Downshift down a mountain or ride the brakes?

[sebastiancrain]

Where I live involves me driving up and down a 15 mile canyon with a 3000 ft altitude difference many days a week.

When I'm going down the mountain, is it harmful to my engine to put it into 4th or 3rd gear to engine brake, or am I better off riding my brakes all the way down?

[Rayven01]

Brakes are a lot cheaper than transmissions... I had the same question, though more for general driving than big hills, and when I looked around online the general consensus was that. It won't trash your transmission (or engine) but it will wear out sooner, and considering the cost difference it makes no sense to wear out your transmission instead of your brakes.

[Chiadog]

Additionally, I think you will pay a premium in decreased gas mileage using engine braking. Just using the brakes may be the cheapest AND best way to go. (IMO)
chiadog

[JohnO]

I'll speak up for the pro-downshifting point of view. When I visited Hawaii I drove to the top of the Haleakala crater. The summit is at 10,000 feet and the 10 mile long road to the summit starts at about sea level, so the road is a 20%, 10 mile long grade. Without downshifting a car would probably coast at 70 mph or more but the curves on the road require a 30 mph speed. I descended in 2nd gear which still required some additional help from the brakes, but I got down no problem. Near the bottom I saw a car that had obviously descended without downshifting. It was parked by the side of the road with heavy smoke billowing from both front fenders. The wheel bearings were so hot that the grease was pouring out of them onto the hot brake rotors and burning.

Obviously this is an extreme example but the point is that there is a threshold at which downshifting is not optional. Generally I will downshift on a hill if the coasting speed would be more that 10 mph over the speed that I want to maintain. If less than 10 mph then I will alternately brake to 5 mph under my desired speed and release the brake until I'm going 5 mph over my desired speed. That way I'm not on the brakes for more that 20 seconds or so at a time and it gives the brakes a chance to recover. If I would need to brake for over 20 seconds, then I'll downshift.

The extra wear on an engine is very minimal since it is a idle anyway. And the wear from a single downshift is about the same as from a single upshift, again since the engine is at idle. Fuel usage is no different since the injectors will be shut off whenever the rpm is above 2000 or so and the throttle is closed.

[beemerphile1]

Downshift and let it rev. It harms absolutely nothing. Believe it or not it doesn't matter at all to the transmission and the engine is actually happier at higher RPM.

High RPM with a closed throttle does not cost you a penny in fuel. Riding the brakes will cost you dearly in increased maintenance cost due to wear and tear.

When you do apply the brakes descending a hill you should apply the brakes with a heavy foot and then release until needed again. Never, never, never ride the brakes continuously. Hitting hard to slow and then releasing allows the brakes to cool. Riding the brakes will burn the pads possibly glazing them and warp the rotors due to overheating.

[tpollauf]

Are we to assume this topic is about a MANUAL transmission ? Does it really matter? Just curious

[JohnO]

It applies to automatic and manual both.

[ColonelPanic]

Put it in neutral and don't use the brakes. Just kidding!

My sister drove down a mountain holding on the brakes of my folks' then-new '95 Monte Carlo. I don't know what she did to it, but Dad struggled for the next 10+ years trying to get the brakes to work worth a crap on that car to no avail.

My vote goes for transmission - downshift that sucker.

[mr.clutch]

Ok I don't usualy chime in but this question is a true safty issue.
First off you NEVER USE ONLY THE BRAKES!!!! it is not about wearing them out or replacement not even rotor warp.What happens to your brakes is that when you over heat them they glaze over and start too fade ( as in NOT WORK at all) so when you do actually need to stop you can't. So riding your brakes is the worse thing you can do for your brakes ,car and what ever is in front of you. i [quote="ColonelPanic"]Put it in neutral and don't use the brakes. Just kidding!

My sister drove down a mountain holding on the brakes of my folks' then-new '95 Monte Carlo. I don't know what she did to it, but Dad struggled for the next 10+ years trying to get the brakes to work worth a (removed) on that car to no avail.


In a case like this the calipers got so hot it boiled the brake fuild inside them witch caused air in the system. The fix is to change the pads, turn rotors and bleed the brakes.

[beemerphile1]

Thought I would add that riding the brakes can also boil the brake fluid which will cause brake fade. If it happens the brakes will recover after cooling as you sit buckled against that tree at the bottom of the mountain.

That brings up a thought about brake maintenance. At the very least, every time the brakes get new pads the entire system should be flushed. Brake fluid is hygroscopic which means it absorbs water from the air. It will even draw moisture through rubber hoses. Water in your brake fluid will cause it to boil at a lower temperature than pure brake fluid itself. That is also why you should always get your brake fluid fresh from a new sealed container. An open container will absorb water. I consider flushing with new brake fluid is one of the most important maintenance issues. Any used vehicle I buy gets flushed immediately.

[revstohigh]

engine breaking gets better mpg than idling does esp since it will idle at higher rpm when at any kind of speed vs parked
if you take this trip regularly i would deff get a high quality set of pads and rotors esp on the front . if its disk in the rear change them out to . brembo's and ebc's are pretty cheap on ebay....

if its drum in the back make sure they are adjusted up this will take a bit of stress of the fronts and give you a nice high firm petal

also flush the system out and use a higher temp/dot brake fluid

maybe even get a break controller so can really play with it

also the tire pressure plays a very big part in breaking so experiment with that i wouldn't go any lower than 28 or higher than 33ish psi for maximum contact area

and yea what everyone else said dont ride the breakes and deff use the engine

or just learn to drift and just use the side walls of the tires to slow you down thats what Takumi Fugiwara would do if his ae86
and dot forget to paint your calipers that helps loads lol

[beemerphile1]

...maybe even get a break controller so can really play with it...

Huh?

What do you mean by a "break controller". All of my vehicles have brake controllers because I tow trailers with brakes. The OP didn't say anything about towing. Is there some other kind of "break controller"? Hopefully the OP won't break anything when using their transmission and brakes.

[revstohigh]

a controller to be able to put more pressure to the rear brakes . in oem form the fronts do about 70% of the work

[09SnowyVibe]

Are you guys sure you can use the transmission's low gears to slow our Vibes down? I ruined a tranny in my other car doing this. A transmission rebuilder told me it is bad for a tranny to put it in low gear. He said it is only for heavy loads or towing uphill.

Using cheap brake parts will cause fade, you guys using premium brakes on your cars? Also the rear drum brakes need to be kept adjusted to ensure the fronts are not doing 100 percent of the work.

[joatmon]

I downshift for going down long mountains. Makes regulating speed easier, keeps my foot off the brakes so when I do brake the guy behind me knows when I actually am slowing down, keeps my brakes ready when I really do need to brake.

In a car, it is more important to be able to stop than it to be able to go

[beemerphile1]

Are you guys sure you can use the transmission's low gears to slow our Vibes down? I ruined a tranny in my other car doing this. A transmission rebuilder told me it is bad for a tranny to put it in low gear...

Yes, I'm sure. In the old days it was rare but you could damage an automatic transmission by downshifting at too high of a speed. With modern computer controls that is virtually impossible. The computer will not allow the transmission to shift in a way that is damaging.

If you are talking about a manual transmission there is no difference. As far as the transmission is concerned, you can drive in first all day long.

[hotbug1776]

Also, just about every automatic I've ever been in during the last 10 years will downshift when going downhill to keep speed under control when using the cruise control. I had a friend with a Cadillac that would also apply the brakes to keep the set speed constant. Don't go insane with the downshifts, 3rd will only go so fast, as well as 4th. I would never use 2nd in a downhill situation, then again, if the road is that steep, a Vibe isn't the right car to be driving down it anyway. LOL

[CharlesinGA]

If the Vibe is an automatic, press the little button on the side of the shifter, below the handle. It will drop out of overdrive and into 4th, which is direct drive. Nothing will be harmed and the transmission is in direct drive, and may actually run cooler than OD/5th.

If this is a straight shift, take it out of OD which is the top gear 5th or 6th depending on the transmission. On a 5 speed, put it in 4th, again direct drive, no load on gears and no worse for the wear than any other gear. I don't recall the gearing on the 6 speed but you may need to drop to 4th in it also, just experiment with what holds the speed you want without braking. You won't hurt the transmission, nor the engine.

The closest I get to "mountain driving" is every year I make a trip (two last year) up I-24 north of Chattanooga and descending from Monte Eagle (especially southbound) I simply push the button on the Auto Trans shifter to drop out of overdrive. Car holds speed nicely on a grade that if I recall, is about 6-7% for about 5 miles.

DO NOT ride the brakes all the way down. That is basic Driver Ed 101 information you should not have to be told.

Charles