The Truth About Cars » imbalance The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. Sun, 27 Jul 2014 20:45:49 +0000 en-US hourly 1 The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. The Truth About Cars no The Truth About Cars (The Truth About Cars) 2006-2009 The Truth About Cars The Truth About Cars is dedicated to providing candid, unbiased automobile reviews and the latest in auto industry news. The Truth About Cars » imbalance Piston Slap: To Love, To Hate Aftermarket Rimz (Part II) Tue, 12 Nov 2013 13:11:24 +0000

Sajeev writes:

In our last installment of this particular ‘slap, a reader had a question about aftermarket wheels.  The solution was rather simple, the wheels discussed were not hub-centric.  But I also mentioned a horrible “death wobble” problem with my aftermarket reproduction SVT Cobra wheels on my Fox Cougar, solution TBD.  It was a big problem until…

photo 1I switched out the junky/unsafe lug nuts (bottom) that came with my aftermarket wheels for some OEM (top) units! Unsafe how? While the bevel that seats the lug nut into the wheel was identical, they were both a thin casting AND completely hollow. More to the point, that chrome end is actually a PLASTIC CAP giving the appearance of a solid casting!

NOTE: sadly, out of blind rage that I risked my life with horrible lug nuts, I threw away the actual problem units. These higher quality aftermarket lug nuts are for photography purposes: imagine a snap-in chrome center on this skinny+hollow design and you get the full picture.  

photoAnd the only reason this happened? My Ranger (pictured here after running a RallyCross) received a healthy wheel upgrade, requiring chrome lug nuts to complete the look. After installing “good” aftermarket chrome lug nuts and these Alcoa forged alloys (shaving 40-50lbs of unsprung weight) the original FoMoCo lug nuts went on the Cougar’s 1993 Cobra wheels and presto…no more death wobble.

Last week I finally drove the Cougar on a notoriously “wobble inducing” stretch of Houston highway and sure enough, the problem is 99% gone. Hence the update you are now reading.

Moral of the story: check the basic components of any system, even if they are “new” and seem to be high quality. Because, odds are, it’s something simple causing the problem.

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Piston Slap: To Love, To Hate Aftermarket Rimz Thu, 28 Mar 2013 15:24:02 +0000 Lance writes:

Hey Sajeev,

A long time (since roughtly 2006ish) TTAC reader, I thought you might be able to help me out a bit, or point me in the right direction. My car (2007 Honda Civic Si Sedan, 17300 miles when bought used off lease, now currently around 39000 miles) vibrates terribly at highway speed. Starts around 55mph, continues to increase until about 80-85 where it begins to smooth out again.

Oddly, the vibration seemed (at the time, about a year ago or so) to have cropped up “overnight” (I don’t drive on the highway often, maybe once or twice a month) and at the time I hadn’t had the car up to those speeds in quite some time, probably about 3 weeks or so. I certainly didn’t recall any vibration the previous trip I took with any highway speeds, but there sure was one obvious then, and it’s gotten a little bit worse since I first noticed it. I’ve been living with it ever since, but I’m getting fed up.

The vibration is not felt in the steering wheel (aside from the steering wheel being a part of the interior of the car, the wheel dosn’t shake side to side or anything like that), it is felt throughout the entire interior of the car as if the vehicle is sitting in a giant paint shaker. Riding in the car at highway speeds feels as if the car was built with the purpose of being a mobile massage chair. As I can’t really drive everywhere at speeds in excess of 80mph, I’d like to find the cause.

The car was aligned and the wheels balanced shortly after I first detected the issue. Of course, the honda guys told me they couldn’t guarantee a balance on aftermarket wheels (which came with the car when I got it, cheapie 18″ ICW racing wheels shod with brand new cheapie Fierce tires if it helps to know the makes/models). They did get the alignment right, the car did and still does track straight down the road as long as the road is smooth and flat and the steering wheel isn’t doing it’s tick/pulse thing (more on that below). I thought the balance would be the problem, but after that didn’t correct the issue I began inspecting the tires for wear patterns and was flabbergasted by what I found.

The wear pattern doesn’t look like any normal sort of wear that I’ve ever seen. It certainly doesn’t look like anything listed in the following image. The closest thing it resembles is an order of cupping, maybe with a side of camber wear… but it’s on both inside and outside edges, and the worn spots extend for about 6 to 8 inches or so, and do not always match up with a worn spot on the opposite side of the tire. If anything, they’re offset from each other a little, side to side. All 4 tires are worn in this manner to some degree. I don’t currently have any photos, the wear is hard to see in person because it’s spread out over a large area. The only way to tell is to notice that some of the shallower grooves in the tread disappear for a few inches before reappearing. Can’t really feel it by running my hand over the tire either. Very, very weird.

The car drives straight, handles fine. Nothing about the handling or alignment causes me concern from a driving-the-car perspective, but the weird tire wear must be caused by something.

That bit about the steering “tick”: The steering wheel has a little bit of a pulse, or tick to the right every so often at highway speed, but that is unrelated to the vibration, and it doesn’t always seem to be present. Minor annoyance, sometimes I don’t even notice it.

The only other thing of note: My family lives in the country, and visiting them means about 15 miles of unpaved road driving at the end of a 4 hour drive. When I first had the car I took that section pretty slow, but even 35-40ish mph was still a pretty hard hit on the tires in a couple places (an embedded chunk of rock I couldnt see which I hit with the tires on the passenger side, and an entrance onto a bridge that all 4 tires hit, which was VERY rough, enough to make me concerned that I might have damaged tires, wheels, even suspension parts, but the honda guys said everything looked ship-shape aside from the alignment. My dad thinks I may have shifted belts in the tires since they’re pretty cheap things and who knows how well they’re really made. My research online tells me this probably isn’t much of an issue but that’s why I’m writing to you!

If you have any ideas what might be the problem, I’d be glad to hear it. I’m thinking of putting lighter rims and new tires on shortly just to have a reprieve from driving a giant red massage chair on wheels. I’d hate to put new stuff on just to wear them out and be shakin’ shakin’ in 6 months or so though.

Help me Sajeev, you might be my only hope!

Sajeev answers:

I could be your only hope?  No pressure there! Anyway, I think one (or more) of your wheels is out-of-round. It sounds like you hit enough bumps/potholes/sinkholes to do two things:

  1. Damage the suspension enough to cause a wear item to prematurely wear and eat up the tire tread in that funny manner.
  2. Bend your crappy, cheapie wheel.

Aftermarket wheels are such a hit or miss, but you often get what you pay for.  The photo above is my Fox Body 1988 Mercury Cougar XR-7.  I shelved my factory 15×7″ turbine wheels (same as the Mustang GT of the era) because they were impossible to clean, needed refinishing, and are so outdated that I could no longer buy a decent summer tire for it.  And the way I drive, I want summer tires!

So I upgraded to 1993 Cobra style wheel, reproductions (probably) from China.  At 17×8.5″ these Rimz are a huge upgrade from stock but with a factory look: they get compliments all the time , even if people regularly say that I need to “modernize” to a different wheel.  I wanted a period correct restomod upgrade, and I got it.  Case closed? Not. These Rimz are stupid heavy, I don’t even want to know the increase in unsprung weight.  Even worse, they occasionally wobble on certain wavy roads and certain speeds…immediately after I did the wheel swap.

So my Cougar has the same problem as your Civic! Wheel balance? Nope. High quality, brand name summer tires?  Not helping. Numerous suspension checks with plenty of new parts?  No dice.

I gave up.  The Cougar looks awesome (to me) and I love the extra grip, and I’m not super concerned with the occasional wobble, because I know exactly where its coming from.  If this was a track car, I’d either get new Rimz or have a wheel shop professionally machine them to perfection.  If that’s even possible!  Is it possible?

Well, now that I’ve thoroughly confused myself, off to you Best and Brightest.


Send your queries to Spare no details and ask for a speedy resolution if you’re in a hurry…but be realistic, and use your make/model specific forums instead of TTAC for more timely advice.


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Piston Slap: The Folly of the 90-degree V6? Wed, 20 Jun 2012 10:23:24 +0000


TTAC commentator Jerszy writes:

Dear Sajeev;

Hopefully you & your fantastic community can help me here.

I recently purchased a 2002 Dodge Dakota Sport 4X4 (3.9 V6, 67k, Auto).

I bought it to replace my 2002 Cougar Sport Package (2.5 V6, 64K, Manual, speed-limited to 139mph) which as you know is not a good suburban truck and can’t really haul things. The Cougar was a fun car, very agile and could haul me around town and being a kitty-car it really did purr. Unfortunately it had to live outside in the rusty north for the last 6 years and was starting to age rapidly. Since I live in a “snow belt” (avg. snowfall ~120 inches a year) it had to be 4 wheel drive.

Now the Dakota is a definitely a truck. Almost as big as the ‘76 Silverado I had 30 years ago and just as four-wheelie as the ‘84 Toyota 4X4 truck I replaced it with. (That Toyota rusted, rusted, rusted so much I had to fabricate a wooden bed for it in 1987!)

Interesting aside with the Toyota, the neighborhood crooks would constantly bust the wing-windows and steal stuff out of the cab, only the first perp got anything and it was nothing but a junky tool-set.

I got so good at replacing the wing window that I could install the window while driving home from the dealership. The tires (which seemed almost magnetic) were also a problem, every screw on the road found a home in my rubber. I bought a set of General Gen-Seal tires at the time (not sure if they make’em anymore) and that cured that problem. Two things stood out about those tires:

· The sound they made when you pulled a screw or nail out, (HSSsssssssssssssss-FIP…) they really worked!

· How the gel on the inside would migrate to the bottom of the tire on a warm day and the out-of-balance thumping down the road for twenty minutes until they rebalanced themselves. (Ahh the memories…)

My only issues with this particular Dakota besides truck-like acceleration and gas mileage (~16mpg) which doesn’t really matter to me as I might drive a whole 3000 miles a year anyway is how rough that engine idles. It runs great otherwise. I have talked to two general mechanics and both thought it was somewhat normal. I am sure for a price they’d look a bit closer but it sure seemed to me that they were serious and didn’t want to pick my pocket.

My question to you is: Is a rough idle normal for this engine?

I can say that it’s only a small problem to me but the fact that runs so well otherwise lends me to believe the mechanics were right. Looking over the 3.9 engines history at Allpar, I find this interesting passage according to Willem Weertman, the head engine designer:

“The reason is that the engine would be rather badly out of balance and would have not been acceptable even in a truck engine. So we had to do some redesigning of the bottom end in order to split the crank pins and make the firing order a little more uniform and it seemed to have worked out ok.”

Should I pursue this issue more vigorously or just pretend that everything is normal and learn to love this as it is?

Since the chief engineer of this engine weighed in on the issue and deemed it “just OK” in my mind that it probably does idle rough as designed.


Sajeev Answers:

Ah, this takes me back! Back to when I started writing for TTAC, saying things like “the pissed-off 3.8L’s presence at part throttle” in reviews of vehicles with 90-degree V6 engines.  And while I enjoyed dancing around technical terms with Farago-like passion and precision, the fact is that these engines are flawed.

You can’t chop off two cylinders from a 90-degree V8 and not suffer a compromise or two. And they will never be the smooth operator you’ve seen in your Duratec-powered Cougar. Or any other modern DOHC V6, for that matter.

While I haven’t driven a 3.9L powered Mopar, your letter (and the Allpar link) suggests it has the same design flaws of the 3.8L GM and Ford products. Wikipedia sums up the problems with this design pretty well.

If you’ve done the basic tune up things, replaced all worn vacuum hoses, etc I suspect you’re stuck with the “charms” of 90-degree V6 engine ownership.  Don’t tell the Buick Grand National fanbois that something’s “amiss” with their rides, either.

Send your queries to Spare no details and ask for a speedy resolution if you’re in a hurry.

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