Home Forums Hunting & Shooting Hunter's Campfire Engine braking (downshifting) with a automatic transmission?

The general answer to downshifting autotrans for engine braking is that it has been good practice (gas engines) but more recent innovations with computer controlled trans features make it wise to know the facts of your own vehicle's setup.

Diesel engines - another matter - engine compression retardation not much help. On my 1952 Mack with the big valve Cummins, the Jake brake (Jacobs exhaust brake) is a big plus. The 2003 Duramax is coupled with an Allison which has an inbuilt retarder. Very good. The 2001 Dodge Cummins is 6 speed manual and will give some egine braking in lowest gears - but trailer brakes are a necessity with that setup.

Don't do that - a brake job is cheaper than an engine repair bill. You're driving a Nissan Frontier, right?

2000 Ford F250 V10. 213k+ miles. I drop out of OD gear all the time here. Cajon Pass, Sherwin Grade. I 40 dropping into Kingman, I15 into Vegas. 213K on my original trans. Just a few brake taps to keep the speed in check and it's all good. I also did the same with a Suburban with a TH400 trans. I guess brake fade isn't a thing to be concerned about for some people.

Transmission designs have gone thru many iterations over the years, but all allow for "engine braking" via downshifting (loading the back side of the gear).

Problem isn't replacing transmission or replacing brake pads. The real issue is bleeding enough energy without boiling the brake fluid and totally losing brakes. It's common to employ brakes sparingly while downshifted.

Yep, the base model 2wd 2.7 L inline four, 2019. No automatic downhill braking software.

I’m learning here that there’s transmissions and then again there’s transmissions.

Fortunately I’m back in Texas, not that big an issue around here.

Brake fade?

Yep.


And brake fires too.

Not sure where Tyrone lives, but some "hills" I've been on will and have eaten up more than one set of brakes on about every type of vehicle going down them.

And it will do it even faster on 9% grades which are not uncommon in some places. (Interstates excepted)

Birdie, with your little four banger, you will not get much compression braking anyway. But it is not like you are running 18,000 gvw.

If you come out West and you see that sign which says "Warning 6 miles 6% downgrade ahead. Trucks use lower gears." You would be well advised to grab the shifter and select a lower gear. About 3'rd on a five speed, 3'rd on a four speed, or 2'nd on a three speed. Even if you are only carrying 1000 lbs in the back.

You definitely want overdrive locked out.

Then apply brakes judiciously to keep the engine well under redline.

It is a hell of a lot better to hit those downhill freeway curves at 50 mph and have the full potential of your brake system to bring you to a stop, than it is to watch the speedo creeping toward 80 coming into a turn and your brakes have already faded to nothing.

We have been using the tranny this way since trannies had two speeds. A few weeks ago I was selecting gears on a 2015 Chevy with a six speed towing a 5000 lb boat down into and back out of Hells Canyon.

Frequent shifting, slipping clutches or bands, and high heat are the destroyers of transmissions.

You're not abusing an automatic transmission by downshifting it manually and taking advantage of engine braking, it's designed to do that. You obviously don't want to slam it into first while you're doing 70 headed downhill but gently downshifting is no problem. You are, however, abusing your brakes by riding them instead of downshifting while coming down a grade. That practice will cause you to replace your brake pads as mentioned, but that's only if you're lucky. If you make a habit of it you'll quickly be replacing rotors or maybe even the whole vehicle when you lose the brakes and go rolling off the side of a mountain.




That couldn't be further from the truth. Modern automatic transmissions are leaps and bounds more reliable than those of 10-15 years ago. They're so good now that manufacturers don't offer manuals on most models. In the past if you wanted to keep a vehicle a long time and didn't want to deal with rebuilding the transmission every 100,000 miles you bought a manual, now that's no longer the case.

My 4Runner 4wd has a descent mode. I hate it. For steep/rocky descents I use low range and shift appropriately for the terrain. I use the shifter frequently on hilly dirt roads in 2wd and have done so for years w/out a problem.


mike r

Our RAV4, 4cyl, auto trans, has a sport mode. If not mistaken, the owners manual states to slide it into sports mode and use it like a standard transmission on steep grades. It gets used that way every time I descend OR 66 into Ashland. I don't know the percent grade of that hill, but I know it's more than 6% and likely closer to 9% in a lot of stretches, with 20 MPH corners thrown in for fun. At times I'm in the 2 gear instead of "drive".

I'd prefer not to burn up a set of brakes every 6 weeks on my trips over there.

"Engine braking with an automatic transmission, good or bad?"

I've done it a few times and never had any problems.

Some good info here.
Some funny crap.
Some just plain BS.


You ain't gonna hurt anything downshifting a newer auto.
Just watch the tach and don't get crazy.
The nanies wont let you overspeed and drop a valve.
But if you try to go too low at higher speed, it ain't good for stuff.


As to real trucks, with electronic engines and retarders
Most meet or exceed pulling HP.
Meaning a 480hp engine is at 480hp braking or more.
The old rule about using one gear lower was with no retarder
And diesels have little hold back, due to no throttle plate and no pumping loss.
(IE. No vacuum)

But with a good retarder you can go down a hill as fast as you go up it in the same gear. And probably never touch the brake.

I always thought the one gear lower rule was stupid.
Think about it. It only applies if you turn around and go back down the hill you just climbed. One side might be different. You might be dropping into a canyon. Or, living here at the Allegheny plateau, you might have climbed it
miles ago. And the east is way worse than many think. I've run 48 personally.
Most of the big western passes are famous and well marked.

We routinely have western drivers have issues here. Our grades are not usually as long, but steeper and no fanfare. Complacency anywhere can kill.

Dillonbuck.

You're right about You've got a few steep hills there. But not many that are 5 + miles of 9% grade going into a river canyon.

When you crest on of those PA hills though, it's best to know what's on the other side though. I'll attest to that. Can be hard to stop with an Amish hay wagon pulling out in front of you.

Over 250k miles on my 2010 Toyota 4-Runner with 5-speed auto trans. I use the tranny/engine combination all the time coming down our steep grades here in the Rockies with never a problem. Except for no manual clutch, the technique is pretty much exactly the same as with a manual transmission.

The road grades on I-70 east and west of the Continental Divide are some of the steepest and longest in North America. That's crazy talk controlling descent speed with just brakes.

My truck does it if cruise control is on. And in tow haul mode if you brake going down hill.

No big hills here, but my truck will engine brake in tow-haul on declines. 10spd F150.

Gotta say, Salt River Canyon was a surprise.
Well marked, followed the signs buy couldn't quite figure out
how I was gonna go down so much. Hadn't went up.

The rim was awesome.

Amish Freightliners are a thing.

So is our propensity to have red lights, really sharp turns,
or a dam T-intersection with a rock wall across the T, at the bottom
of a steep grade.

This x10

Traveling I-70 across Colorado with my 2015 Frontier towing 1500 pounds.
Auto trans is already locked out of OD.
There is usually so much traffic I just try to maintain a reasonable speed when climbing.
When we hit the down grades I stay right and down shift one gear.
Generally can run about 50 to 60 mph and don't have to overuse the brakes.
Couple years back a buddy was following with his Ram and similar trailer weight.
When we stopped he asked about my brakes. .
He was riding his brakes and was using his up pretty bad.
Had to explain use the transmission gearing & engine braking and don't be in hurry.
We took a 20 minute rest so his brakes cooled down.