Tried this in tech and got a big nothing. Thought I'd try it here.

The question: is the hydraulic circut (the "stuff" that holds brake fluid - lines, resevoir, etc) completely independent of the traditional brake circut (from master cylinder to calipers) on a 95 GS-R? It sure looks like it to me, but there's parts of both systems that I can't see.

The reason I ask: I run rather expensive brake fluid. In the process of diagnosing my current ABS problems I plan to flush the ABS system. Which of course requires fluid. Since this will be a troubleshooting exercise, I'd love to *not* use my Motul brake fluid. Motul and (AFAIK) everything else doesn't mix together well. Oh, and Motul tends to absorb moisture, requiring frequent bleeding. It [the ABS system] has old Motul in it now - if I could switch to Valvoline or some other "cheap" fluid, that would be great.

Background: My ABS system started flaking out this past weekend. We (some of the Honda Challenge racers) were at the Carlisle import show this weekend, where they have a small autocross/road course set up. I'd get two laps on this small (30 second or so?) course and the ABS would fire on the rear wheels pretty regularly. This is commin entering a corner, esp. on poor pavement. Well by about lap three, I was continually surprised with locked up rear brake(s) and, worst case, a spin off the track. Not fun.

What's different about the car now: Not much. Just moved to different brake pad compounds, and that's it. Shouldn't affect anything. Just want to flush the system with regular brake fluid, not the high $$ stuff.

 

I'd like to know too. My ABS light started coming on a few weeks ago and only comes on about 3 times a week now. There is an ABS resevoir (sp?) but doesn't look like I can add fluid. Its a rectangular box on the passenger side under the hood with a rubber cap on it. I remove the cap but it's not on open hole like the engine oil filler on the valve cover.

I am using Motul 600 also, so maybe I need to switch back to some regular cheapo DOT 3 fluid.

 

I'm pretty sure the brake fluid in the ABS and brake system are totally separate. I emptied all the fluid out of my ABS system and drove around with the ABS light on and the brake system was totally fine except there was no ABS. The brake fluid level by the brake master cylinder stayed full the whole time.

 

The '94-'97 Integra ABS system does not share brake fluid with the rest of the braking system. There is a seperate fluid reservior attached to the ABS module which holds the fluid. Therefore, the ABS system needs to be bleed seperately. BE EXTREMELY CAREFUL, the ABS system is under extremely high pressure. There is a bleeder nipple on top of the ABS module. This nipple should be opened very slowly and should only be opened about 1/8 - 1/4 of a turn. DO NOT OPEN IT MORE THAN 1/4 OF A TURN, as this could cause high pressure brake fluid to shoot out of the bleeder nipple (I'm speeching from experience on this one ).


I would recommend using a brake fluid in the ABS system which has a low moisture absorbtion. Moisture in the ABS system would not be a good thing as this could cause some problems. Also, I periodically in the wet (and with no cars around me), will apply the brakes hard enough to activate the ABS. This causes the fluid to be circulated through out the system and it activates the ABS module valves.


Where did you installs different brake compounds (front, rear, both)? Could it be that the brake pad compound has a higher coefficient of friction and this is causing the brakes to lock up easier. Or could it be that the tight autox circuit was causing a sudden weight shift towards the front wheels and the rear wheels were becoming "unloaded" and this was causing the rear brake lock up? Just a few possiblities.

 

Karl,
I don't know if you auto-x regularly, but you tend to engage ABS very often when auto-xing and it also seems to come on sooner (to the driver) because we drive so agressively when auto-xing that we don't realize how hard we apply the brakes. In many cases the auto-x lot surface sucks and has a lots of debris, rocks, sand, etc. all contributing to ABS coming on sooner than they would normally do on the street. You also have to think of it this way: Most of the braking in auto-x is like "emergency braking" on the street.
The only that worries me is why (I assume, you didn't say) you never locked them in the front, and only the rear which may have something to do with different brake pads fr/rear, assuming nothing is wrong with your ABS or brake system. Is it possible you have better pads in the rear than the front? How about tires? Are your rear tires bald compared to the front ones?
Bleeding the ABS fluid I think is an excellent idea and everyone should do it every 1-2yrs anyway. Since it's totally seperate from the regular brake fluid/system, I 'd change to regular Honda fluid since you 've had Motul in there before. If not Honda fluid then something different than what you had before just in case the old fluid caused the problem.. Good luck and let us know.

 

I know how to bleed the regular brake system, what is the proper procedure for bleeding the ABS system? The little rubber cap over my ABS bleeder valve is all dry-rotted.

 

I can consult my Helms manual later tonight and I can post the proper procedure for bleeding the ABS system.

 

Here is the procedure for ABS brake fluid replacement (from the Helms manual):

1.) Remove the bleeder cap from the maintenance bleeder on the modulator unit.

2.) Attach the wrench to the maintenance bleeder.

3.) Connect a rubber tube of the appropriate diameter to the maintenance bleeder, and set the other end of the rubber tube in a suitable container.

4.) While holding the rubber tube with your hand, slowly loosen the maintenance bleeder 1/8 to 1/4 to collect the brake fluid in the container.

CAUTION: Do not loosen the maintenance bleeder too much. The high-pressure brake fluid can burst out.

5.) Tighten the maintenance bleeder.

6.) Start the engine and let it idle for a minute. Stop the engine.

7.) Check the brake fluid level in the reservoir. It should be below the MAX (upper) level line.

8.) Repeat the steps 4 through 7 to drain the rest of the brake fluid from the modulator unit.

9.) Remove the cap, and refill the reservoir to the MAX (upper) level with fresh brake fluid.

10.) Repeat steps 4 through 8 twice, and refill the reservoir to the MAX (upper) level with fresh brake fluid.

11.) Tighten the maintenance bleeder to the specified torque (8 lbf-ft).

12.) After replacement, start the engine and make sure that the ABS indicator light goes off.

 

hay BSQ so you wana drain all the fluid out before adding the new fluid? im gona do this in a few days