Going Downhill Manual Shift...Brakes Or Tranny?

[pulykamell]

@Balthisar

I question whether gravity is enough to make a situation dangerous, i.e., you just don’t go that fast.

I’ve driven plenty of hills on windy mountainous roads with hairpin turns that if you didn’t control your speed with (preferably) your transmission or brakes, you’d most likely end up dead in a ravine. Not in Illinois, of course, but Colorado, San Francisco, through the Appalachian states, Bavaria, etc.

[Sycorax]

I (female) have always used the tranny to slow down; my car is 16 years old and still on it’s original tranny.

[DesertDog]

@Balthisar

Everyone’s mentioning hills, how fast do you coast down them? I’ve gone down large, long grades in everything from subcompact manuals (Civics), to huge 2.5 ton manual trucks (military), and in a whole array of automatics from midsize (Fusion) to giant SUV’s (Expedition). In my experience, there’s always some type of terminal velocity that’s reached within the bounds of what’s manageable. I’ve often found myself needing to use the accelerator when going down a hill in order to avoid slowing down beyond the speed I want to travel at.

Don’t get me wrong; you have to anticipate other traffic, curves, surprises, and so on, and sometimes dropping it down a gear – in an auto or a manual – is needed prior to making a new maneuver, but barring other contributory factors that might make a situation dangerous, I question whether gravity is enough to make a situation dangerous, i.e., you just don’t go that fast.

I drove from Carson City to Crystal Bay (North shore of Lake Tahoe) five times a week for three years. There were 13 miles of 6% grade from the top to the bottom into Carson. Luckily, although curvy, the grade was constant and I quickly learned that if I topped the pass at this speed in the 3rd gear, I could idle all the way down without touching either throttle or brake, subject to traffic. Oh, and ice, of course; winter descents were more tricky.

By the same token, ascending that grade quickly made the tranny fluid look and smell like burnt coffee. A flush and cleaning the filter made it almost good as new (Toyota made good transmissions).

[butler1850]

@masterofnone

Well there’s hills and then there’s hills. Some places in the midwest there are hills the locals will point out that I can’t even see. You’d have to get out and pour a glass of water on the road to tell if your climbing or descending. Here, not so much. My daily commute has a 4.5 mile section with 1000’ of vertical drop. The top half of that road is what I would consider a mild slope, and coasting would be possible with an occasional tap of the brake or gas. The bottom half would burn up the brakes in short order, and would be impossible to coast down safely.

So says the man in a state where the speed limits on “secondary roads” is a CHALLENGE, not an upper legal limit.

Windy roads, and long downhills in mountainous country, especially if unfamiliar to the driver, can tax any car’s brakes.

Even in “flatland country” of southern NH, there are some hills on my commute that will accelerate me from the speed limit of 40mph (or my normal 45) to 55 or 60mph on the downhill. Not particularly unsafe, but well into the ticket zone if there happens to be a cop at the bottom. (which isn’t unusual for one to be driving by)

[masterofnone]

@butler1850

So says the man in a state where the speed limits on “secondary roads” is a CHALLENGE, not an upper legal limit.

The speed limit on that road is 40, even though it has hairpin turns that logging trucks can’t maneuver without backing up, and in several spots the road is a car and a half wide.

[SpoCkss]

@tetranz

Shifting down and using the engine braking feels like the cool thing to do (some of the point of having a manual I guess) but … as someone pointed out to me, clutch, gearbox and engine cost a lot more to fix or replace than brakes which are supposed to wear out.

If you press a little the throttle when the clutch is down, so that the revs go up a bit and only then you release the clutch for the downshift, (in racing terms its called “blipping” or “heal and toe” technique, i suppose there’s very little harm to the clutch.

[SpoCkss]

@Balthisar

Everyone’s mentioning hills, how fast do you coast down them? I’ve gone down large, long grades in everything from subcompact manuals (Civics), to huge 2.5 ton manual trucks (military), and in a whole array of automatics from midsize (Fusion) to giant SUV’s (Expedition). In my experience, there’s always some type of terminal velocity that’s reached within the bounds of what’s manageable. I’ve often found myself needing to use the accelerator when going down a hill in order to avoid slowing down beyond the speed I want to travel at.

Don’t get me wrong; you have to anticipate other traffic, curves, surprises, and so on, and sometimes dropping it down a gear – in an auto or a manual – is needed prior to making a new maneuver, but barring other contributory factors that might make a situation dangerous, I question whether gravity is enough to make a situation dangerous, i.e., you just don’t go that fast.

say that to train drivers

[pulykamell]

@SpoCkss

If you press a little the throttle when the clutch is down, so that the revs go up a bit and only then you release the clutch for the downshift, (in racing terms its called “blipping” or “heal and toe” technique, i suppose there’s very little harm to the clutch.

“Heel and toe” technique refers to braking and blipping at the same time (usually with double clutching, more on that in a second), not the maneuver you’re describing there. What you’re describing is called “rev matching.” There’s also the double clutching method, which apparently is not necessary for synchromesh transmissions, but is the way I was taught, which goes: clutch in, neutral, clutch out, blip, clutch in, shift, clutch out. Double declutching revs brings the layshaft and engine up to speed, while clutch-in rev matching only revs the engine and the synchromesh still has to work to bring the layshaft up to speed with the engine when you throw your clutch back out.