ABS pump - not in the FAQs ?

[apapada]

Hello,

first off, let me just say that I already have checked the FAQs and already have the answers to most of my questions. I would still have a few questions however...

#1. Why does the NSX has an ABS pump anyway ?

#2. If other cars have noisy ABS pumps, (I didn't know that) then what makes the NSX's be so darn loud ? Any way to quiet the system down ?

#3. If the ABS pump comes while/right after/the next day ABS has been activated, how does the system behave on a track ? I am planning on tracking the car but cannot/dont want to imagine hearing this sound after braking hard and ready to negotiate a set of chicanes !

Any insight on these questions is highly appreciated.
Regards,
Alex

 

[prova4re]

My pump was real loud every time I started the car until I found a fix here.

http://www.danoland.com/nsxgarage/brakes/abs/abs.htm

I hope this helps you.

 

[Soichiro]

The ABS is a high pressure system. After it is used the pressure drops and needs to be replenished. This is when the pump turns on.

>> I am planning on tracking the car but cannot/dont want to imagine hearing this sound after braking hard and ready to negotiate a set of chicanes !

You don't understand what will be happening at the track - you will not be trying to lock your tires (and invoking the ABS) at each corner. Listen to your instructor and you will be fine - hundreds of us have used our NSX's at the track for years and the ABS system is not an issue.

 

[Briank]

Yes the pump is noisy but it runs very seldom unless you are braking hard enough to activate the ABS. I have only heard mine run when I pull out of the garage and am slowly driving down the street. It only runs to replenish the pressure in the acumulator if needed and then only when you are moving. You may what to check the pump mounting bracket it mounts to the bottom of the abs valve assy. The mounting bolts are isolated in rubber the rubber may be shot or ?

 

[DanO]

In ’91, the NSX was one of the first vehicles to have four-wheel independent ABS control. I believe since 2000, the NSX has a newly designed and modern ABS w/o a loud pump. I’m not exactly sure how modern designs work, but I don’t think they use the pump/accumulator like the earlier model NSXes. It would be cool if someone could scan in the 2000+ ABS Service Manual pages!

If you find that your pump is running often, then there may be some kind of ABS malfunction and you may want to check it out yourself or have it checked out.

I’ve never heard of a properly running ABS being an issue at the track.

HTH,

DanO

 

[apapada]

My pump was real loud every time I started the car until I found a fix here.

http://www.danoland.com/nsxgarage/brakes/abs/abs.htm

I hope this helps you.

My pump is fine. I am just wondering about the noise AFTER the ABS has been activated. I read in the FAQ and was told it is "normal". I dare to say however that such an alarming noise cannot be considered "normal". I have never had any car do such a noise after the ABS was activated. Why is the NSX different ?

 

[apapada]

You don't understand what will be happening at the track - you will not be trying to lock your tires (and invoking the ABS) at each corner. Listen to your instructor and you will be fine - hundreds of us have used our NSX's at the track for years and the ABS system is not an issue.

I have been at the track before (never with an NSX) and do want to understand fully what is happening... at all times. I'm not just driving with my brain, my hands, my feet and my eyes, but with my ears too ! I just can't imaging hearing this sound everytime the ABS comes on. And yes, I do not plan on locking the tires at every corner, but for some corners (think Road Atlanta, turn#6), if the ABS is not coming up, you are either not coming hard enough on the brakes and you're about to go in the kitty litter, or you were not going fast enough in the first place... nuf said

 

[Tony Montoya]

My Supra makes a similiar noise and my BMW has a brake bomb too. It also has 4 wheel ABS but BMW never bragged about it in 1991.

 

[Lud]

The NSX ABS system is quite good about letting you brake hard without intruding. And your braking distance with ABS activated will always be longer than the threshold braking distance, so using ABS as a "crutch" for poor threshold braking technique is never the fastest way around the track.

Having said that, I am certainly not Mario Andretti and have gotten into ABS at the track more than once. I never heard the pump run while I was out on the track, but I have heard it run in the pits the next time I started the car. So it was certainly not a distraction on the track.

There is nothing you can really do about the noise unless you disable the ABS system. That is simply the nature of the earlier NSX ABS systems. I suppose if you poured enough effort and money into the project you could find a way to put the later-model NSX brake and ABS system, which does not make as much noise from the ABS pump, into an older NSX, but I think it would probably be a lot more hassle and expense than it's worth.

P.S. Tony - BMWs (and several other cars) had 4-wheel ABS in 1991, but the NSX was the first car (in the US at least) with 4-wheel independent ABS. Other cars could pulse the brakes on all four corners, but did not manage each wheel independently of the others - in other words, for example, if one rear wheel was locked, their ABS system would pulse the brakes on both rear wheels, while the NSX would pulse only the wheel that was locked up.

 

[Tony Montoya]

The other systems should be called three wheel ABS. This would not be good for marketing though.

 

[kgb_agent]

I have heard what I believe is the ABS pump only once and it was immediately after pulling out of the garage. I stopped the car and did a walk-around; I could find nothing wrong. It sounded like someone threw a broken beer bottle in the garbage disposal. A horrible shreik. Does it always sound like this?

 

[DanO]

Does it always sound like this?

That's it! And they say the NSX has no character

 

[Soichiro]

apapada wrote:
>>for some corners (think Road Atlanta, turn#6), if the ABS is not coming up, you are either not coming hard enough on the brakes and you're about to go in the kitty litter, or you were not going fast enough in the first place... nuf said

Road Atlanta is my home track and I have driven there dozens of times in many cars. I have crashed at turn 6 too - I think I know the limit there! Your assertion that not using the ABS before this corner indicates you are not braking hard enough or going quick enough makes no sense.

 

[nsxtasy]

A horrible shreik.

I would describe it as a pleasant and eager whisper, similar in its spirit of anticipated excitement to Michael Buffer's well-known exhortation.

Your assertion that not using the ABS before this corner indicates you are not braking hard enough or going quick enough makes no sense.

I think Lud explained this very well. The most effective braking technique on the track is "threshold braking", which means braking until the brakes are on the threshold of locking up, but they don't actually lock up and don't activate the ABS. If you are using ABS on the track, then you are not using all of the car's braking potential. I think ABS is a great thing, because it's there if you make the mistake of locking the brakes - but the better you are, the less you'll use it.

 

[apapada]

apapada wrote:
>>for some corners (think Road Atlanta, turn#6), if the ABS is not coming up, you are either not coming hard enough on the brakes and you're about to go in the kitty litter, or you were not going fast enough in the first place... nuf said

Road Atlanta is my home track and I have driven there dozens of times in many cars. I have crashed at turn 6 too - I think I know the limit there! Your assertion that not using the ABS before this corner indicates you are not braking hard enough or going quick enough makes no sense.

If you pretend to know your car+tires capabilities on every track, under any conditions, then good for you. But in most cases, with most ABS and tires, unless you operate right before the ABS activates, you just don't use your tires+brakes potential. This is not always valid, but in most cases under most conditions it is. That's what I meant in my previous post, and hope you now see the point.

 

[apapada]

The NSX ABS system is quite good about letting you brake hard without intruding. And your braking distance with ABS activated will always be longer than the threshold braking distance, so using ABS as a "crutch" for poor threshold braking technique is never the fastest way around the track.

In most cases Lud you are right. It does depend on the tires, the conditions and the ABS algorithm however. There are some case where this is not true however. (we have seen this many times during testing at the Laurens Proving Grounds)
For instance, on the dry most ABS have a operating efficiency very close to 100%. This performance does drop significantly as the test conditions become worst and the coefficient of friction drops at ice levels. (Unfortunatly, this is when we need ABS the most !)

Having said that, I am certainly not Mario Andretti and have gotten into ABS at the track more than once. I never heard the pump run while I was out on the track, but I have heard it run in the pits the next time I started the car. So it was certainly not a distraction on the track.
[/B]

Thank you ! This is the answer I was looking for.

P.S. Tony - BMWs (and several other cars) had 4-wheel ABS in 1991, but the NSX was the first car (in the US at least) with 4-wheel independent ABS. Other cars could pulse the brakes on all four corners, but did not manage each wheel independently of the others - in other words, for example, if one rear wheel was locked, their ABS system would pulse the brakes on both rear wheels, while the NSX would pulse only the wheel that was locked up. [/B]

I do believe that you are referring to a 4-channel ABS, versus a 3 or 2 channel ABS. In any case, the wheels controlled have always been opposite (LF-RR or LR-FR), and no ABS that I have ever studied would ever pulse two wheels at the same axle together. Afterall, the ABS is nothing but a device to maintain control+steering capability during hard deceleration of the vehicle...

 

[Lud]

I do believe that you are referring to a 4-channel ABS, versus a 3 or 2 channel ABS. In any case, the wheels controlled have always been opposite (LF-RR or LR-FR), and no ABS that I have ever studied would ever pulse two wheels at the same axle together. Afterall, the ABS is nothing but a device to maintain control+steering capability during hard deceleration of the vehicle...

I wasn't trying to get bogged down on non-NSX details, and shouldn't have even given an example. But I believe you are mistaken about not pairing both rears together on a 3-channel systems. In fact I'm not aware of a 3-channel system that does NOT pair both rears together... If it exists, can you list some vehicles using it?

Rear wheel ABS, found on some light trucks and some early SUVs based on the same trucks, has a single-channel, single sensor system that detects rear wheel lock up and modulates pressure to the rear wheels accordingly. BUT it does not involve the front or steering wheels. Many people have crashed because they thought they had four-wheel ABS and acted accordingly - locking the front wheels and losing steering control. This is not a very good ABS implementation.

2-channel systems, as you described in your LF+RR, RF+LR example, do indeed pair wheel diagonally. However....

3-sensor, 3-channel systems are generally an entry-level system now and are being phased out (if they haven't already), but until a the mid-90s this was the best available on most vehicles! Three channel systems provide for control of the two individual front wheels (2 channels) and both rear wheels through the third channel. There are three sensors - one at each front wheel and one for both rear wheels.

3-channel, 4-sensor systems have replaced 3-sensor systems as standard on many cars. They have a sensor for each wheel and three channels controlling the front wheels individually and the rears as a pair. They will probably continue to be phased out as more cars get 4-channel systems.

4-channel, 4-sensor systems (or any system with 1 sensor and 1 channel per wheel) are the best general design currently available. One sensor and one channel per wheel allow the system to modulate pressure to each individual wheel as needed. The NSX was the first car in the US to have this type of system. Many more have followed.

 

[nsxtasy]

I want a 5-channel, 5-sensor system - so it can also detect when the wing bolt holding my spare is loose.

 

[ncdogdoc]

I want a 5-channel, 5-sensor system - so it can also detect when the wing bolt holding my spare is loose.

But then our gerbils could not add that extra 5-15hp (depends on the number of gerbils) we get from them spinning the tire around creating the flywheel energy effect!!

(I would have a smiley gerbil doing something stupid right here, but as I am on a different computer and do not have all the smiley pages memorized as do Ken, PhoenixNSX and NeoNSX, you will have to just imagine a gerbil(s) doing something stupid right now)