Brake bias problem....HELP!

[RStom - Hungary]

I have a '92 brought back from the US to Europe. Tha car is full stock and it is in OK condition, but I have problem with the brake bias.

The deceleration of the car is very poor. When I brake the car is moving to the left and the left front tire is stopping very early. When it stops the ABS starting to wotk, which means that the brake pedal is pulsating, but after it there is this terrible "brrrrrrrrrrrr" noise coming from the ABS unit (not from the pedal which I now is normal) for about 1-2 sec.

On the other hand I have the feeling that the right front tyre does not braking at all...or very limited. After I stop and try to touch the brake rotors, the left front is very hot, both rear is not very hot but hot, but the right front is only warm (I can even touch it)

There are new rotors and quite new brake pads (installed by the previous ovner) on the car. I have changed the brake fluid, which was terrible dirty, and take into parts the calipers and the pistons. Cleaned them and move them in and out, put is back, but the same problem occured as it is written above. The only imporvement was that the terrible "brrrrrrrrr" noise from the ABS unit is only when I brake hard (before the clean this noise was even when I started to roll with the car and it lasted for 30sec and some cases even the yellow ALB lamp was on). If I take a look seperately to the brake pistons and I push the brake pedal the pads are moving, but when I put is back on the rotors and try to brake with the car, than the problem is as I wrote above.

PLEASE HELP what could be the problem.....

Thanks in advance
Tamás

 

[dablackgoku1234]

When you removed and cleaned the brake calipers, was the front right seized?

Did you check the brake lines? Maybe the line has worn out and is expanding or possibly leaking.

Did you flush the ABS brake fluid as well?

 

[goldNSX]

First of all: Kick the original owner in the butt for not changing the fluid!

Second: The ABS system does make the sound like you described but I would not describe it as 'terrific' This is Honda's v0.1 version of ABS and it sucks really badly from todays standards (ok, 20 years later). After the ABS was working it's normal to have this noise for a few seconds as it charges the system again. If the noise (plus indicator light) is there without braking this is a very common problem which you solved by flushing it so far as I understand.

Third: Take your car to a 'brake dyno', a machine for testing the torque built up as any single inconsistancy will be detected. It seems to my as if one of your front calipers is not ok, presuming your pads and discs are ok. I'm not sure what you did to the pistons. Have you fully overhauled them or just moved them a little bit back and forth? What about the dirty brake fluid? Was is only brown or could you see some fine particles in it. If the later is the case and these your calipers and the rest will really like it. I'd give everything a real good flush, means taking things fully apart.

Also have a look here: http://nsxcb.co.uk/testvb/showthread.php?t=6286&page=6

BTW the NSX brakes suck anyway because the rear ones remain quite cold and a lot of braking goes (unnecessarily) to the front. That's why they suck compared to Porsche brakes. It quite normal.

Good luck!

 

[pgilliam1]

As goldNSX points out NSX brakes leave a lot to be desired. It is not unusual for the calipers to seize on the earlier cars and rebuilds are fairly easy, inexspensive and effective. The noise resulting from the hard breaking is the ABS pump and it is normal to hear after every time the ABS kicks on. If your fluid was that dirty you probably could use a rebuild on all 4 calipers. Daliracing.com offers a kit to rebuild them for just under $300US. Good Luck and Happy Motoring!

 

[RStom - Hungary]

First of all: Kick the original owner in the butt for not changing the fluid!

Second: The ABS system does make the sound like you described but I would not describe it as 'terrific' This is Honda's v0.1 version of ABS and it sucks really badly from todays standards (ok, 20 years later). After the ABS was working it's normal to have this noise for a few seconds as it charges the system again. If the noise (plus indicator light) is there without braking this is a very common problem which you solved by flushing it so far as I understand.

Third: Take your car to a 'brake dyno', a machine for testing the torque built up as any single inconsistancy will be detected. It seems to my as if one of your front calipers is not ok, presuming your pads and discs are ok. I'm not sure what you did to the pistons. Have you fully overhauled them or just moved them a little bit back and forth? What about the dirty brake fluid? Was is only brown or could you see some fine particles in it. If the later is the case and these your calipers and the rest will really like it. I'd give everything a real good flush, means taking things fully apart.
Good luck!

First: I will do

Second: Yes...hope so

Third: Thanks I take it fully apart. The brake fluid was only brown dirty with some jelly in it...but no fine parts in it

 

[BrakeExpert]

How much do ya wanna take the wheels off?

When one brake is warmer than the other side by a lot, there are a few things to check. You said there were new pads and rotors. Check that these rotors are not warped, like they were bed in wrong and have hot or cold spots. This translates into brake vibration, whether it be side to side or back and forth.

Check each caliper's piston stroke by taking the caliper off, and going to push the pedal. Make sure each piston actually moves (like none of the calipers are seized or seizing.)

Check the rear brake pads. They can be misinstalled, because there is this "tab" like a small cylinder on the back of the INNER brake pads. This must go into the caliper in one of 4 ways. The caliper's piston has a + shape, and that little tab goes into the + . The piston when the caliper is installed has to be up and down, not like an X .

Check that when the car was bled, that there is no air in the system. At idle, the pedal shouldn't feel "spongy" meaning you practically gotta push it to the floor. Air in one line and not another caus also affect side to side bias because one caliper is physically pushing harder than the other!

Do the brakes give any vibration at driving speed? This can be caused by a poor alignment or not mounting the wheels with a torque wrench (or if you don't have one, at least try to tighten all 5 lug nuts with an even amount of force, like don't leave one easy and overtighten the hell out of the one next to it.)

If the rotors and pads are good, sand the pads down and use a proper bed-in procedure for the brakes. Typically this consists of 10 firm stops from 60mph to about 10mph, while not stopping to zero, and only giving the brakes maybe 30 to 60 seconds between each hard stop to cool, as you want em to get hot. Then you stop the car, and when the car comes to a complete stop, leave it and let it sit for at LEAST a half hour. The part of the rotor under the pad does not cool at the same rate as the rest of the disc, and thus the rotor is slightly thicker at that part. If you were to keep driving with these hot rotors on a stop and go, that raised part is gonna get more wear, and eventually, your rotors will warp.

At the bottom of the list, check the physical brake pedal where it attaches to the booster inside the car. There is this stupid thing in some NSXs called a delay valve for the brakes which I'm told can go bad and combined with other problems, cause this crap for you (someone correct me if i'm wrong about the functional usage of the delay valve.)

Also make sure the pads are all on correctly. I know its simple, but stuff like a broken retainer clip can make something wear wrong and make all sorts of vibration and noise.

If you'd like, take some pictures for me, as there are other little tell tale signs I may be forgetting to mention as usually they are one in a million.