Front brake calipers vs....

[Turbo6inKY]

I must admit..this is getting a bit confusing. I surly appreciate the advise but ..for the last few day i have been reading many,many postings from guys that have done the blazer dual piston swap with a better pad and some also with the 12" caprice dual booster ..many utube vids all claiming its "night and day". The fact that the pad area and piston area is greater it seems logical there would be more contact area so by default better braking...add more vac assist to that to create clamping pressures. This is a very researched upgrade. Can find many utube vids on the swap...i can't believe they are all mistaken. Gbody.com covers this is depth too.

People on Youtube claim some herb they found in a cave made their dick 10" long or that some politician is a genius. They're all doing it for the views.

Engineers don't care about Youtube. They do the math and check the results.

Here's a spot with the actual formulas:

Disk Brakes - Torque and Force

Forces and torque activated with disk brakes.

www.engineeringtoolbox.com

Here's a handy brake rotor torque calculator that does the math for you, and also has some extra stuff that'll tell you how much brake torque you need to accompish a desired deceleration rate

Jake Latham's 2000 Radical Prosport

Plug in your numbers, then start fiddling with them. You'll see quickly that rotor diameter has very little effect when you're talking about a quarter inch increase in diameter (remember, you're going to the center of the pad, not the edge for the calculation). Going from a 10.75" rotor to 11" is not even a 3% change in that variable. But changing out a pad with a 0.4 coefficient with on that has a 0.6? That's a 50% increase in that variable, and they're multiplied together. It's all about the pad.

All these folks saying it's night and day are crediting the Blazer swap with the effect they received from simply servicing their neglected brakes. New pads, new fluid, replacement lines. A lot of the time they also got new wheels and tires. Their stock setup probably had play in the bearings which can make the pedal feel mushy. The blazer spindle is a newer style cartridge bearing that doesn't get loose, it just starts making noise until it falls off. None of them ever have any data, just how it "feels".

I ran several full seasons using the old Wilwood kit that used a 10.75" (stock diameter, fit inside a 15" wheel) rotor. I thought it was absolutely terrible until I got a set of stupidly high friction race pads. Suddenly my brakes worked (after they warmed up). Now, a rotor that small couldn't shed the heat and I ended up in a situation where I was completely replacing the rotors and pads and bearings after every event, but during the event, they worked fine. 140-60 for Turn 1 at Putnam no problem, lap after lap, for a whole weekend.

I switched to the 12.88" rotor kit with the six piston calipers not to get more stop but to get more life out of the parts. I ran a whole season on one set of rotors and just two sets of pads with the bigger kit, but I cannot claim the car brakes in a shorter distance. That's actual data. Real information.

The puny stock brakes are actually sized appropriately for the weight of the car and the stopping distance targeted by GM. What they lack is durability, especially in extreme use cases, but that's the same story with all stock brakes up until the early 2000s when the automotive press suddenly started caring about performance and OEMs realized blangin' brakes could drive sales.

Properly serviced and with good pads and tires and adequate line pressure? They will work fine. Anything bigger is either bling, or you're doing something dumb like me.


And here's my final point:

THERE IS NOTHING WRONG WITH BLANGIN' HUGE BRAKES. If you have the cheddar, do it. They look awesome. Just be honest with yourself about why you're doing it - because it looks super cool.

 

[TurboBob]

I did the blazer brakes because it is a modest upgrade. And for the wheel speed sensors since I'm playing with traction control.

The brakes are a noticable improvement, but its not like a huge improvement. The pedal is a little lower, which would be expected with more piston area/volume, but I'm sure there are other factors.

Certainly the brakes are new now, but the old brakes weren't original. Probably 5 years old.

Anyone in the Detroit area can swing by and try them out.

Bob

 

[TurboBob]

this is a traction control test using the right front (blazer) wheel speed sensor and the stock VSS. Just a quick test, not really tuned.

A good A/B test would be more definitive, but would get me in a bit of trouble around here

 

[ttypewhite]

Some great ideas...would like to see what this setup looks like?

Without this check valve from Summit I would agree that it wouldn't be a huge difference. I too wasn't impressed until I did this and the difference is night and day. I have a 1" intake spacer that I drilled and tapped for a #6 AN fitting and ran that line to the MC. To anyone that has done this mod.... try it, you will be presently surprised at how much better your system becomes over that plastic crap that restricts everything.

 

[turbocamino1]

Without this check valve from Summit I would agree that it wouldn't be a huge difference. I too wasn't impressed until I did this and the difference is night and day. I have a 1" intake spacer that I drilled and tapped for a #6 AN fitting and ran that line to the MC. To anyone that has done this mod.... try it, you will be presently surprised at how much better your system becomes over that plastic crap that restricts everything.

Thats an amazing find,imo. Do you suspect it is a function of ; being a better sealed line,a better one way valve ,or better vacuum signal from intake? or all the above. ...also, in the last pic..are they Blazer calipers on the 10.5 rotor?

 

[turbocamino1]

I ran several full seasons using the old Wilwood kit that used a 10.75" (stock diameter, fit inside a 15" wheel) rotor. I thought it was absolutely terrible until I got a set of stupidly high friction race pads. Suddenly my brakes worked (after they warmed up). Now, a rotor that small couldn't shed the heat and I ended up in a situation where I was completely replacing the rotors and pads and bearings after every event, but during the event, they worked fine. 140-60 for Turn 1 at Putnam no problem, lap after lap, for a whole weekend.

Thanks you for all that... A road race application is surely a different animal. In a short shut down,drag race application brakes are cold and get hot pretty fast but have to perform fast...in just a few hundred feet . Without getting into bigger wheels sizes the the 15" stuff is a big limitation it seems. Did you find the Hawk HPS was not as good as the EBC yellows?

 

[1KWIKSIX]

I did the blazer brakes because it is a modest upgrade. And for the wheel speed sensors since I'm playing with traction control.

The brakes are a noticable improvement, but its not like a huge improvement. The pedal is a little lower, which would be expected with more piston area/volume, but I'm sure there are other factors.

Certainly the brakes are new now, but the old brakes weren't original. Probably 5 years old.

Anyone in the Detroit area can swing by and try them out.

Bob

Bob, installing residual pressure valves in both front & rear brake lines will take care of that extra travel you’re experiencing in your brake pedal.

Wilwood Disc Brakes

MasterCylinder No: 260-3279, master cylinders, aluminum tandem, combination remote, compact master cylinder, go-kart master cylinder, handle-bar master cylinder, rebuild kits, high volume, hvm master cylinder, tandem, bleeding kits

www.wilwood.com

Wilwood Disc Brakes

MasterCylinder No: 260-13706, master cylinders, aluminum tandem, combination remote, compact master cylinder, go-kart master cylinder, handle-bar master cylinder, rebuild kits, high volume, hvm master cylinder, tandem, bleeding kits

www.wilwood.com

 

[Nigel]

This is a good topic to refresh what is out there, good technical info presented, and for guys to figure the solution they want to go with.
Lack of powermaster parts seems to rule that out as an option anymore, maybe something is out there, don't know.
On my last car I did a vacuum booster, this was back in the late 90s, bought the kit from kirban. Kept stock brakes other than the booster, hated it, did not stop well. I did not have a lot of spare cash then, but had I kept that car, I would have upgraded the rest of the system. Ttypewhite presents some good stuff for that. I would do similar to what he has shown if I went vacuum again. The line pressure data Chuck presented tells the tale in my opinion.
I went hyrdroboost on the current car, but to make that work well I would recommend a new reservoir like from PSC. Everything else is stock and the reason I went hydroboost was to keep it that way and have serious stopping power. I will eventually get the pump mod done, but it works well enough now from the standpoint of pump wine, but could be better. The hydroboost with the stock brakes will give you all of the stopping power you could want, it is not something for a road course though with the stock rotors, drums, pads as repeated stops would probably have stuff on fire (metaphorically or possibly in reality). Would likely need a power steering fluid cooling system too for a road course, for street use I have had zero problems with respect to heat or braking power.
Turbo6inKY gave good info around good road course brakes. I don't have any experience in this area, other than stock components will get real hot and fade with repeated high speed stops. I don't think either solution is as simple as bolt on a new booster, need some other supporting stuff to make the system work well. Either can be made to work to your satisfaction and application, as shown in this thread, good stuff.

 

[TurboBob]

People on Youtube claim some herb they found in a cave made their dick 10" long or that some politician is a genius. They're all doing it for the views.

Engineers don't care about Youtube. They do the math and check the results.

Here's a spot with the actual formulas:

Disk Brakes - Torque and Force

Forces and torque activated with disk brakes.

www.engineeringtoolbox.com

Here's a handy brake rotor torque calculator that does the math for you, and also has some extra stuff that'll tell you how much brake torque you need to accompish a desired deceleration rate

Jake Latham's 2000 Radical Prosport

Plug in your numbers, then start fiddling with them. You'll see quickly that rotor diameter has very little effect when you're talking about a quarter inch increase in diameter (remember, you're going to the center of the pad, not the edge for the calculation). Going from a 10.75" rotor to 11" is not even a 3% change in that variable. But changing out a pad with a 0.4 coefficient with on that has a 0.6? That's a 50% increase in that variable, and they're multiplied together. It's all about the pad.

All these folks saying it's night and day are crediting the Blazer swap with the effect they received from simply servicing their neglected brakes. New pads, new fluid, replacement lines. A lot of the time they also got new wheels and tires. Their stock setup probably had play in the bearings which can make the pedal feel mushy. The blazer spindle is a newer style cartridge bearing that doesn't get loose, it just starts making noise until it falls off. None of them ever have any data, just how it "feels".

I ran several full seasons using the old Wilwood kit that used a 10.75" (stock diameter, fit inside a 15" wheel) rotor. I thought it was absolutely terrible until I got a set of stupidly high friction race pads. Suddenly my brakes worked (after they warmed up). Now, a rotor that small couldn't shed the heat and I ended up in a situation where I was completely replacing the rotors and pads and bearings after every event, but during the event, they worked fine. 140-60 for Turn 1 at Putnam no problem, lap after lap, for a whole weekend.

I switched to the 12.88" rotor kit with the six piston calipers not to get more stop but to get more life out of the parts. I ran a whole season on one set of rotors and just two sets of pads with the bigger kit, but I cannot claim the car brakes in a shorter distance. That's actual data. Real information.

The puny stock brakes are actually sized appropriately for the weight of the car and the stopping distance targeted by GM. What they lack is durability, especially in extreme use cases, but that's the same story with all stock brakes up until the early 2000s when the automotive press suddenly started caring about performance and OEMs realized blangin' brakes could drive sales.

Properly serviced and with good pads and tires and adequate line pressure? They will work fine. Anything bigger is either bling, or you're doing something dumb like me.


And here's my final point:

THERE IS NOTHING WRONG WITH BLANGIN' HUGE BRAKES. If you have the cheddar, do it. They look awesome. Just be honest with yourself about why you're doing it - because it looks super cool.

I have a theory question: the stock caliper is a single piston, the piston is like the open end of a cup, so it hits the pad on the perimeter. The braking force is related to the piston area, so we count the area inside the perimeter.

The blazer brakes (and other multipiston brakes) have the same thing, but would we not count the area between the pistons in the same way? i.e. the effective piston area is slightly larger than the sum of the piston areas? The reason I ask is that my experience with the blazer brakes and the 'internet stories' all seem to indicate an improvement even though the piston areas are very close.

Just a theory question.

Bob

 

[Nigel]

I have a theory question: the stock caliper is a single piston, the piston is like the open end of a cup, so it hits the pad on the perimeter. The braking force is related to the piston area, so we count the area inside the perimeter.

The blazer brakes (and other multipiston brakes) have the same thing, but would we not count the area between the pistons in the same way? i.e. the effective piston area is slightly larger than the sum of the piston areas? The reason I ask is that my experience with the blazer brakes and the 'internet stories' all seem to indicate an improvement even though the piston areas are very close.

Just a theory question.

Bob

I think the main improvement is the increased rotor diameter you get with the blazer conversion, if I recall correctly it does have a lager diameter?

 

[1KWIKSIX]

I think the main improvement is the increased rotor diameter you get with the blazer conversion, if I recall correctly it does have a lager diameter?

Maybe only 1/4” larger diameter, so doubt there would be any appreciable difference from that. However, the two smaller pistons will create more pressure evenly & spaced out more than the single piston brake caliper

 

[Mr.Spool]

My experience stock vs duel/bigger brakes.
Switching out the pads
switching to stainless braided lines (which stops the fluid expansion,big one there)
Switching to synthetic brake fluid(doesn't expand and heat up)and
Drilled/slotted rotors but keeping the stock diameter.
Results= big time
we gained the ability to hold more boost off the footbrake drop 60fts and cut stopping distance to the point I dont need a shoot to slow the car down
The powermaster really came alive.
I have a much higher end brake system on my other car and have driven wildwood/ baer upgrades and would rate these mods as the do it 1st over spending the major $$ on revamping the entire brake system.

 

[turbocamino1]

Where i landed on parts for this project after taking in all the info i could ::: Contacted several salvage yards that had a 98-05 2WD Blazer listed in their inventory and found out pretty quick that these parts get pulled off day one, so no luck there. Did find 2 e-bayers with a pair of spindles along with the 10 hard to find bolts included. Paid stupid money for them but the set i got had been cleaned and painted. Chose the "Detroit Axle" center bearings as they are American made and most reviews say they live a long life. Got 10, 2.5" wheel studs from Jegs as my wheel center section is thick and the ones that come on these brngs are 1.5". "Rock Auto has the Blazer calipers,new or remaned, w/brackets,drilled and slotted rotors and the dust shields. I haven't picked which Hawk HPS pads yet as there are multiples heat range choices and havent figured that out yet I currently have Steel braided brake lines and believe they will reach/fit. I also bought the 90 Caprice 12" dual diaphragm booster from AZ /Duralast and found the firewall gasket on Amazon. My currant master cyl is an oem 1" bore and will keep that i think.DOT 4 fluid. I will most likely try the big one way booster check valve as Mr Ricketts suggests ,hoping it will speed up the vacuum into the booster when going from "go to whoa" Doing this on a friends lift that will not be open until August sometime. I will let yall know how it works out. Any critiquing still appreciated.

 

[Nigel]

Maybe only 1/4” larger diameter, so doubt there would be any appreciable difference from that. However, the two smaller pistons will create more pressure evenly & spaced out more than the single piston brake caliper

I think the main benefit from the multiple pistons is it narrows the distance from the inner radius of the pad contact to the out radius of the pad contact, thereby giving you a larger effective radius while maintaining or increasing piston area. While the difference in the outer radius may be 1/4" the total benefit in effective radius is likely larger. Somebody would have to take some measurements to confirm or dispel.