mmarshall

Few things, IMO, are more annoying while driving than having to put up with a constant, back-and-forth shimmy in the steering wheel or pulsation in the pedal when the brakes are applied. I'll save the pulsating-pedal problem (which is usually due to out-of-round brake rotors or wheel-lug nuts tightened improperly) for another thread. Here, I'll concentrate on the shimmy problem.....and some of what my own car-ownership experience in the past has been dealing with it.

First, I want to say that, though this was a quite common problem a few decades ago with even brand-new cars right off the assembly-line, the automakers, overall have dealt with it very well since then. New cars, today, come out of the plant in much better condition, with far fewer problems in tire-mount/balancing, than, say, in the 1980s. Back then, on the average (in my experience), you could pick maybe one out of every three or four new cars at random sitting on the lot, and it would have or shortly develop a steering-shimmy problem, or (slightly less-common) a premature brake-rotor problem before one should reasonably expect it. Now, though the problem has not been entirely eliminated (I experience it maybe once a year or so in reviews/test-drives) the difference is like night and day. So, the chances of getting a Shakey-Jake front end are MUCH less....but what about the occasional vehicle that DOES experience a problem? And, of course, all new tires will eventually wear out and have to be replaced....so then, of course, a shimmy problem could also arise with replacement or aftermarket tires. (I ran into that several times myself with both new and replacement tires years ago).

First, in a few cases involving mainly FWD or AWD vehicles with front axle half-shafts, steering-wheel shimmy can be caused by poorly-engineered/manufactured or poorly-assembled components that cause a drivetrain-harmonic imbalance in the spinning axle-shafts or wheel hubs...though that is relatively uncommon. That, of course, usually involves a fix that is more complex than the average car-owner, wheel/tire shop, or dealer-service bay can handle...it has to be solved at the factory level. But much more common are relatively simple, easier to fix problems involving wheel/tire mount, runout, and balance. And, with most new vehicles today, not only do you have a multi-year warranty on those components, but (usually) also free adjustments at the dealer for the first year. So, in most cases (unless accident-caused) it won't come out of your pocket or the insurance company's.

The term "Runout", as applicable to something that is circular-shaped and spinning, refers to an out-of-round condition that is significant enough to cause a noticeable shake or vibration. To roll smoothly and be free of shimmies, especially at higher road speeds, a wheel/tire assembly has to be almost perfectly round, with no up/down motion as it spins (known as "hop") or side-to-side motion. This, of course, can work both ways. A perfectly round tire can be mounted on a bent or defective wheel (fairly common with stamped-steel wheels, but rare with precision-cast alloy wheels). Or, more common with today's alloy wheels, is a perfectly round wheel with an out-of-round tire (runout)....though, in general, today's tires are also much less likely to be out-of-round than in the past, particularly from respected manufacturers like Michelin and Continental.

But, nevertheless, there are still a number of ways that things can get messed up when these wheels and tires are mounted. I've already explained the importance of a lack of runout. But equally important are the condition and accuracy of the wheel-balance machines in the shop itself. Also important is the training and skill level of the technician himself/herself in how to properly USE that machine.....I've seen a number of tire shops that hired a bunch of essentially slap-happy kids, just barely out of high school, that had little or no idea of what they were actually doing on those machines. I've actually had to show them, more than once, places to check for runout that they just weren't doing...or how to correct it. Then there is the issue of the physical condition and the calibration of the balance-machines themselves. Wheels and tires are usually balanced by small weights, made of lead or other metals, that are attached or hammered onto the wheels at a machine/computer-indicated spot to exactly balance the excess weight on the opposite side of the wheel. To (properly) indicate that exact spot for the weight (s), the machine has to be periodically calibrated and checked for accuracy. That, of course, costs extra money for the shop...and some shops, of course, have El Cheapo owners or managers.

Of course, even a perfect balance alone won't necessarily solve the problem. A brand-new or properly-calibrated machine can tell where to put the weight (s) on and balance even a square-shaped tire down to a gnat's a**...but, as I mentioned previously, what kind of ride are you going to get with a tire shaped like that? That's why it is so important to start off with acceptably-round tires and wheels to start with.

So, in a nutshell, here are my recommendations:

First, although you can (sometimes) get a better deal with cheap cut-rate tires, you often get what you pay for. Though a cheap tire doesn't necessarily guarantee runout (and all American-market tires have to meet minimum DOT Safety standards), you're more likely to get a well-made, perfectly-round tire from a manufacturer known for quality (I myself have found the Continental ContiProContact to be an excellent tire...it's one of my favorites). So, choose a good tire to start with, and you'll lessen (but not necessarily eliminate) your chances of having problems.

Second, choose what appears to be a good reputable tire shop. I've seen some excellent ones and some real bozos....even from big nationwide companies like NTB, Merchants, and Just Tires. Dealership service departments can also vary quite a bit from one to another....but I've generally been impressed with what I've seen at Car Max....they have some nice service departments.

Third, when shopping for tires, ask the shop's Manager or Lead Technician when was the last time the shop's balance and wheel-alignment machines were calibrated. That is not an insult to them or the shop......you have a perfect right to know that information if you are going to trust your car (maybe your life) to that shop and spend your money there. If you doubt the qualifications or skills of the persons doing the work on your car, ask about them...I've seen some excellent ones, and I've seen some bozos.

Fourth, when the actual wheel/tire assembly is bolted onto the balance machine (usually with a large spinner) and spun, ask if you can actually look at the tire/wheel assembly while it is spinning, and note if you see any noticeable up/down hop or side-to-side motion...dead giveaways of runout. If you note any rolling-problems with a tire on a stamped-wheel, ask the technician to do a 90 or a 180...that means taking the tire and the weights off, shifting the tire a quarter or a half-way around the wheel, and re-spin/balance. That sometimes works if a slightly out-of-round tire is mated to a slightly-out-of round wheel....doing a 90 or 180 will make it round and roll smoother, because the high spot on the tire (may) match that of the low spot on the wheel. If a 90 or a 180 doesn't do the trick, then have the Technician actually measure the tire with a runout gauge...a spinning tool that rolls around the edge of the tire and measures its out-of-roundness....any tire technician should be able to easily do that. Standards vary....but the most commonly-accepted standard for tire runout is 0.03". If that amount or greater is indicated on the gauge, you have the right to ask to exchange the defective tire for another one...measured, of course.

Fifth, ask the shop whether, if shimmy problems DO occur after the sale that can't be explained by any other cause, you have the right to have that shop (or another one in the same chain) do a free remount/balance....especially one with maybe a better or more-recently-calibrated machine. When I owned my Mazda Protégé, for example, back in the early 1990s, and it came time for new tires, I had to try 5 or 6 different NTW (today known as NTB) shops before I was satisfied with the job they did on my new Michelin all-seasons. Each shop CLAIMED to be able to do it right......but only one shop actually COULD.

Happy Tire-Shopping.

MM

robert1408

Having recently retired from the tire bizz, I agree with this post. I can add a few items about balancers. Fortunately, modern balancers can almost always be calibrated with a weight slug that screws into the flange. it's fast, easy and you don't need a service call. Rapid temperature change was the most common cause of calibration errors.

Getting the wheel correctly mounted and centered on the balancer shaft is important. I could write about this in detail but it would bore most people.

Never put your face or eyes in line with a spinning tire. Those balancers are spinning around 400-450 rpm. Anything slinging off the tire (valve cores, caps, wheel weights, pebbles etc.) can hit you at 40+ mph. Far safer to spin the tire by hand plus it's easier to see the run-out on a slower spinning tire.

mmarshall

Good point on the face and tire-line. Most of the shops I dealt with only spin the tire to about 55 mph or so (not a really high speed, like for race-balancing). I never saw anything fly off myself (or got hit).....but, yes, your point is well- taken.

Byprodrive

iTrader: (1)

Good points & thread MMarshall, my 1st of many automotive jobs was at a great NTW store where I was trained for 2 weeks before being allowed to speak with a customer. I doubt that happens much these days. Doing the balance procedure properly the 1st time saves the shop money, not to mention return business. During my 2 years at NTW we Never had any problem with a Michelin tire & I always buy Michelins to help minimize balance issues from installers.
Anytime you use unknown wheels, new or used, you should check the unbalance runout of the wheel by spinning it on the balancer. If it is acceptable, (generally requiring 1/2oz or less weight for a bare wheel) don't install the weights until the tire is mounted to the wheel also. Often the shop fails to lower the air psi to proper spec from the psi used to seat the bead of the tire to the wheel. This is usually 10-20psi over spec & can cause shimmys & rough ride.

mmarshall

Thanks. This is an issue that, for years, could be a real pain in the a**. Fortunately, today, new-car assembly/factory standards are far better, and the chances of getting a wobbler much less. In general, the quality of the work at most tire shops has also gotten better over the years. Part of it, of course, is simple necessity. Customers, in general, are more demanding than they used to be (though I was always a fiend, myself, about having a shake-fee steering wheel). And, of course, few new cars today, outside of a few entry-level ones, still come with relatively cheap-to-replace stamped-steel wheels and plastic wheel covers. Most vehicles today, outside of econoboxes and work-trucks, use expensive, precision-cast wheels. If a tire shop damages or screws one of those wheels up because the technician was sloppy or careless taking it on or off the tire-mount machine or wheel-balancer, it could cost the shop some real $$$$$.

In fact, I actually saw that happen at a local NTW shop....back before it became NTB. I was getting a new set of Michelin all-seasons re-chcked (the original NTW branch couldn't get them right). Right next to my car, on another rack, was a beautiful black BMW 760...even back in those days, they ran a good 100K or more. Gorgeous window-tinting and paint job...shone like a mirror (though black generally isn't my favorite color). Technicians and shop guys were frantically working on it like a bunch of ants running around their nest. I politely asked what was going on. Turned out it was Patrick Ewing's car.....the famous Hall-of-Famer NBA basketball player. He had driven down to the D.C. area from New York City (where he played on the Knicks), left his car there to get new tires, and hitched a ride downtown to negotiate with the (then) Washington Bullets for a (possible) contract. While he was gone, the guys working on the car had damaged the car's EXPENSIVE original alloy wheels. Since they obviously couldn't replace them right there in that shop with factory-originals, they gave him (free, on the house) four of the nicest and most expensive alloy wheels they had in the shop that would fit. They were working frantically to get them on and ready to go before he he got back.

The Bullets contract, BTW, didn't go through, and he ended up driving back home to NYC...and the Knicks.


Michelins, in general, have an excellent reputation. The Michelin XZX tires I put on my first Mazda (not the ones I described above) were like iron in durability. I was not satisfied with the car's original tires....but the extreme durability of those XZX replacements came with their very hard rubber-compound and a resulting lack of wet/snow traction. Nevertheless, the front tires went 80K miles (without regular rotations) and the rear almost 100K before I sold the car. I wasn't getting any shimmy out of them, and my basic philosophy was "If they ain't broke, don't rotate them". Back then, though, shimmy was a lot more common than it is today.

But some other brands are catching up to Michelin today. Continental also does some superb tires today....as does Bridgestone.

What was your job at the shop? Balance? Alignment? Tire-Inventory? Customer-Service at the front desk? Manager?

I8ABMR

great write up buddy. I had vibrations with my LS460 for 31 months. It was a nightmare.....especially when it comes from bad tires, wheels. and driveshaft. It was a engineering exercise to figure it out. Sadly it last close to 3 years. Now I think I may keep the wheels stock, only go with Michelins, and I usually have Lexus balance my tires because discount ( although they try) just can not get a balance perfect on the first shot....at least not with after market wheels and summer tires in my experience

mmarshall

Thanks.

Tires and wheels I can understand (though generally uncommon now, it's not rare). But the driveshaft also had a defect? If it was a RWD LS460, the driveshaft wouldn't have affected the front wheels and the steering wheel. But if you had an AWD model with bad front half-shafts, that would be a different story.....you might get something through the wheel. Nevertheless, it's hard to believe that an LS460 would have gotten out of the factory with a drivetrain defect like that. Even by today's standards, the LS460 is not only an exceedingly well-made car, but, IMO, one of the best luxury cars on the planet. If the driveshaft WAS damaged or deformed, my betting is that it happened after the car was built (perhaps by running over road debris or an obstacle)....not at the factory.

Och

iTrader: (3)

Vibrations coming from an unbalanced tire can easily wreck havok on the rest of the drivetrain, and cause damage to driveshafts.

I didn't read you entire post, so you might have already covered this, but I'd like to make a suggestion to anyone concerned with potential vibrations.

1) Do not ever buy non factory rims. Aftermarket rims usually have a large hub bore, so they never sit tight on the hub, and are instead relying on the lugs to be centered - and as a result they are usually never properly centered, and putting extra stress on wheel studs. Constant vibrations are almost guaranteed.

2) Avoid low profile tires. If you must use low profile tires, don't buy cheap ones. Invest in some Michelins - its very rare to get a Michelin tire that is out of round.

3) Use tire shop that has proper equipment. I recommend shops that have Hunter 9700 balancing machine and mechanics that know what they are doing.

doge

Not all aftermarket wheels are crap, how ever most are.

If you do want to use an after market wheel for what ever reason make sure they are TUV certified

US DOT has very loose restrictions on wheels, any cheap Chinese wheel can be sold in the states. They are usually made out of poor metal and are poorly designed meaning they have no strength.

BIG $ doesn't equal good wheels. Many of these so called "luxury" wheel companies are only good at marketing. Lots of companies who advertise on these forums sell poor quality wheels.

Diesel350

Great post mmarshall, I’m having an issue with vibration in the seat at highway speeds over 60 mph not in the steering wheel really. I have a RWD and I bought my car with the dealership putting brand new crappy Nexus tires on it. I took it to a rim shop to inspect the rims and tires and there was a slight bend in one of the rims and he said the tires looked fine. They fixed the bend and balanced the wheel but that did not fix the issue of the vibration in the seat. I then took it to a local tire shop here to balance the tires and that still did not fix the issue. I then took it to a Firestone for a balance and that still did not fix the issue. Should I take it to a place to get it forced balanced? Could the tires just possibly be defective? Suggestions?

Diesel350

Doge,
Can you recommend some good after market wheels that don't cost over $4 grand a set? You can PM if you'd like.

doge

Im no expert I know more about what NOT to buy than what to buy. Take a listen to this podcast it explains what to look for and which brands are good.

http://www.thesmokingtire.com/2013/t...of-hre-wheels/

SC300Es

This is a great write up.

Byprodrive

iTrader: (1)

Bold type highlights the root of the problem. As I stated in my previous post have the bare wheel tested for imbalance by spinning on the wheel balancer to see how imperfect it is. Obviously the shop did not fix the bend perfectly. Mounting the wheel on the right rear of the vehicle will minimize the vibration felt by the driver.

Byprodrive

iTrader: (1)

[QUOTE=mmarshall;

What was your job at the shop? Balance? Alignment? Tire-Inventory? Customer-Service at the front desk? Manager?[/QUOTE]

Sales/service writer at front counter. Later offered assistant manager promotion but declined the increased hours for small pay increase.