ninefiveone

Re: Rental cars and braking performance in a single panic stop.

Very different requirements to get a car to stop well once in a panic stop situaiton (60-0) than for track usage. All the brake upgrades out there focus on track usage. That's all about having the brakes effective scrub speed from 140-60, with good modulation so that you don't lock up the brakes, and under temperatures in the 1200F range.

If you want good panic stop ability, buy oem pads. There's a lot of things that go into good panic braking but very little that goes into a track ready brake upgrade is any good for a panic stop. In the end you need a brake pad that works effectively bone cold. None of the track pads work cold as well as they do hot.

As for the original question, for street usage, there's very little point in changing the brakes. The bias valve is a tried and tested improvement in braking performance overall but again, under specific circumstances. In a wet corner or cresting a hill, more rear brake bias may not be what you want. If you want to be able to just jump on the pedal in all circumstances and come to a relatively drama free stop, fresh fluid and good oem-ish pads are all you need.

So figure out what you want and you'll have your answer.

Robby

Hugh-

that was sort -of my point in introducing the rental car statement- another comparison would be many BMW's, some Audis, Type R's, etc, that all stop in under 120ft from 60-0 w/SINGLE piston calipers that are MUCH smaller than even a standard 951- someone had mentioned that BR's MIGHT help in a single panic stop & part of my input was to say that the larger calipers really should not make any dif. if anything, I would think they might hurt single stop performance w/heavier rotors, etc- just look at 911's- they've gotten longer stopping results from the 964 to the 996- haven't seen any 997's yet. I've seen 964T's stop in well under 110ft & am now seeing 996TT's stopping in just OVER 120ft... this is interesting to me, considering the better suspensions, chassis, brakes, etc... Anyway, I find it hard to believe that OEM pads would be the best street pad out there, considering how far technology has come... It seems to me that we could find something that would be a little better for single stop performance that would also have a little better fade resistance that wouldn't cost $90/wheel- well, it's not PBR Deluxe, OR, Axxis MM's....


NZ- thanks man- let me know....

Pavlo

I read an article on autoX and how to prepare your car for it, and for the braking part the author said that upgrading to SS lines and some nice pads (carbon perhaps) will make a difference. It is not an expensive upgrade that will make your car stop better and make the pedal feel more "percise".

Matt Sheppard

You do gain a little something else. . . 7 lbs of unsprung weight per wheel!

Robby

yes- SS lines are a great improvement IMO- only $69/set at Paragon & you can do it while you're doing the 5/33 bias valve, new fluid, & pads- ATE blue...? Anyway, it wont really add much to your labor this way & you'll have hit most of hte basic areas- Cervelli used to use dif MC's to get less pedal travel- some people were into taking the FRONT calipers of their early 951's & installing them on the REAR of their cars when going to BR's.... Cervelli & others had said this would cause too much pedal travel b/c of the extra total piston volume & you'd have too much rear- I think this is DEFINATELY the case w/a 5/33- IMO, the rear calipers are MORE than enough for the rear of any of these cars & you're best bet is to just use the 5/33 to get the most from them- whether you use BR/BB's or Turbo S calipers wont effect pedal travel or anything here b/c they all have the same piston diamters- ACTUALLY- MANY people (including KVR) have said the Turbo S calipers have larger ones- 38x44 vs 36x44- I even had a guy who claimed to have measured them both, but, PET files, evidently, claim they're the same... in any event, the Turbo S rotors seem to be the best balance to me for a good street set-up, but, I can see people wanting to do BR's too... IIWY, I would wait until I actually NEEDED new calipers OR possibly got new larger wheels- I have to admit I would run BR's if I went to 18's, but, I'd never run 18's up front- I'd have to fill the wheel up w/more rotor- guess that would mean I'd have to do BR's all around then- not sure how rear BR's would work w/front Turbo S- the rear rotor would be larger, as well as pad, but, the pistons would also be much smaller- not sure how that would affect things... oh well, IF I ever end up w/ my 17x8 / 18/10 Fikse Profil 13's, I'll cross that bridge then.... :-)

ninefiveone

Robby - I think you're really looking under the wrong tree. You've been posting on this same type of topic for at least a year, maybe two. Always asking about 60-0 braking performance.

If you're looking for improved single panic stop performance, porsche simply isn't the place. Or track upgrades.

Improved chassis, brakes, and suspension on a porsche are targeted at handling and track usage. Not for a 60-0 test.

Now if you're looking for technology improving panic braking, I'd look at mercedes.

But I'll throw this out, since it's a topic you're interested in. How do those numbers look if you examine 80-0 stopping distances or 100-0? I can't say I have those facts in front of me but I'll be surprised if rental cars perform as well in those tests.

I'd have to say that 60-0 is where a rental car is most likely to perform well. It might not turn well, it might not accelerate well but you can be sure it'll stop once really well.

On the subject of stainless steel lines, I've never seen the benefit. They're simply regular brake lines inside a flexible steel sheath. That steel sheath doens't prevent the brake line from expanding the slight bit that it does. What people are more likely seeing is the benefit of new lines and fluid, much like new sparkplug wires always outperform old ones.

Robby

Hugh- I've mentioned it many times that 100-0, 120-0, etc, are all different & that 60-0 is largely dependent on tires, moreso than brakes, etc. Why do I ask about 60-0? B/c it's the only test most people here can duplicate- most of us do not have thousands of dollars for testing equipment, but, many of us here DO have G-techs, which are simple devices to use- funny how many will buy those things & use them for 0-60 & 1/4 mile when that's not what Porsches were "designed for" but, don't ever use them for 60-0... Of course, our cars perform just as well from 0-60 as they do from 90-120, etc.... .they're right where they're supposed to be, HP/weight, despite many claims to the contrary... In any event, I would LOVE to find out how these cars would stop from higher speeds, like 100-0, or, 120-0... as for 150-0, there are magazines that have done such tests, &, the 911 turbos that were tested did not do as well as many other cars, unfortunately- I would really like to know why early tests of 964 Turbos did better than new 996TT's from 60-0 & 80-0 when tire technology is "supposed" to be leaps & bounds above.... It's also funny when people get BR/BB's & claim that their cars stop so much better & left marks from their seatbelts, etc, when, in reality, the single stopping intensity has not been increased at all... of course, I would have to see hard data to believe either way... whatever the case, this thread was originally about upgrading from early Brembos to later Turbo S or BR/BB's for what I presume to be a street car & I'm stating that I would LOVE to see ANY tests that demonstrate that a street car would be better off w/much larger calipers- cars like Mercedes & BMW, etc, are doing better panic stops than Porsches w/much less high-tech multi-piston calipers, etc... this is true- but, no one here can definitively say that these cars cannot ALSO outbrake OUR cars at MUCH higher speeds & for more sustained periods before brake fade. too many variables anyway, but, for now, I'm just concerned w/getting the most from my brakes & I don't think that spending $2k+ on front brakes alone will help in any way for the driving that 99% of the cars here mostly see....

As for SS lines- they might not help distances, but, they definately help pedal feel- ALSO, remember that the original lines are 17+ yrs old- when one can replace them w/$69 SS Paragon lines & save $, etc, it seems to be a good upgrade to me, &, if nothing else, a good maintenance item... I had SS lines on my 89 Integra- the rubber ones replaced were 150k old... I didn't notice at all... my Porsche Mech had told me to be VERY careful when he installed the new SS lines on it b/c I could lock the wheels up (invoke ABS) easily, etc... I did not believe him- the truth is, I DEFINATELY noticed a BIG dif.... it wasn;t as major as he had said, but, I was impressed to REALLY notice them at all, considering my past experience- may have something to do w/specific lines, may have something to do w/fluid, may have something to do w/old rubber lines being worn out, but, whatever the reason, I honestly felt the $69 was well spent....

ninefiveone

Robby - Just playing devils advocate here but....

...if you feel that a porsche is not designed for the 1/4 mile, or 0-60, what makes you think a porsche is designed for 60-0? 60-0 has no relevance at a track (which is what most people assume a porsche is designed for). 140-60 is worlds different from 60-0.

60-0 is a pretty useless statistic for most performance cars. If you want to know why 964 turbos performed better in that statistic, it's very simple. The weight distribution was different, the cars weighed less, the suspension was different and they use essentially the same brakes.

I have first hand experience that new benzes and bmws will not outbrake most porsches from high speeds for sustained periods of time and not suffer brake fade. Take almost any new BMW or Benz to the track for a day and see how they perform. I've driven any number of AMG and M-series cars at the track and except for the M3 CSL, they all will not take the same abuse as stock porsche's generally do.

You are very correct in assuming that spending $2K in brakes will not impact 99% of driving you do on the street. This, by the way, is why OEM setups tend to work best on the street vs track setups. They are different usages that require different parts.

Robby

Fair enough, but, at the same time, I really don't feel that OUR Porsche's WERE designed for the track- they are street cars off the showroom floor- as for the 964's- why then, do the 993's & 996's not brake shorter from such low speeds? Also, personally, I would rather keep statistics from higher speeds anyway- 80-0 would be better than 60-0, but, I think a nice round 100-0 would be an excellent speed- it's kind of a medium speed b/t high-speed street & low-speed track..... but, unfortunately, the only statistics magazines usually give are: 60-0, 70-0, & 80-0, so... it's hard to find relative data OR equipment to use for our own tests.... Often times people say they went to BR/BB's & that their car stops SO much better, etc, & they are referring to single stops- this is really just seat of the pants stuff & I'd wager that just having new parts & fluid, would do the same thing w/the old calipers, etc... Saying these things is sometimes attempted justification for spending so much $, BUT, it also makes other people think they will benefit from doing the same, &, often times, this just isn't true....

As for the Mercedes & Bimmer braking on tracks like our cars, I'll take your word for it, but, would think they would hold their own for a short time anyway- of course, on a race track, you've got to deal w/lap after lap.... Most of those cars have gotten SO heavy, that it's almost impossible to conceive they would be able to keep up really... I HATE the new 3-series btw- I really thought the E36 was the perfect design, only, I never went for one b/c I hate the interior & the engine seemed to expensive to mod, plus, the gearing was WAY too short, etc... (M3's)- otherwise, a REALLY cool car right out of the box- I guess my prob is, that I can't ever leave anything alone, &, I would think that after 16yrs + (Turbo S in USA) that brake pads & such would have been designed to help out lower-speed panic stops while STILL preventing some of the fade noise that many OEM pads submit too.... This doesn't mean that I think a street pad should be able to sustain it's ability as much as a good track pad, but, I would think we could get a little closer to the best of both worlds by now w/the right stuff.... what would it take to get 60-0 stops in <110ft w/street tires w/out noise & serious fade issues while still allowing the car to stop well...?

Also- one question- you may know- would a car w/a stiffer suspension (front) stop shorter than a car w/a softer suspension? OR, at least up to a point? Say, from 175lb to 300lb springs on one of our cars? Danno had once told me that the same amount of weight was redistributed w/stiff springs than w/soft springs & I didn't see how this was true- I would thikn stiffer springs would PREVENT some of this weight transfer....? What about 911's- they have most of their weight on hte rear at rest- this seems to be of benefit in straightline stops- would the same amount of weight go forward in on of their cars regardless of their front suspension set-ups? Would the same amount of weight go forward in one of their cars as one of our cars, considering the comparable susp rates & assuming a full-panic stop from a given speed? Lot's of variables here I know, but, the initial question is still valid- does the stiffness of front springs change the amount of weight that is transfered forward &/OR would stiffer ones shorten stops?

ninefiveone

well, if your assumption is that a porsche is designed for the same things as any other car... why drive a porsche?

Having spent a lot of time at tracks in various cars, I can say that porsches are much better suited for track duty in showroom stock condition than anything out there short of a Lotus Elise or Ferrari. The company spends significant time testing their cars on race tracks for the sole purpose of improving that type of performance. BMW's focus more on handling dynamics in street situations with M-series cars seeing more road track testing than say a 7-series.

As for why people feel they have improved braking performance, there are many metrics for brake performance. 60-0 is but one. Modulation and fade are others. Brake upgrades are rarely going to impact that one statistic you're so interested in.

Think of it this way (an oversimplification but not overly so): Your run of the mill car has brakes that are more like an on/off switch. For a 60-0 stop, one slams on the brakes and waits for the commotion to stop. A huge improvement in utlimate braking performance just isn't going to be that noticeable at such a low-moderate speed. One of the things a brake upgrade brings is greater capacity at speeds that mattter (>100), better ability to modulate how much brake you want at any speed, and ability to repeat that performance again and again. None of those are all that important on the street usually.

A mb or bmw will hold it's own for a short time at the track. But who goes out, does three laps and calls it a day? or only 5 laps? Now you see why people upgrade their brakes for track use.

So you're interested in 60-0 and wonder why no one is working on bringing out brake pads that improve that, etc. Because current performance is generally good enough. trying to get that number lower is pretty much an academic exercise with little real world value. You're a the point where reaction time means a lot more than what the braking system can do.

No, stiffer suspension doesn't change the amount of weight being transferred. What better suspensions do is improve the size ofthe contact patch for each tire to make the most of the grip available. Note that I said better, not stiffer. Stiffness doesn't change weight tranfer, it changes body lean or pitch, and how you perceive the weight transfer. To the degree that it prevents a tire from lifting, that will improve ultimate grip, but doesn't change weight transfer.

Imagine a a big board that is gripped by a big vise on one end. If the board is soft, as you walk out to the end of the board, the board sags. That's like a car pitching forward on soft springs.

Now imagine that board is stiff. As you walk out to the end, it doesn't sag at all. That's a car with stiff springs. Same weight and it's still transferred

Let me suggest you spend some time at the track to see the larger picture around vehicle dynamics. A g-tech, some rental cars and your porsche are good for some fun but you're like a guy with a hammer. Everything looks like a nail.

Robby

Well, I've already stated that I understand the dif b/t track braking & street braking, &, I've said several times that I'm not really interested in 60-0 in & of itself- it's just a simple reference. Personally, I'd rather see all cars tested from 150-0... Well, how about 120-0, since many cars can't even hit 150....? But again, the only consistent stops to compare, unfortunately, are 60-0, 70-0, &, 80-0...

951: 60-0: 145ft & 80-0: 256ft (R&T '87)
Turbo S: 60-0: 133ft & 80-0: 232ft (R&T '88)
Turbo S: 30-0 34ft & 60-0: 124ft (MT '88)

You left out a couple of cars when mentioing cars that are better on track compared to most- Early Acura NSX (~205ft from 80mph). RX-7TT's & E36 M3's were two others that could stop this short, as well as 964T's & C4 Vettes that actually stopped in the 104-108ft range from 60mph & ~200ft from 80... The Elise has done even better, but, it's at least ~1000lbs lighter than any of the other cars mentioned...

So, I guess my problem is this.... WHY CAN'T a Turbo S be made to stop shorter than some of those 200ft (from 80) contenders? I mean, think about it- the car is as light, or lighter than any of the above (except Elise) & has MORE brake... More potential, right? I mean, these cars really were NOT designed for the track- IF so, why wouldn't they eliminate all of the power BS (they still left a lot of crap & extra wiring, etc, in the CS versions), not to mention the weak spring rates- the Turbo S is actually slightly undersprung for street, much less track- No, I think that if the 951 were designed for track, that they all would have been designed like the Cup cars &/or Rothmans, etc, at the very least. In any event, these cars ARE closer to track cars than many production street cars (of their era at least), but, do you think that larger, multi-piston calipers, w/larger pads &/or rotors (up to a point) would HURT their panic stop potential? I mean, I can't understand why we couldn't AT LEAST do as well as the best of the others all things considered... But, it seems like we're consistently 10-30ft longer..... That's a good amount, &, just like 0-60 times correlate in a somewhat linear way w/1/4 mile, 0-120, 0150, etc, then, so does 30-0, 60-0, correlates to
80-0, 100-0, 120-0, 150-0, etc....

As for high speed stops- would would you consider 150-0 to be a better reference for track brakes? I personallly would, although good street pads can usually make at least one stop from 150mph at least once- still, it's much closer to summing up braking potential than 60-0. I've seen E36M3's & Supra TT's stop from 100mph in ~330ft & the some of the best modded street cars in the world are stopping from 150mph in a little under 700ft- a Renntech Mercedes won the braking part of C&D's 0-150-0 a few yrs back w/692ft IIRC. The 993's & other 911 variants were MUCH higher, like mid 800's.... THIS should be a high enough speed where track brakes should really help out.... So, my question is, what does it take? I mean, obviously tires- I mentioned that WAY back- tires are a big part of 60-0- do it really doesn't take HUGE brakes to stop short from 60mph in a single panic stop, but, I would think the 951's, w/their big calipers, etc, could get just as good, if not slightly BETTER, than other street cars w/out tons of fade....? Might very well fade moreso than track pads, but, there have to be some middle ground...

I've tried SEVERAL pads- stock pads (OEM?) were stopping my car from 60 in 125ft- then, I bought Zimmerman drillled rotors w/PBR Deluxe pads- stopped in 123ft- then, a month or two later, added SS lines & 5/33 bias valve- 122ft... then, tried another pad up front- can't remember what- 125ft- now I have Axxis MM's & I'm sure they wont get below ~130ft- HORRIBLE initial bite- I'm dying to get some decent pads w/good bite when cold, but, not fade too badly on really hard street driving- fine if they fade on the track, but, not on street- The PBR's made noise & faded during some spirited street runs, not HARD runs, just spirited... the Axxis MM's just sucked out loud- they get a LITTLE better when warmed up, but, I have to apply large amounts of pedal pressure- the PBRs took hardly any pedal pressure- I like that- the stock ones were in b/t...The stock Porsche pads are supposed to be made by Pagid- not sure if mine really were- OEM? The PO had them on there & the wear indicators were connected.... Anyway, the 944 Turbo S usually stopped b/t 124ft & 133ft from 60mph when new.... NOW I have stiffer susp (275 front & 25.5 t-bar w/100lb helpers) AND 993 Cup 2 wheels- 225/45/17 & 255/40/17 w/Pilot PS2's- had SP8000's on stock Club Sports w/worn-out stock susp on all previous tests.... I plan to do some tests soon- also want to see if ABS really reduces stopping distance- it really SHOULD, but....

Anyway, it would seem for my situation, shorter stops, that pads would be crucial- I'm considering Ferrodos, maybe some of the Hawks, or possibly Pagids- orange, blue, or black...which is which? Any suggestions? I want good street stopping ability when fairly cold- I don't want to have to hit 5 or 6 hard stops to get them working their best- not worried about rotor life or some dust, but, don't want tons of it.... I DO want some fade resistance, but, I don't expect it to be track-like fade resistance- just, preferably a little better than stock, w/slightly more aggressive single stop ability...

Anyway, I'd still like to know what some of these cars can do from 60-0- IF some of these track set-ups get much better when warmed up, then, warm them up first & THEN run the tests... I only constinue to ask about this b/c their are always new people on the board & i know that new people get new testing equipment (like G-Techs) occasionally, plus, I know a LOT of people here have G-Techs, etc. 60-0 is also fairly easy on the car, compared w/0-60, 1/4 mile, etc... I would just love to know how some of these cars are doing with & w/out mods....

Anyway....

Peckster

You are so negative!!!

But they are nice and shiney.

joseph mitro

i took my M3 to the track with stock rotors and pads (95K) and only after five 20 minute sessions did i start noticing any fade.

Robby

I've never had ANY personal track experience w/any of these cars, but, that's what I've always heard- I've known a few guys who have tracked M3's & have claimed that when bone stock, they did very well...

ninefiveone

I give up.

Cheers!