy car and modern grippy tires).

The OP is running Brembos off a 5th-gen Camaro which are gigantic in comparison. Combine those with the light weight of an A-body as opposed to a B-body Charger (heavier than Coronets, Satellites of the same years) I really think power assist is not needed.

But really that's just my semi-educated but untested opinion. I just got the pads bedded in on the 11.75" discs on my Duster and have not yet tried to lock them up. If I find that I'm unable to do that I'll report back and correct myself.
 
That's a crapton of brakes for a light A body. What on Earth do you have planned for the car?
 
RustyRatRod said:
That's a crapton of brakes for a light A body. What on Earth do you have planned for the car?
Click to expand...
Not much. 408 stroker built by mike from b3. 450hp 500ftlbs of torque Hdk front k frame subframe connectors etc etc. I liked this option because if I ever had an issue on the road I can go to an auto zone and get replacement parts for a Camaro instead of trying to find parts that work with willwoods or anything like that.
 
inertia said:
I would also add that there are finned aluminum (no name displayed) 4 piston calipers in varying puck sizes that are used on many imports, for $20 to $80 each on VW, Mazda, Toyota, Nissan, at the junkyard.
OP, if you can return those calipers, keep the decal, lol !
Click to expand...
Already painted them and think I’m past the point of return hahaha
 
Kern Dog said:
Uhhh....






UNboosted master cylinders are often a poor choice for a 4 wheel disc arrangement because the calipers need more force than the driver can provide. The booster makes it possible.
I have tried 4 different master cylinder sizes when I've tried to make a manual MC work with 4 wheel discs. All of them gave an hard pedal with far too little braking force. I just couldn't press the pedal hard enough to slow the car in a rapid and safe manner.
Also, 4 wheel disc systems should NOT need a proportioning valve. The caliper piston count and sizing is what should determine the proportioning.
You want the fronts to have double the surface area of the rear. In short, a 2 to 1 ratio in brake force front to rear.
Click to expand...
As far as booster vs non booster, my cousins who build big boost 240sx cars originally thought no booster would be fine too. And quickly switched to getting a booster. The car is primarily going to be used on the street. Road trips with the family through winding country roads and such so I would like it to be an easy drive
 
Thanks for all the replies! Definitely alot of good info. I was kind of suspecting dr. Diff would be my best bet. The products I have linked i got from him personally in an email a while back. I was just doing some further research and saw the other options and really wanted to weigh all of my options and get some experience from real life driving and builds. Thanks!
 
Kern Dog said:
Uhhh....






UNboosted master cylinders are often a poor choice for a 4 wheel disc arrangement because the calipers need more force than the driver can provide. The booster makes it possible.
I have tried 4 different master cylinder sizes when I've tried to make a manual MC work with 4 wheel discs. All of them gave an hard pedal with far too little braking force. I just couldn't press the pedal hard enough to slow the car in a rapid and safe manner.
Also, 4 wheel disc systems should NOT need a proportioning valve. The caliper piston count and sizing is what should determine the proportioning.
You want the fronts to have double the surface area of the rear. In short, a 2 to 1 ratio in brake force front to rear.
Click to expand...
When I spoke to dr diff he did say the valve was necessarily needed. But more based off application. Considering what you’re saying. And considering I’m using front and rear calipers off the same car, they should function properly with no proportioning valve needed, as long as the master cylinder and such all have big enough bore. So perhaps I’m better off hooking it up with out the proportioning valve and going from there. I was also thinking it’s only another $65 in the grand scheme of things so to just put one in just for the sake of not re doing things, even if I don’t need to adjust anything atleast it’s there incase I do
 
The purpose of a proportioning valve is to allow full pressure to the front and to reduce it to the rear. It can be more complicated but that is the general function of them.
4 wheel drum cars had NO proportioning...they were designed so that the wheel cylinders at each end were engineered with "natural proportioning". Of course, the engineering was not exact so you'd get rear wheel lockup sometimes but the goal was to get the car's equipment as close to 60/40 as possible, front to rear.
4 wheel disc systems in NON stock applications may benefit from a proportioning valve ONLY if rear wheel lockup is detected. You do not want the rears to lock up before the fronts because that condition usually leads to a spin out even with a good driver at the wheel.
If NO rear wheel lockup exists, a proportioning valve is as pointless as traction control on a slant six Chrysler Imperial. It will never come into play.
 
Kern Dog said:
The purpose of a proportioning valve is to allow full pressure to the front and to reduce it to the rear. It can be more complicated but that is the general function of them.
4 wheel drum cars had NO proportioning...they were designed so that the wheel cylinders at each end were engineered with "natural proportioning". Of course, the engineering was not exact so you'd get rear wheel lockup sometimes but the goal was to get the car's equipment as close to 60/40 as possible, front to rear.
4 wheel disc systems in NON stock applications may benefit from a proportioning valve ONLY if rear wheel lockup is detected. You do not want the rears to lock up before the fronts because that condition usually leads to a spin out even with a good driver at the wheel.
If NO rear wheel lockup exists, a proportioning valve is as pointless as traction control on a slant six Chrysler Imperial. It will never come into play.
Click to expand...
Awesome thanks for that info really appreciate it!
 
I used to run the Gen 1 Viper Brembos and Cobra rear discs. I use the 15/16" master with no power assist. They worked perfectly. I recently upgraded to the wilwood 6 piston and changed nothing else. They work even better. No reason to have power assist.

FYI. I now have the HDK kit and I used a Mustang 2 drop in replacement that uses the C5/C6 hub/brake. I ended up using the rotor I was previously using with the Brembo, which is a 2012 SRT Charger rear rotor- 13.75". Be aware of the corvette rotors as the brake surface isn't offset very far from the hub face. Once you install that big caliper, wheel fitment can become a problem.
 
racerjoe said:
I used to run the Gen 1 Viper Brembos and Cobra rear discs. I use the 15/16" master with no power assist. They worked perfectly. I recently upgraded to the wilwood 6 piston and changed nothing else. They work even better. No reason to have power assist.

FYI. I now have the HDK kit and I used a Mustang 2 drop in replacement that uses the C5/C6 hub/brake. I ended up using the rotor I was previously using with the Brembo, which is a 2012 SRT Charger rear rotor- 13.75". Be aware of the corvette rotors as the brake surface isn't offset very far from the hub face. Once you install that big caliper, wheel fitment can become a problem.
Click to expand...
Interesting. I figured wheel fitment might become interesting, I have the wilwood drop spindle with a bracket to run these Camaro calipers and corvette rotors. It’s already pre assembled tho to where I just bolt on the caliper and rotor. Hub and such is already on. My bolt pattern is going to change to a Chevy bolt pattern and I’m going to have to drill out my rear to the correct bolt pattern. But I’m thinking if I got anything other than the style rotor he recommends(the place I got the brackets) If it would even line up with the caliper correctly at that point.
 
The catalogs show disc offset, widths, bolt pattern, virtually anything.
Ended up with "Mini" discs for 1 build for big offset.
Mod or fab the brackets as nec.
I'd be concerned about the emergency, and if your gonna need internal brake drum/shoes, or go the "cobra" caliper route .
 
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inertia said:
The catalogs show disc offset, widths, bolt pattern, virtually anything.
Ended up with "Mini" discs for 1 build for big offset.
Mod or fab the brackets as nec.
I'd be concerned about the emergency, and if your gonna need internal brake drum/shoes, or go the "cobra" caliper route .
Click to expand...
I was thinking of getting the wilwood kit they sell it seems to be a small caliper I’ll have to find a way to mount and then run a cable for the emergency brake
 
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