Disc brake conversion (70 Dart)

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StPaulSwinger

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Hi all,

I'm looking to upgrade from my stock 9" drum brakes to disc. I got the brake related parts shown in the pics below (including the four wider rims) from the Dart's previous owner. Not sure if these are worth saving and reusing or just as cores etc but would love any input or advice on where best to start looking for the rest needed to upgrade my brakes (I plan to leave the rear drums for now until I swap out the rear end from the stock slant six 7&1/4). I've come across a few brake sellers but am not familiar enough to have a good feel of where to look or what might look like a good deal but isn't worth the time/aggravation etc.

Thanks for your help as always!

dart brake calipers.jpg


Dart Control arms.jpg


Dart Wider rims.jpg
 
Well for one thing those are 73 up, "B' body pin type calipers in your picture, that won't work on an A body car, due to the fact where the rubber flex hose, brake line attaches to the caliper.
There have been dozens and dozens of threads on these disc brake conversions, and what to do, use, for the conversion.
Use the search feature on this forum, and GOOGLE will also be your friend.
And those upper control arms won't work either.
They are 73 up, B body UCA's.
You found a "B" body set of brakes.
 
Mostly agree with hemi71x. The spindles will work for you, the UCA's won't, and I wouldn't waste my time with anything other than the spindles. Turn the calipers in as cores and buy some new rotors and bearings.

You can run pin type calipers on an A-body, it's not that big of a deal. You just have to use different hoses and plan the routing out that's all. It doesn't work well with stock parts, but there's plenty of hoses available to make it work.
 
Why waste your time with rusty OLD parts get yourself a Wilwood conversion kit you get all NEW parts and NO need to change the upper control arms installs really easy and looks better and works BETTER then ANYTHING the factory produced..
 
Why waste your time with rusty OLD parts get yourself a Wilwood conversion kit you get all NEW parts and NO need to change the upper control arms installs really easy and looks better and works BETTER then ANYTHING the factory produced..

I dunno, maybe because he can use his current upper control arms with a set of $50 tapered ball joint adapters from DrDiff? There's no need to change his current control arms to use those spindles. Then he can use the spindles he already has, and buy a new set of rotors, bearings, pads and calipers for a few hundred bucks at most? And have a car that stops just fine?

You know, instead of writing a $800 check to Wilwood based on advice from a guy with front tires so skinny they can be locked up with a set of cantilever brakes from a Huffy? The checkbook mechanic strikes again.
 
Then he can use the spindles he already has, and buy a new set of rotors, bearings, pads and calipers for a few hundred bucks at most? And have a car that stops just fine

Don't even try to compare that factory old beat up **** to the quality of Wilwood..not even close!! thanks for the laugh:rofl::rofl::rofl:..
 
I still run drums at a buck twenty. lol makes the quarter exciting.
 
Don't even try to compare that factory old beat up **** to the quality of Wilwood..not even close!! thanks for the laugh:rofl::rofl::rofl:..

More checkbook mechanic logic. I spent the most money, therefore my parts must work the best. Ok buddy, just keep telling yourself that.

Do you have a Wilwood wheel chock? As much time as your car spends in the garage I would think that would be money well spent for you. You’d get more use out of it than you do your brakes, that’s for sure.
 
Why waste your time with rusty OLD parts get yourself a Wilwood conversion kit you get all NEW parts and NO need to change the upper control arms installs really easy and looks better and works BETTER then ANYTHING the factory produced..

You forgot to mention that new wheels and tires may be required, as a lotta stock wheels won't clear most aftermarket calipers, particularly Wilwood. ! !
Another cheque, no problem !!
The guy just wanted to improve his brakes, not stop a 10 sec car. sheesh
 
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You forgot to mention that new wheels and tires may be required, as a lotta stock wheels won't clear most aftermarket calipers, particularly Wilwood. ! !
Another cheque, no problem !!
The guy just wanted to improve his brakes, not stop a 10 sec car. sheesh

Correct. The Wilwood hubs in the kits for A-bodies now require a center hole diameter of 3.050", which means stock wheels won't clear them. It actually means a lot of aftermarket wheels won't clear them either.

On top of that, the Wilwood brakes aren't better than the stock 73+ disks for actual braking force, so if you're hauling in a 10 second car the Wilwoods won't necessarily stop you any faster. And here's why-

The Wilwood kit for A-bodies with 15" wheels uses an 11" rotor, which is pretty much the same size as the factory rotors (10.95"), so no advantage there. And they actually have LESS brake piston area. The wilwood specs show the piston area as 4.80 square inches. Even the factory 73-75 A-body single piston calipers have a piston area of 5.3 square inches, and those are the calipers with the smaller 2.6" piston diameter. If you use the later '76 A-body calipers, or any of the B/E/F/M/J/R calipers with a 2.75" piston diameter they have a 5.94 square inch piston area. The Wilwood brakes probably have less pad area as well. Wilwood lists the spec for pad area at 6.36. While I couldn't find an exact pad area for the 73+ disk brake pads, the length listed by raybestos is 5.610, and the height is 1.7" from the pads I have laying around. That puts the area at 9.5 square inches. It's a bit less than that because the pads aren't square, but, not by a lot. It's definitely not less than 7 square inches. Which means the 73+ Mopar brakes have more pad area as well.

Specs for the wilwood calipers Wilwood High Performance Disc Brakes - Caliper Product Number: 120-13844-RD - Test

So, the physics says the Mopar calipers can generate more braking force. Now, the Wilwood brakes are quite a bit lighter than the stock stuff. And the multi-piston, fixed design will be more efficient at transmitting the braking force to the rotors than the single piston floating calipers Mopar used. But given the disadvantage the Wilwood brakes have in piston and pad area, I seriously doubt they put more force to the rotors than the 73+ Mopar brakes. Yeah, the Mopar brakes are heavy, and the single piston design is simple, but they've been proven over millions and millions of miles. Heck, that basic design came on cars from 1973 all the way up to 1989.

I'm not saying that the Wilwood brakes aren't nice, they are. But other than the weight they save, they aren't slam dunk better at stopping your car, and they're significantly more expensive.
 
Ya ok if you say so:eek::eek::rolleyes::rolleyes::rofl::rofl:

See, here's the best part. I don't say so. The math says so, based on specs provided by Wilwood and Mopar. Braking force is just physics and math, and based on the numbers from Wilwood, the Wilwood brake kits you can get for A-bodies that fit 15" rims aren't better than the 73+ Mopar disks at generating brake force. The '73 Mopar brakes have more piston area, more pad area, and just as much rotor diameter.

Are the Wilwood brakes shinier, fancier, few pounds lighter, sure. But you're just spending more money for something that doesn't actually create more braking force than the '73 Mopar brakes do. And isn't that what brakes are supposed to do? Create more braking force?

Now, if you think I've done the math wrong or used the wrong numbers, by all means lets see the right info. Let's see the proof. But the endless "Wilwood is better than everything factory" isn't going to cut it, you have to come up with evidence now.
 
Appreciate everybody's help and guidance as always! As someone new to these projects it's great hearing that input "live" to either corroborate, or correct, other threads (sometimes years old and possibly out of date) or things straight from manufacturers etc.
 
See, here's the best part. I don't say so. The math says so, based on specs provided by Wilwood and Mopar. Braking force is just physics and math, and based on the numbers from Wilwood, the Wilwood brake kits you can get for A-bodies that fit 15" rims aren't better than the 73+ Mopar disks at generating brake force. The '73 Mopar brakes have more piston area, more pad area, and just as much rotor diameter.

Are the Wilwood brakes shinier, fancier, few pounds lighter, sure. But you're just spending more money for something that doesn't actually create more braking force than the '73 Mopar brakes do. And isn't that what brakes are supposed to do? Create more braking force?

Now, if you think I've done the math wrong or used the wrong numbers, by all means lets see the right info. Let's see the proof. But the endless "Wilwood is better than everything factory" isn't going to cut it, you have to come up with evidence now.

Actually you didn't do any math. You just looked up piston area. Which shows your limited knowledge of how brake calipers are designed.

The problem with single piston brake calipers, slides and bushing mounts, is under braking the pads can flex and produce uneven friction coupling on the face of the brake rotor. Which causes uneven wear or tapering,noise, vibration; or all of those.. And if that's the case, it doesn't really matter what size the pads are. If they have a tendency to not perform properly, your braking force calculations can really only use the diameter of the caliper piston and not the pad area. Yes, the larger pad can absorb more initial thermal heat shock, but that's about it. The reason why multi piston brake calipers sometimes don't have large brake pads is because the manufactures are trying to eliminate pad flex that produces uneven wear,pad tapering and heat. Plus if they can achieve a more desirable "even" brake pad wear with a multi piston design and a smaller pad. The benefits of a larger brake pad's thermal shock heat absorbing is really has no benefit if the brake pad is being pushed into the rotor unevenly or the pad flexes even just a little outside the caliper piston diameter.

And usually modern multi piston calipers have more aggressive piston seals to pull the pads back off the rotors when the driver releases the brake pedal. Why? To produce less heat because your pad is dragging on the rotor after braking. Dummy.

Those old designed brake calipers when worn just don't perform great, they get by. They flex, they quit sliding, rotating on worn parts and a whole bunch of other problems.

I have awesome pictures of Brembo and Baer testing prototype ZR1 and CTS-V calipers over base model calipers on our 500 HP brake dyno at work. You can't beat the even clamping force of a multi-piston caliper and it's repeatability. Even under extreme temperatures. That's a fact.

Willwood, Baer, Brembo all base the number of pistons, piston size and pad size based of vehicle weight and what stopping force is needed. Usually you don't need 6 or 8 piston calipers on and old car. But those do produce a more even clamping force and better wear when designed for that application.
 
Actually you didn't do any math. You just looked up piston area. Which shows your limited knowledge of how brake calipers are designed.

The problem with single piston brake calipers, slides and bushing mounts, is under braking the pads can flex and produce uneven friction coupling on the face of the brake rotor. Which causes uneven wear or tapering,noise, vibration; or all of those.. And if that's the case, it doesn't really matter what size the pads are. If they have a tendency to not perform properly, your braking force calculations can really only use the diameter of the caliper piston and not the pad area. Yes, the larger pad can absorb more initial thermal heat shock, but that's about it. The reason why multi piston brake calipers sometimes don't have large brake pads is because the manufactures are trying to eliminate pad flex that produces uneven wear,pad tapering and heat. Plus if they can achieve a more desirable "even" brake pad wear with a multi piston design and a smaller pad. The benefits of a larger brake pad's thermal shock heat absorbing is really has no benefit if the brake pad is being pushed into the rotor unevenly or the pad flexes even just a little outside the caliper piston diameter.

And usually modern multi piston calipers have more aggressive piston seals to pull the pads back off the rotors when the driver releases the brake pedal. Why? To produce less heat because your pad is dragging on the rotor after braking. Dummy.

Those old designed brake calipers when worn just don't perform great, they get by. They flex, they quit sliding, rotating on worn parts and a whole bunch of other problems.

I have awesome pictures of Brembo and Baer testing prototype ZR1 and CTS-V calipers over base model calipers on our 500 HP brake dyno at work. You can't beat the even clamping force of a multi-piston caliper and it's repeatability. Even under extreme temperatures. That's a fact.

Willwood, Baer, Brembo all base the number of pistons, piston size and pad size based of vehicle weight and what stopping force is needed. Usually you don't need 6 or 8 piston calipers on and old car. But those do produce a more even clamping force and better wear when designed for that application.

Actualy, I DID do math, because you can't look up the piston and pad areas for the Mopar parts. :p

As far as my "limited" knowledge of caliper design, you better read my post again. I clearly stated that the multi-piston, fixed calipers were more efficient. The 2.6" piston Mopar calipers are 10% larger in piston area, the 2.75" piston calipers are 23.4% larger in piston area. Is it possible that the Mopar floating calipers lose 10% more braking force because of their design compared to the Wilwoods? Sure, that's totally reasonable. Is it possible that they lose 23.4% of the braking force generated compared to the Wilwoods? I think that's unlikely. Especially with the larger pad area. Sure, they're less efficient, but the generate significantly more braking force. All of which I mentioned in my post, if you actually read it instead of just disagreeing with me. Given how much more force the Mopar calipers generate, I don't think it's a slam dunk at all that the Wilwoods still transmit more braking force. And even if they do, it wouldn't be by a lot. Meaning, you're spending a ton of extra money for little gain.

The Wilwood brakes in question, Dynalites, didn't even come with outer seals just a few years ago. I had a set, I sold them because I didn't want to run calipers without outer seals on the street. Now, the Dynalites have been redesigned since then and have seals now to mirror other street going multi-piston calipers, but how well they pull the pistons back is something you'd have to test. I assume you haven't, since you post lacks any specific details and just deals in vague generalities. You make it sound like the 73+ Mopar calipers will drag the pads all the time, which isn't true. They get knocked back just like any other pad. I put 60k miles on the last set of pads I ran on my Challenger, I can't imagine they were dragging all that much. Heck I'm still using the rotors, and I never had an issue with brake fade. The pads were worn quite evenly as well, as have all the other pads I've changed out of 73+ mopar calipers.

The Dynalites are only 4 piston calipers too, not like the Baer's, Brembo's, or ZR1, etc calipers you mention. They may lose less braking force to flex than the Mopars, but they don't transmit 100% either.

So, same standard applies to you as stroked340. Let's see the numbers that show that the 73+ Mopar calipers lose more than 24% of the braking force they generate when compared to the Wilwoods. Otherwise you're just speculating, and I think the difference between the two calipers is small enough that the Wilwoods aren't worth the price compared to their performance.
 
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If NASA needs anybody to design a brake system for the next generation Martian Rover, you guys should apply for the job.
Who in the real world gives a s*#t about all this technical bs that is being thrown out here in this guys posting in just wanting to put disc brakes on his car.
The common Joe Blow, enthusiast, just want's to get rid of the drums.
Ok, my rant is over.
 
Bottom line..buy WILWOOD when you can afford them...leave the old crappy factory design to those who want to be CHEAP!!
 
If NASA needs anybody to design a brake system for the next generation Martian Rover, you guys should apply for the job.
Who in the real world gives a s*#t about all this technical bs that is being thrown out here in this guys posting in just wanting to put disc brakes on his car.
The common Joe Blow, enthusiast, just want's to get rid of the drums.
Ok, my rant is over.

Jim I totally agree. StPaulSwinger can use the 73+ parts he has with some new and reconditioned parts and he'll have excellent brakes, and he doesn't even have to worry about considering significantly more expensive options.

I think some of the discussion about actual braking force is worthwhile though, because people incorrectly believe that more expensive aftermarket brakes are always somehow inherently better, without even considering the actual physics at work.

So, yeah, I think showing that the Wilwoods will actually generate LESS braking force at the caliper is important. Now, the opinions can fly about whether or not the Wilwood design can make up for the 24% disadvantage they have in piston area. But I think a reasonable person can look at those numbers and realize that, at best, the Wilwood Dynalites are realistically in the same ballpark as the 73+ Mopar calipers for stopping power. The margin in performance between the two is likely small, probably only a few percent in either direction.

Bottom line..buy WILWOOD when you can afford them...leave the old crappy factory design to those who want to be CHEAP!!

Actually, the bottom line is that the Wilwoods are mostly just more expensive, and that even an optimistic interpretation of the physics would put them in about the same performance ballpark as the 73+ brakes.

So they're a great choice if you have money to burn and like bragging about performance you don't understand, but not nearly as great where the rubber actually hits the road.
 
Jim I totally agree. StPaulSwinger can use the 73+ parts he has with some new and reconditioned parts and he'll have excellent brakes, and he doesn't even have to worry about considering significantly more expensive options.

I think some of the discussion about actual braking force is worthwhile though, because people incorrectly believe that more expensive aftermarket brakes are always somehow inherently better, without even considering the actual physics at work.

So, yeah, I think showing that the Wilwoods will actually generate LESS braking force at the caliper is important. Now, the opinions can fly about whether or not the Wilwood design can make up for the 24% disadvantage they have in piston area. But I think a reasonable person can look at those numbers and realize that, at best, the Wilwood Dynalites are realistically in the same ballpark as the 73+ Mopar calipers for stopping power. The margin in performance between the two is likely small, probably only a few percent in either direction.



Actually, the bottom line is that the Wilwoods are mostly just more expensive, and that even an optimistic interpretation of the physics would put them in about the same performance ballpark as the 73+ brakes.

So they're a great choice if you have money to burn and like bragging about performance you don't understand, but not nearly as great where the rubber actually hits the road.

Actually you are quoting yourself and them trying to back up what you posted with misinformation that you quoted as fact. Something you do an awful lot... You also don't read very well when it comes to trying to understand something. And now you claim to be a physicist, mechanical engineer and a finite element engineer. 72 *b+l -u (N)b ^l -u Not Albert Einstein or Stephen Hawkings talking Wheelchair could teach you anything.

The disadvantage in our old Mopar calipers comes from what area of the pad that can be reliably used to to calculate the braking force with focus placed on overall function of the mechanical components and factoring in the inherent design flaws. It's not just 24% more piston area. You would never really understand why a lot of multi piston calipers have different diameter pistons in them or why manufacturers choose to use sequential piston sizes in the same caliper. (Psssst it's just another way to combat uneven pad wear and promote uniform clamping force ).

If the OP wants to just upgrade to disc brakes on the cheap he could just rebuild the old Mopar ones and it will work. That might be all he really needs for HIS car. But if a guy wants to buy a Willwood setup that will work better. He's not just a "check writer", like you say. . He might actually need better more reliable braking. Maybe he just wants to upgrade his car to maxim performance potential in certain areas of his own car. And we don't need your analysis on you being right Dr. 72bluNblu PhD.

Your own car doesn't need SPC uppers, Howe racing ball joints, QA1 Lowers, Hellwig sway bars, Caltrac sliders, incorrectly welded in sub frame connectors or even 275 & 295 width tires on 18" rims to drive around on the street. That said, you don't even need your Cobra calipers on 13" rotors ... You don't race it you've stated many times over. You claim to drive like your grandma in it everywhere, which explains how you get 60k miles on a set of brake pads? (Dude, you might want to change them out more often than that. Pad materials do deteriorate from the metal backer plates). You really only need a Slant 6, 4 wheel drum brake car.
 
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Actually you are quoting yourself and them trying to back up what you posted with misinformation that you quoted as fact. Something you do an awful lot... You also don't read very well when it comes to trying to understand something. And now you claim to be a physicist, mechanical engineer and a finite element engineer. 72 *b+l -u (N)b ^l -u Not Albert Einstein or Stephen Hawkings talking Wheelchair could teach you anything.

The disadvantage in our old Mopar calipers comes from what area of the pad that can be reliably used to to calculate the braking force with focus placed on overall function of the mechanical components and factoring in the inherent design flaws. It's not just 24% more piston area. You would never really understand why a lot of multi piston calipers have different diameter pistons in them or why manufacturers choose to use sequential piston sizes in the same caliper. (Psssst it's just another way to combat uneven pad wear and promote uniform clamping force ).

If the OP wants to just upgrade to disc brakes on the cheap he could just rebuild the old Mopar ones and it will work. That might be all he really needs for HIS car. But if a guy wants to buy a Willwood setup that will work better. He's not just a "check writer", like you say. . He might actually need better more reliable braking. Maybe he just wants to upgrade his car to maxim performance potential in certain areas of his own car. And we don't need your analysis on you being right Dr. 72bluNblu PhD.

Your own car doesn't need SPC uppers, Howe racing ball joints, QA1 Lowers, Hellwig sway bars, Caltrac sliders, incorrectly welded in sub frame connectors or even 275 & 295 width tires on 18" rims to drive around on the street. That said, you don't even need your Cobra calipers on 13" rotors ... You don't race it you've stated many times over. You claim to drive like your grandma in it everywhere, which explains how you get 60k miles on a set of brake pads? (Dude, you might want to change them out more often than that. Pad materials do deteriorate from the metal backer plates). You really only need a Slant 6, 4 wheel drum brake car.
 
Another reason to consider the Wilwood path is that it offers two bolt circle patterns. I like my current wheels and they are 4". However there greater wheel choices in the 4.5 bolt circle pattern.
 
Another reason to consider the Wilwood path is that it offers two bolt circle patterns. I like my current wheels and they are 4". However there greater wheel choices in the 4.5 bolt circle pattern.

The last time I tried to put a 14" Rally wheel on a Wilwood, it wouldn't mount on the studs cuz the caliper is way too big, and in the way. Same with a regular 15" wheel. I hope someone can shed some light on that.
The price of the brakes is high, but to then find your favorite wheels don't fit, could be annoying and costly to say the least. cheers
 
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Actually you are quoting yourself and them trying to back up what you posted with misinformation that you quoted as fact. Something you do an awful lot... You also don't read very well when it comes to trying to understand something. And now you claim to be a physicist, mechanical engineer and a finite element engineer. 72 *b+l -u (N)b ^l -u Not Albert Einstein or Stephen Hawkings talking Wheelchair could teach you anything.

The disadvantage in our old Mopar calipers comes from what area of the pad that can be reliably used to to calculate the braking force with focus placed on overall function of the mechanical components and factoring in the inherent design flaws. It's not just 24% more piston area. You would never really understand why a lot of multi piston calipers have different diameter pistons in them or why manufacturers choose to use sequential piston sizes in the same caliper. (Psssst it's just another way to combat uneven pad wear and promote uniform clamping force ).

If the OP wants to just upgrade to disc brakes on the cheap he could just rebuild the old Mopar ones and it will work. That might be all he really needs for HIS car. But if a guy wants to buy a Willwood setup that will work better. He's not just a "check writer", like you say. . He might actually need better more reliable braking. Maybe he just wants to upgrade his car to maxim performance potential in certain areas of his own car. And we don't need your analysis on you being right Dr. 72bluNblu PhD.

Your own car doesn't need SPC uppers, Howe racing ball joints, QA1 Lowers, Hellwig sway bars, Caltrac sliders, incorrectly welded in sub frame connectors or even 275 & 295 width tires on 18" rims to drive around on the street. That said, you don't even need your Cobra calipers on 13" rotors ... You don't race it you've stated many times over. You claim to drive like your grandma in it everywhere, which explains how you get 60k miles on a set of brake pads? (Dude, you might want to change them out more often than that. Pad materials do deteriorate from the metal backer plates). You really only need a Slant 6, 4 wheel drum brake car.

For a guy with a 500 hp brake dyno, you seem to be short on data. You don't need to calculate anything, put a '73+ mopar caliper on your dyno and give us the numbers. Heck, put a Wilwood Dynalite caliper on there next and completely settle this. Should be pretty easy for a guy with a brake dyno to get all the information we need.

The last time I tried to put a 14" Rally wheel on a Wilwood, it wouldn't mount on the studs cuz the caliper is way too big, and in the way. Same with a regular 15" wheel. I hope someone can shed some light on that.
The price of the brakes is high, but to then find your favorite wheels don't fit, could be annoying and costly to say the least. cheers

Pretty much none of the stock wheels will fit the Wilwood brakes anymore. The hub bore for the Wilwoods has to be 3.050" with their new redesigned hub, and that's larger than pretty much all of the stock wheels. The wheel studs used are also 1/2", so they won't usually work with stock wheels because the stock SBP studs were 7/16". And the rallye wheels don't clear the calipers.

So, there's really no advantage to using the Wilwoods to keep the SBP. You have to buy new wheels anyway, might as well go BBP. Heck, with a hub bore of 3.050" a lot of BBP aftermarket wheels won't fit either.
 
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