Upgrading to 11.75” discs on the front?

[71DodgeDemon340]

I never ran Wilwood stuff on my personal cars. So I don’t know what master works for that setup.

Does Dr Diff make the disk brake spindle to Wilwood caliper adapters ?? If so he would know. Or maybe whomever makes it.

Not sure if dr diff makes the adapters but they are listed on the website

 

[72bluNblu]

Any reason why i should worry about the wilwoods not having dust boots? My car never sees rain or snow

I would say yes. I really dislike the fact that the Wilwoods don't have seals, although I heard that the more recent 4 piston calipers do have them. Don't own a set so I don't know. I recently pulled an old set of wilwood 4 piston calipers off a buddies car that had seized up pistons. Now, those were older design wilwoods that definitely did not have seals, and that car had sat for awhile before my buddy got it. But those things were complete trash.

So, just because the pistons are stainless doesn't mean they can't have problems. Dirt and junk getting into the caliper past the pistons is still bad, and you can still seize a stainless piston in an aluminum caliper.

For now im going to stay with my 1-1/32 master. Ok heres my options.

1. buy the complete stage 2 plus kit from doctor diff. $850

2. Upgrade to the larger piston calipers, braided hoses and buy the 11.75 caliper brackets along with wheel bearings and 11.75 rotors/pads. $450

3. Upgrade to the wilwood 4 piston calipers, braided hoses, wilwood caliper 11.75 brackets along with wheel bearings and 11.75 rotors/pads. $700

4. leave my current calipers (not sure if they are 2.75 pistons will have to check) upgrade to braided hoses, get the 11.75 caliper brackets along with wheel bearings and 11.75 rotors/pads. $380

Your #1 option should be more like $740, since you already have the spindles you need. And that would make it the same option as #3 really.

For me it would be #2 or #4. Check to see if you have the larger piston calipers already though first.

I run the Wilwood brake kit on my Dart. That includes the rotors, calipers, and master cylinder. I bought the car with the setup. The biggest issue with the Wilwood system is it severely limits what wheels you can run. The rotors use a 3.1" hub bore and that alone makes wheel choices difficult.

View attachment 1715687374

That's a different kit. The DoctorDiff 2+ kit uses factory 11.75" rotors, not a wilwood rotor and hub. So it's factory disks with a custom caliper bracket that allows the use of the wilwood caliper on the mopar rotors. No worries on the gigantic wilwood hub in this case.

I mean is there anyway the 4 piston calipers wont stop better than the factory style?

Is it possible? Yeah maybe. I can tell you the factory 2.75" calipers generate more clamp force than the 4 piston wilwoods do by the math. But it's not really a good comparison, because the single piston floating calipers will lose a lot more of that generated force because of flex, uneven application of the force across the pads, etc. than the multi-piston fixed calipers will. So I would say that in this case the wilwoods would likely perform better as long as they're functioning properly. Having said that, I've seen the wilwoods seize up. And I've seen the factory calipers work with some ungodly looking sludge for brake fluid. I would bet that the wilwood calipers would give you better braking with everything in new condition, but I don't know if in your application it would really be worth the extra money.

 

[71DodgeDemon340]

I would say yes. I really dislike the fact that the Wilwoods don't have seals, although I heard that the more recent 4 piston calipers do have them. Don't own a set so I don't know. I recently pulled an old set of wilwood 4 piston calipers off a buddies car that had seized up pistons. Now, those were older design wilwoods that definitely did not have seals, and that car had sat for awhile before my buddy got it. But those things were complete trash.

So, just because the pistons are stainless doesn't mean they can't have problems. Dirt and junk getting into the caliper past the pistons is still bad, and you can still seize a stainless piston in an aluminum caliper.



Your #1 option should be more like $740, since you already have the spindles you need. And that would make it the same option as #3 really.

For me it would be #2 or #4. Check to see if you have the larger piston calipers already though first.



That's a different kit. The DoctorDiff 2+ kit uses factory 11.75" rotors, not a wilwood rotor and hub. So it's factory disks with a custom caliper bracket that allows the use of the wilwood caliper on the mopar rotors. No worries on the gigantic wilwood hub in this case.



Is it possible? Yeah maybe. I can tell you the factory 2.75" calipers generate more clamp force than the 4 piston wilwoods do by the math. But it's not really a good comparison, because the single piston floating calipers will lose a lot more of that generated force because of flex, uneven application of the force across the pads, etc. than the multi-piston fixed calipers will. So I would say that in this case the wilwoods would likely perform better as long as they're functioning properly. Having said that, I've seen the wilwoods seize up. And I've seen the factory calipers work with some ungodly looking sludge for brake fluid. I would bet that the wilwood calipers would give you better braking with everything in new condition, but I don't know if in your application it would really be worth the extra money.

thanks for the honesty blu, if the wilwoods had dust boots i probably wouldnt hesitate but that kinda concerns me. They do have seals just no dust boots.

the 4 piston wilwoods should have more clamp force right? Four 1.75” pistons vs one 2.75” piston?


I try to drive the car at least once every week or so all year, some moderate hills but nothing crazy, really dont drive many twisty mountain roads, i like going fast in a straight line lol but would like to have a optimum brake setup. The current setup works but figured might as well upgrade while i have to swap the calipers around

 

[72bluNblu]

thanks for the honesty blu, if the wilwoods had dust boots i probably wouldnt hesitate but that kinda concerns me. They do have seals just no dust boots.

the 4 piston wilwoods should have more clamp force right? Four 1.75” pistons vs one 2.75” piston?


I try to drive the car at least once every week or so all year, some moderate hills but nothing crazy, really dont drive many twisty mountain roads, i like going fast in a straight line lol but would like to have a optimum brake setup. The current setup works but figured might as well upgrade while i have to swap the calipers around

You have to remember that when you calculate brake force you basically only use half the caliper. With the 4 piston fixed caliper set up the pistons face each other so you have opposite forces . So when you do the math you only use 2.

 

[71DodgeDemon340]

You have to remember that when you calculate brake force you basically only use half the caliper. With the 4 piston fixed caliper set up the pistons face each other so you have opposite forces . So when you do the math you only use 2.

What setup did you go back with on your buddies car that you pulled the wilwoods off of?

 

[71DodgeDemon340]

if you like your current pedal feel I’d go #4 for just aggressive street cruising.

both my abodies have just 11.75 rotors with factory calipers.

I manage out at Willow Springs with that setup. But repeatedly slowing at the end of the long straightaway from 110+ mph to make a 50 mph curve could use better brakes.

Are you running solid disks?

 

[autoxcuda]

Are you running solid disks?

Not sure what you mean by solid?

they are not slotted or drilled. I run semi metallic pads. The pads are old mopar boxed pads that were supposed to be police duty.

They are parts store 11.75” rotors.

 

[71DodgeDemon340]

Not sure what you mean by solid?

they are not slotted or drilled. I run semi metallic pads. The pads are old mopar boxed pads that were supposed to be police duty.

They are parts store 11.75” rotors.

thats what i meant lol just plain vented rotors, guess they arent solid lol.

 

[71DodgeDemon340]

Whats a good pad to run with the factory calipers

 

[72bluNblu]

What setup did you go back with on your buddies car that you pulled the wilwoods off of?

11.75’s with factory single piston sliding calipers. Massive improvement. But again, both of his wilwood calipers had frozen pistons in one side so they were not functioning properly prior to being replaced.

Whats a good pad to run with the factory calipers

I run semi-metallics like autoxcuda. There are pads with higher coefficients of friction than that, but you have to be careful. Some of the higher performance pads also need to be at temperature to work their best, when they’re cold they don’t perform as well. The nice thing about semi-metallics is that they work the same cold or hot, which is better for a street car.

 

[71DodgeDemon340]

11.75’s with factory single piston sliding calipers. Massive improvement. But again, both of his wilwood calipers had frozen pistons in one side so they were not functioning properly prior to being replaced.



I run semi-metallics like autoxcuda. There are pads with higher coefficients of friction than that, but you have to be careful. Some of the higher performance pads also need to be at temperature to work their best, when they’re cold they don’t perform as well. The nice thing about semi-metallics is that they work the same cold or hot, which is better for a street car.

Any good brands? How are the bendix pads?

 

[72bluNblu]

Any good brands? How are the bendix pads?

They’re good. I’ve used Bendix, Raybestos, Wagner etc. Hell they may all be made in the same place.

Firm Feel also sells carbon metallic brake pads for the 73+ sliders, not sure where they get them/what brand they are though.

 

[71DodgeDemon340]

They’re good. I’ve used Bendix, Raybestos, Wagner etc. Hell they may all be made in the same place.

Firm Feel also sells carbon metallic brake pads for the 73+ sliders, not sure where they get them/what brand they are though.

I was looking at the bendix titaniumetallic II pads. They are riveted but do the rivets not interfere with the mating surface of the caliper?

 

[autoxcuda]

They’re good. I’ve used Bendix, Raybestos, Wagner etc. Hell they may all be made in the same place.

Firm Feel also sells carbon metallic brake pads for the 73+ sliders, not sure where they get them/what brand they are though.

be careful with the firm feel. years ago a friend put them on a car and when they were cold... forget about it. Those were like race pads

That was 20 years ago... so might have changed since then. Need to ask them.

now they might be a great pad to change out for race day.

 

[71DodgeDemon340]

Also any real difference between riveted and bonded pads? Ive only seen riveted shoes lol

 

[AndyF]

I mean is there anyway the 4 piston calipers wont stop better than the factory style?

Uh yeah. The number of pistons has very little to nothing to do with how well the brakes work. Braking performance is all about having the proper balance between the parts. Piston area is the critical number, not number of pistons.

 

[AndyF]

be careful with the firm feel. years ago a friend put them on a car and when they were cold... forget about it. Those were like race pads

That was 20 years ago... so might have changed since then. Need to ask them.

now they might be a great pad to change out for race day.

Those are race pads. Need to warm them up before trying to stop.

 

[AndyF]

thanks for the honesty blu, if the wilwoods had dust boots i probably wouldnt hesitate but that kinda concerns me. They do have seals just no dust boots.

the 4 piston wilwoods should have more clamp force right? Four 1.75” pistons vs one 2.75” piston?


I try to drive the car at least once every week or so all year, some moderate hills but nothing crazy, really dont drive many twisty mountain roads, i like going fast in a straight line lol but would like to have a optimum brake setup. The current setup works but figured might as well upgrade while i have to swap the calipers around

You are just asking a simple math question. 1.75 squared x 2 is 6.12. 2.75 squared is 7.56. The factory 2.75 caliper has 24% more braking force than the Wilwood four piston caliper. Swapping the Wilwood calipers on your car will reduce braking force significantly. As in, you'll feel the difference and you won't like it.

 

[72bluNblu]

You are just asking a simple math question. 1.75 squared x 2 is 6.12. 2.75 squared is 7.56. The factory 2.75 caliper has 24% more braking force than the Wilwood four piston caliper. Swapping the Wilwood calipers on your car will reduce braking force significantly. As in, you'll feel the difference and you won't like it.

It really isn’t that simple. Yes, the 2.75” piston factory caliper has more piston area than those 4x 1.75” piston wilwood calipers. And let's get the math right. The 2.75" caliper has a piston area of 5.94 square inches. The 4 piston wilwoods come in at 4.81 square inches (only 2 of the 4 count for the math). A Viper caliper, which is also a fixed 4 piston caliper with 40 and 44mm pistons, only comes in at 4.30 square inches of piston area.

But the math assumes 0 losses, 100% efficiency. No leakage past the seal, no piston tilt in the bore, no caliper flex, no friction on the sliders, equal pressure all the way across the brake pads, etc. Which isn’t real world. And the single piston sliders have more efficiency losses than fixed multi-piston calipers. A lot of times you can see that right on the pads, as they tend to not wear evenly on the single piston sliders.

Don’t get me wrong, I’m not saying I’d switch to the wilwoods. With the 11.75” rotors, for my money I’d keep the factory single piston sliding calipers. They’ve worked great for me for 70k miles on my Challenger. But I also don’t think the Wilwoods will be a significant decrease in actual real world braking force. I’ve done the math, and the efficiency difference between the single piston sliders and multi-piston fixed calipers can probably account for most of the difference in the math.

If there isn't more going on than that, even a Viper caliper would lose to a factory 2.75" single piston caliper in clamp force. And that's not real world.

 

[Kendog 170]

Also is there any benefit in going from the single piston to 4 piston wilwoods

I have 4 piston Wildwood on my Hadrtop, and 4 piston Kelsey Hayes on my Ragtop. My Ragtop was converted to BBP 1974 Factory single piston when I bought it with 100K. I put 100K more on it and only maintained wheel bearings and pads. Same rotors and Calipers . I thought they worked real good , parts are cheap, three less Calipers to deal with, less $ to deal with. More wheel options 4.5 BP . I just coverted back to KH small bolt patern for Stock look. JMO

 

[Kendog 170]

Ohh, I meant three less pistons to deal with.lol

 

[71DodgeDemon340]

Ordered rotors and bearings from oreillys through work yesterday and when i inspected them I wasnt impressed with the finish on the rotors. I personally like the non directional finish you see on most new rotors or after they have been resurfaced. so that would mean having the surface touched up. Which would run me $30. Plus the national bearings are made in china which im not too thrilled about.


I ordered timken bearings from summit which according to the reviews should be us made and cheaper than my cost on the nationals. Also ordered the stoptech slotted brake rotors, they cost me about $50 more a piece than the plain rotors from oreillys. They say they are machined here in the usa and have a black e coat finish which should last a long time. Also ordered the bendix titaniumetallic II riveted pads, never used riveted brake pads before so will see how they do with the slotted rotors. I decided to skip the wilwood calipers and reuse my single piston calipers if they are 2.75” pistons.

 

[mopowers]

And let's get the math right.

In Andy's defense, his math was fine for what he was trying to show. He was expressing the percentage difference in piston area and simply factored out pi and the radius conversion to simplify the math a tad. The answer's still the same - ~24% difference.

 

[71DodgeDemon340]

What are the correct calipers i need? I believe the ones i have are 79 volare calipers which are 2.75 pistons but from what im reading when you rear mount those calipers theres potential for the brake hoses binding or hitting the control arm? The calipers i have now are upside down because the hoses i had wouldnt work with the calipers right side up.

 

[autoxcuda]

What are the correct calipers i need? I believe the ones i have are 79 volare calipers which are 2.75 pistons but from what im reading when you rear mount those calipers theres potential for the brake hoses binding or hitting the control arm? The calipers i have now are upside down because the hoses i had wouldnt work with the calipers right side up.

Pick calipers on the rear:

Stainless Front Brake Flex Hose Kit