Soft-Grinding Noise in the Front

[nimdivino]

Hello guys,
For a while now, I've been hearing this soft-grinding sound thats coming from infront of the car. Its really hard exactly to pin-point where the sound is coming from because it stops by the time I pop the front hood. It normally starts making the sound right after I leave my drive-way. Then about 30 seconds later it stops.

Today, the sound goes on and off when I was heading to work (25 miles). When I entered the basement parking, it made the sound so I parked right away but by the time I opened the hood, the noise stopped again. Kinda frustrating really.

It seems like its coming out of the ABS side. It can't be that my front tire is rubbing because I can hear it when I'm completely stopped.

I'm hoping that its just my ABS because I'll be removing it anyway.

Any ideas?

Car is a 1991

Thanks so much..

 

[ffffanman]

On my 91, the optional Mice in the front tyre squirrel cage boost thing make a noise from time to time, but nothing like a soft grind, Unless its ladies nite, then lots of bumping going on!!!
Seriously, can't imagine what it could be since it stops when you stop your car.
Have you checked the three fans for debris of any sorts, papers, rags, mice.
Don't stick you hand into the rad area with out undoing your battery though.
I actually was thinking you might have something in one of the condenser fan housings.
Trev

 

[Deltron Zero]

Does it sound more like clicking? If so, it's probably the ABS pump.

 

[ffffanman]

Ya, Nim, have you ever heard the noise the abs makes when it pulses?
If you haven't, then that is what it is, well but that noise is not a soft grind noise that the abs pulse makes.
Hum, record it, youtube it and there we go.
Trev

 

[nimdivino]

Hello guys,
Maybe its clicking.. but really fast clicking.

Alright, enough describing this thing. I'm not very good at that..

I took a sound-recorder before heading to lunch, then just as I pulled-out of my parking-space, the mysterious sound is alive once again.

Here it is.

http://home.comcast.net/~nimdivino/nsx/sound/abs-sound.wma

First 14 seconds, that's recording while the hood was closed. By the 20th second, hood is opened and I pointed the recorder to the ABS. Its obvious the sound is coming from ABS.

So that sound is loud enough to embarass me, so for the meantime I'm going to drive the car with the ABS deactivated (that seems to stop the sound completely).

I'm going to order the ABS Killer kit from Dali soon. I knew I should've done that couple weeks ago. meh.

Anyway, thanks a lot guys..

niM

 

[Briank]

ABS pump running noise and its perfectly normal.

 

[nimdivino]

That's normal? I didn't hear the sound for the 1st year of owning my car. And its kind of loud to be normal.

niM

 

[Briank]

A fluid flush and valve exercise should reduce the amount the pump will run so you will not hear it as often. This is a maintenance item that is mostly overlooked until problems occur.

 

[nimdivino]

Oh I see.. Thank you for that information.. Its great to hear that its not broken.

Thanks again

niM

 

[ffffanman]

It is broken, its running all the time or all the time you don't want it to. lol
That is not normal!
The noise produced is normal when the unit is actually working, like in an icy skid.
Trev

 

[davidf]

I have that problem when I back down the driveway it starts doing that, {only pre-warm up} but the ABS still works when I slam the brakes. I have exercised them to death but the resorvoir still pukes some over night.:frown:

 

[Big_D]

I am glad you recorded that. I have the same noise and it is difficult to describe. I was thinking it was the ABS pump also.

 

[Deltron Zero]

I would only disable the ABS if it's really really bothering you. You don't want to be caught in an emergency braking situation on a wet road without ABS. My pump was going nuts so I had to pull the fuse. I'll eventually upgrade to the NA2 ABS system, but it's soooo damn expensive.

 

[ffffanman]

Mr. Deltron, I consider the 91 abs system junk.
How do you find your upgraded one?
Trev

 

[Deltron Zero]

Mr. Deltron, I consider the 91 abs system junk.
How do you find your upgraded one?
Trev

SOS sells NA2 ABS systems. They're actually 2001+ systems. Pretty pricey, but probably my only solution.

http://www.scienceofspeed.com/products/braking_performance_parts/NSX/ScienceofSpeed/NA2_ABS_System_Upgrade/

 

[ffffanman]

Sorry, I thought you had upgraded, my bad.
I did make a mistake.
Trev

 

[nimdivino]

Deltron Zero:
Yeah it is really bothering me, and I hated the feel that 1 time I activated the ABS. Almost crapped on my pants because I thought my brakes mulfunctioned in the last second. I thought I was going to hit that car infront of me. scary.

Maybe the newer ABS for our cars are better designed or whatever but I'm definitely removing the one I have on my car because it doesn't serve any purpose to me.

 

[OLDMNSX]

Guys,
This problem is solvable. Now if you want to throw a bunch of money, (aprox $12-1500) at it, that will solve the problem. If you want to do a little work it can be taken care of. If you will do a search on the subject "ABS" you will find quite a bit of information. A lot of it was before I even had an NSX. I have kind of taken this project on due to the fact I have had this problem and want to find a solution to help the comumity. Unfortunately I have one full time job and two part time jobs and have not had the time I would like to devote to this project. By this time of the year I have finished the second part time job and hope to have time this winter to finish my ABS solenoid flush equipment.
Basicly what is happening is that at least one of the solenoids in the ABS modulator is seeping pressure off of the reserve pressure that is stored in the ABS accumulator (the round sphere that looks like a gold grapefruit or a nice "D" cup). This seeping causes the pressure switch located on the accumulator bracket to tell the pump to actuate to replenish the pressure. By flushing the fluid and getting the air out of the fluid along with cycling the solenoids the solenoids usually reseal and the problem is solved. Remember this system operates at a normal pressure of 4800PSI. The pump is actuated to repressurize at 2800PSI. As you can see it only has to be a small seep to reduce the pressure substanially.

A fellow named Dan (DanO) produced a very nice DIY that is located in the WIKI section. He did a great job and I Thank Him. The one thing that I have added is a way to keep the return fluid, that is dirty or has air in it, from being returned back to the pump. To do this I have made some fittings that fit where the plastic reservoir is located.

I have helped around a dozen people actually fix their problem. I am happy to help others if I can.
Brad

 

[cybernsx]

Thanx, Brad.

Appreciate the note ... I'll look up the DanO thread because you can now add my '91 to the list of those with this issue.

In the past, probably 1 out of 5 times I would start my car, I would hear this noise for about 5 seconds and it would simply stop and not return again during that day. Today, it did it and I drove away to enjoy this beautiful Fall day. After about 45 minutes of mildly spirited driving, I was heading home and I heard the sound. This had never happened before 'while I was driving' and after being warmed up. It kept cycling on and off while I made my way home. After stopping in my driveway, the front ABS brake reservoir acually overflowed a bit. I removed the cap and saw the fluid slightly bubbling (and then replced the cap). When the cap was on, the reservoir appeared 'over-filled' (completely full). After coolong down, the level is now at the 'minimum' line, and the sound remains constantly 'on'.

Time for a little DIY project!

 

[ftuhy]

My '96 used to make the clacking sound as I headed down my driveway for 15 - 20 seconds if my car had sat for more than a week. I did the "DanO flush" a year ago. Since then, the only time I heard the clacking (a short burst) was last week when I stopped hard on blacktop that was coated with pine needles.

So, it sure worked well for me.

Frank
'96 NSX-T, red/tan