Is "engine braking" bad for my car?

When I’m driving I tend to use mostly the engine to slow down on the approach to junctions etc rather than just using the brakes - ie I change down through the gears and bring the clutch up slowly on each gear to slow the car down.

I was always led to believe (by my dad, who learnt to drive when cars were a little more, er, basic) that this was a good thing - “saves wearing out the brake pads” was among his reasons. Recently though, one of my friends commented on this when I was giving me a lift, telling me I shouldn’t do it because it was bad for the engine. He didn’t really give much of an explanation though, and didn’t press it for fear of having to walk :wink:

So, was he right?

Consult the words of The Perfect Master, my son.

Boy, is there nothin’ too obscure for ol’ Cec?

It’s fun. Face it, this is the main reason anybody drives a stick-shift car in the first place, as opposed to an automatic like a normal person. You get to shift gears like Al Unser Jr. and tame a hurtling hunk of steel, even if all you’re doing is going to the corner for a box of baby wipes.[/quote
That made me chuckle, and I have not the foggiest who Al Unser Jr is. But then the main reason I drive a stick-shift car (or “manual” as we quaint Englanders call them) is that nobody but grandmothers drives automatics over here…

Brakes are a piece of cake to replace. And cheap.

Can’t say the same for a clutch. Or transmission.

Yes, I always thought the logic sounded a bit funny, but you know - he’s my dad, the fount of all knowledge :rolleyes:

Still, seeing as my car is old and worn out anyway, I’m just going to keep on downshifting like Al whatsisname. When the clutch gives up, I’ll buy a new car and re-edumacate myself in driving technique…

In some situations, engine braking is justified. These situations are mostly confined to descending long, steep downhill passages of roadway, wherein one’s brakes are less than wholly qualified to provide the needed stopping power. Cheaper to change out or repair a tranny than to change out or repair your new Dopermobile 2004.
I will concede that roadway situations like this are uncommon in the US, excepting Appalachian mountain and rocky mountain situations.

As others (and cecil) wrote, it’s not the engine that you’ll damage, but the clutch, transmission, and related components. The amount of wear you’d add by downshifting varies immensely with technique. Even things like holding in the clutch when stopped instead of just leaving the transmission in neutral causes wear.

Al Unser Jr is to Americans as, say, Damon Hill is to Brits. He’s a younger member of a racing clan.

Americans (and Canadians, Japanese, and Australians?) like Automatic transmissions. The rest of the world doesn’t. I had to factory order a Toyota Corolla because I wanted it with a manual transmission and just one expensive option (side air bags). According to the dealer, about 95% of Corollas sold in the US are automatics. Move up to something larger (say, a Toyota Camry) and the percentage of automatics is around 98%. Many cars in this class (Ford Taurus, Chevrolet Malibu, Chrysler Sebring) don’t appear to have a manual transmission available at all.

Just thought I’d throw in my two cents worth. When you downshift instead of using your brakes you are taking advantage of pumping loses and no wear is occurring in the engine (other than the pistons going up and down more often) as opposed to the brake pads or linings that wear when you use them. I don’t believe the transmission is experiencing any particular wear other than the syncro rings which wear a little bit every time you change gears whether you are shifting up or down. Likewise, the clutch experiences wear everytime it slips as you shift from one gear to another regardless of whether you’re shifting up or down. But I’m sure it wears much more each time you start in first gear. That said, I think it’s usually pointless to continually downshift every time you slow down unless you’re going down a long hill or expect to need to accelerate again such as when merging onto the freeway.

Well, some people also have manual transmissions because they’re cheaper…

In any case, is this really “engine braking”? I’d always though of this as just downshifting, whereas engine brakes are something tractor trailers have that isn’t merely downshifting.

In any case, hills are a great place to limit the speed of your descent by shifting to a lower gear. Downshifting, aside from the clutch wear, presents the danger of revving your engine if it’s too fast. But if you downshift to limit your speed as opposed to decelerating, you’ll have a lot more control over your vehicle and lessen the chance of overheating your brakes. This goes for automatics as well as manuals. I never really needed to put this into practice until I was driving my car through Saltillo, Mexico last month.

Tractor trailer rigs may be equipped with a “Jake” brake. This is actually a device that maximizes the vacuum present in the rig’s motor, thereby increasing the (already considerable) engine braking provided by a large-displacement diesel motor.
Your compression ratio seems to be somewhat proportional to your engine braking ability.
For instance, a 1980s Mercedes diesel motor might have had a 21:1 compression ratio. A comparable vehicle with a gas engine might have had a 10:1 compression ratio.
When I drove a Mercedes diesel of that era, I had extremely effective engine braking, to the point that backing off of the gas quickly could make my passengers uncomfortable. I can barely imagine how a Jake brake would feel.

Oh no, another Jake Brake misconception. Jake Brakes do not utilize engine vacuum, they negate engine compression. Basically, they open the valves after the compression cycle and before the power cycle so the compressed gas is exhausted instead of pushing the piston back down. As a result, you utilize all the compression braking with no subsequent power from that compression. This is why you may see a sign at the city limits of a town “No Jake Brakes”. The sound of the compression release is LOUD. If a truck hits the Jake, everyone within a quarter mile will know it.

*Originally posted by r_k *
**Boy, is there nothin’ too obscure for ol’ Cec?

And yanks like me who have been forewarned.

A nice person told me to be sure to rent an automatic since it’s hard enough keeping on the proper side of the road without having the added distraction of left-handed shifting. Never would have thought of it if she hadn’t have mentioned it.

A very important point Unca Cec neglected to mention is that, although Little Al downshifts all the time – his shifter is sequential, like a motorcycle, so he has to downshift – he never downshifts to slow his car. That’s what the brakes are there for!!!

Al Unser, Jr. currently races in the Indy Racing League. He’s won the Indianapolis 500 twice, the Championship Auto Racing Teams (CART) national championship twice, the IROC championship twice, and he won 31 CART races in 18 years of running in that series.

5cents’ comparison of Unser, Jr. to Damon Hill is apt: both are sons of successful open-wheel racers. (Al Sr. won four Indy 500s. Damon’s dad, Graham was a two-time Formula One champ and won the Indy 500 once.)

However, his characterization of Little Al as “a younger member of a racing clan” betrays both a certain age and an unfortunate lack of attention to the racing scene. At 41, and with more than 20 years in racing, Al is one of the older drivers in the top open-wheel racing series these days.

Australians are somewhere between Rest of World and USA, I think. Nowhere near the 95-98% figure mentioned in this thread for automatics in the US, but probably more automatics than in the UK, for example.

I watched my dad drive, have had 6 motor bikes, driven both manual & automatics, always used to use engine braking. On the bikes most had 4-5 gears and you had to change down through all of them to get to neutral, (1st gear down neutral then 4 up)

Whilst working for an IT company(400 drivers), we had a bad Insurance accident record they made us all go on an advanced driving course with ex police driving instructors.

They taught me to brake progressivly up to a junction and at the last moment dip the clutch and apply the hand brake (similar to an automatic action). This still worries me years later as my question was “what if the brakes fail”. I understand about wear & tear on the transmission but I think there is cause to still use engine braking at some times.

Of cause on steep hill etc as well!

Thanks, KenGr, I didn’t know that’s what they were called. I’ve seen signs that prohibit “engine braking,” though, near residential neighborhoods. I’ve heard them and they are loud.

I think one of the reasons the United States has such a prevelance of automatic transmissions is that we don’t care about the price of gasoline. It’s cheaper than some bottled water here. Don’t Europeans like their automatics because they’re more fuel efficient (and is this still true?)? I realize that cars can be small because parts of Europe are so small, but I’d always suspected the “real” reason wasn’t because anyone really wanted to drive around in a death-trap, but because it used less gasoline. Heck, I even remember new cars in 1993 that had manual chokes for some strange reason (this was in Germany).

And to top off the fuel concern… if you’re going to be driving a subcompact with an anemic 1.0 liter engine, you’d best choose the stick. At low horsepower ratings the performance gap that favors manuals over automatics is especially pronounced.

Hey, I’m not much younger than Al. Are you calling me old?!?

P.S. Damon Hill is 43, and retired out of F1 racing a few years ago.

You mean Europeans like their manuals because they’re more fuel efficient? Which I think is true, I can’t remember exactly how an automatic gearbox works but there’s more of a loss in power through the torque converter than with a manual. It went over my head a wee bit so someone else should explain.

I only ever drive a manual and I brake to slow the car before I shift down a gear or blip the throttle to bring the engine speed up a bit to account for the change in gear ratios. I always suspected that the tug you feel as the engine slows the car is placing a strain on the transmission or some part of the engine, like someone pointed out, its cheaper to replace your brake pads :slight_smile:

A manual has no torque converter. A torque converter is like two fan blades stuck in the same sealed box, and the box is filled with molasses. If one fan is turning (due to the engine spinning it), then other fan (which is hooked to the transmission) will want to spin. This setup isn’t 100% efficient, but perhaps 90 to 95% - some of the input power will just go towards heating up the fluid.

Manuals are much closer to 100% efficient, as the clutch gives a solid (well, almost - it’s friction, sort of like a brake) connection between the engine and the transmission.

Modern automatics have a lock-up torque converter, which (as it sounds) locks up the two sides of the torque converter, making the efficiency basically the same as a manual. Note however that lock-up torque converters only work when you’re cruising - they have to disengage when you change speeds a lot, so they do nothing for gas milage in city driving.