Engine braking with a 2012 4Runner.

[zack sc]

This post is about engine braking. I realize this is a widely discussed topic, but I am posting it here for a reason as I explain below. I have a Scamp 13 with electric brakes, and my tow vehicle is a 2012 four-wheel-drive forerunner. Almost every morning I drive down a narrow paved road losing about 600 feet of elevation in a quarter mile or so roughly. I maintain a speed of about 10 miles an hour and I’m really not sure to what degree I should use engine braking versus the brake pedal.
If I shift into four-low, and use an automatic transmission setting of 3, my need for brake-pedal braking is greatly reduced. Another option is to put it in a automatic transmission setting of L, and not use 4WD. Of course there are a lot more possibilities, and because I do it so frequently, I would love to get advice as to what is best in terms of the transmission, the engine, the brakes or other considerations. I have previously gotten advice from people in all of directions.
Based on my past experience on this site, I feel like there are people here who are exceptionally knowledgeable, thoughtful and experienced, so I’m looking forward to getting some expert advice.

[Jon in AZ]

Just off-hand, I wouldn’t use 4-low on dry pavement, especially if there are turns. Your owner’s manual may have something to say about that. Just put the transmission is the lowest gear and use the brakes as needed. At the speed and distance you’re talking about, there’s little likelihood of overheating the brakes.

[Raspy]

Using 4WD on dry pavement will cause a lot of tire wear and is hard on the system, unless it has a "full time" option. Modern vehicles don't have a 2WD low option. Dry pavement will not have a traction problem, so 4WD is not needed anyway. Avoid 4WD.

Using a low gear to raise the engine RPM is fine, and will give more engine braking.

Riding the brakes all that way, almost every day, will definitely shorten the life of the brakes.

It seems your best option is to select L on the tranny, and brake as needed.

[Darwin Maring]

Raspy is absolutely correct. The only way to go.

[julmar]

I have a 2012 4runner. Yes you can select “s” instead of “d” then 1st 2nd 3rd. Whatever you want. I use it all the time for steep grades or going uphill.

[zack sc]

Originally Posted by Raspy

Using 4WD on dry pavement will cause a lot of tire wear and is hard on the system, unless it has a "full time" option. Modern vehicles don't have a 2WD low option. Dry pavement will not have a traction problem, so 4WD is not needed anyway. Avoid 4WD.

Using a low gear to raise the engine RPM is fine, and will give more engine braking.

Riding the brakes all that way, almost every day, will definitely shorten the life of the brakes.

It seems your best option is to select L on the tranny, and brake as needed.

Thanks all. Thanks Raspy. When I put it in L (2WD) then I hardly need to use the brake pedal much at all, and so the trailer brakes are not activated much. Is that okay for my tow vehicle transmission, engine and ...?

Does the year of the TV matter (mine is 2012)? Some people say that the newer 4Runner transmissions are not as robust.

[Raspy]

I can't imagine how you could hurt the trans by doing what you are doing. That's why they give you an L option.

[Jon in AZ]

“L” just means first gear. As long as the engine revs don’t get too high, you’re fine. As Raspy says, this is what it’s for.

[Bill in Pittsburgh]

I cannot speak for 4 wd as I have never owned one. As per engine breaking I can say with confidence no damage to your engine unless your engine is pushed beyond acceptable rev limits for that engine. I have a brother-in-law that goes to extremes to get high fuel efficiency. He would put his vehicle in neutral on long downgrades. It took some time to convince him that his electronic fuel injection was feeding his engine fuel while idling down hill in neutral and that no fuel was being fed to his engine while engine breaking.

[Steve Carlson]

I downshift my FJ Cruiser (same drivetrain as a 4Runner) on downgrades all the time when towing my camper. Especially if you downshift before you get going too fast, it really helps save your brakes from overheating.

[Air Doug]

I downshift to an appropriate gear all the time in my 2017 4Runner when going downhill with the Snoozy. And for the first couple of years the trailer brakes weren't even working. After ~50k miles on the 4Runner, the brakes are still original and fine. These things have big brakes!

Interestingly, in the 2017, when you brake while going downhill, the 4Runner will automatically shift to a lower gear. So that is even more reason to say that it is okay to do so manually.

As an aside, most Snoozy's have surge brakes which will activate under engine compression braking.

[kolocar]

I have always understood that engine braking downhill does not hurt the engine (with the rev limit caveat mentioned previously) and definitely can keep the brakes from overheating and/or glazing.

We have driven up and down Pike’s Peak twice. Both times coming down I shifted manually into 1st gear to avoid hard and repeated braking. Was driving an earlier model Chevy Tahoe with 4-speed automatic transmission.

A bi-product was watching the engine temperature drop below normal operating temperature since there was no stress on the engine downhill. Also there’s a ranger station part-way where they check the brake temperature. If your brakes are too hot they want you to wait there until they cool enough for the rest of the downward journey. I have never had to rest there because of brakes overheating.

[David Marowski]

Also remember that when using engine braking in 2WD, your rear tires wear faster because they are the only ones doing the braking.

[Bill in Pittsburgh]

Also remember when using your brakes on 2 wd or AWD your front tires wear faster as they do the majority of braking plus they are asked to steer at the same time.
We can't win, tires are going to wear out.

[Jon in AZ]

Exactly. And the short 600 yard descent at slow speed described in the original post won’t amount to a hill of beans in the big picture. How many times a day are you going to haul the trailer up and down that hill?

On a serious note, when it is necessary to use the brakes (along with downshifting) to control speed on a longer descent, it is better to brake in short, firm bursts with cooling time in between. Continuous application is more likely to lead to overheating, brake fade, warped rotors, and other bad stuff.

[CharlesinGA]

Originally Posted by Jon in AZ

Exactly. And the short 600 yard descent at slow speed described in the original post won’t amount to a hill of beans in the big picture. How many times a day are you going to haul the trailer up and down that hill?

On a serious note, when it is necessary to use the brakes (along with downshifting) to control speed on a longer descent, it is better to brake in short, firm bursts with cooling time in between. Continuous application is more likely to lead to overheating, brake fade, warped rotors, and other bad stuff.

No, he said it was a 600 foot drop in elevation, in a quarter mile, which is a 45% grade. Makes me wonder how they paved it. That's equal to having a 12/6 roof or close to it.

Charles

[zack sc]

Originally Posted by CharlesinGA

No, he said it was a 600 foot drop in elevation, in a quarter mile, which is a 45% grade. Makes me wonder how they paved it. That's equal to having a 12/6 roof or close to it.

Charles

The part I’m sure of is that it’s a 600 foot drop. That’s the change in elevation from where I sleep to where I hang out during the day. Your math is making me think that maybe it’s a half mile or 3/4 of a mile or maybe a little more that it occurs over because, it’s not 45°, but it is quite steep. I’ve been going down in L, as people suggested, and revving at about 2 to 3000 RPM., Which seems to work really well. I appreciate all the experienced seasoned and wonderful advice.

[Jon in AZ]

Originally Posted by CharlesinGA

No, he said it was a 600 foot drop in elevation, in a quarter mile, which is a 45% grade. Makes me wonder how they paved it. That's equal to having a 12/6 roof or close to it.

Charles

You’re right, I confused the numbers, though 600 yards is actually more than a quarter mile. Still, that would be absurdly steep for a highway vehicle, of course. My point stands. The distance is so short and the speed so slow there would be no measurable wear on any components from using the lowest gear and using brakes as needed.

2000-3000 RPM is nothing to a modern V6.

[CharlesinGA]

Kinda reminds me of a Youtube video I watched earlier this year. The people were visiting a city owned campground around a lake just outside of town, but on much higher ground than the town. The title of the video included 17% grade, which I could not believe. I used Google terrain to determine the beginning and ending elevations, and the distance, and came up with about 11% which, from watching the video was probably about right, quite steep even still. I did some more looking and the video creators had got the 17% from a comment someone had posted on Freecampsites dot net or one of the other similar web sites. They just assumed it was correct. The city website noted it was a steep grade, but didn't say what, and street view didn't show any signs posting the grade.

Charles

[Raspy]

Here's my favorite grade. 26% on the Sonora Pass.

I've travelled this road many times and it never gets old