any serious mechanics here?

JonMikal · Apr 21, 2005

having a brake issue with a '90 civic. i like this little car and generally keep it running well myself, but, im stumped. the brake pedal is going to the floor. usually i would look for a leaking cylinder or expecting to see low or no fluid. fluid is full! any ideas?

Canon Fan · Apr 21, 2005

Does the car stop at ALL?

If so pay attention to the rear brakes. The rear brakes are what gives you a "solid feeling" in the pedal. Most likely they are out of adjustment or need to be replaced. Keep in mind that Honda rear "drum" brake shoes are pretty thin to begin with (normally only about 3/8 to 5/16") I would say if they are down to 1/16" just replace them. If they still have some meat you can adjust them by turning the little "star" wheel adjuster that fits in between the two shoes. Expand the adjuster until you feel slight drag on the the drum when you put it back on and try to spin it. DO NOT tighten them so much that the drum is VERY difficult to turn or the brakes will fry the rest of the way very quickly!

If the car does not stop at all I will need you to inspect a few things first.

Hope this helps a little

ferny · Apr 21, 2005

If your foot is hitting the floor and nothing is happening then it isn't the shoes which are the problem. I would have said air in the system but you've said the fluid level is fine. So if sounds like the servo has gone. Drop it into a garage near you and they'll take two second to find the problem and they've actually there with the car to make sure that what they find to be the problem is.

Erm, I'm not a mechanic. :mrgreen:

meotter · Apr 21, 2005

i was going to say air in the lines also... were you braking very hard for a while that might have boiled the fluid to introduce the air in the lines?

could be a bad brake line also... the rubber might have a weak point that is bulging instead of transfering the hydraulic power of the pedal to the caliper.

honestly it could be a lot of different things, but without a better background story or the car in front of us, it's a tough diagnosis...

you might want to try crx-forum.org, i used to go there a lot when i was really into my 89 crx

they're a very knowledgable bunch.

Canon Fan · Apr 21, 2005

ferny said:
So if sounds like the servo has gone.

What servo are you reffering to? (I'm just thinking this may be a language misunderstanding or something) but seriously the only electrical valves (or I suppose servo's) that would possibly be related would be ABS cyclic motor packs and or bleed valves and even then you would normally get an annoying amber or red ABS warning light on the dash panel but still have normal brake operation.

You are correct though about the air bubbles but if no work has been done recently I wouldn't expect that to be a problem either.

I guess the biggest question here is did this happen gradually or just all of a sudden overnight? If it was all of a sudden I would say the internal seals in the master cylinder are bad and need to be replaced. This would allow the pedal to go to the floor without stopping the car and no loss of fluid.

ferny · Apr 21, 2005

You are correct though about the air bubbles but if no work has been done recently I wouldn't expect that to be a problem either.

If he's been raggin' the balls off it there could be a problem. Normal fluid doesn't like the extra heat from excessive braking. Naughty Jon. *waggles finger* :mrgreen:

What servo are you reffering to? (I'm just thinking this may be a language misunderstanding or something) but seriously the only electrical valves (or I suppose servo's) that would possibly be related would be ABS cyclic motor packs and or bleed valves and even then you would normally get an annoying amber or red ABS warning light on the dash panel but still have normal brake operation.

http://www.kfz-tech.de/Engl/Bremskraftverst.htm

could be a bad brake line also... the rubber might have a weak point that is bulging instead of transfering the hydraulic power of the pedal to the caliper.

That'd just give a woolly feeling to the peddle though wouldn't it? It'd just feel spongy rather than his foot hitting the floor.

Big Mike · Apr 21, 2005

If you are not leaking or pushing out any fluid...I'd would think that it's the seals in the master cylinder.

If it is the master cylinder, you might want to look for a rebuild kit or even just the rubber piston seals. It's a fairly easy thing to rebuild and it will cost a lot less than a new master cylinder.

I did this with the master cylinder for my clutch.

JonMikal · Apr 21, 2005

this happened yesterday. i should have given you more info, sorry.

the car stops fine, but at a stop light while pressing the pedal, it goes to the floor. releasing the pedal - the pressure returns briefly. while driving you have the chance to pump if needed. im sure at some point pumping wont help, then i'd have some good pics :shock:

JonMikal · Apr 21, 2005

Big Mike said:
If you are not leaking or pushing out any fluid...I'd would think that it's the seals in the master cylinder.

If it is the master cylinder, you might want to look for a rebuild kit or even just the rubber piston seals. It's a fairly easy thing to rebuild and it will cost a lot less than a new master cylinder.

I did this with the master cylinder for my clutch.

ive rebuilt master cylinders before but couldnt remember the symptoms i had. sounds like i should focus there first and see what happens.

thanks a lot everyone! i appreciate your taking the time to respond!

ferny, i'll try to slow down a bit

Big Mike · Apr 21, 2005

JonMikal said:
this happened yesterday. i should have given you more info, sorry.

the car stops fine, but at a stop light while pressing the pedal, it goes to the floor. releasing the pedal - the pressure returns briefly. while driving you have the chance to pump if needed. im sure at some point pumping wont help, then i'd have some good pics :shock:

That's what my clutch was like...it just got worse and worse from there. Actually, it was my slave cylinder that went bad on me...and on my particular model of car, the clutch slave is located inside the trans-axle. Which meant that I had to remove the tranny to swap it out. After I did that and had put it all back together, there was even less pressure in the clutch...it took me a while to figure it out but the new seals in the slave had caused the seals in the master to blow out...so that's when I had to rebuild the master. The moral of the story...if you are rebuilding the master...you might as well do the slave as well.

JonMikal · Apr 21, 2005

Big Mike said:
The moral of the story...if you are rebuilding the master...you might as well do the slave as well.

good advice. thanks

thanks for link ferny

meotter · Apr 21, 2005

i don't believe his 90 civic has ABS.

i was going to suggest the brake cylinder in the drums might have broken, as it did in my crx, but stopping was ugly... definitly more noise & ruckus when hitting the brakes then a pedal hitting the floor.

to test the master cylinder just pump the brakes with the car off... the pedal should become rockhard and immovable. then turn the car over and the pedal should slowly sink back to the floor. that is what SHOULD happen.

if something else happens, then there is a good chance your master cylinder is bad.

Canon Fan · Apr 21, 2005

Ah yes Ferny I see our miscommunication :mrgreen: here in the states I know it as a vacuum assist booster :wink:

After reading Jon's follow ups I am pretty certain the master cylinder will be the ultimate cause of the problem, but what do I know I was only an ASE Certified Automotive Technician for 10 years and this exact scenario is on the Cert test (in one form or another

)

PS- The above was typed with a laugh guys so don't go all postal on me now