Brake Disaster

ASSISTANCE Suspension, Brakes & Wheels
1

So here is my two year long nightmare:

I purchased a '92 DA9 GS two years ago. On the first drive, it had very soft brakes, with the pedal nearly dropping to the floor. I assumed it was either a bad master cylinder, or air in the system, or old brake lines, or even a combination of many things. I bought the car with the intention of making it my new daily driver.

Once I had the car home, I did a little inspection and found some serious brake work was needed. I replaced the master cylinder with a remanufactured product from PartSource, swapped in Russell stainless steel lines, four new calipers, Hawk HPS pads in all four corners, and Eurorotors in all four corners. I then bled the entire system with Prestone DOT4.

The master cylinder was bench bled before installation with a bench bleeding kit. After installation, the brake system was bled properly: the brake pedal was depressed, then I open the bleed screw until the fluid stops flowing, then I close it firmly, then the pedal is released. Repeat, repeat, repeat until no air, then move to the next brake. The bleeding process was in the order of: rear right, front left, rear left, front right - with somebody depressing the brake pedal for me.

The pedal feels exceptionally firm, right at the top of the pedal stroke - until you start the engine. With the booster under vacuum, the pedal sinks very loosely 4/5 of the way down, with the remaining travel offering minimal resistance. Driving the car is a nightmare, where I must augment my braking with the handbrake, which provides a dramatic difference, but no more than what you would expect for a handbrake.

I assumed the master cylinder was faulty and exchanged it at PartSource. I bench bled the new master cylinder and reinstalled. I bled the entire brake system with new fluid. The pedal became exceptionally hard, but as soon as the engine was started, I found the same soft pedal as before. I checked all the connections, found no leaks and could see no loss in fluid at the reservoir. I asked some advice, including the staff at PartSource and thought it could be a bad batch of master cylinders, so I returned/refunded the one I had.

I went to my crashed DB2 parts car and pulled the master cylinder off. It worked fine when it drove, so I hoped it would still be okay. I installed by the same process as above, and found the same soft pedal after starting the engine. I then thought it could be something to do with the ABS system.

I (carefully) drove the car to the nearest Honda dealership and asked for the ABS system to be flushed and tested. They called me back reporting the ABS system flushed and tested out okay, but that the brake pedal was soft, most likely due to air in the system. I explained I was having difficulty with it for some time and was not able firm up the pedal; I asked them to bleed the system. The dealership bled the brakes with Honda DOT3 fluid and called back reporting no change to the pedal response. They claimed the master cylinder was faulty and wanted to change it. I explained that the current master cylinder was the third installed, etc., etc. but they insisted that a Honda master cylinder, at $350 plus install, would do the trick. Desperate, I initially agreed, but fortunately, a non-ABS master was delivered so they had to reinstall the original, saying there would be a delay until the correct part arrived. I cancelled the job and took the car back.

After a lot of consideration, I ordered a brand new, genuine Honda master cylinder from a dealership in the US for $220ish delivered and installed it myself with the assistance of an experienced Integra enthusiast, only to be back with the same problem.

I began to suspect the solenoids in the modulator were failing, despite the results from the Honda dealership’s tests. I removed and replaced the entire ABS’s mechanical system as a whole from the DB2 and installed into the DA9 - that is, the modulator, pump, accumulator, etc., without opening either system (took a long, long time). I bled the entire system again, to get the same soft brake pedal.

I examined the calipers closely and thought there was too much play with the guide pins. When the brake was depressed, the caliper was not moving with linear motion, but rather a slightly curved motion. My girlfriend’s DB1 needed front calipers, so we agreed to use these calipers to see how they worked on her car. Once installed and bled, her brakes work fine. I installed the second, new (remanufactured) calipers on my DA9, bled, soft pedal. As a note, the rear calipers appear to be functioning normally and the handbrake is tight and responsive.

I then suspected my stainless steel brake lines. I removed them from my DA9 and put them on my girlfriends DB1. Once bled, her brakes work great. I bought new stainless lines, installed, bled, soft pedal.

I removed the master cylinder and inspected everything closely. I found two extra gaskets between the master cylinder and booster, two were old and swelled up, stuffed right into the booster and the one closest to the master cylinder was new and firm, staying on the master cylinder’s rod. I pulled the two old ones out, cleaned everything as best as I could and examined the booster for mechanical problems. I compared the booster with another I had handy and found no dissimilarities. I reinstalled everything, bled the entire brake system and got the same soft pedal after starting the engine. I checked the vacuum hoses and check-valve, everything was operating normally.

It’s been two years.

Seriously, what the hell?

2

I must say I see alot of you checking and replacing the Master Cylinder but not the power booster at all. They can go bad. My 92 Si I ran through a similar problem but after the 2nd Master Cylinder I replaced the booster as well and it was back to being able to brake fine. I have a similar issue with the integra I just bought today (couldnt live without another DA ^^) and I have a brand new booster/master cylinder in the boxes going to be installed tonight. I will post up if this works but I am 99% positive I will have normal 100% breaking power after those 2 parts.

If you have another brake booster off your parts car and see if the problem goes away. Wouldn’t hurt ya know.

3

[QUOTE=TommyBDragon;2215484]I must say I see alot of you checking and replacing the Master Cylinder but not the power booster at all. They can go bad. My 92 Si I ran through a similar problem but after the 2nd Master Cylinder I replaced the booster as well and it was back to being able to brake fine. I have a similar issue with the integra I just bought today (couldnt live without another DA ^^) and I have a brand new booster/master cylinder in the boxes going to be installed tonight. I will post up if this works but I am 99% positive I will have normal 100% breaking power after those 2 parts.

If you have another brake booster off your parts car and see if the problem goes away. Wouldn’t hurt ya know.[/QUOTE]

he speaks the truth!!! this is where i would start

4

I had a bad break booster for a while and the pedal doesnt get soft it gets really hard. This was my experience but perhaps something different could be wrong with your booster

5

My clutch master cylinder was def on its way out but the booster was also causing an issue as after we replaced that the pedal felt much better. I would say do it, if its not the issue return the booster and keep on seeing what the issue could be.

6

yeah check other abs componants, my power booster was going out and wasnt holding consistant pressure. As a result my brake pedal would start firm then sink, firm sink as if the engine was off. I just did a abs delete and now my brakes are solid and firm…

7

I’ve posted this in a few forums looking for answers and realised I should provide additional information:

As I mentioned before, when the brake was depressed with the engine is off, the pedal was exceptionally firm right at the top of it’s travel. Once the engine was started (giving vacuum to the booster), the pedal sank 4/5 of the way down, with the remaining fifth of travel providing minimal braking force (aggressive downshifting provides more decelleration).

Now, when I disconnected and plugged the vacuum tube from the intake manifold and drove the car (now with no booster effect) the braking pedal was firm, but brake force still proportional to the pedal location when the booster was hooked up. In other words, unless I depressed the unboosted brake with everything my two legs can provide to get that pedal at least 4/5 of the way down, there was zero brake response.

When I removeed the master cylinder and examine the the pin that protrudes from the booster, its movement was consistent with the pedal, with maybe a millimeter of play. The boosters I have on hand have similar play. The plunger on the master cylinder was also solid, and when I put the two back together, the brake pedal offered about a millimeter or two before becoming solid.

I believe the booster is not at fault because of all this. If the booster had failed, I would hear a vacuum leak, or be experiencing no change in pedal height after starting the engine, or something along the lines of an equally firm brake pedal regardless of the engine being on or off.

Since the brake response is dependant strictly on how far the brake pedal is depressed, I believe the problem is somewhere after the booster - after the master cylinder, even.

I am curious to know what would happen to brake response if the ABS system was not charging itself. If the original ABS modulator had failed then I swapped in a good ABS system but missed a connection, the ABS pump may not be charging the system. How can I tell? If the system is working properly, then it would be charged and the pump would not run.

Furthermore; Honda has a computerized tool that induces ABS operation when they are testing and bleeding the ABS system. How can I induce modulator activity without this tool?

To answer the question as to why I haven’t just changed the booster: I have two spare boosters, one from a non-ABS DA9 (wrong booster - too small) and one from the DB2 parts car. Unfortunately, the DB2 was hit on the front driver’s side and pushed the strut tower infront of the booster, making its removal less than gentle. In trying to get it out, I severely damaged it. The two and four studs for the master cylinder and firewall resemble modern art more than an engineered auto part. In my efforts to find a new/remanufactured booster I’ve found it to be a hard to find and very expensive part, especially when I really feel it is not causing the problem.

At this point I have the following options on the table:

  1. Take it back to Honda and have the replacement ABS system flushed and tested.
  2. Attempt to induce the ABS pump to run on my own (erp… this scares me a little)
  3. Replace the booster with a new/remanufactured product (if I can find one - checking auto wrecker next week)
  4. Convert to non-ABS (I would like to avoid this as it’s a daily driver, not a track car)

Does anybody have other suggestions? Does anybody have advice on what I’ve listed above?

Thank-you to mirrorimg on clubintegra.com for your suggestion. I would have suspected my bleeding as an issue, if it wasn’t for Honda having the same results. As for deleting the ABS altogether, I would prefer to avoid this since it’s a daily driver. The ABS in the G2 may not be the greatest, but the ABS in my current DD DB2 has realized a slippery road before I had on numerous occasions.

8

if it works fine with the booster unplugged then the issue is within the booster. The booster is supposed to only hold enough vacuum to assist with braking and yours may be holding too much vacuum making the brakes too easy

9

Have you checked all your rotors run out? Possible rotor kick back.

Otherwise you might invest in something like this plugged into you system in various locations to diagnose your problem at less cost and time then throwing parts at it.

http://www.jegs.com/i/Stainless-Steel-Brakes/884/A1704/10002/-1?parentProductId=755048

10

Perhaps I hadn’t described my testing the booster very well.

Even though the pedal is firm, the brakes do not work with the booster unplugged. The only change is how easy the pedal depresses.

The braking performance seems to be how far the pedal is pushed down, where there is nothing for the first 4/5 of travel and minimal braking for the remaining fifth. This seems consistent regardless of whether there is boost or not.

11

how is the play on the brake pedal? if there isnt enough play in it it wont allow fluid to move through the master cylinder properly.

12

i am not sure but i think i have a similar issue. i mean ur issue sounds horrible and i feel for u. but wat i have is, replaced all for calipers rotors and brakes. only with oem grade ofcourse. also did a new master cylinder. oh before my brakes only engaged when the pedal was 2/3 the way down. after replace ment it worked okay i suppose bled everything as it should. my ls compared to my bros rs and gs is crap. my bros rs brakes engages hard, just great! im still scratching my head about this too. u might just have to live with it bro, but let’s hope it doesn’t cause an accident. btw good luck if ur still searching for the answer.

13

Unfortunately, it’s totally not drivable; it would never pass a safety.

You say you have an LS though, so no ABS and a similar issue. That gives me a clue, providing what we are describing is the same thing. Have you checked every inch of brake line between the master cylinder and the wheel well?

I ordered the part suggested by DB2-R81. I’m curious to know what my pressures are going to be in each corner.

14

wow. very descriptive. that is excellent.
i don’t suspect the booster either, as it seems to pass the quick booster test. and air in the system would more likely cause a spongy pedal that sinks to the floor slowly with consistent pressure. usually though, for future reference, when you change the MC you should bleed the lines at the MC. pump the brakes. hold. crack one line at MC. tighten. crack the other. and repeat. that way you get the air out at the top of the lines. because if it gets stuck there (the highest point in the system) it will never reach the caliper bleed screws.
but that’s besides the point. what you have is a low pedal that holds pressure, correct?
you said when you pulled the MC off for inspection, you found 2 gaskets between it and the booster. there should only be one. the old one must have stayed behind with the booster, as they tend to do. remove it and leave behind the new one only

15

I was going to say the same thing about the o-rings behind the master cylinder.
Leaving two o-rings behind the booster will cause a low/soft pedal for sure.
You may also have air trapped in your ABS hydraulic unit, which would best be removed
with an ALB checker.

16

[QUOTE=AllmansTEG;2216133]I was going to say the same thing about the o-rings behind the master cylinder.
Leaving two o-rings behind the booster will cause a low/soft pedal for sure.
You may also have air trapped in your ABS hydraulic unit, which would best be removed
by deleating the ABS all together.[/QUOTE]

Here I fixed that for you!

17

[QUOTE=welfare;2216090]wow. very descriptive. that is excellent.
i don’t suspect the booster either, as it seems to pass the quick booster test. and air in the system would more likely cause a spongy pedal that sinks to the floor slowly with consistent pressure. usually though, for future reference, when you change the MC you should bleed the lines at the MC. pump the brakes. hold. crack one line at MC. tighten. crack the other. and repeat. that way you get the air out at the top of the lines. because if it gets stuck there (the highest point in the system) it will never reach the caliper bleed screws.
but that’s besides the point. what you have is a low pedal that holds pressure, correct?
you said when you pulled the MC off for inspection, you found 2 gaskets between it and the booster. there should only be one. the old one must have stayed behind with the booster, as they tend to do. remove it and leave behind the new one only[/QUOTE]

I’ve never heard of air being trapped at the top like that. As I understood, bench bleeding allows a significant savings of time by purging the air the short route - right out of the master cylinder. If one didn’t bench bleed before installation one could still get the air out, but it would take a very very long time. I will keep that in mind though, thanks for the advice. (All that said, I did bleed each master cylinder before installation - plus Honda did once too)

As for the gaskets, I found two additional to the one I installed. So there was actually three in there, in total. I have already removed the two extra ones and cleaned everything as best as I could. There was no difference in pedal feel once it was back together, unfortunately.

I wish I could get my hands on an ALB checker, but unfortunately I’m going to have to take it back to Honda for that. As I mentioned, I really want to avoid removing the ABS system. This is to be my daily driver and for me, ABS is more for when I’m not paying attention on the highway in with winter months.

18

Just a word of experience and caution. The crude first generation ABS system on these car is relatively underdeveloped and cycles to slow to be very effective and is unlikely to save you when you are “not paying attention on the highway in the winter months”

Once the ABS system stops working correctly and it will, be prepaired to pay big dollars for service and nonobtainable parts.

There is good reason why most people remove the system beyound weight and a clean engine bay.

No pressure vessel in any industry would be certified after 15+ years, why bet your life on your ABS systems pressure vessel, lines…ect.

19

Your Brake Booster is bad
As lawngnomeslayer said
Try and change with the one from your parts car.

20

I’m having the exact same problem. I too have ABS and not too long ago my ABS pump started making a horrible noise when running and it started happening with more and more frequency. I assumed that it had just gone bad but It wasn’t affecting my braking so I let it be until I could get myself another one, but what I didn’t know is that it was leaking and it drained my MC. The previous owner somehow cut a wire on the MC level sensor and I had no idea I was loosing fluid until I had no more brakes. I replaced my pump and bled out the ABS system but now my brakes won’t engage until the pedal is depressed to 3/4’s the way down. I’ve notices that if I pump the brakes once while braking I get slightly more resistance and a noticeable engagement increase I’ve tried everything I can think of but haven’t been able to get my brakes back to normal since. Here’s to hoping you find a solution that works for me too. Either that or I’m going with the ABS delete option. SoCal living doesn’t put me into to many instances of needed ABS.