I have a 97 Accord LX (4cyl/no abs/92k miles) that has a two part brake problem that has me (and several others) stumped. I'm hoping someone here has had a similar problem. It all began several months ago and is gradually getting worse. First part of the problem is when first applying the brakes after the car has sat overnight, the pedal goes nearly to the floor with very poor braking. This goes away after a minute or two and braking becomes normal. The car sees a lot of interstate driving and this is where problem part two comes in. You can drive the car for 300 miles or so without stopping and there are no problems. But once you stop for gas or a rest stop, when returning to the road, the car behaves as if the brakes are applied with a very firm pedal. Suddenly the car holds back and starts shaking violently. If you pull over for a few minutes and return to the road, the problem goes away. It seems to be both front brakes that are the problem. When this happens, you can feel the front wheels and they are reaaallly hot! The pads were replaced last year with Performance Friction pads and not cheap part store pads. I replaced the brake booster last week thinking this was the problem. It made no difference. I was thinking the master cylinder is bad but from past experience, if a master cylinder goes bad, when sitting at a stop the pedal continues to go to the floor...this isn't happening. My next step will be to replace the master cylinder even though it doesn't appear to be bad. Any ideas would be greatly appreciated.

 

I would use regular part store pads but name brand (raybestos, Wagner, etc). The reason for this is the pads you are using could have a high temp operating range so the do not work cold. If this doesn't work you need to check the basics. Check all the brakes, hydraulics, linings, hardware, hoses, etc. The problem is there you just have to find it.

 

Anyone else want to chime in?

 

ya i wold change the master cylinder


good luck

 

Part of this sounds like air in the brake lines. Have you put fresh fluid in there lately? Bleed all the air out? Since you changed a bunch of other stuff, I suppose your fluid is fresh & properly bled?

I'd also suspect the adjustment of the piston push-rod. When you changed the booster, there's an adjustment on the length of the push-rod, that has to match along with the length of the rod that sticks out of the master cylinder.

When you're NOT pressing on the brake pedal, there's a port in the MC that has to be open to the reservoir. That makes sure the brake pressure is zero when your foot is off the pedal. If you mess with that adjustment, like if you want to adjust the pedal height, the brakes might not completely release when you take your foot off the pedal.

 

All of these ideas are key things to check out. I agree with everyone...the only thing I didn't see is if you even had brake fluid, but I think you aren't that dumb. As far as the violent shaking, that just sounds scarcy....I would definately find out the problem quickly.

 

i agree with jimblake, that it sounds like air in the brake line. You are showing all the symptoms of it. just do a quick bleed and get the air out and see if that fixes things before you spend any more money. Cause if the air in the line gets hot and expands it could apply the brake. Bleed the line first

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by tjohnson329 &raquo;</TD></TR><TR><TD CLASS="quote">... Cause if the air in the line gets hot and expands it could apply the brake. Bleed the line first</TD></TR></TABLE>If the brake pushrod is adjusted correctly, that won't happen. You know how, when you put new pads in, you push in the piston & the fluid goes back into the reservoir? That's exactly what should happen when the fluid boils; the fluid pushes back into the reservoir.

If the boiling fluid is able to apply the brakes, that means the brake piston rod is too long, & the MC piston isn't out far enough.

 

could be air in the lines.......definately check the master cylinder........good luck......

 

Yep buy a new master cylinder.... and no pads... while your at it why not get new rotors too? Just spend some money and change your whole braking system... it's worth it, since this car can still drive to about 400k... lol

 

I have a similar experience on mine. Doesn't feel like any of the stated fixes. Feels more like something to do with vacuum. I notice mine seems to do it more during or after A/C use. No fluid is leaking and the inconsistency of it doesn't seem like air in the lines.

 

Replaced the master cylinder yesterday and it still does the same thing. No improvement whatsoever. All the lines are bled, and yes, the master cylinder was bled before putting it on. I am at a total loss. I have owned enough Hondas over the years to know that they should not be giving this type of problem with only 90k miles on the odometer. The brake lines show no problems. The calipers move freely and look like new. I am running out of ideas quickly.

 

How did you do the pushrod adjustment?

In your top post you describe 2 things - pedal going to the floor & brakes applying themselves. Did BOTH of these things stay completely unchanged with the new MC?

 

replacing components are not always the solution. You have to look at the whole picture. This is a common problem here when someone states a problem and then all of a sudden 15 people identify the component that is at fault without even doing any test or even looking around for possible causes.

A booster to work, unless i am an idiot, required a diaphragm and good vacuum supply from the engine. Now you have a good diaphragm (you replaced the booster) so maybe do not have enough vacuum going in your booster. Maybe an vacuum leak... Look at this very carefully. test it out by pulling the hose going from the intake to the booster and measure vacuum pressure. A low reading may be the cause. then if that is the case, you have a hose leak or obstruction or blockage in the exhaust system.

I am just giving you an idea here. You can take it for what it is worth.

fs


Modified by filthy_shovel at 7:32 PM 6/30/2004

 

That's a good idea and the only thing I haven't tried. I'll try this tomorrow and let you know how it goes.

 

Did you ever figure anything out?

 

When you bled the brakes did you do both front and back?