My father and I have this “discussion” that he believes downshifting my transmission going downhill is infinitely better than braking. I’ve told him that I don’t ride my brakes enough to freeze my brakes and the brake wear is better than transmission wear. Who is right?
Your father is right for the most part. For small hills it doesn’t matter, you can just use your brakes. For long descents, using your brakes may overheat them to the point of boiling the brake fluid. The risk of riding the brake is not freezing of the brakes, but loosing braking all together, which on a long descent would be very bad. I don’t think the decision should be be based on wear but on safety.
“I don’t ride my brakes enough to freeze my brakes”
Freeze?
Ummmm…NO
As most of us have consistently advised in this forum, your father’s way of doing things is correct.
Downshifting a transmission needlessly can increase wear and tear on it, but when driving down a steep grade, downshifting does not fall into the category of “needless”.
As rripstop stated, use of only brakes on a downgrade can result in overheating the brake pads and in extreme cases can result in the brake fluid getting so hot that it literally boils. The result of this situation is loss of braking power. Unless one has a heat detector attached to his/her brake mechanism, this situation is impossible to detect until it is too late. Because of that, the idea is to prevent a case of overheated brakes.
The way to prevent overheated brakes is by downshifting.
Dad is correct.
Brakes freezing? Huh?
The idea of overheating modern brakes is old wifes(mechanics) tales.
As the fluid heats it does lose some effectiveness however not to the point of failure if vehicles are driven legal speeds on public roads.
NOT going to happen…Maybe if you neglect your brake fluid.
Brakes are MUCH cheaper to repair than transmissions…However on a long SERIOUS downgrade, there is nothing wrong with dropping a gear to take the load off the brakes…
“Maybe if you neglect your brake fluid.”
Well, based on a huge number of posts in this forum, I think that many–perhaps most–of the drivers on the road do neglect to have their brake fluid changed every 3 yrs/30k miles.
Think about it–Don’t we often get questions along the lines of, “Why is my mechanic/dealership trying to rip me off by suggesting that I change the brake fluid, coolant, and trans fluid at 30k/60k/90k”? Some forum members have even responded that they have never changed their brake fluid and that no bad consequences ever befell them–despite the fact that brake fluid absorbs moisture from the air and can definitely be diluted with moisture after a few years.
My brake fluid and your brake fluid are not likely to boil, simply because neither of us neglects maintenance. However, the percentage of posts in this forum that reflect lax maintenance is staggeringly high, so what we do is probably not representative of what most folks do.
This is not a black & white issue. With long downgrades it is generally better to downshift. Even though modern brakes are better, they still can overheat and modern rotors tend to warp when they overheat.
In addition many cars will use a little less fuel if you are in gear. If the engine is is being turned over at a higher RPM than idle speed, many cars will stop using any fuel until the engine is below idle speed.
I don’t recommend that you do this all the time. Remember brakes are cheaper than transmissions.
Joseph is right; we live near the mountains, and on a long downhill grade, we downshift to keep the brakes from fading. The additonal engine braking works great.
Equally, when going uphill we downshift to get more power and make it easier on the engine cooling system.
This stuff is in most car owner’s operating manuals, the world’s most UNREAD best-seller.
If you are going down a serious grade, your vehicle will benefit greatly from shifting to a lower gear and taking advantage of engine braking to control vehicle speed. Brake fade and brake failure from overheating is not necessarily the cause of overheated or boiling brake fluid. If this were the case, mountain roads would not have runaway truck ramps on them. These ramps are designed to give semis with brake failures due to overheating a relatively safe way to stop their trucks. Semis have air brakes, no brake fluid to boil, but their brakes still overheat and fail under severe circumstances. Brake fade and overheating failure is most often caused by the friction material overheating and becoming ineffective.
I recently took Hiway 1 down the California coast from San Francisco to Santa Barbara. That stretch of hiway would have toasted and worn out the brakes. There is some misconception about this down shifting. It doesn’t require dropping from OD to first gear at 60 mph. The idea is to anticipate the down hill grade and as you crest the hill at 40 mph down shift until the engines compression is able to hold the speed. Even on the steepest grades with some severe turns it wasn’t necessary to drop below second gear. It is a smooth and unnoticeable action to the passengers.
"I don’t ride my brakes enough to freeze…"
You will never know that…until it’s too late.
DO NOT WAIT TO SEE IF YOU HAVE ENOUGH BRAKES LEFT, DOWNSHIFT FIRST !
Yes, I’m yelling this at you. And from horrendous personal experience.
I’m getting real tired of seeing this subject pop up here of late and feel I need to be standing in front of all of you, pounding my finger in your left shoulder.
It’s called brake fade
You don’t ‘freeze’ your brakes, you over heat them and they just stop working.
Yes that’s right, they just - stop - working !
By the time that happens you could be going too fast to downshift.
Or; attempting to downshift, plus weight momentum, plus speed too fast for the next lower gear, equals OH S— !
— I’m not kidding ---- downshift !
1992 Ford Explorer towing single axle box trailer with rock band gear.
Long downgrade about 65/70-ish is normal for this stretch.
Momentum speed increase require braking every quarter mile.
Soon brakes…are NOT.
Downshift, out of overdrive into third.
Speed mintained now at about 65.
I’ll need to stop in the next two miles but brakes barely slow the rig.
Downshift to the second gear position but rpms ar too high for it to take.
BOTH FEET ON BRAKE PEDAL garners two mph reduction.
– DUDE, I need to stop in a mile !!!
Downshift to low position ( rpm still to high, nothing happens ) , stand on the brakes with both feet, heart pounding, WHAT NOW ?
Approaching intersection 50 mph now, generally not too fast for this stretch of road but now it’s time for everyone to begin stopping…BUT NOT ME !
–I’ll need to just run the red light and hope there’s no one in the way at the time.
The luck this night is the late hour and resulting lack of traffic.
But,
OH-
MY -
GOD -
What a scary ride.
Lesson learned ; DOWN-SHIFT first !!!
Maintain slower than ‘speed limit’ if hauling extra weight.
Save your brakes for braking.
I only dodged a bullet that night but did NOT get the drive done correctly.
What if ?
Cross traffic existed ? ( flash lights , honk horn, and pray )
Same lane traffic had existed and stopped for the light ? ( Go into the oncoming lanes to go through the red )
Either way,
----- >> there was going to be a wreck because I didn’t downshift at the begining of the descent and waited too long to find out about BRAKE FADE.
Thanks everyone. From everyones comments, i believe that my dad is mostly right. Last night i was braking on the curves on a small hill, but he believes in downshifting all the time.
Addendum to my post;
After an hour of cool down and slow driving…
The brakes worked perfectly normal.
The next day my mechanic’s inspection found nothing to fix.
Good rotors, good pad thickness, and they worked normally ever after.
‘brake fade’ will surprise you…
at the worst possible moment.
The downshifting idea is a very strong carry over from the past. My Dad at 78 will downshift on a hill that takes 5 minutes to decend and offers no chace for brake fade, I drive the same pass road (Gates Pass in Tucson AZ) about 100 times a year and never down shift, we have 86K on our 2004 F-150 with no brake component changes yet (except fluid).
I just never let the speed get over 35 (very irratating too the people behind that want to rally on the curvy road) but 35 is the limit and the road has many bicyclist.