Brake pedal alternates between firm and soft

[capnblinski]

I'm having an issue with my brake pedal modulation. On wet rainy days the pedal is nice and firm, but once the weather clears the pedal becomes mushier. Has anyone had this problem, and if so, what would it take to fix?

2000 Camry LE 5sfe
172xxx miles

[bdy0003]

Hmm...lets start out with...Have you replaced the brake fluid? If yes, how long ago? What color is the fluid now?

[capnblinski]

Haven't ever replaced the brake fluid. I've had the car nearly two years (it was well maintained) and the fluid in the reservoir looks clear/very slightly yellowish.

[71Corolla]

Humid air can make your brakes work better, it improves contact/friction between the pad and rotor, making the pedal feel better (because it requires less pedal force). How do your pads look, brand of pad if known. What about the rotor? What is the condition of the drum/shoes?

To fix the problem permanently, replace the pads and rotors if needed, inspect and/or replace the rear brakes, and flush the fluid.

[capnblinski]

Over the years I have noticed small differences in pedal feel with humid/non-humid conditions -- the present mushiness is just more pronounced.

The brakes are very good when the pedal feels firm -- there is no grabbing or pulsation of the pedal like you get with bad rotors. They are the best brakes I have had so far on a car -- seeing that it is the most modern car I've had -- and the previous one-owner took good care. The pads are about halfway and the same with the rear shoes. Don't know the brand of pads but through researching here on TN, I've been planning on the Akebono's when the time comes for pad replacement.

So I will do a flush of the brake system also -- there must be a DIY here somewhere, and then get back to yin's with the results.

[ajkalian]

Originally Posted by capnblinski

So I will do a flush of the brake system also -- there must be a DIY here somewhere, and then get back to yin's with the results.

Make yourself a PowerBleeder. Thread is here.

PowerBleeder - Bleed your brakes the easy way. Many pics.

.

[fenixus]

mushy brakes feeling can be dozen of things, start with the life savers first (new pads and resurface rotors, flush the brake fluid with any Low Moisture Activity formula like Castrol or Valvoline) then think of testing other items.

your problem *could* be related to early sign of failing Master Cylinder cup seal (there is two of them on the piston).

other than that, old rubber brakes lines at calipers can be calling for replacement. I am actually one of those people who replaced MC (old one was rusted), both front calipers with "new" remanufactured Cardone (old ones had sticky pistons), installed new pads and resurfaced rotors all around, replaced faulty ABS with burned out computer (used a junk yard working pull) and still having the mushy brake pedal LOL

the last 2 things left in system are rubber brake lines and brake booster... and something tells me it's the rubber lines being responsible for the pedal feeling ... I'm not there yet to replace them though hehe ...

[71Corolla]

Properly bleeding the brakes is very important IMO. Cheapest way is to use the two person method, one pumps the pedal 2-3 times with the bleeder closed, then holds the pedal down as the other opens the valve. The valve is then closed before the pedal is released. I find this method works really well and purges the air out quickly. Another way is to use a one-way valve, I use this method, although my hack job device is starting to fail on me. I would like to get a hold of a proper bleeding system at some point it would save me a lot of time.

If you just take a hose and drop that into a jar of fluid, then you will automatically get air into the system when you open the bleeder, and pumping the pedal will not move the fluid effectively, every time you let up on the pedal, the fluid and any air will partially sucked back into the system.

Some people have mentioned that allowing the pedal/master cylinder to go all the way down to the end of the travel can be bad for it, because the rubber parts will contact an area that it never normally does, and can cause damage. I've never had this happen personally but I can understand how it could occur. A way to prevent this is to put a block of wood under the pedal to prevent full travel.

[capnblinski]

Thanks guys and happy new year by the way.

That PowerBleeder is too cool! How much to make one for me? lol.

I'll post back asap on the fix - hopefully new brake fluid will be all that I need.