Increased braking effort in cold

[RickyCRX]

Brake pads have a specific temperature range that they work in. If it's too cold, they will not have as high of a coefficient of friction against the rotor surface. If they are too high above the temperature range, they will not work, either (this is called pad fade, and is experienced during repeated high-speed braking or when going down big hills at high speeds and nailing the brakes, etc)... Auto manufacturers pick a pad compound that will be ideal for most 'average' situations. If you are doing heavy towing without a brake controller on your trailer and overheat the brakes, they will be less effective. On a cold morning, your brakes will not be warmed up yet and will not bite as well as they would after they have a couple of stops in them to build up heat.

I have a mild street/track compound pad on my wife's daily driver and the first time she hits the brakes in the morning leaving the neighborhood, she has to stand on them a bit harder than normal. After that, they have a little bit of heat in them and work beautifully for the rest of her commute to work.

Brake fluid does not significantly increase viscosity when it's cold outside.

One other thing to keep in mind. The way an automatic transmission works, the engine will always be pushing the vehicle due to the torque convertor. On very cold mornings, the high idle will be in effect, causing the engine speed to be higher without applying throttle with the gas pedal. This will cause you to need more braking force applied to slow the vehicle down at low speeds. To test this, next time you start up in the morning, slid the shifter to neutral as you approach a stop sign/light and I bet it will also help you slow down quicker.

Nothing is wrong with your vehicle; everything IS operating normally, just as the dealer will tell you.

Ricky

 

[Northof49]

Coming from a Volvo and Audi, the Toyota is definitely under-braked. That was the first thing my wife noticed about the truck when she got it home. I think the rotors are too small for the weight of the vehicle.

The 4Runner should not be "under-braked" compared to those vehicles what-so-ever. Afterall, it has class-leading braking and is designed to stop with a 7,000lb trailer in tow.....don't think many Audi's are pulling that these days. Pedal feel and braking power are not one and the same.

I know from experience that it will easily lock up the ABS at 90mph, and not warp the down loooong mountain passes with heavy loads.


I would bet cold hard cash that the 2 variables RickyCRX suggested are extremely accurate.....pads/rotors not up to temp combined with higher idle = gotta push pedal harder. Dealer will say the same thing unless something is noticeably out of whack.....which doesn't sound like the case, so the dealer will say "it's normal."