Do trucks have to be so noisy?

Modern cars are getting quieter these days. You can barely hear them approaching, apart from the sound of friction of the tyres on the road. Aside from the minor issue of not noticing something approaching as you cross the road, I like the quieter traffic that we have had in the past decade.

Except for trucks, which continue to be loud belching roaring monstrosities. Is there a reason why they’re still just as loud and cacophonous as they ever have been? Are there moves to make them quieter beasts too?

I work at a drive thru store…and I’d say it’s not just that trucks are loud…it’s that a lot of people with mid 80’s or older trucks sometimes let them get in bad shape…making them ultra-loud…and then there are guys who want the truck to be loud so they make it louder…I often do not see this when the person is driving a sebring or focus or something…

TANSTAAFL Quiet exhaust systems usually come at the expense of power which isn’t a good tradeoff for trucks where the priority is maximum efficiency and no restriction on peak torque when it’s required.

That said I don’t think trucks are as loud as they used to be, particularly with turbochargers which can dampen the exhaust pulses. Listen for a whistling sound that rises and falls in pitch as the driver shifts through gears. Compare that to an old army deuce and a half which absolutely roars.

A lot of large trucks are diesel. Diesel is a lot louder than gasoline. Although diesel cars are proportionally louder than gasoline cars, there are very few diesel cars in the US (to my knowledge only VW and maybe Mercedes sell one).

That seems like a fair answer. I figure there had to be some good reason for it.

Quiet truck technology exists, but it’s been suppressed in a calculated conspiracy to drive the OP gradually insane.

Oops, forget I said that.

A lot of noise from trucks comes from the use of engine brakes, also called Jake Brakes. Truck drivers like Jake Brakes because it uses the compression of the engine to slow the truck down, which means it’s not burning up brake pads, so its cheaper for maintenance costs. The down side of Jake Brakes is that the engine becomes really noisy when you use them, so much so that Jake Brakes are actually banned from use in many places.

Also, trucks used by businesses tend to be kept in service much longer than cars. It’s not uncommon to see 15 (or more) year old trucks still used every day for delivery work. They are built sturdier in the first place, and usually carefully maintained, so they last longer.

This means that it takes quite a but longer for old, noisy trucks to be replaced by newer, more quietly designed trucks.

As a former truck driver there is one more thing that springs to mind. A truck engine is several times larger than car engine. Size makes it harder to dampen the sound.

Most truckers aren’t jerks, and will self regulate. I seldom have heard the use of engine brakes in the United States, and then only in certain areas – never in populated spots. Where I’m currently stationed, though, you’d think (and probably be right) that these trucks just don’t have conventional breaks. It seems that all they use are their engine brakes, and it scares the bejeezus out of me every time one of those SOB’s do it when next to me. And this a populated, urban, middle class area!

During my internship, I lived in a tiny town that was the only route for trucks going to and fro. Like most construction jobs, these guys were on the road at 5:30-6:00. The problem is that I lived on the street they used and it was enough of an incline that they would hit their jake brakes RIGHT NEXT TO MY APARTMENT AT 5:30-6:00 EVERY MORNING. The ones going the other way would of course downshift and rev up to get up the hill. At 6am.

The folks at Jacobs get pretty unhappy when people refer to all engine brakes as ‘Jake Brakes’, and they like even less when a sign is put up banning ‘Jake Brakes’. Different companies manufacture engine brakes, calling them all Jake brakes would be the same as calling all cola drinks ‘Coke’. Jacobs claims that a jacobs engine brake is not loud on a vehicle with a proper exhaust system :rolleyes:

Unfortunatly many drivers use the jake brakes for normal stopping or even slowing down in traffic. Some drivers even leave it turned on all the time (The engine brake will not activate while the gas or clutch is pressed) and lift off the gas to activate it when they want to slow down a bit :mad: . There are drivers who use the engine brake to bring the engine speed down between gears to allow faster shifting - You hear them pulling away from a stop --Voooorm, braaapt, vrooooom, braaapt, etc.

As far as normal engine noise is concerned some of it is necessary due to the size and power output of the engine. However many of the drivers that own their own rigs are in the same group that puts ridiculously loud pipes on their Harleys and mufflers with huge outlets on Civics, IE idiots who think a louder vehicle is ‘cooler’.

Around here there is custom exaust place whose ad says “turn your ‘going to the market’ truck int a ‘get me noticed’ truck”. it might might be chrome and other visual things, but I think they are also going for sound.


I read something to the effect that trucks had to have some exhaust restrictor in place. This could be a muffler or a turbo. Since many trucks run turbos, they could get by without having a muffler. This might have been in regards to diesel pick up trucks, not semi trucks, and I can’t find a cite handy.

All big trucks I have seen run a turbo. On the exhaust there is not much that looks like a muffler to me. All the exhaust parts I see are just pipes so it could be that trucks are allowed to count the turbo as a ‘muffler’. I will look at my truck a little closer tomorrow to see if I can find anything that looks like a muffler.

BTW - I assumed this thread was about big trucks and not pickup trucks/SUVs.

Yes, I’m talking about bigger trucks, from ‘delivery’ sized to 18 wheeled monstrosities. Pickups, which we call Utes or Utilities, are just the same as cars, mostly, at least in terms of the noise I’m talking about.

Per the PA motor vehicle inspection requirements, all Medium and Heavy Trucks and Buses:

Interestingly enough, there’s a discussion on an LJ community for disabled people where some blind people are airing their concerns about exactly the opposite thing as you guys. If anyone’s interested, I’ll dig up cites.

Apparently hybrid and electric cars are quiet enough that several of them have had close calls when trying to cross the road, because they depend on listening for traffic to figure out when it’s safe to cross. **elenfair ** knows more than I do about service animals, but it sounds like sometimes the animals get mixed up with the lights or the person tries to override the animal’s call.

This is something that’s never occurred to me, but then, I’m the deaf one in the bunch :slight_smile: