First Look: 914-6 Alloy Rear Calipers, ...about 30 days out. Options

[balljoint]

Oh boy!

I just got a package from PBR in the mail. (IMG:style_emoticons/default/smile.gif) Pretty exciting!

Thanks Erc!

I will let you guys know how they fit!

[IronHillRestorations]

Porsche has put aluminum calipers on their top of the line cars for years. Remember when the S alloy calipers were the top shelf?

One guy writes about "flex" and causes speculation.

99% of the guys in the 914 world are stoked!

Awesome stuff Sir Eric of Stoppage! (IMG:style_emoticons/default/smilie_pokal.gif) (IMG:style_emoticons/default/smilie_pokal.gif) (IMG:style_emoticons/default/smilie_pokal.gif)

[mepstein]

Porsche has put aluminum calipers on their top of the line cars for years. Remember when the S alloy calipers were the top shelf?

One guy writes about "flex" and causes speculation.

99% of the guys in the 914 world are stoked!

Awesome stuff Sir Eric of Stoppage! (IMG:style_emoticons/default/smilie_pokal.gif) (IMG:style_emoticons/default/smilie_pokal.gif) (IMG:style_emoticons/default/smilie_pokal.gif)

Not to mention their race cars. Does anyone do high performance steel calipers?

[Matt Romanowski]

Porsche has put aluminum calipers on their top of the line cars for years. Remember when the S alloy calipers were the top shelf?

One guy writes about "flex" and causes speculation.

99% of the guys in the 914 world are stoked!

Awesome stuff Sir Eric of Stoppage! (IMG:style_emoticons/default/smilie_pokal.gif) (IMG:style_emoticons/default/smilie_pokal.gif) (IMG:style_emoticons/default/smilie_pokal.gif)

I'm not saying it's not really cool that he's doing this, but I'm asking about the material. Go look at other aluminum calipers and you'll notice something really different - they are forged. As you know, the forging adds a lot of strength.

Now, I'm not saying that you these won't be good calipers, I'm asking if they have been tested and work. Taking a design that was engineered for steel and making them out of aluminum isn't guarenteed to work the same.

[914_teener]

I'm not saying it's not really cool that he's doing this, but I'm asking about the material. Go look at other aluminum calipers and you'll notice something really different - they are forged. As you know, the forging adds a lot of strength.




Not necessarily true......meaning adding strength by forging.

[mepstein]

Porsche has put aluminum calipers on their top of the line cars for years. Remember when the S alloy calipers were the top shelf?

One guy writes about "flex" and causes speculation.

99% of the guys in the 914 world are stoked!

Awesome stuff Sir Eric of Stoppage! (IMG:style_emoticons/default/smilie_pokal.gif) (IMG:style_emoticons/default/smilie_pokal.gif) (IMG:style_emoticons/default/smilie_pokal.gif)

I'm not saying it's not really cool that he's doing this, but I'm asking about the material. Go look at other aluminum calipers and you'll notice something really different - they are forged. As you know, the forging adds a lot of strength.

Now, I'm not saying that you these won't be good calipers, I'm asking if they have been tested and work. Taking a design that was engineered for steel and making them out of aluminum isn't guarenteed to work the same.

If you want tried and tru steel, I have a new set of perfect PMB 914-6 GT calipers I can sell you.

[Eric_Shea]

The Brembos we sell are cast. Same process. No flex. Much larger 48mm pistons as well. Everyone we've sold them to absolutely loves them.

Not sure about all the flex talk in calipers. Vic Elford can win Monte Carlo and race at Le Mans on aluminum calipers for 24 hours yet I hear from a lot of Internet racers that can't make it a lap around Riverside without complaining about "flex".

I have aluminum calipers on all my cars. I love them and highly recommend them.

[mepstein]

The "flex" myth is huge in the bike industry. Every year the manufactures quote 12.8% stiffer than last years bike. Stiffer wheels, stiffer soles on shoes, stiffer bars, stems and all kinds of crazy stuff. The stiffer is better hype is typically bought by the bike racer that isn't winning at the races. Can't be the rider, has to be the equipment.

[bulitt]

One former Boss of mine would spend thousands of dollars every year on new golf equipment...and he really sucked. So one day I very politely asked him why he did it and he told me "he just wanted to rule out equipment as a factor in his poor performance" (IMG:style_emoticons/default/blink.gif)


Checking the Wilwood site, their calipers are cast also. And Eric's prices are in line with their offerings.

[ChrisFoley]

One former Boss of mine would spend thousands of dollars every year on new golf equipment...and he really sucked. So one day I very politely asked him why he did it and he told me "he just wanted to rule out equipment as a factor in his poor performance" (IMG:style_emoticons/default/blink.gif)

(IMG:style_emoticons/default/lol-2.gif)

[biggy72]

Stiffer is better is true for most parts on the suspension, but I'm not sure you could tell anything at all if a caliper flexes .020 under hard braking. And that would be flexing quite a bit. The only thing a flexing caliper would do is change the brake feel. I wouldn't be surprised if the flex lines end up having more give than any caliper flexing could provide as far as changing how the brakes feel.

[Matt Romanowski]

The Brembos we sell are cast. Same process. No flex. Much larger 48mm pistons as well. Everyone we've sold them to absolutely loves them.

Not sure about all the flex talk in calipers. Vic Elford can win Monte Carlo and race at Le Mans on aluminum calipers for 24 hours yet I hear from a lot of Internet racers that can't make it a lap around Riverside without complaining about "flex".

I have aluminum calipers on all my cars. I love them and highly recommend them.

I have aluminum calipers on both of my cars. They were all designed from the beginning to be made out of aluminum. Brembo, Alcon, PFC, Wilwood, etc all spend huge amounts of resources on trying to make their calipers stiffer. Will there be unintended consequences of changing the same design from steel to aluminum? No doubt. Are they big enough to be a problem? Don't know - that's why I asked if you had used these calipers yet.

Just becuase they were good 44 years ago doesn't mean they are good today. Wanna argue that Goodyear Blue Streaks are as good as Hoosiers? Maybe we should all use slide rules instead of computers becuase that is what they used when they engineered stuff for Vic's car?

I hope these are great calipers and work well. I think it's awesome that you are developing parts for 914s (and Porsches in general). I'm not trying to be a jerk, but changing the material a brake caliper is made out of is a major change. I think it's appropriate to ask if this was an engineered, analyzed change or just one of ease of manufacture or becuase it is lighter.

[ConeDodger]

Eric, Matt has a good point. These should be tested.


I volunteer... (IMG:style_emoticons/default/evilgrin.gif)

[Eric_Shea]

Sorry Rob. These will flex way too much for you. (IMG:style_emoticons/default/biggrin.gif)

The Brembos were cast copies of ATE steel A-Calipers. Hey Rob, how are your Brembos working out?

Tensile Strengths Steel and Aluminum

Structural steel ASTM A36 Steel
Yield strength (MPa) = 250

Carbon steel 1090
Yield strength (MPa) = 250

Aluminium
Yield strength (MPa) = 414

Human skin (mine is getting thicker with all this Internet philosophic discussion) (IMG:style_emoticons/default/biggrin.gif)
Yield strength (MPa) = 15

Aluminum
(IMG:http://www.914world.com/bbs2/uploads_offsite/upload.wikimedia.org-1110-1345214481.1.png)

1. Ultimate strength
2. Yield strength
3. Proportional limit stress
4. Fracture
5. Offset strain (typically 0.2%)

Steel
(IMG:http://www.914world.com/bbs2/uploads_offsite/upload.wikimedia.org-1110-1345214481.2.png)

1. Ultimate strength
2. Yield strength
3. Fracture
4. Strain hardening region
5. Necking region
A: Engineering stress
B: True stress

The Yield Strength of aluminum will always be the same regardless of the "caliper design". Now, let's get into real world observations: I've "NEVER" seen a broken aluminum caliper but I've seen "innumerable" steel calipers with mounting ears fractured off and sealing flanges fractured. Steel is much more brittle than aluminum. The aforementioned Brembos have been in use since the mid-70's and again, I've "never" seen one broken or fractured. Same material depth on the mounting ears and around the piston flanges. Again, an aluminum copy of an ATE steel caliper that was used on virtually every European make sedan and sports car. Finally, virtually all modern calipers are all made of aluminum now as it's lighter and stronger and better suited for the application of being hung off a cars suspension. They're using computers now and... they're using aluminum to manufacture calipers. Some "slide rule" designs were ahead of their time (Porsche seems to be famous for this).

Brembo, Alcon, PFC, Wilwood, etc all spend huge amounts of resources on trying to make their calipers stiffer.

Back it up. Can you tell me how you could possibly know these companies spend huge amounts of resources to make their calipers stiffer or is this a general claim? If I were to make a general claim it would be that their engineers look at the numbers I posted because modern (computer) design practices dictate the use of the "Yield Strength" figures.

All the brake companies will tell you the flex is in the caliper design, not the fasteners.

Again, back it up. You've spoken to "All the brake companies"? I've searched for your "flex design" criteria. I think you're making general statements that people could easily confuse with facts and even those are wrong. E.G.: with 4 M8 fasteners running from the nose to back... the fasteners "definitely" do play a factor in flex or no flex. If the fasteners were made out of rubber; would the caliper flex? Aluminum? Now steel? Steel is used where it is needed in modern computer designed aluminum calipers.

So Matt... are you worried about actual "Strength" or are you concerned that these will literally "Flex" their way off the car? Or is there another point that you feel needs to be made?

[sixnotfour]

May I please be on the list for a pair in Natural finish Anodized, Narrow.= lighter
Regards

[Matt Romanowski]

The Yield Strength of aluminum will always be the same regardless of the "caliper design". Now, let's get into real world observations: I've "NEVER" seen a broken aluminum caliper but I've seen "innumerable" steel calipers with mounting ears fractured off and sealing flanges fractured. Steel is much more brittle than aluminum. The aforementioned Brembos have been in use since the mid-70's and again, I've "never" seen one broken or fractured. Same material depth on the mounting ears and around the piston flanges. Again, an aluminum copy of an ATE steel caliper that was used on virtually every European make sedan and sports car. Finally, virtually all modern calipers are all made of aluminum now as it's lighter and stronger and better suited for the application of being hung off a cars suspension. They're using computers now and... they're using aluminum to manufacture calipers. Some "slide rule" designs were ahead of their time (Porsche seems to be famous for this).

If you want to play armchair engineer, which aluminim alloy are you using. Blanket statements like "steel is much more brittle than alumimum" show that you haven't worked with many different aluminum alloys. Try bending 6061-T6 and see how it does? There is a lot of work that goes into alloying a metal and picking the correct one for the application.

Brembo, Alcon, PFC, Wilwood, etc all spend huge amounts of resources on trying to make their calipers stiffer.

Back it up. Can you tell me how you could possibly know these companies spend huge amounts of resources to make their calipers stiffer or is this a general claim? If I were to make a general claim it would be that their engineers look at the numbers I posted because modern design practices dictate the use of the "Yield Strength" figures.

I've spent probably 10 hours talking to brake caliper engineers from Wilwood, PFC, and Alcon about the merrits of different designs and caliper flex and strength. Or, if you would like, PFC will tell you at http://www.performancefriction.com/motorsp...e-calipers.aspx. Notice the number of times they tell you the calipers are forged and have gone through FEA analysis. Also notice that most new aluminum calipers have either a bridge bolt or an acutal part of the caliper body cross the pad area to hold the two halves from spreading.

All the brake companies will tell you the flex is in the caliper design, not the fasteners.

Again, back it up. You've spoken to "All the brake companies"? I've searched for your "flex design" criteria. I think you're making general statements that people could easily confuse with facts and even those are wrong. E.G.: with 4 M8 fasteners running from the nose to back... the fasteners "definitely" do play a factor in flex or no flex. If the fasteners were made out of rubber; would the caliper flex? Aluminum? Now steel? Steel is used where it is needed in modern computer designed aluminum calipers.

Most of the flex comes in the caliper material and design. Does some come from the fasterner? Sure. Is it the majority? No. Notice most new hi-pefrormance calipers are forged out of special alloys. They are also designed [i]to be made out of alimunim, not steel.

So Matt... are you worried about actual "Strength" or are you concerned that these will literally "Flex" their way off the car? Or is there another point that you feel needs to be made?

Neither. Will they be strong enough? Probably, but I don't know. Will the flex themselves off the car? Probably not, but I don't know. Do you? Did you test them? Do the engineering? After all, brakes aren't that imporotant.

Maybe I wasn't clear in my original posts - will these flex and cause pedal feel problems? What will they do when they get hot? I'm sure you've come across the stories how the aluminum 911S calipers can be really spongy compared to the steel calipers. Wonder why?

Also, if you would like to make attacks, I'm happy to talk to you about being an "internet racer." I'm happy to put my track experience up against anyone on this site. What's you're track experience? Or better, what's your engineering background?

[Eric_Shea]

No personal attacks Matt... I was wondering the same. Just a general observation of all the Internet racer chatter about flex in calipers that have put others at the top of the leaderboards.

These are exact replicas of a proven design in a stronger and lighter material. Try bending a beer can... you win. I'm not going to get into it further.

My track experience? Schooled at Skip Barber and Bob Bondurant. With Skip, Terry Earwood was my instructor. With Bondurant, Bob himself at Blackhawk Farms. 18 years PCA on Mid-America, Las Vegas Motorspeedway, Atlanta Motorspeedway, Miller Motorsports Park. I haven't raced now for about 5 years. Probably not as much as you but, enough not to be talking out of my ass and, enough time on S-Caliper not to complain about them.

No engineering background. I sourced others for that. I just build thousands of brake calipers and just trying to make a quality product for the industry. (IMG:style_emoticons/default/beerchug.gif)

[ConeDodger]

To answer your question Eric, I have had no problems at all with my Brembo front calipers. In fact they cool off so quickly it's spooky. Nothing odd in the peddle feel at all. I would have no concern whatsoever putting these on the rear where they do less work of braking...

[balljoint]

Eric,

Are these a straight swap for my existing rear calipers?

[Matt Romanowski]

No personal attacks Matt... I was wondering the same. Just a general observation of all the Internet racer chatter about flex in calipers that have put others at the top of the leaderboards.

These are exact replicas of a proven design in a stronger and lighter material. Try bending a beer can... you win. I'm not going to get into it further.

My track experience? Schooled at Skip Barber and Bob Bondurant. With Skip, Terry Earwood was my instructor. With Bondurant, Bob himself at Blackhawk Farms. 18 years PCA on Mid-America, Las Vegas Motorspeedway, Atlanta Motorspeedway, Miller Motorsports Park. I haven't raced now for about 5 years. Probably not as much as you but, enough not to be talking out of my ass and, enough time on S-Caliper not to complain about them.

No engineering background. I sourced others for that. I just build thousands of brake calipers and just trying to make a quality product for the industry. (IMG:style_emoticons/default/beerchug.gif)

I've done Skippy School and probably 40 days at Watkins Glen, 100+ at NHMS, 30 or more at Lime Rock, 15 at Pocono, and a couple at Summit Point, Road America, and Sebring over the last 14 years. I've helped other folks with everything from a stock 914 to a GT2 911 (running 180 mph at Road Atlanta), a couple different Formula Fords, a couple of Formula Continentals, and a bunch of other stuff inbetween. I've set up a number of schools using the most senior Skip Barber instructor and the person that drove the data car.

I can tell you lots of different things about what brakes will do on a 914 including stock calipers, Carerra calipers, Boxster calipers, and Wilwood Superlights (the best so far). Flex in the calipers can change a lot of things. Just think, when you start to go fast enough, you flex the spindle and get pad knock back from that.

Things like caliper flex, bias bar hysterisis, and compressibility of the brake fluid are real problems when you push a car hard. The alloy that you choose for the calipers makes a huge difference. The strength difference from something like 1100 to 7075 is almost double. I've purchased trailer loads of aluminum, some coming directly from Alcoa for special applications. The devil is in the details and all aluminum is not created equal (even when it's supposed to be).

I do hope you calipers work. It's great that you are restoring old calipers and bringing new things to the market, I just want them to be well engineered and as good as the originals.

Edit: Here is a good chart to show the difference in aluminum alloy strengths. Notice the difference in strengths - 7075 is basically twice as strong as 6061 (the most common machinable aluminum) http://www.aircraftspruce.com/catalog/pdf/aluminumalloy.pdf