Saw some car report on cable TV that talked about brake fluid turning to foam at Elev. 14,000 feet at Pikes Peak , CO. and other problems with altitude.
Many mountain roads on the left coast are elev 8000+ - anything to do or look out for except snow snakes and snow/ extreme heat? Blew a thermostat west of Denver once - no fun.
j
Obviously, don't ride the brake pedal, downshift when going down long inclines.
~~~~~~~~~~~~~~~~~~~ Good advice Ray! Although disc brakes are much less apt to fade than drums, they still WILL on occasion if overheated by a long downhill run with the driver riding them. My solution is to slow down fairly rapidly to a speed that's a little less than is warranted, and allow the car to speed up to a little more than is desired, then putting on the binders rather hard again until the speed is lower than warranted again, etc. Also, retarding speed with a lower gear always helps. There's nothing more dismaying (and frightening) than having to apply the brakes and finding that they've faded to the point where you have no brakes. I've been there, and that is why I'm ultra-careful with long downhill stretches.
I've never had a problem with brake fade, even when coming out of the mountains with front disc/rear drums. Reading the owner's manual will tell the driver what those other gear positions are for ;-)
Shifting to lower gear is well known - how about excessive rpm on a long especially steep grade of say in excess of 15% that may exist on even major highways in CO? Small streets and roads may exceed 20% in many places. (20 ft drop for every 100 ft horizontal. Any gravel or coarse sand will cause your feet or wheels to slide.)
Just how reliable is the emergency brake once the primary brakes have failed? (for whatever reason) Or perhaps the "emergency" brake is for parking only?
How bad was your brake failure in terms of 'pucker-factor'?
j
Is it safe to read the manual while going down a steep mountain road?
Your Sienna has an RPM limiter to prevent engine damage from excessive RPM. I've driven 30 or more miles in 2nd or 3rd gear with no ill effects. As someone suggested, an occasional stab of the brakes along with use of a lower gear will keep speed and brake fade under control.
"Emergency brake" is a misnomer. It is a parking brake. The parking brake will stop the vehicle, but it will take a much longer distance because only the rear brakes are being used. As to whether they will work after the service brakes have failed depends on what caused the brake failure and the type of parking brake. The parking brake is actuated by a cable so if the service brakes suffer a hydraulic failure, then the parking brake will still work. If the brake linings have burned away, then the parking brake will probably not help much (which is why periodic brake inspections are important).
Current Toyotas with rear disc brakes have a drum parking brake, so if the rear pads have worn away or if there is hydraulic failure, then the drum parkng brake will still provide some stopping power.
That said, catastrophic hydraulic failure on a modern vehicle is very rare. So rare that I've never encountered it or heard of it firsthand.
My brakes have never failed.
As long as you look up at the end of each page!
If the drive train is in control of the engine how does the rev limiter limit the rpm? Ron
That is good to know. Almost 50 years ago I was showing off with a small two cycle motorcycle and was gearing down - and creating some insane rpms and brew the flywheel in front of a large crowd. Damage to everything including both legs. j
My Sienna CE does not have rear disc brakes - as far as I know - it was an option that I was told was not important . What does this do for the parking brake?
Ray - I think I said before that you have lived a sheltered life. You never had to jumpstart worn out and abused military vehicles, at night in 40 below and no lights allowed - other than what was created by striking battery terminals incorrectly.
Thanks again for all the answers. j
LOL...
The Electronic Control Unit limits RPM by cutting fuel. Of course, if you are going down a steep enough grade, you will still have to give the brakes an occasional stab.
In my Kia and in my old EuroVan, the gear positiions appeared to be for:
1- Creeping 2- Crawling 3- Extremely Slow 4- Darn Slow 5- Just Plain Slow
The area that the brake friction material contacts the braking surface is known as swept area. For a given swept area, disc brakes will generally dissipate heat better than drum brakes, and disc brakes do not need periodic adjustment like drum brakes need. That said, with careful driving techniques like downshifting and not riding the brake pedal, drum brakes should provide adequate stopping power and fade resistance.
It's not so much that I have lived a sheltered life, it is that I believe in proper maintenance and care of my vehicles. When I lived in San Francisco and went camping and fishing in the Sierra Nevadas once or twice a month, I checked the condition of my brakes often. I've been to Michigan's UP, Burlington and St. Albans VT, where it occasionally got to 40 below. Although I didn't have to work without lights, and although my vehicles never needed jump starts, I have probably gotten more cars started than most people who don't drive a tow truck. For some reason, the people I know who drive junk cars and don't have AAA call me when their cars won't start.
I've driven from coast to coast, up and down some long, steep roads, and spent time in hot and in cold climates. My point is that with proper care and maintenance and with proper driving technique, a modern passenger vehicle should be able to handle any public road in the continental U.S. without worrying about something blowing up.
How does this cutting of fuel differ from taking the foot of the gas pedal - in terms of reducing rpm and provide motor braking power? The lack of fuel has often been equated to lack of lubrication - some bright guru once told me to step on the gas, from time to time, for that reason. Is this really valid for a 4 cycle car engine that does not have lubricant in the fuel?
j.
What you say is correct. My point is that often many of us have gotten into situations where we had little or no control. Like people in the military in Iraq now and Korea in the good old days. Or having zero control over maintenance etc. My worst nightmare was warming myself over burning sticks of TNT in an open fire on top of a three foot layer of live artillery and other ammo. And tossing that same live ammo from vehicle to vehicle like firewood. The justification was that if anything goes wrong then you will hear nothing and the show must go on. j
The only difference is that the RPM fuel cut is much more abrupt than lifting your foor from the throttle pedal.
Fuel has some lubricative properties, primarily in the fuel pump. Stepping on the throttle pedal will not provide any practical lubrication to a 4 cycle engine.
Even in a 2 cycle engine, fuel is the medium for delivering the lubricant, which is the oil mixed with the fuel; it is not the primary lubricant.
No wonder you think it is safe to use gas to clean your garage floor!
That is NOT stating my point of view correctly. I was looking for a good alternative to what I believe I labeled extreme hazard that should be avoided if possible. This was a case of burning your house (at worst) vs. turning yourself into a vapor or dust instantly. j
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