Brakes on a 97 Civic

are the brake drums self-adjusting properly? can you hear them click when you back them off, then pump with the brake pedal?

if you replaced the master cylinder, is the travel the same as it was before?

Yes, the rear brakes are self adjusting, and they are adjusted properly. The travel is the same with the new master cylinder.

i'll take your word for it, but how do you know? what did you check?

in inches, how much travel before the brakes start to engage?

I removed the drums and checked the hardware, and verified the drag on the drum.

there shouldn't be any drag on the drum when properly adjusted. if the threads on the adjuster screw are rusted or even greased, they can fail to self-adjust. i recommend removal, cleaning, refitting, then checking operation.

to check operation, reassemble screwed all the way in, then when reassembled, press on the brake pedal 20 times. each time you release, you should hear the self-adjuster click. then remove the drum again and be sure you can see the adjuster has screwed itself out a few mm. if it has, reassemble and pump the pedal until the clicking stops. you then should be good. if not, you need to clean and reassemble again. no grease.

what is the pedal travel before engagement?

"wjcimbri" wrote in news:4b70d17e$0$31284$ snipped-for-privacy@cv.net:

I have LOTS to say on this one. but don't have the time just now to write it up.

In short, you have numersous problems.

Given that the front disk pads engage the rotors before the rear shoes engage the drum, and do 70-80% of the stopping, I think I would look elsewhere besides the rear drums for clues to this issue.

actually, that's not true - the rears come on first, but the proportioning valve applies progressively more to the fronts as the pedal continues to be pressed.

other than air in the hydraulics, a problem with the hoses or some serious caliper misalignment, maladjusted rears are the only place where you can cause this kind of pedal travel.

"wjcimbri" wrote in news:4b70d17e$0$31284$ snipped-for-privacy@cv.net:

A low pedal is indicative of several problems, which may or may not be present in combination:

1) aftermarket pads (wrong friction-coefficient for your brakes); 2) pads not floating freely on their mount brackets; 3) calipers not floating freely on their pins; 4) one or more hydraulic pistons sticking in their bores; 5) rust buildup between caliper, pads, and squeal-shims; 6) persistent air bubble (usually in caliper); 7) misadjusted master cylinder pushrod.

Complete removal of air from the calipers is sometimes only possible by using the "turn and tap" method, with the caliper off the rotor. This usually only affects rear calipers though, which you don't have.

If you're looking for a "magic bullet" fix, you probably won't find one. Your brakes need a good going-over by someone who understands how brakes work.

while you are correct in theory on #7, it's almost never seen in practice and i personally think it inviting trouble to cite it as a cause. unless something is broken, which is not a calibration problem, the position on the original master cylinder never changes. and if the master cylinder is replaced with the correct one, the new one is the same also. imo, this should /not/ be on the list of "diy likely causes".

jim beam wrote in news:_8-dnYFUQekzh- vWnZ2dnUVZ snipped-for-privacy@speakeasy.net:

It is _often_ seen when a master cylinder is replaced and the pushrod is not adjusted to suit.

It is a legitimate cause of a low pedal under certain circumstances.

Given that testing for that involves nothing more than pushing on the pedal with your fingertips, it's worth checking.

disagree. for straight replacement with the same master cylinder with the same part number, the internals are all identical. if they are identical, there is no reason to adjust the pushrod because the power servo doesn't change and neither does the pedal lever. the only possible reason to change the length of the pushrod is if the master cylinder internals are different [using a different cylinder] or if the pedal pivots are worn. if the latter, they should be replaced - the push rod should not be monkeyed with to compensate.

not through anything other than extreme wear or use of an incorrect/non-standard part. if the former, the parts should be replaced.

indeed, but with the above proviso.

we have seen the result of this here before - if people monkey with the pedal adjust, they can end up with the cylinder vent holes closed and the brakes come on as the system warms and expands. that is a serious safety issue.

Exactly. I can't even remember the number of times that I've had to re-adjust the pushrod due to low pedal concerns.

Absolutely. After the usual suspects are eliminated.

What must be remembered here is the human factor involved in cylinder manufacture/remanufacture. That factor always results in variations...

JT

then there is something seriously wrong with your car dude. you need to fix the cause, not monkey with the symptoms. master cylinder brake pistons do not wear. once set, you do not need to "adjust" them.

no dude - there is ZERO human factor in their manufacture. these are all produced by highly consistent and accurate computerized machines. every single piston has consistency and accuracy you can't even /contemplate/ with your foot.

jim beam wrote in news:zuWdnci1Cd5sJOvWnZ2dnUVZ snipped-for-privacy@speakeasy.net:

Provision for adjustment is built-in to the booster/MC connection for the single and sole purpose of matching two individual components that must work together precisely. Much like the throttle body and the Throttle Position Sensor.

This adjustment is necessary on account of manufacturing tolerances.

If you install a replacement MC (OEM or not), you MUST make sure the pushrod adjustment is correct.

Pedal height adjust is different from MC pushrod adjust.

Grumpy AuContraire wrote in news:BN6dneCTHaqsQuvWnZ2dnUVZ snipped-for-privacy@giganews.com:

That's why I listed the MC pushrod LAST in my list.

Perhaps I should have specified that I was listing things in order of likeliness.

Not just that, but tool variance and wear. Production quantities always involve some degree of tool wear, which changes dimensions during the run.

indeed, and like the tps, it requires no further attention unless worn. and the only things that can wear are pivots/contact points, not the internals of the master cylinder.

absolutely, but that variance is in the pedal/welding, not the piston/cylinder assembly which is highly precise.

dude, with respect, every single master cylinder i have ever replaced [and there have been many] - with conforming oem - has had the resultant pedal travel be precisely as it was before - not surprising since hydraulic pistons don't wear.

really, if you have experienced difference between pistons, there has to be some kind of issue, it's not a simple adjustment thing.

height is a function of the stop tab. pushrod adjusts travel, and thus depression before the equalization valves are closed.

any dimensional differences on hydraulics are measured in hundredths of mm. that affects pedal travel not even a tiny bit.

My experience is on a number AND variety of vehicles. You lose once again.

Then you are seriously out of touch with reality. The above may be the single most stupid thing you have uttered.

JT