Brake upgrade for non-S

[Paul]

Congrats!

I was going to make the Air Force a career (ROTC) but in 1969 my draft number was 324 and a lot of my classmates were just back from Vietnam (GI Bill) and told me I was crazy.

I did go on to get a private license and an instrument rating and bought a Piper, but I envy your flight experience, since I've always wanted to push the throttles on a fighter!!! I have shot approaches several times at Patuxent.... My brother is stationed at Mountain Home (a lifer).

But I still doubt that the Boxster would need to have 100 more hp than a 996 to have the same drag limited top speed.

[MNBoxster]

Originally Posted by Paul

Congrats!

I was going to make the Air Force a career (ROTC) but in 1969 my draft number was 324 and a lot of my classmates were just back from Vietnam (GI Bill) and told me I was crazy.

I did go on to get a private license and an instrument rating and bought a Piper, but I envy your flight experience, since I've always wanted to push the throttles on a fighter!!! I have shot approaches several times at Patuxent.... My brother is stationed at Mountain Home (a lifer).

But I still doubt that the Boxster would need to have 100 more hp than a 996 to have the same drag limited top speed.

Hi,

I hear ya, my Draft Number came up #12! So I ran to the NROTC Office, raised my right hand, and signed up (I had been in JrROTC in HS) as a Naval Flight Officer. This allowed me to complete school before reporting, but my intention had always been NAVY AIR.

Then, I passed the Flight Exams (got my Private License at 17) and was off to NAS Pensacola for Basic Flight Training (T-34C Turbomentor). Then to NAS Beeville,TX for Advanced Jet Training (AF-9F). Luckily, I graduated high enough to get a coveted 'fleet seat' and was off to NAS Miramar.

RAG (Replacement Air Group) VF-121 for training and certification in the F-4 PhantomII, this included Air-to-Air (NAS Miramar), Gunnery (NAWS China Lake), then back to Miramar for Seaquals.

Finally, I was assigned to VF-142, the "Ghostriders", on the USS Midway and did 8 WestPacs, mostly MigCap, ResCap, but also some IronHand. Two tours on Yankee Station (Gulf of Tonkin) and one on Dixie Station (Mekong River Delta - South China Sea). Got my 3,000 Flight Hours and shot at a few times.

Then Graduate School and off to Pax River for Test Pilot School and 3 years in the Navy Flight Test Center flying nearly everything in the inventory - F-8, A-4, F-4, F-14, F/A-18, F-16 (yes, this was originally spec'd for the Navy and still carries it's Tailhook today). It was fun - I got to fly REALLY fast airplanes and spend copius amounts of the Taxpayer's Money - for Pay!...

Happy Motoring!... Jim'99

[insite]

Originally Posted by Paul

But I still doubt that the Boxster would need to have 100 more hp than a 996 to have the same drag limited top speed.

jim - i think you're off by a decimal point. i get 10HP more to go the same top speed.

[demonz]

From the pic in my Bentley manual, the brake calipers of the base vs. the S look identical except the red paint.


The bigger rotor is apparent enough.


Anyone know for sure?

[SD987]

986/987 S brakes also use a power boosted brake system not used on the base models that requires less actuating force, thereby making the response more direct.

The Boxster S employs a mechanical vacuum pump instead of a conventional sucking jet pump to provide the vacuum for the brake booster. The pump is driven in tandem configuration together with the oil extraction pump of the right cylinder head (bank 2, cylinder 4) by the exhaust camshaft of the right cylinder bank (bank 2, cylinder 4–6). This design enables a high and constant level of vacuum supply and subsequent effective brake boost even when the most unfavourable underlying conditions apply, e.g. low external air pressure at high altitudes, and in highly dynamic driving involving a high proportion of full-load operation, e.g. on race tracks.

I got my degree via mail-order from RETS Electronic Institute. Dual-major in TV/VCR Repair and HVAC. Now top that !

[Adam]

Lets get to the bottom line here, instead of a comparison degrees? If you track the car the boxster S big reds are better than the base brakes. If you are just driving it on the street the base brake are more than adequate. Nuff said.

[demonz]

Full moon tonight I'll try this again. Can anyone tell me if there is an actual difference between the CALIPERS of the base vs. S besides the paint. They look identical.

[racer_d]

Originally Posted by demonz

Full moon tonight I'll try this again. Can anyone tell me if there is an actual difference between the CALIPERS of the base vs. S besides the paint. They look identical.

1) 1 difference is the caliper will be wider to fit around a wider rotor
2) the brake pads, iirc, are larger on the S brakes.

So, with S brakes you get a) larger caliper b) larger rotor c) larger pads. Those three differences will allow slightly better braking performance when "cold" and likely much better performance when "hot" due to better heat management capabilities.

The penalty for the larger brakes, potentially, is greater unsprung mass (larger often = heavier, unless you go to PCCBs)

Lots of folks who track upgrade brakes because of the perceived benefits. Mostly what they acheive is greater "heat management" abilities. If your "stock" brakes can cause them to lock up, then you effectively have "enough brake". If you can't lock the brakes (imagine your abs was disabled) then you could benefit from larger brakes.

Porsche brakes are designed to handle REPEATED, high speed stops with no loss of performance. The S brakes are perhaps as much "marketing" as functional. You can say you have "911" brakes and yes, at the track, they are an improvement over stock brakes.

You could also put your money into using high quality DOT4 brake fluid, changing more frequently than the Porsche recommended 2yr interval, and use more abrasive/better pads in your stock calipers. If you can find a way to increase airflow over your brakes, even better

[arenared]

Originally Posted by demonz

From the pic in my Bentley manual, the brake calipers of the base vs. the S look identical except the red paint.

The bigger rotor is apparent enough.

Anyone know for sure?

They are NOT the same.

Boy, this thread sure degenerated pretty quickly. The need for bigger/larger brakes depends on the usage. A 3.4L has 50% more power than a 2.5L and will generate speed a lot faster. If you are over-heating the stock brakes, then you are perfectly justified in putting in bigger brakes. I presume the poster that put in a 3.4L did so because he drives "enthusiastically". The difference in weight between base and S is minor. Going to 350mm GT3 brakes is another story however which is why Porsche offers PCCB in that size.

Contrary to what most people think, IMHO, upgrading the fronts without the rears is a mistake. The problem is that by enlarging the fronts, you increase front brake bias. The cars already have heavy front brake bias. There are significant gains to be had with shifting brake bias to the rear.

[MNBoxster]

Originally Posted by arenared

They are NOT the same.

Boy, this thread sure degenerated pretty quickly. The need for bigger/larger brakes depends on the usage. A 3.4L has 50% more power than a 2.5L and will generate speed a lot faster. If you are over-heating the stock brakes, then you are perfectly justified in putting in bigger brakes. I presume the poster that put in a 3.4L did so because he drives "enthusiastically". The difference in weight between base and S is minor. Going to 350mm GT3 brakes is another story however which is why Porsche offers PCCB in that size.

Contrary to what most people think, IMHO, upgrading the fronts without the rears is a mistake. The problem is that by enlarging the fronts, you increase front brake bias. The cars already have heavy front brake bias. There are significant gains to be had with shifting brake bias to the rear.

Hi,

This is a fallacy. Power has nothing to do with it at all. Power will get you to 60 or 90 MPH faster, but the brakes are still hauling the car down from 60 or 90 MPH just like before, no change whatever. If they were adequate before, they still are. They are more fade resistant, but this is a non-sequitor on a Street Car which has adequate cooling time between normal brake applications.

If you Track the car there is an improvement worth the expense, if not, there simply isn't. You can brag that you have the 911 upgrade, and if you are ever in an accident situation where you could only stop within 7 ft. of the other guys bumper, than the 'S' brakes will be an asset, otherwise, not at all...

Happy Motoring!... Jim'99

[David N.]

More power needs bigger brakes. Why? Because idiots like me get into kinetic energy trouble a lot faster when given more power.

Example, I'm speeding up to pass a guy on the freeway. If I'm in a C6, I'm going to end up increasing my speed a bit more than if I'm in a Ford Ranger. Yeah, I could drive less aggressively, but power and Los Angeles traffic can do that to you pretty quick. Good, fade-free braking has saved my ass on more than one account, I say upgrade!

-David

[arenared]

Originally Posted by David N.

More power needs bigger brakes. Why? Because idiots like me get into kinetic energy trouble a lot faster when given more power.

Jim'99, if you're happy with your brakes, then I'm happy for you. But, I think that if you posted over on the TT or GT2/GT3 forums that they should "upgrade" to base Boxster brakes to save unsprung weight 'cause that's all they'll ever need, I don't think your posts will be too well received.