91-99 ALB brake test results

I'm going for the 99+ ABS pump soon. To measure the effectiveness of the new system I did a base-line test with the 'old' ALB system. 3 runs with each system should be enough for a good comparison.

Testing conditions

- full tank and fluids
- 97+ brake discs with HAWK HP+ pads, front 97+ calipers, rear 91 calipers with Racing Brake adapters
- Tires Goodyear 205/45/16 + 245/40/17, 2.4 + 2.6 bar tire pressure, 5 mm and 4.75 mm thread depth
- 5 minutes drive to the 'test-track'
- Measurement device: AP-22
- Weather: heavily raining but no aquaplaning, 20 degrees outside

Test run

- Calibrate the AP-22 always at the same place (the calibration has to be done before every run)
- Get up to a speed of exactly 100 km/h on the flat road and start braking 100% at a sign and let the ALB do the rest until the car fully stopped.
- same road
- 5 or more minutes test interval

Remarks
Why wet? The ALB is said to be working worse in bad road conditions. So the wet conditions should reveal more deficiencies than the dry ones.
Why only three runs? During the runs I saw by the data (variance) that three runs may be sufficient (I've expected a much higher variance in the wet). I've done 5 runs in total, one of them was a pretest, an other one was like trying to avoid the ALB and brake better than the ALB system.

Data



Run 1: av. g: 0.63, distance: 64 meters
This was a test-run to give the brakes a good cleaning and warming up. There has been a problem at about 70 km/h as the car behaved strangly. Instead of running straight and decelerating constantly it scaringly jumped a little bit from side to side.
Run 2: av. g: 0.70, distance: 61 meters
Good run
Run 3: av. g: 0.67, distance: 59 meters
Good run
Run 4: av. g: 0.65, distance: 69 meters
Try to brake better than the ALB system. However the ALB system was not deactivated and got in action 2 times. If you try to get the ALB stop assisting you have to lift the brake pedal a little bit (not fully!) but just enough to stop the ALB function. Sometimes it was just too much, esp. at 80 and 50 km/h.

Can you do better without the ALB?

In theory: The deceleration (g-force) is at it's highest right before the point the wheels are about to lock. The ALB remains your steering capability but at the cost of g-force because the optimal grip is not reached well enough. Moreover, the ALB lets the tires slide on the wet surface (for short intervals) which results in lower g-forces but this is comparable to the case of having no ALB at all and locking the wheels fully.

So can you do better than the ALB? Yes you can, but only for a part of a run! The run started at 0.6 g where the others averaged at 0.51. And g-force is more important at higher than at lower speeds. During run 4 the ALB started acting at around 80 km/h but too late for a good g-force-point. It raised up to comparable values until I decided to shut the system off. by lifting the brake pedal a little bit right before 50 km/h (low value) and finished the run with no ALB acting up. As you can see at 40 km/h the g-force is equal to the other runs but gets better below 40 km/h without the ALB. Below 40 km/ you can see the advantage of braking just below the point of the wheels lock. Unfortunately that doesn't count very much for the braking distance at these low speeds. The run was 'f*cked up' from 80-50 km/h resulting in long 69 meters.

Run 5: av. g: 0.66, distance: 59 meters
Good run

Run 2, 3 and 5 are used for the benchmark.

Expectations

The ALB acted still a little bit weird and slowly. If the newer pump is much faster it should help in lower braking distances and higher vehicle stability.

Observations/results

Good to know that the variance of the 3 countable runs is very low. The av. braking distance is 60 meters. With the 99+ ABS pump I'll do the exactly same tests and we'll see if and how much better it is.

Drop of g-force at 20 km/h

Quite interesting is a drop of g-force at 20 km/h in three (the countable ones!) of five runs. It seems as if the ALB (while working quite slowly) is disturbing the traction of the tires. The tires provide excellent grip below 30 km/h. But that doesn't result in a shorter overall braking distance by much.

g-force at 90 km/h

If you can raise the g-forces at the beginning of the brake-maneuver (while the car is fast!) it would be the most effective zone for shorting the braking distance. I guess it's related to the brake system and weight-transfer. Too bad I didn't do some runs with the 91-96/OEM brake pads configuration. But I wasn't happy with that combo anyway as it didn't bite hard enough initially. I wouldn't have been surprised to see even worse results.

Inputs highly appreciated!

...to be continued in about a month.

Thomas,
WAY TO GO. Thanks for the good work. Can't wait for the next test results. Your work is dove tailing right in with what I am doing.
Brad

Gold- Please give the before and after pedal pressure a test. I just did the late mod conversion over a winter. The pedal now moves about 3/4" before the pedal stiffens up. I "thought" the pedal used to firm up with almost no movement. Either I'm not remembering the feel over the winter, or the late model system allows more movement, which sucks. TIA.

Tanto2 said:

Gold- Please give the before and after pedal pressure a test. I just did the late mod conversion over a winter. The pedal now moves about 3/4" before the pedal stiffens up. I "thought" the pedal used to firm up with almost no movement. Either I'm not remembering the feel over the winter, or the late model system allows more movement, which sucks. TIA.

Click to expand...

Sounds like air in your system.

Hi Thomas,

First of all, excellent work :smile: My compliments.
It reminds me that I still have to do my own AP-22 measurements for the differences between the OEM brakes and the big brake kit.

You seem to have had the same problems I had with my initial testing. Namely, low G-forces at the beginning of braking. This surprises me a bit, because you are already running bigger rotors and agressive pads (Hawk HP+).

I wonder if you have done an ABS-flush. I have done that about two months back and if made a world of difference when one of my solenoids was stuck, letting one of my wheels lock up under heavy braking.

I am not sure if doing the testing in the wet is such a good idea. Now, you will have to find similar wet condition when you will be doing the reruns. With dry-road testing the road is simply dry or not. I would think that finding similar conditions is easier than similar wet conditions.
Nevertheless, is it good to know that in wet conditions, the braking distance is 50% longer than under dry conditions.

Other than that, VERY GOOD WORK !!

Thanks Marteen! We've a lot to discuss in Le Mans. :wink:

Testing in the wet is appropriate enough as the variance of the three runs is small enough even with more or less rain. During one run it was raining heavily but no aquaplaning or longer brake distance. The retest will be done on the same road, I just have to wait for a rainy day. :wink:

The ABS flush has been about 8 months ago but with in the first run the car was behaving strangly. I guess the soleniods just needed to be waken up. So I cancelled that run.

The low g-forces at the beginning are maybe due to the brake design or the load transfer. The brake design actually could be better with a caliper with multiple pistons on each side. The wheels don't lock from the beginning of the maneuver straight away. It just feels like the pads have to be 'seated' on the brakediscs to reach their full potential. But we have to admit that the NSX doesn't have Porsche like brake design. The NSX can reach well over 1 g under hard braking but the time and way is lost in the beginning. I think you can only get wrid of this by changing the calipers to another design. Just my thoughts.

I've also done a ABS test with my daily driver and the reaction and the modulation time is WAY faster. I felt much more influence of the NSX ALB than the 2007 ABS system on my daily bitch. I bet a beer that the braking distance in the same conditions is 55 m or less with the new ABS system. Anyone hold against it?

goldNSX said:

Thanks Marteen! We've a lot to discuss in Le Mans. :wink:

Testing in the wet is appropriate enough as the variance of the three runs is small enough even with more or less rain. During one run it was raining heavily but no aquaplaning or longer brake distance. The retest will be done on the same road, I just have to wait for a rainy day. :wink:

The ABS flush has been about 8 months ago but with in the first run the car was behaving strangly. I guess the soleniods just needed to be waken up. So I cancelled that run.

The low g-forces at the beginning are maybe due to the brake design or the load transfer. The brake design actually could be better with a caliper with multiple pistons on each side. The wheels don't lock from the beginning of the maneuver straight away. It just feels like the pads have to be 'seated' on the brakediscs to reach their full potential. But we have to admit that the NSX doesn't have Porsche like brake design. The NSX can reach well over 1 g under hard braking but the time and way is lost in the beginning. I think you can only get wrid of this by changing the calipers to another design. Just my thoughts.

Click to expand...

Hi Thomas,

Yes, we will have a lot to discuss I think at Le Mans :smile:

Concerning your test, yes, as long as you can duplicate the circumstances than it should be no problem. But it would be nice to have a dry-road comparison also :smile:

Have one question though.
Did you do your test by just braking as hard as you could and let the ABS do the work or did you 'feather' the brakes to prevent the ABS from kicking in as much as possible.

As for the brakes, of course you are familiar with the fact that the master brake cylinder for the 1997+ NSX is also larger than that of the 1991-1996 models. Perhaps that would help shortening the build-up time in the NSX brakes.

I am not sure that multiple piston calipers would make a lot of difference. First of all, the OEM sliding caliper 2-piston design is similar to the 4-piston fixed caliper design in aftermarket brakes.
Since a fixed caliper by design cannot press the outside brake pad against the rotors, you simply need an extra set of pistons on the outside side to do that for you. And that equals to having wider calipers that might or might not fit under your wheels of choice.
The only thing I can think off is that because the mass (weight) of the caliper is of course much larger than that of a mere set of two extra pistons, the caliper-inertia you have to overcome with the OEM calipers results in a more delayed response from the brakes.
But I am sure that someone who has more knowlegde about this can give more insight in this.

MvM said:

Have one question though.
Did you do your test by just braking as hard as you could and let the ABS do the work or did you 'feather' the brakes to prevent the ABS from kicking in as much as possible.

Click to expand...

4 of 5 runs where 'panic stops', jumping on the brake pedal and let the ALB do the rest. One was a warm-up (light blue dotted) the other three are used for the benchmark.

The 5th run (Run 4 in the graphic, yellow dotted) was a try to brake better than the ALB, means lifting the pedal if the ALB kicks in and as soon as the ALB is quiet try to press a little bit harder.

As for the brakes, of course you are familiar with the fact that the master brake cylinder for the 1997+ NSX is also larger than that of the 1991-1996 models. Perhaps that would help shortening the build-up time in the NSX brakes.

I am not sure that multiple piston calipers would make a lot of difference.

Click to expand...

I'm changing the master to 97+ too but I don't think it will contribute much to the brake response. You maybe need less pressure to let the ALB kick in.

I guess that the smaller or better said high-precision 4 piston calipers will built up the pressure much faster than the OEM one which will help you at the beginning of the maneuvre and that's where it counts!

I hope to have all the parts here by the 20th of this month and will surely install them before Le Mans and do the test run again.

goldNSX said:

I hope to have all the parts here by the 20th of this month and will surely install them before Le Mans and do the test run again.

Click to expand...

Thanks for the explanation on your procedure, is looking good :smile:

Would be nice to install everything before the Le Mans event.

Did you see this thread?
http://www.nsxprime.com/forums/showthread.php?t=87093&page=4

Apart from having built a wonderful NSX-R, Chris is is also busy with the ABS conversion. He is only just one step ahead of you.

Perhaps you two could help each other if need be :smile:

MvM said:

Did you see this thread?
http://www.nsxprime.com/forums/showthread.php?t=87093&page=4

Apart from having built a wonderful NSX-R, Chris is is also busy with the ABS conversion. He is only just one step ahead of you.

Perhaps you two could help each other if need be :smile:

Click to expand...

Oh, thanks very much for the link. I didn't see that thread so far. Interesting what Chris' feedback will be. Here in Europe there are very, very few 99+ NSX's to compare. I'm still undecided if I should do a full photo-story about the thread but thinking about how filthy my hands will look like...I'll put it on the scale for sure but the brake effectiveness is much more important IMO.

As for the tools there's not very much needed except for a special tool shown in the picture (the upper tool) which saves the threads of your old lines. On the NSX you need a 10 mm.

...on we go with DRY results: (MvM suggested to me to do some runs on a dry road which was a very good proposition (see results). Special thanks to MvM!)

Testing conditions -> the same as above but

- DRY road (the same test track), 20 degrees outside.

Test run -> the same

Data



3 runs with the ALB system, 2 runs with the ALB shut off (fuses taken out) like above trying to brake better than the ALB (dotted lines).

Run 1: av. g: 0.83, distance: 47 meters
Run 2: av. g: 0.84, distance: 47 meters
Run 3: av. g: 0.81, distance: 49 meters
Run 4: av. g: 0.78, distance: 53 meters (-1 m as I was not fully braking below 20 km/h (0.43 data point) for whatever reason)
Try to brake better than the ALB system. However the ALB system was fully deactivated which resulted in smoking tires for about half of the run.
Run 5: av. g: 0.77, distance: 56 meters
Try to brake better than the ALB system. However the ALB system was fully deactivated which resulted in smoking tires for about half of the run.

Can you do better without the ALB?

I ended locking some of the wheels during part of the two runs which felt like braking on ice (lower g-force). So locking up the wheels is no good but as in the wet scenario you can reach higher g-forces at 90 km/h if you don't lock up the wheels as this happened below 80 km/h. Run 5 shows again that you can do better (0.43 was an error by not fully stopping, my fault, sorry).
But both runs (4+5) ended with longer braking distances due to locked up wheels.

Run 1, 2 and 3 are used for the benchmark.

Expectations

During all runs the ALB acted slowly and still a little bit weird. The car was not very stable in comparison to my daily beater (see below).
I did the same all ceteris paribus with my daily beater (Peugeot 207 Turbo, small 'housewife car' but with a 2007 ABS system) one hour earlier. The data from the 207-runs, the observered vehicle stability, the ALB acting slowly and last but not least my butt tells me that there is NO uncertainty at all about a faster ABS system being better and shortening the braking distance than the slow ALB.

Observations/results

Again the variance of the 3 countable runs is very low. The av. braking distance is 48 meters on a dry road, quite much (see my daily beater's results). In contrary to the owners manual that the ALB will not mainly shorten the braking distance, I think that it will do for most real scenarios. The probabilty is quite low that you can do it. You can but I couldn't do and think about Murphy's law. So the ALB system does shorten the braking distance at least in the dry.

Drop of g-force at 20 km/h

There's no problem observed at 20 km/h on a dry road.

g-force at 90 km/h

Inputs again highly appreciated!

...to be continued in about two weeks as the ABS will be installed then.

BTW: My tires did more road noise while driving home and I've lost about 0.5-1 mm rubber on them. Sponsoring this test would be highly appreciated as I soon need new tires after these tests.

Thanks to Chris from SOS for offering me the ABS parts for an attractive price!

And here are my daily beater's results I did one hour earlier on the same road. Don't be shocked but this is how it looks like: http://en.wikipedia.org/wiki/Peugeot_207 (I love gas-saving vehicles :wink The car is about 100-150 kg lighter than the NSX I guess. The rear brakes are Mickey Mouse style but the brakes overall are biting very hard (ok for at least one full stop :wink.



NSX dry average: 48 m
207 dry average: 40 m (no spelling error, no joke!)

NSX wet average: 60 m WTF!
207 wet average: 44 m (again no spelling error)

8 m difference sounds quite much and it's enough to hurt a pedestrian severly with 40 km/h. 16 m is far inacceptable as you're still driving with 50 km/h which leaves a pedestrian near to no chance to survive while a small housewife-car already stopped!

BTW: Did the wheel sensor/hub change too with the 99+ ABS system? I believe that the newer systems operate at a higher signal frequency than the older NSX system.

goldNSX said:

3 runs with the ALB system, 2 runs with the ALB shut off (fuses taken out) like above trying to brake better than the ALB

Run 1: av. g: 0.83, distance: 47 meters
Run 2: av. g: 0.84, distance: 47 meters
Run 3: av. g: 0.81, distance: 49 meters

Click to expand...

First of all, my complimentes of for doing these tests. Very informative.
I am VERY happy with you doing the tests with your NSX on a DRY road and not just on a wet road.
However, I am seriously starting to think that something is not 100% right with either your ABS and/or your braking system or perhaps your shock absorbers.
Getting braking distances of 47/49 meters from a starting speed at 100 kph is TOO MUCH. Especially if you consider that you are have ALREADY upgraded both your brakes to the 1997+ sizes and your brake pads to Hawk HP+, which is a much more agressive pad than the OEM pads.
If I look at your average G-forces on a DRY road, then I do not see much difference with those you have achieved on a WET road.

I have only done some brake-testing results from my old brakes. These test were done on a dry asphalt (tarmac) road as a preliminary test to have a base-line.
Only have a few results available though.

Front:
282x28mm Stoptech Aerorotors - Axxis Ultimate pads
Wheels: BBS RSII 17x9
Tires: Falken FK452 225/35/ZR17

Rear:
282x21mm OEM rotors - Axxis Ultimate pads
Wheels: BBS RSII 18x10
Tires: Falken FK452 265/35/ZR18

The results were that I would get a consistent braking distances of around 40-41 meter with peak G-Forces around 1.08 G (also with a AP-22).

Braking Distance - Average decelleration (m/s2)
40 meter - 9.65 m/sec2 (my car)
47 meter - 8.21 m/sec2 (your car)

For some reasons, you system is about 17.5% behind my old system, despite the fact that you had upgraded your brakes.

The fact that you get good resuls with your Peugeot 207 Turbo makes me think that it cannot be the road. An uneven road or a road with loose gravel on it can of course account for longer stopping distances, but in that case, the 207 would also need more distance.

Still, am happy to see a baseline in both wet and dry circumstances.

BTW, I have a Excel spreadsheets which I use to calculate braking distances, decelleration force, braking time for both metric and US system which I have send to your private email address.

Marteen, thanks for the data! I had your result in mind as you've sent me an AP-22 log some while ago.

There are two possible explanations: tires and shocks.

The tires are quite small in the front, 205/45/16. The Eagle F1 is said to offer plenty of grip. 245/40/17 in the rear is also quite small as well.

The shocks are indeed a little bit too soft (rebound) for the Zanardi springs, a 6.5 kg/mm.

For the tests I'll use the same configuration just to see how the new ABS can cope with it. Tires/shocks will be my next winter's project. :wink:

I started working on my car today. All of the parts have been removed except for the front brake lines.

Weight of the components: Old ABS with pressure releaved (sucked about half a liter of brake fluid out) 10.0 kg. With fluid: about 10.4 kg.
The ALB computer is not included in this number.

Weight of the new components with the GT-ROM cable: 4.0 kg

So it's -6.4 kg for sure, maybe -7 kg depending on the ALB computers weight.

Brake tests should follow this week (depending on the weather).

Hi Thomas,

Thanks for the update. Weights have been noted down in the sheet of course.
Dumb question perhaps, but why would you want to remove de front brake lines?
Am looking forward to your results.

MvM said:

why would you want to remove de front brake lines?

Click to expand...

You have to change the front brake lines due to the shape needed of the new ABS system. The rear brake line are multiple-part so you only have to change the ones in the front between the valve and the ABS.

EDIT: front brake lines done, bending, time and patience are needed but one hour later...

More weights:
ALB/ABS protection bar (with 4 screws): 200 gr
ALB computer: 942 gr

Total weight savings: 7.5 +- 0.1 kg (16.5 lbs)

I finally did the ABS 99+ runs in the wet and my expectations have been overexceeded by far.

Testing conditions (only deviations from the conditions stated above)

- Tires ... 4 mm and 3.5 mm thread depth (instead of 5/4.75 mm)

Tires with less thread depth are said to have less grip, at least in the wet.

All the other conditions have been the same, same weather, same road, same car, same tires and so on (see list above).

Data

I did six runs because I didn't believe my eyes after doing the first three runs. More runs are only bad for my tires and don't hurt the statistical analysis at all, in contrary it will be improved with more data. The dotted light blue line is the average of the 3 runs with the old ALB system (only the three benchmark runs).



Run 1: av. g: 0.77, distance: 51 meters
Run 2: av. g: 0.81, distance: 50 meters
Run 3: av. g: 0.77, distance: 51 meters
Run 4: av. g: 0.77, distance: 52 meters
Run 5: av. g: 0.75, distance: 53 meters
Run 6: av. g: 0.74, distance: 53 meters

All runs were used for the benchmark.

The spaghetti-like graph can simplified by calculating the average of all runs, avg. of the 3 runs with the old compared to the avg. of the 6 runs with the new system.



The variance of the 6 runs is very low again. The av. braking distance is 51.7 meters with the 99+ ABS which is -8 m compared to the 91-99 ALB system (59.7 m). I was astonished by the difference as I've expected less difference than that. The car was much more stable under ABS activity, except for one run but even in this one it was more stable than in all 91-99 ALB runs.

High variance of g-force at 30 km/h

In the previous runs I observed a g-force drop at 20 km/h. The new system does not show this. Although the variance at 30 km/h is higher than at other speeds. Maybe it's a resonance effect (slower pump resonance at 20 km/h, faster pump at 30 km/h).
But again: that doesn't result in a shorter overall braking distance by much.

g-force at 90 km/h

With the old system the observed g-forces at 90 km/h were disappointing and I was about to accuse the brake calipers/rotors/pads for that. The new system improves the initial g-forces by far and that's where is counts most as your car is fast then.

Statistical analysis

A one-side T-test shows ultra-high significant results which means that the difference is not a result by chance.

ALB
59
59
61

Mean 59.7
StdDev 1.2

ABS 99+
51
50
51
52
53
53

Mean 51.7
StdDev 1.2

Difference -8.0
t 0.000

So it's no cheating like taking the best of this and the worst of that as it's found very often.

Summary
The 99+ ABS improves the average braking distance by 8 meters in wet conditions compared to the old ALB system. The car is more stable during hard braking.
Nice but small sideeffects are no maintainance as it's flushed with the rest of the brake system and less weight.

Sidenote
As my braking distances are quite long due to whatever reasons (tires, suspension) the effect can be smaller in other configurations. So please don't expect a braking distance of 30 meters with the new system if you already have 38 meters with the old pump.

Runs in the dry will follow...

Hi Thomas,

Thank you for this excellent experiment. I do not know the road and the exact conditions under which you performed the test, but getting the results down from almost 60 meters to about 52 meters is just excellent (even though the distances are still a bit long)

No doubt the new ABS system is an improvement over the older system. So I think this is something that I will definately need in the future as well :smile:

BTW, it was a pleasure to look at the clean layout of the new system in your car at Le Mans. You car looks very sleek and clean.
Ever since I got back from Le Mans the weather has been pretty bad again overhere, raining a lot. But I really need to do some of this testing myself also and when I do, I will let you know the results.

Am looking forward to your results in the dry.

Here we go with the dry results...

Data

I did three runs.



Run 1: av. g: 0.91, distance: 43 meters
Run 2: av. g: 0.91, distance: 42 meters
Run 3: av. g: 0.90, distance: 43 meters

The variance of the 3 runs is very low again. The av. braking distance is 42.7 meters with the 99+ ABS which is -5 m compared to the 91-99 ALB system (47.7 m). Again, the car was much more stable under ABS activity, except for one run but even in this one it was more stable than in all 91-99 ALB runs.

Statistical analysis

A one-side T-test shows ultra-high significant results (t = 0.001) which means that the difference is not a result by chance.

Summary
The 99+ ABS improves the average braking distance by 5 meters in dry conditions compared to the old ALB system. The car is more stable during hard braking.
Nice but small sideeffects are no maintainance as it's flushed with the rest of the brake system and less weight.

I'm very satisfied with the results.

PROBLEM
What I'm not satisfied with is the behaviour of the ALB (Antilock in the US) light or the function of the ALB system. There must be something wrong on my car. If I start the engine it happened occasionally that the ALB light stays ON and there is no vibration of the pedal while moving the first meters meaning no ABS. If I restart the engine it goes away and don't light up again. It's like it can't light up the fire from time to time. Anyone else?

Sidenote: I got the 02+ wheels today and couldn't resist to mount the tires too. 215/40 and 255/40 but I won't test them with the ABS system as it's simply too much stress for the tires (now being more angular than round :wink. But it should be even better with them.

That is quick :smile:

Niced results!! Getting 5 meters of you dry road breaking distance by just changing the ABS is excellent. !!!

As far as your light is concerned, you might want to check with Science of Speed or others that have done the same conversion. Perhaps you still have a bad connection somewhere?

For the rest, hats off for you consistent testing and posting your results here on Prime. No doubt that the newer ABS is a real improvement and an excellent investment to keep the NSX up to date.

MvM said:

No doubt that the newer ABS is a real improvement and an excellent investment to keep the NSX up to date.

Click to expand...

Thanks again. I had to hurry up because my wheels arrived. :tongue:

As you say there's no doubt that it's a vast improvement of the new over the old system. And looking back I was always (like many here on prime) looking for mods for going faster (chip, header...). I didn't like the brakes in the past but didn't use them either (it's natural: noone like to use thing he doesn't like ). :wink: Now I have to say that it's a great bang for the buck. I've expected a shorter braking distance of about 2-3 meters but 5-8 is remarkable.

My daily beater is a 2007 and with ESP and electronically regulated brake distribution you can gain a little bit more. With the wider tires on the 02+ wheels I think I'll be up to date in the dry now, not sure about the wet.