We have a 2011 Toyota Sienna. Whenever we're driving on the freeway in the mountains (think I-80 in the Sierras, or between SLC and Park City etc), and we hit a downhill section, the van just takes off like a bullet. This makes us apply the brakes quite often to maintain control. But, when applying the brakes, we get a pretty strong vibration coming from the front, up into the steering wheel. It only happens after using the brakes for a while, so I'm guessing the heat from braking may be warping the rotors? After things cool down, the brakes are fine again.

We've got a trip to Lake Tahoe coming up, and I'm not looking forward to the drive between Carson and Tahoe, so I'm looking for advice on what might be the problem, and what we can do about it?

Thanks

Just wondering is this with cruise control on?

quote:

Originally posted by blueye:
Just wondering is this with cruise control on?

Sometimes, yes. But we've learned that even with CC on, the van accelerates very quickly, and find ourselves riding the brakes for safety.

Downshift the transmission to let the engine help with braking? At least turn off the overdrive. There may be a section in the owner's manual that addresses driving in the mountains.

Drive like a trucker?

Before heading downhill, choose a "safe speed". Decelerate to 5-10 mph below that and turn off overdrive/ manually put it in the next lower gear.

When vehicle accelerates to your chosen speed, firmly apply brakes (not stomping on them) until you reach the original speed.

Release brakes when that speed is reached.

Repeat as necessary.

Riding them will overheat them and failure will eventually happen. Nothing good would come of that.

Get your rear brakes checked as well. They may be stuck in the open position. Also check your brake fluid. If this is a constant issue, your fluid may have been cooked. See if it is black or smells bad.

If rotors are worn thin after six years, heat could temporarily distort. Measure and replace if required. OEM parts preferred, but most folks buy cheap iron from China.

How many speeds in your transmission? I'll guess a 2011 is a five-speed. Fifth is a rather extreme overdrive, which will give you little or no engine braking, and fourth might be too. Shift down to at least fourth before descending such a steep grade. Don't carry engine braking to extremes and over-rev the engine, however. Brakes are cheaper to replace than engines. Also not recommended to use the cruise control on steep downgrades. It can maintain speed or accelerate, but can't slow you down.

quote:

But, when applying the brakes, we get a pretty strong vibration coming from the front, up into the steering wheel.

Pulsation from the rotors warping. This will eventually become permanent. Does the pedal get soft? This is an indicator of brake fluid boiling. This normally takes a lot of heat, but if the fluid gets any moisture in it, the threshold will be greatly reduced, as water boils far sooner than brake fluid. At this age you might consider having this fluid flushed out.

If I'm descending a long grade and brake, my 2009 Corolla (four-speed auto) will downshift to third by itself and maintain it until such time as I stop gaining speed. Sure, I could do the same thing myself, but it does it so well I don't need to. Yours doesn't do that?

I have a 2011 Tacoma that does same exact thing.

Your rotors are warping with the heat as you stated.

I bought high performance rotors and pads, best price was amazon actually after a search, rotors have groves and are drilled for heat dissipation.

Perfectly smooth now.

Think I had $170 ish into it for front rotors and pads.

If it were me, before the trip to Lake Tahoe I'd have the front brake pads and rotors replaced (or DIY) and rears inspected.

On the drive to Tahoe, I'd downshift before a long downhill descent so the motor is braking. Most highways have signs notifying of length and grade of descent so you'll know ahead of time to downshift at the crest.

If the pulsation is not permanent, meaning it only comes on after you have really heated up the brakes during a long downhill stretch, it may not be warped rotors. You could be overheating the pads and they are depositing what is essentially melted pad material onto the rotor surface. This feels exactly the same as warped rotors but is a different cause and thus a different fix.

So I agree that you should check the rotors for warping and replace if needed with some good quality OEM rotors that aren't as prone to warp. But also look at new pads as thin heavily used pads overheat (and boil brake fluid) much more easily than new thicker pads due to the mass involved. Better quality pads that don't break down until a higher temperature are also worth looking into.

To avoid excessive speed going downhill find and use the overdrive lockout. That button will stop the transmission from shifting into the highest gear.


If turning off the OD doesn't slow you down enough, then brake until you can manually down shift to 2nd. Typical speeds around 35ish. Your manual probably had a section on this topic.


Let the motor do the work. I've lived in Colorado most of my life, and have watched a lot of brake fires and failures happen because people just aren't aware they should downshift. I see lots of trucks on the side of Vail Pass and Silverthorn sitting there burning or buried deep in the runaway ramps. Even professional truckers don't always know how to do it correctly.

Stay right, slow down, get there alive with all your metal parts unmelted. Enjoy the smell of victory as you watch all the noobs go flying by with smoking wheels.

I had the same experience in our 2010 Highlander the first time we took it on I-70 from Denver to ski country. The next year I used the transmission and stayed in a lower gear and had no vibration and good pedal feel the entire time.

Cruise control should disengage when you apply the brakes so that's not the problem.
What kind of brake pads and rotors are on the car? I would bet they are an off-brand.

Strange seeing this thread. I have a 2012 Sienna that we took on vacation last April and it included lots of steep grades at various locations including in Utah in the ski resort areas of the Wasatch mtns and on I-70 on our return trip through Colorado from west to east. Never experienced anything like what you are reporting.