Brake upgrade on non abs car of little value?

[monnieh]

OK, so the first thing I want to do on my Viper (after taking Bobby's driving school) is to upgrade the brakes. But here's my question:

I can already get the brakes to lock-up way too quick on my non-abs car, would'nt better brakes be kinda pointless as I am already reaching lock-up so quickly?

I know if I practice my brake modulation a whole lot then it might make a bit more sense, but in reality I am not going to be able to "work" on my brake modulation on the street.

What do you think, Is there much point to upgrading the brakes on a non-abs car for a "average" driver like me?

 

[Eddie N]

are you planning on tracking the car? or is this strictly for the street?

- eddie -

 

[monnieh]

Good question!

Actually street, as I simply can not afford to race right now.

 

[GTS Dean]

jus-slow - you are sooooo clueless. Go back to your cave and lurk.

 

[GTS Dean]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by monnieh:

Actually street, as I simply can not afford to race right now.

<HR></BLOCKQUOTE>

If you can afford an ABS system, you can afford track time to learn how to modulate your brakes and get some corner-weighting help. If you can afford an ABS system, you can afford a Stop Tech or Dilusi setup with some REAL brakes.

 

[monnieh]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Mark Young:
Monnieh, why do you think a brake upgrade on an ABS car is somehow more effective than on a non-ABS car? All ABS does is keep the wheel from locking up - you can do the same thing yourself with a lot of practice at threshhold braking. Thats it.

Do a search for more info, this topic has been beaten, and beaten, and beaten, and beaten...

<HR></BLOCKQUOTE>

Hi Mark, thanks for the EXCELLENT information. I appreciate it. To answer the above questions, the ABS system is capable of modulating the brakes better than I will ever be able to.

I can already lock up my wheels so quickly that I barely have time to respond with threshold braking. Yes practice is what is needed but not something I can practically do enough of to be good at.

I suspect that ABS equiped viper would be able to outbreak any human.

The bias issue is something I had forgotten about. But I thought you could adjust the bias without upgrading?

BTW: I did search but no info. on this specific question of non-abs upgrade.

 

[Eddie N]

the way i have always understood it was that bigger rotors and bigger pads create more friction under braking which slows you down faster decreasing the distance from 60-0, 100-0, etc..

optimal stopping distance numbers do not occur when the brakes are locked up.. when the brakes lock and the car begins a slide, the contact patch liquifies from the heat and the friction between the tires and the road is drastically reduced resulting in a longer stopping distance..

when car and driver/motor trend does a 100-0 braking test, i highly doubt they stand on the brake locking the front wheels for 130 feet consequently flat spotting 2 perfectly good tires..

the trick is being able to modulate the brake pedal at the maximum braking threshhold BEFORE locking occurs... this will result in the best possble stopping distances.. that being said, it is now quite easy to see why bigger rotors and pads can reduce stopping distances quite dramatically...

ABS was created to not only allow the driver to steer the vehicle in the event of a panic stop, but to also take driver skill out of the equation... antilock brakes use a computer to modulate the brakes for you, which in turn avoids lockup, and reduces the stopping ditance..

yes, i have a brake fetish...

- eddie -

 

[Eddie N]

ahhhh!! you replied while i was typing my reply..

this is what it comes down to monnie.. if you panic stop and lock up the brakes it doesnt matter if you have 14.2 inch stoptechs or 8 inch rotors from a yugo, you're gonna go for a ride..

now, if you let the abs do the modulation for you and panic stop, yes the bigger rotors and pads are going to make a difference because the brakes will never lock..

the reason for the decrease in stopping distance is what i described above.. bigger contact patch between the pad and the rotor creating more friction thus slowing you down faster...

- eddie -

 

[Toby]

http://www.Baer.com/BaerFeatures/ViperEradiSpeed.shtm

This link tells some facts about how upgraded brakes outperform a stock configuration. Other places in the site talk about different variables also.


I have a Baer system going on my 69 Camaro and the quality is first class all the way.

 

[Eddie N]

DISCLAIMER: in the following post i am taking for granted that the $5000 for the brake upgrade is easily justifiable if safety and faster lap times are your main concern.

in short, if you have an abs equipped viper, yes the brake upgrade is worth it because it WILL decrease stopping distances on the street...

if you dont have an abs equipped viper, its still worth it, if you're cool and collected enough during a panic stop to modulate the brakes with out locking them up..

if you track the car semi seriously, then its also definitely worth it..

as far as the free mod to increase brake bias to the rear, it is my opinion (and a few others that i have talked to) that the stoptechs are more than adequate by themselves.. playing with the rear bias is a scary thing for me.. if you screw it up and put too much bias to the rear and they lock on you, its not going to be fun.. picture pulling the ebrake at 75 mph on the freeway because bambi got lost..

wasnt very "in short" huh?

- eddie -

 

[JonB]

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Originally posted by Mark Young:
I think what Dean is trying to say (albeit succinctly) is that neither of you have it quite right.

Monnieh, why do you think a brake upgrade on an ABS car is somehow more effective than on a non-ABS car? All ABS does is keep the wheel from locking up - you can do the same thing yourself with a lot of practice at threshhold braking. Thats it.
<HR></BLOCKQUOTE>

Exactly. And what Eddie N said, too. Better brakes help ALL Vipers, even street-only. Brakes are the weak-link (til '03!!)

Street examples: #1...You are going too fast approaching a corner, especially on a "canyon drive." Do you want better brakes? No fade, less lockup likley? YUP!
#2...... Pa Kettle pulls out in front of you, oblivious to your "ten over" speed. Do YOU want better brakes on the street? YES!
#3....Too fast in town, showing off. Lite is yellow, baby carriage in crosswalk, no car behind you.....
#4....... Jennifer Lopez is walking by on the sidewalk, and you THINK she looks longingly your way..........

If you answered YES or HECK YES to any of the boves, you COULD be a candidate for better brakes !

 

[Eddie N]

its me again, just had to add something..

some times i have to wonder what dodge was thinking.. why build a car that has first class looks, accelleration, handling, but then outfit them with so so brakes?

- eddie -

 

[WCKDVPR]

Just some additional info -

Maximum braking is achieved when the tire is rotating approximately 15% slower than if it were free rolling over the same surface. "Threshold braking" is putting and keeping the tire rotation at this point.

A locked up tire has approximately 30% less stopping force than a tire at threshold (15% slip angle). This equates to 30% longer stopping distances for locked vs. threshold.

ABS is designed to emulate threshold by modulating pressure to the caliper to keep the tire from locking up. It tries to give you some portion of that 30% less distance when you would have otherwise done a panic lock up. For the record ABS does not give you the whole 30%. Therefore a perfectly executed threshold stop would be shorter than what you could achieve with an ABS panic stop.

Stock Viper brakes are not very good in that they are very difficult to modulate at threshold and lock up very easily - Monnieh's comment that they "lock-up way to quick" is exactly the problem. Stock Viper brakes also tend to require a significant reduction in pedal force to get them to release (unlock). This all contributes to longer stopping distances. Better pads help but are not the end-all.

Larger brakes (calipers/pads/rotors) provide the capability to achieve and maintain "threshold" easier. They resist lock up more and generally have greater ability to release from the rotor with a minimum reduction in pedal force (also highly dependant on the pad choice). In essence, more brake "feel". Larger brakes also function better (with the appropriate pad) at higher temperatures than smaller brakes.

For the "novice" - myself included - it is much easier to achieve better stopping distances with brakes that are easy to modulate. The pros out there can do some great things with stock brakes and good pads, but it is not something you are going to get without a significant amount of practice.

I would definitely recommend a brake upgrade, especially in a non-ABS car.

Hope this helps,

 

[Eddie N]

Mike,

thank you for providing some more details to satisfy my brake fetish

.. there is only one thing i dont understand:

<BLOCKQUOTE><font size="1" face="Verdana, Arial">quote:</font><HR>Maximum braking is achieved when the tire is rotating approximately 15% slower than if it were free rolling over the same surface. "Threshold braking" is putting and keeping the tire rotation at this point.<HR></BLOCKQUOTE>

can you plug some numbers into this formula so i can understand this a little clearer?

is this a viper only formula or does this apply to all automotive platforms?

great piece of info.. much appreciated.. will you be going to buttonwillow Nov 30th-Dec 1?

- eddie -

 

[WCKDVPR]

Eddie,

You are most welcome.

The slip angle for greatest traction is a function of the tire and the road surface - it is independent of vehicle. Different tires have different optimum slip angles. 15% is a good generic number. I have a book at home that gives these numbers for different tires. If I can find it, I will post these tomorrow.

Numbers - simply, if the car is going 100 mph, you want the tires rotating at 85 mph for maximum braking. Seems goofy, but that's how it works.

Another interesting tid-bit on slip angles goes with "forgiving" tires. Those that you can "feel" braking away and are pretty easy to drive around the limit (most street tires, cheap street tires even more so). These have a fairly wide range (several degrees) of slip angle around their maximum grip where the level of grip is fairly constant. If you are a little less or a little over the optimum angle there is not a very large difference in grip. Easy to drive. Most race tires on the other hand have a very high level of grip at the expense of a very peaky grip to slip angle curve. A lot of grip at one slip angle and much less just off that angle. The faster you go the better they stick (approaching the max slip angle) and then you go just barely over the optimum angle and the grip drops substantially - and you slide/spin without warning. The once they let go, they're gone feeling.

I need to head home, I'll try and get some more info to you tomorrow.

Yes, I will be on the Mustang Embarrassment Committee at Buttonwillow on 11/30. Happy to talk with you there in more detail as well.

Regards,

 

[luc]

Mike, be nice to my Mustangs,because I will also be at BT!!!!!.

Luc.00GTS (street car)

Race cars
1965 Shelby 1.44 at laguna
1969 Mustang convertible 650hp,1.41 at laguna
1991 Roush Mustang T/A 1.52 at TH (and learning to drive the car)

 

[Mark Young]

I think what Dean is trying to say (albeit succinctly) is that neither of you have it quite right.

Monnieh, why do you think a brake upgrade on an ABS car is somehow more effective than on a non-ABS car? All ABS does is keep the wheel from locking up - you can do the same thing yourself with a lot of practice at threshhold braking. Thats it.

The brake upgrades that are out there for the Viper do more than just dissipate heat. JusSumFastGi was sort of right, but his advice was wrong (which is what Dean is talking about). To reduce the stopping distance on the Viper you have these options:

- change pads: although this technically doesn't allow you to stop any quicker (given that you can already lock your wheels) you'll find that different pads have different feels and some are much more effective than others.

- increase contact patch: bigger front tires will reduce braking distances because there's more friction between your tires and the road.

- adjust the bias: the Viper's rear brakes don't do much at all. If you get the rears to do more work, the car will stop quicker.

So, monnieh, to answer your question... if you're not doing any track time, just change the pads. Find ones that have a feel that your confident with and practice threshold braking. Next time you buy tires, buy 285s or 295s instead of the stock 275s for the front.

But to JusSumFastGi, the Viper brake upgrades WILL reduce stopping distances - dramatically. Look at the stopping distance of the Lethal 750 in the Car & Driver shootout. That car probably has an extra 200 lbs of stereo equipment, but with StopTech's 4-wheel upgrade, it'll leave your teeth on the dash from 100-0. I know firsthand - cause my teeth marks are on it on the passenger side!

Hope that helps! Do a search for more info, this topic has been beaten, and beaten, and beaten, and beaten...

 

[Mark Young]

You were basically telling monnieh that a brake upgrade won't help him stop any quicker (at least thats how I read it) and that is not true.

The brake upgrades available use different piston sizes to modify the front-rear brake bias. By getting the rears to do more work, the car stops faster. Its pretty simple.

Visit stoptech's website if you want to learn more.

 

[WCKDVPR]

Luc,

I am always nice to the Mustang guys. I own a GT350. I just didn't think it was very nice of certain Mustang guys to run some highly prepared cars (one I hear was a T/A) with experienced drivers against three street Vipers (stock, stock, and mostly stock) and two "other" cars in the relay and then give the Viper guys grief about "kicking the Viper's butt".

I'm hoping five Vipers will show for the Buttonwillow event so we can run a complete "team" of Vipers in the relay. Should make it a bit more interesting.

Are you running the T/A in the relay? Is this the car I saw in April at Thunderhill for the Shelby track event? Just curious, was the 1:52 at Thunderhill with turn 5 or with the bypass?

Let's hook up at Buttonwillow, I would really like to check out your car!

Regards,

 

[luc]

Hi Mike,

Yes the 1.52 at Thunderhill was with the by-pass,but was timed by a friend so I'm not sure how "real" this # is.

It is the same car that you saw in April,only difference being some new tires and a little more seat time for the driver.

I did not run the T/A with the Mustang team in the relay nor am I planning to do it at BT since the clutch beside being vey expensive,is not designed to be used for a "drag racing" start.

I am racing my 69 Mustang convertible at Laguna next weekend (26/27)for the SCCA Vintage,if you have time,stop by or otherwise I will see you at BT.

Luc.