I recently upgraded to Hawk HP+ and Brembo brakes all around and wanna know the improvements I'm getting.

Something must be wrong with my method cause I'm getting allmost 200% reduction compared to the stats posted by road and track for the gsr. In fact the values I'm getting are better than any car in the mag by far.

Current (shitty method):

- Accelerate to 60 mph, hit cruise
- Pick a road sign
- Slam brakes as I pass the sign
- Measure distance from front of car to sign.

The only mistake I can think of is how I'm synching the hitting the brakes to passing a sign.

Does anyoen know of a more effective method? I was considering having a friend stand neer the sign and watch for when the lgihts come on to correct for either early or late braking.

I know the methods arent super accurate, but I can tolerate a 10% error

 

a G-tech can measure Gforces under braking.. not sure how accurate it is though.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jet Black &raquo;</TD></TR><TR><TD CLASS="quote">I recently upgraded to Hawk HP+ and Brembo brakes all around and wanna know the improvements I'm getting.</TD></TR></TABLE>

This isn't a direct answer to your question, but if you were able to activate ABS during full braking with your old setup, these upgrades won't have any effect on your stopping distances.

 

Ya, I'm aware of that, lets just say that this setup can lock em up with the ebrake with medium pressure @ 80 mph, whilst before I couldnt lock the rears @ 8mph. So yeah...it grips ALLOT more

 

I just got the impression from your first post that you were trying to determine how much of a reduction there was in your braking distances with the new setup vs. a stock setup. Some people think that bigger rotors or better pads will automatically decrease their stopping distances, so I just wanted to clarify that that isn't the case. Nice upgrade though.

 

thanks.

Ya, I understand the physics behind it. I'm still a bit curious though, as the general impression is that better brakes will reduce your stopping distance even if they both lock up. I'd need to check it out....physicsally its bs....but I'm betting there'll be some stuff we didnt consider that will make upgraded brakes brake better even if both lock up.


Well I tried again tonight with a buddy looking for the lights, we measured 3 times and got values between 84 and 99 ft for 60-0. Using large strides as measurements for meters and then steps for ft, both values are underestimations of the actual unit...so I cant wait to check the actual value with a measuring tape.

Its at least a 44 ft reduction comapred to road and tracks measurements...thats a big big change

 

I can think of a couple things...

First, ditch the large-strides measurement for distance. That's not very repeatable.

Speedometer probably reads high (they all do). You might have to go 63 in order to be going a TRUE 60 mph??? Stopwatch & measured-mile to check that?

Your choice of road might be slightly uphill? Headwind? Mostly the texture of the road surface is really important.

C&D has an instrument package that tells them when they begin braking. (Don't know about R&T.) Maybe they start when the foot touches the pedal - you don't start until the brake lights come on. That's a few feet right there.

I think you're biggest measurement uncertainty is distance. 2nd is probably your true speed. Texture of the road surface isn't a measurement uncertainty, but it might be the biggest difference between your test vs. the magazine.

Last, what about math?
44/140 is like a 31% reduction. How can you possibly get a 200% reduction???

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake &raquo;</TD></TR><TR><TD CLASS="quote">How can you possibly get a 200% reduction???
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If when you started braking you ended up as far in the opposite direction as the guys in the test went forward?

 

^^^^^ hahahahhahhahahhahahhahahahhaahahahaha

 

When my civic was tested by Sport Compact Car, they used a radar gun attached to a laptop to measure 1/4 mile times and braking distance.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by JimBlake &raquo;</TD></TR><TR><TD CLASS="quote">I can think of a couple things...

44/140 is like a 31% reduction. How can you possibly get a 200% reduction???</TD></TR></TABLE>

***

I hate that stupid % reduction or increase I allways screw it up. And come to think of it, that 200% is completely fucked up. I was getting results roughly 50% of the original (as low as 74 feet vs 144)....you can kinda see where I got the 200%


Well here is the thing: Starting when brake lights turn on is correct, since they'll illuminate before the brakes even engage. Having a friend monitor the time they go on, allows for a fairly good correction to find the right start point...not perfect, but it corrects innacuracies on my part.

I know large strides is a bs measurement, but the error isnt that great. I get fairly consistant measures (off by no more than .5 strides over 30), and by counting a number of strides over a known distance, corrections can be applied.

I hadnt thought about road texture....its kinda tough to know what they use as a road texture. I allways test on a as level as possible road, and have yet to do so in a significant wind.

I hadnt thought about speedo beeing off, but even 10% isnt extremely significant...its large, but not huge. (yes I know the distance will reduce in a more than linear relation) I usually do the tests at 100 kph though, which is 62.5 mph. Then again, I have 205 tires so my speedo might be a bit more off. I'd need a radar gun

My buddy and I came up with a good idea, but its still gooing to be a problem to test.

I can wire up a chronometer to the brake switch to activate as soon as the pedal is pressed. Then I just need something to turn it off as soon as I stop....unsure how I'd do that precisely. Once I have the time and speed diff, I can calculate the distance and acceleration. Thing is I'd need a pretty precise chrono as braking isnt a very long process. Or maybe wire into the abs sensor to find the total number of tire rotations during braking

I wish I could get my hands on some real equipment.

 

If you've checked your distance measurement & it's pretty consistant, that's better.

Braking force is limited by the tire's traction against the road. You can easily apply enough brakes to slide, or activate ABS. So if you're using a grippier surface, you get that much more braking force. That's not an error for either you or the magazine, once you understand the difference.

Speedometer is more important than that. 10% more speed means 21% more kinetic energy.

Timing the braking is probably harder than measuring the distance. If you're going to put some kind of switch on the brake pedal, maybe better to use it to trigger something that marks your position. Like maybe use that to trigger a digital camera in the side window to record your position when you hit the brakes.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jet Black &raquo;</TD></TR><TR><TD CLASS="quote">
Well here is the thing: Starting when brake lights turn on is correct, since they'll illuminate before the brakes even engage. Having a friend monitor the time they go on, allows for a fairly good correction to find the right start point...not perfect, but it corrects innacuracies on my part.</TD></TR></TABLE>

As I understand it, by the time the brake lights illuminate, at 60mph the car has already gone 10ft. I was reading this in an article about LED taillights that come on instantly rather than the 1/10 oif a second delay required by bulbs. 1/10th of a second at 60mph is 10 feet.

That inaccuracy alone costs you 10%. Factor in human reaction time (another 1/10th) and you've got 20% right there.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Jet Black &raquo;</TD></TR><TR><TD CLASS="quote">
I know large strides is a bs measurement, but the error isnt that great. I get fairly consistant measures (off by no more than .5 strides over 30), and by counting a number of strides over a known distance, corrections can be applied.
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Measuring with strides is hugely inaccurate. It gets you a good idea, but for what you are trying to do it won't work.

To increase accuracy:
Test your speedometer by using the measured mile section of a local highway, it should take you exactly 60 seconds at 60mph. Or borrow a GPS unit from someone and test it that way.

Get a string, measure it 100 feet long.

Mark off 100 feet on the level piece of highway.

Approach 1st marker, hit brakes, and try to stop before the end.

Also, the times reported by the magazines are on stock tires. If you have better tires than that, that's where your getting the decrease from, not the pads/rotors.

Or, get a Gtech. Yes, they are accurate and they just released their road race/autox firmware and software so it just doesn't do straightline stuff anymore.