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Old 03-12-2019, 12:36 PM   #751
Norm Peterson
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Quote:
Originally Posted by Charlie-III View Post
Looks pretty decent.
I believe the basic premise of this thread is, can you currently lock the brakes/invoke the ABS?
If yes, better brakes gain little until you increase tire grip.
The big catch here is that when poo actually is about to happen, only a little "gain" can mean the difference between contact and only soiled underwear.

In fact, this is precisely the logic behind today's "brake assist" nannies - the system applies the brakes more rapidly than an unsure driver will ever do, shortening the stopping distance by getting you up to max deceleration sooner. But aside from brake assist not being under the driver's control, it really isn't any different from installing pads with stronger 'bite', that develop a similarly high amount of braking from less pedal pressure and generally less pedal stroke.

Whether it's artificially increasing the rate of hydraulic system pressurization or increasing the 'mu' of the pads/rotors, they're just different ways of getting brake torque up to where you need it sooner than with standard mu pads and average-driver rates of pedal application.


There is one caution . . . once you've driven a car equipped with pads that have noticeably stronger bite than OE or mass-market OE replacement (especially mass-market bargain ceramics), you may never want to go back. The necessary pedal modulation is something that most people should be capable of learning.


Norm
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Last edited by Norm Peterson; 03-12-2019 at 12:44 PM.
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Old 04-15-2019, 01:51 PM   #752
AFdot7
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This is a very helpful post and I can see your point. I ended up upgrading my stock cast iron brakes to a Wilwood kit mainly because I was having a terrible time with my OEM brakes leaking, uneven wear, and eventually both rear calipers seized up. I had bought the car used with only a few thousand miles on it, but you could tell the car sat idle a lot. I made the upgrade because the timing was right and I got a great deal. I did noticed a huge difference and I'm glad I upgraded, but you make a good point.
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Old 04-28-2019, 10:01 PM   #753
goodolmrwilson
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Thumbs up

Davenow,

Great thread. Thanks. Tried to explain all this to my 16 yo son a while back, but it seemed to really sink in after he read your post and some of the replies!

He just saved himself (and me) a bunch of cash.

I did let him paint his calipers and get a set of shiny cross drilled rotors though Now everybodys happy

Peace.
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Old 04-29-2019, 08:16 AM   #754
Norm Peterson
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Quote:
Originally Posted by goodolmrwilson View Post
Davenow,

Great thread. Thanks. Tried to explain all this to my 16 yo son a while back, but it seemed to really sink in after he read your post and some of the replies!

He just saved himself (and me) a bunch of cash.

I did let him paint his calipers and get a set of shiny cross drilled rotors though Now everybodys happy

Peace.
Have him read my post #751 above.

Pads with stronger initial bite will get you stopped a tiny bit shorter because the amount of braking force at the contact patches ramps up faster. It may only be a small thing, but it's there.


Norm
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Old 05-18-2019, 07:57 PM   #755
boosterlimitedtb
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Just swapped a 255 into an 02 RS. Would my stock brakes be enough to stop with this extra power I'm getting?
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Old 05-20-2019, 08:38 AM   #756
Charlie-III
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Quote:
Originally Posted by boosterlimitedtb View Post
Just swapped a 255 into an 02 RS. Would my stock brakes be enough to stop with this extra power I'm getting?
As a DD/AutoX car?
Yes.

Fresh fluid, maybe SS lines, better pads and decent tires are a good start.

Track car, maybe upgrade other bits.
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Old 05-20-2019, 09:15 AM   #757
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Quote:
Originally Posted by boosterlimitedtb View Post
Just swapped a 255 into an 02 RS. Would my stock brakes be enough to stop with this extra power I'm getting?
For the street, the question becomes: "Can I invoke ABS?". If yes, then your brakes do everything you need. If you're on the track, you can certainly boil brake fluid, in which case you'd first want to consider higher dry boiling point fluid and if that doesn't work, then consider what class you're in and only then, consider bigger brakes. If you're in showroom stock, doing time trials, something to remember is that during practice, brake ducts are legal. I ran them for many years on various cars, just blowing into the back of the calipers/center of the disks. Come time trial time, snip the zip ties, remove the ducts and instant-legal.

The question isn't the extra power.....it's how fast are you going where you have to slow down. A 165 hp car going 120 mph needs the same braking power as a 5000 hp car going 120 mph.
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Old 04-22-2020, 02:07 PM   #758
Caferacer79
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I have been saying this for YEARS!! It's basic physics....yet I always hear "oh dude, you're running XXX hp and stock brakes. that's dumb"

after a while you get tired of explaining it to people.

HOWEVER, I will say, in my own personal testing, as far as pedal feel and reducing stopping distance, some upgrades do make sense, but not for the reasons people think they should for...i.e. more HP. I drive a an Audi A3 Quattro. That is a HEAVY car. It's been a few years so I can't actually remember the numbers, but we did real-world testing of stopping distance. By simply swapping out pads to a better compound over stock, and going to slotted rotors....we were able to actually measure a noticeable difference in stopping distance.
This is of course, taking into consideration tire friction coefficients, road temp, ambient temp, etc.

In summary, with the stock brakes, in a 60-0 stop, I was just barely able to break traction and have the ABS kick in. With upgraded pads and rotors, and all other variables being as equal as possible, I was able to get the tires to break traction sooner, and allow the ABS to do its job sooner, effectively shortening the stopping distance. GRANTED, I recall it was only a few feet, nothing to write home about, but still, a difference. And another benefit, was overall less heat saturation at the rotors after a panic stop, which plays a role in stop and go spirited driving . after a few red-light launches and grabs, you would notice a difference

as a side note....people also need to "stop" calling them "breaks". It's BRAKES...although the argument can be made that you are taking a break from travelling hahaha
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Old 04-22-2020, 06:11 PM   #759
Norm Peterson
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At least theoretically, and most likely for practical purposes with a skilled driver, you want to stay just below where the ABS gets involved. A released brake does reduce total stopping power and will result in longer stopping distances.

The advantages of ABS are not what most people think they are.


I hear you on "breaks". Like "thread depth" for tires.


Norm
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Old 05-23-2020, 01:22 PM   #760
Dubclutcher
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Useful info
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Old 05-23-2020, 02:18 PM   #761
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I believe the basic premise of this thread is, can you currently lock the brakes/invoke the ABS?
If yes, better brakes gain little until you increase tire grip.


This is the part that is not correct and why I have hated this thread for the last 15 years.

When the tire is locked it is sliding - i.e. very little traction - and the brakes are not moving - so they are not doing anywork. The power drain is the LOWEST

When the tire is rolling at it's max grip/slip angle it has much more traction - so the power requirement to do this is HIGHEST. And the brake's are moving and creating heat rapidly

Yes the tire controls the absolute limit - until the brake cannot hold the tire at it's limit with any precision.

ABS is not it either - you are still sliding the tire - just less.

This is static versus dynamic friction - that is all

This will be my yearly NASIOC post
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