#NVH

With the pandemic altering daily life for just about everyone alive, the slogan “the new normal” has exploded into popular parlance. Everything has changed and nothing, allegedly, will ever be the same. Governments are issuing stringent lockdown orders the likes of which haven’t been seen in our lifetimes, companies are initiating aggressive new health protocols, and gigantic tech firms are deciding what constitutes harmful information online as they act as censors for the public good. Worst of all, there’s little reason to drive anywhere — unless you’re planning on bugging out to live in the woods.

Whatever form society takes after the pandemic subsides, those eerily empty roads probably won’t be among the lingering changes. People are already chomping at the bit to get out there and do something, meaning most folks will return to their road-going ways. Which doesn’t mean COVID-19 won’t have an influence on future designs. Automakers are already mulling the possibility of adding better air filtration systems as a selling point.

Doug updates us:

Hello, just an update on this problem: an indy shop I had used before on another Mercedes put my 2007 S550 on a lift and diagnosed it with a failed transmission mount. Just a little $60 part at the tail end/output end of the transmission.

Because it had failed, the transmission was essentially resting on the frame crossmember, pretty much directly beneath the center console/armrest where I felt the vibration so acutely. I was skeptical it could be that simple/cheap, but sure enough it eliminated the problem! It’s super smooth and silent now. The other likely culprits, the flex discs at each end of the driveshaft and the center carrier bearing for the two-piece drive shaft, all look new and can’t be original. They must have been replaced by the first owner.

Doug writes:I have a 2007 Mercedes-Benz S550. I accidentally bought it in 2014 off eBay (long story) for about trade-in ($13,000), with 150,000 miles on the odomater. In a twist of good luck, it turned out to be a one owner car and using CarFax I was able to see and verify that it had been maintained by the selling dealer right up to a few weeks before its eBay appearance. A call to the dealer confirmed the complete service history. Even the brake pads and rotors were new, and it had a newish and very expensive set of Michelins. Almost three years later, it has been very reliable for my teen daughter and has 180,000 miles. It had a few quirks I have fixed myself (clogged charcoal canister, minor trunk leak caused by a missing rubber plug, sticking power driver seat) and only one real repair (dead stereo amp rebuilt by Becker).Now that my daughter is off at college and content with a ZipCar, I am driving it and intend to keep doing so. I have noticed a vibration in the center console area of all places, while driving around town. You feel it through your arm resting on the console lid. It’s a deep vibration, if that makes sense — coming from under the car.You don’t feel it in the seat, nor do you feel it in the steering wheel. You do not feel it at a standstill, just at 20-30 mph. It goes away at higher speeds, and the car is rock solid and smooth as glass at 75 mph. I am stumped as to the cause, and with the age of the car, I don’t want to set a dealership or even an indy shop loose on it without more of an idea of the cause. I was thinking maybe a motor mount, but it seems like I would feel that all the time, and especially at idle, which I don’t. I was wondering about maybe some kind of driveshaft or transmission mount or connection point, but it seems like a fault that would get worse with increasing speed instead of going away. Do you have any ideas?

U Relay Got A Problem? (photo courtesy: APaGttH)

TTAC Commentator APaGttH writes:

Sajeev!

Long time listener, first time caller. The patient: a 2005 Saturn Relay FWD3 with 151K miles, GM 3.5L V6 and 4-speed automatic. I am the fifth owner and this is our grocery getter and general abuse vehicle. I’m the longest owner – 4 years and about 55K of those 151K miles have been in my garage. I can’t comment on how well it was cared for from year 2 to year 6, but I have done everything by the book since 96K miles.

The Saturn developed a rough idle of sorts about a year ago. I swapped out the spark plugs, changed the fuel filter, and flushed the fuel injection. The car continues to idle rough. No CEL and no CEL history.

My 98 booming with a trunk of funk, Don’t Believe the Hype. (photo courtesy: Ford)

GCH writes:

Sajeev:

Could you/somebody please explain what a “flat plane crankshaft” is in the new Mustang GT350, and older Porsches and Ferraris?

I have seen numerous references to it online and in print but nobody, including Wikipedia explains it in non-calculus terms.

photo courtesy: www.flyinmiata.com

TTAC Commentator johnny ro writes:

Hi Sajeev,

So I like my new 2010 Miata Touring (second car and half time daily driver), and picked it because it looked good on the side of the road by my house, low miles (19k), priced OK(mid 14’s), I had the dough saved up for a bike and I am happy with the current Vstrom, and last but not least it is an automatic. The OEM suspension seems firm to me but obviously not race ready. Roads in Northeast are usually not-so-new ranging down to horrible. Miata people say its mushy and floaty, those who want to autocross or race.

We had two updates to a previous Piston Slap this weekend, surprisingly within two hours of each other. Let’s hear from the OP first:

TTAC Commentator sundvl76 writes:

Sajeev, reporting back:

You may be interested in this, if for no other reason than to add to your diagnostic toolbox; my experience certainly can’t be unique: Several comments below your post also suggested the motor mount(s) as the problem. I more recently discussed this with a professional wrench acquaintance, who also said that the mounts can be expected to go south after ~80K miles; he suggested using a padded floor jack to lift slightly on the engine during a time when I detected the “rough” idle (the oil pan on this vehicle, and maybe all Duratec engines, is waffled cast aluminum). Bingo! The vibration ceased when I did that.

TTAC Commentator sundvl76 writes:

Sajeev,

Your post of 2 Mar 2011 was a great explanation regarding the cause of the “T” joint oil leak I’ve been experiencing. No one on any of the normal Ford sites has been able to pinpoint the problem, so I thank you for the information. (I’d discovered the source, but didn’t know the cause/fix until your post.) TTAC is now on my Favorites list!

While Noise, Vibration, Harshness (NVH) control built into a modern machine is normally your friend, it often kills you with kindness. That’s when NVH hides things that should never be hidden. Shameful. Cowardly. Pathetic. And while I wasn’t expecting this level of deceit when merely replacing the shift knob on the otherwise stock transmission in my 2011 Ford Ranger…well it was thrust upon me. And it can happen to you, too.

[Editor’s note: This piece was originally published in February 2009, and like so much of TTAC’s content, it’s timeless enough to deserve another moment on the front page. Enjoy!]

Rolls-Royce used to advertise the fact that their cars were so quiet that the loudest sound you heard was the [analog] clock ticking on the dash. Who said the British don’t do hyperbole? As a quiet car connoisseur, I’d have to say a Clinton-era Cadillac provided the quietest ride I’d ever experienced; if the time was one of peace and prosperity, then so was the car. Nowadays, automakers are telling us that their cars are quiet, or at least quieter than ever before. I’m not buying it. A number of recent drives have been notable for their aural uncouthness. So I set out to find the truth about automotive sonic signatures. Has nostalgia dimmed my memory (if not my hearing)? Is progress on the noise suppression front been less impressive than industry propaganda would have you believe?

What keeps powertrain engineers up at night? C’mon, get your mind out of the gutter. The move towards downsized, turbocharged engines is creating a number of new engineering challenges, and “torsional excitations” grabbed the spotlight at this year’s Society of Automotive Engineers Congress. Steven Thomas, manager of Ford’s global transmission and driveline, research and advanced engineering, illuminated the issue [via Wards].

As we reduce the engine torque, particularly just off idle prior to the boost coming on, we’re going to adversely impact the ability to accelerate the vehicle. I would challenge you all to think about new ways of dealing with this. We could really use new designs to deal with these challenges to optimize the fuel economy, but at the same time deal with (noise, vibration and harshness) and performance issues presented by these new engines.

The problem: the increased inertia of forced-induction engines. The practical example: a turbocharged Fiesta. A worthy adversary, a worthy cause. Let’s do this.