KH Discs vs 73+ Discs

KH or 73+ Discs

  • Total voters
    74
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BillGrissom said:
The K-H calipers are technically superior, but are they really an option? You can't buy the parts new. You can buy rebuilt calipers and new rotors, but also need the special spindles and hubs. The rare rusty ones that show up on ebay command high $$$. A member here has offered nicely rebuilt setups, but at high price (~$750) and don't know if he can even scrounge parts anymore. For the same price, you can buy a Wilwood setup w/ 4-piston fixed calipers.

Re SBP, you can now buy new 17" alloy wheels in SBP, so you aren't limited in any way.

Re DOT 5, I have run it in several cars for decades and have not seen a spot of internal rust since. If water drops got in the system they would not be absorbed and could theoretically cause rust depending on where they settle. Don't let water drip into your reservoir, which is true for any brake system. Fill it carefully and don't touch it, and you will never have to fuss with it again. I have newer MC reservoirs with tight-fitting plastic caps on all my cars, so no concerns.
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Well, they're only an option because I have a rust free setup that's going to be lying around my garage for awhile.

While the 17 x 7 and 17 x 8 wheels aren't the best (only fitting a 225/45 on the front and a 245/45 on the rear) the handling will be far better than the 14" wheels and super tall sidewall tires he's got on it now. And for $1k you can get a complete wheel and tire setup front and back if he really wanted to as I debated that for awhile.

My only worry is that he wouldn't have enough money to do an entire front suspension, rear end, and brake swap to bbp stalling his project further. It's running right now, but IMO, it's scary dangerous. He definitely needs an alignment (his Dart almost looks hella flushed it has so much camber) and his springs are saggy (the car sits really slow). On top of that, he still has to fix a big exhaust leak as well (right now he can only drive with the window's down without getting high off fumes).
 
MuuMuu101 said:
So, I have a friend with a '67 Dart that wants to do a suspension rebuild and update his front 9" drums to disc brakes. He's got a friend of a friend who may offer him a set of 73+ disc brakes with 10.75" rotors and 1 piston calipers. He's also interested in my KH disc setup and he was wondering what would offer the best stopping power. I was thinking the KH discs due to the larger rotors and pad surface area, but I'm not sure.

Currently, the guy is running small bolt pattern all the way around. He's thinking about replacing his rear end and he could either take some of my sbp 8 3/4 stuff (axle, 10" drums, ring and gear, differential, etc.), or he has a line with the other guy on taking his 8 3/4 stuff (B-body with A-body perches, axles, and 11" drum; no center section). I don't really care if he buys my parts or not, but I just want to help him get a good and safe car.

Personally, I think he should go with the bbp stuff as it will give him more options on brake setups, wheels, and tires (he talks about potentially autocrossing the car in the very distant future). What are your thoughts?
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I like the KH disc brakes since the wheels, backspace, and rear will stay the same, he can upgrade as time and funds become available. Steel and Aluminum rims are available, from 14 inch and up. Nothing wrong with KH 4 piston calipers and DOT 5 fluid. Been running that setup in the 66 and 68 for 20+ years, no corrosion and steady performance. My cars are not "show" cars. That said, I also run 77 Cordoba pinned calipers and large rotors on the 67 Barracuda with a Moser custom 8 3/4 rear to match backspace with the BBP stock wheels. Like the 68 Hemi automatic Darts and Barracudas. The BBP system is quite a bit heavier than the KH system. Both setups are very good, especially with good rotors and pads available.
 
RustyRatRod said:
I just disagree the KH stuff is superior. Why were they replaced? Why didn't the bigger cars get a version? Bottom line is they SUCKED. They were replaced with a better, newer, more modern version.
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The bigger cars got the BUDD brake system in '67 and '68, also with 4 pistons per caliper.
They worked quite nice on my '67 Newport... right untill the unobtanium seals started leaking because of the rusty cylinders in the calipers.

The factory most likely found a cheaper to produce brake system and went with that later on.
 
..4 pistons,4 seals,4 boots, 1 inlet tube,1 transfer tube,fixed caliper and adjust bearings to .001-2.
..Replace with a single piston floating caliper with one seal and 1 boot!
 
I talked with my friend with him today. I told him more about the positive and negatives of both setups. He seems to sway more towards the KH discs as they'd be cheaper for the short term. I'll most likely sell him a lot of my extra parts (0.87" T-bars, my old 7 1/4 with better gearing and larger drums, my '71 Demon front end parts, etc.) to help him out and just cut him a deal. I'd still have to get rid of my 8 3/4 and 273 leftovers plus whatever comes back from the Dart.
 
BigBlockMopar said:
The bigger cars got the BUDD brake system in '67 and '68, also with 4 pistons per caliper.
They worked quite nice on my '67 Newport... right untill the unobtanium seals started leaking because of the rusty cylinders in the calipers.

The factory most likely found a cheaper to produce brake system and went with that later on.
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Last sentence says it ALL , sorry RRR you are way off , you might know cars , but bean counters run what parts will be used , and they don't care if they are better just cheaper
 
So I am going with the ram man 76 Dart pinned single piston. I told the Ram man I wanted KH set up, Wayne showed me the math and the single piston has more surface coverage than KH. I was also able to keep all my stock stuff from upper and lower control arms, small bolt patten and 14 inch rims, even down to the single reservoir master.

So happy this conversion is out for the smaller cars, can't wait till it gets here.
 
Okay so I'm a bit slow on the uptake of this discussion.
My understanding is
* KH setup = FIXED type
* 73+ setup = FLOATING type.

Having ridden sport bikes I can tell you that most if not all come with "multi pot" fixed calipers and semi floating rotors for street and full floating rotors for the track.

The primary performance benefit of the fixed type is pressure equalization from the "multi pot" calipers (reduced warping and light weight rotors) and self centering (reduced drag) from the floating rotors.

If I apply that logic to cars wouldn't it stand true that the fixed caliper (KH) with multi pistons be preferred over the floating type (73+) as a performance option.

Presuming the discussion is not about TCO ($$$) of the setup

Also, I think we are saying that the floating Caliper has pad wear issues in that the pad on the side closest to the piston wear sooner than the outside pad causing uneven wear.

Floating
[ame]https://youtu.be/ol-wDa6kAgQ[/ame]

Fixed
[ame]https://youtu.be/61_5Lt7kGHg[/ame]

Not to be a wise *** but when I hear 4 piston caliper from 68 - 72, I think performance way ahead of it time especially when this type of configuration is preferred perfomance stopping setup today.

What am I missing?
 
64_Barracuda said:
So I am going with the ram man 76 Dart pinned single piston. I told the Ram man I wanted KH set up, Wayne showed me the math and the single piston has more surface coverage than KH. I was also able to keep all my stock stuff from upper and lower control arms, small bolt patten and 14 inch rims, even down to the single reservoir master.

So happy this conversion is out for the smaller cars, can't wait till it gets here.
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Single reservoir master ?? First thing I would change , there is a real safety reason they changed from single reservoir
 
..you guys are overthinking this.
Both systems work fine on our light A bodies if in good repair...Having said that if i had to choose based on experience i would side RRR,and i prefer the single piston pin callipers.
...They are so simple and easy to work on.
 
jerry6 said:
Last sentence says it ALL , sorry RRR you are way off , you might know cars , but bean counters run what parts will be used , and they don't care if they are better just cheaper
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Ok.
 
I voted '73-up, the way I see it if he spends money on SBP parts he will eventually have to "throw it away" (or sell I guess) when he does decide to go to BBP.

Brake maintenance with sliding calipers is not that bad everyone talks about it like it's a serious reason not to go with them. Makes sense if you are super lazy and cruising a trailer queen once a week but overall if you are racing your car a lot (with turns and stops) you should be regularly checking and maintaining your brakes fairly often anyway.

FWIW look into an 8 1/4" rear, since he wants to race around corners and not at a drag strip with slicks it would probably hold up fine and compared to the 8 3/4" they are everywhere and super cheap.
 
64_Barracuda said:
So I am going with the ram man 76 Dart pinned single piston. I told the Ram man I wanted KH set up, Wayne showed me the math and the single piston has more surface coverage than KH. I was also able to keep all my stock stuff from upper and lower control arms, small bolt patten and 14 inch rims, even down to the single reservoir master.

So happy this conversion is out for the smaller cars, can't wait till it gets here.
Click to expand...

He's showing you a simple setup that he sells...plain and simple. Without going into the math (hat tip, ntsqd), he's in business to make a profit. The simple single piston calipers are cheap to produce and market with likely a larger profit margin, and he can make bank off the simplicity of design, which sells more units, and to him that's worth more profit.

Think about this aspect though--SSBC has been in business selling aftermarket brake systems for at least three decades. Take a look at their drum to disc kits--they're multi-piston fixed calipers (except for rear disc kits), and strangely enough they very much resemble those 40+ year old KH designs. This is not a coincidence. When properly maintained, they are no different than any other braking system and are plenty reliable. Newer vehicles benefit greatly from CNC machinery and other processes which can faithfully reproduce those complex designs for cheaper per unit cost and that enables our favorite manufacturers to use better parts and such on the cars we drive. I can't speak for a new Challenger or Charger, but I can say with certainty the new Mustangs use multi-piston calipers even on the low option base trim models. Again, this isn't a coincidence...it's better equipment.

I agree that the single piston caliper setups are easy to maintain and swap to, and for the vast majority of classic car enthusiasts, they offer more than satisfactory performance at a low cost with readily available repair/replacement parts. But, just like we all know, cheap rarely means great and as long as you're not clouding your own judgment in that perspective, you'll be fine. Not everyone wants to be king of the world, not every hot rodder or classic car enthusiast wants to drive a $80K pro-touring ride despite how cool they are...most of us want just to drive our toys and enjoy them. Simple systems like the '73-up brakes fulfill that market segment, and as long as people are driving A bodies with front drums with a desire to upgrade, those systems will exist. But, for those who want something different, those systems will be available too. Speaking ill of either setup is just pissin in the wind...like has been said, numerous times on this site before, pick your parts, pay your money...just be aware of what you're dropping the money on...
 
I am ok with what I am getting. So I did the math based on the piston surface coverage vise an KH from 1965. Granted it's not much greater coverage but enough to satisfy my requirements.

I don't know why my choice to go this way bothers you. My car is all stock I just wanted better stopping power. Besides I only have to worry about two Pistons leaking vice 8.

Thanks for your interest though.


ntsqd said:
"Surface coverage"? What do you mean by this? Larger brake pad contact area? If so, it is a frequent and common misunderstanding that this somehow equates to brake performance. It doesn't. All it determines is the service life of the pad due to the volume of the friction material. The formula for determining brake torque has no variable for the brake pad area. The simple version looks like this: B(t) = (F x mu) X R(c), where: B(t) = Brake Torque F = piston area (one side only) X system pressure mu = brake pad Coefficient of Friction R(c) = radial distance from the spindle centerline to the centroid of the brake pad. The K-H calipers have all of the right ingredients to be a great caliper for performance use. A decently designed rigid, cast iron body; fixed mounting - pistons on both sides of the rotor. Whether they deliver on that I've no idea, but there are plenty of other options available that do deliver. FWIW normal piston retraction by the seals is about .015". If your rotor is wobbling enough to make contact with the pads when the brakes aren't applied you've got problems. Sliding calipers biggest Achilles Heel is the sliding mechanism. Once that ceases to work as designed the inside pad wears much faster that the outer pad and the caliper isn't truly clamping the rotor - it's just pushing one side only. Which works the wheel bearings too. Then look at the actual shape of sliding calipers, they're basically a C clamp with no reinforcement around each end of the pads. Compare that to the K-H design where that reinforcement is present. If you pressurize one of each type of caliper to the same pressure and then measure the before and after body dimensions at the pad centroid you'll find that the sliding caliper has opened up 2X-10X more than the K-H design. That difference is fluid that your foot has to move. So the fixed caliper not only flexes less, but that lower flex translates into less total brake pedal movement. Translation: a less mushy pedal and better brake modulation. Sliding calipers are easier to make, that makes them less expensive and when you have to make 500,000 of an item a savings of even a few pennies on each makes a huge impact on the bottom line. http://forum.ih8mud.com/threads/comments-on-brakes.256361/
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I have been researching this for about 5 years or so. no one sells a kit to keep 14 inch rims. Besides my 65 has the same caliper so it does help somewhere in the end.

I don't really care much on someone's profit margin. That's why they are in business.

I would gladly pay double for the SSBC kit but they don't make anything for my car. So in a sense Wayne really is the best choice for my car.

That and most other kits you all speak of are Japanese kits or GM. I am ok with all Mopar.


txstang84 said:
He's showing you a simple setup that he sells...plain and simple. Without going into the math (hat tip, ntsqd), he's in business to make a profit. The simple single piston calipers are cheap to produce and market with likely a larger profit margin, and he can make bank off the simplicity of design, which sells more units, and to him that's worth more profit. Think about this aspect though--SSBC has been in business selling aftermarket brake systems for at least three decades. Take a look at their drum to disc kits--they're multi-piston fixed calipers (except for rear disc kits), and strangely enough they very much resemble those 40+ year old KH designs. This is not a coincidence. When properly maintained, they are no different than any other braking system and are plenty reliable. Newer vehicles benefit greatly from CNC machinery and other processes which can faithfully reproduce those complex designs for cheaper per unit cost and that enables our favorite manufacturers to use better parts and such on the cars we drive. I can't speak for a new Challenger or Charger, but I can say with certainty the new Mustangs use multi-piston calipers even on the low option base trim models. Again, this isn't a coincidence...it's better equipment. I agree that the single piston caliper setups are easy to maintain and swap to, and for the vast majority of classic car enthusiasts, they offer more than satisfactory performance at a low cost with readily available repair/replacement parts. But, just like we all know, cheap rarely means great and as long as you're not clouding your own judgment in that perspective, you'll be fine. Not everyone wants to be king of the world, not every hot rodder or classic car enthusiast wants to drive a $80K pro-touring ride despite how cool they are...most of us want just to drive our toys and enjoy them. Simple systems like the '73-up brakes fulfill that market segment, and as long as people are driving A bodies with front drums with a desire to upgrade, those systems will exist. But, for those who want something different, those systems will be available too. Speaking ill of either setup is just pissin in the wind...like has been said, numerous times on this site before, pick your parts, pay your money...just be aware of what you're dropping the money on...
Click to expand...
 
jerry6 said:
Ok crap , thought you'd give me an RRR beat down . Ok , where's the reall RRR ?
Click to expand...

Oh I am right here. Believe me. I am not however "way off" as you indicated.

I gave MY OPINION, which is CORRECT for ME, regardless of anything else. I PREFER the single piston caliper in most instances. Period. I said what "I" prefer. I didn't say someone else's outlook was right or wrong. Simply that I like single piston calipers better. That means I am correct. Maybe you like guys better than girls. That's correct for YOU but not ME.
 
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