My guesses: A wheel or tire changed shape at apeed and went out of balance. A tire could have been ruined by over-inflation during mounting.

The cone shaped mounting holes in the mag wheels were oversize and the wheel was not truly tight,although the nuts had been driven home.

If the wheel nuts were of the acorn type, the nuts could have bottomed out before the wheel was tight.

Wheel bearings were loose.

Loose tie rod ends or other loose joints in the front end. (You didn't say which end of the vehicle was shaking. Maybe it was a backend problem.)

Steering damper missing or sacked out.

The power steering unit had too much feedback gain and began to oscillate above 70 mph.

Were the universal joints checked? Were the universal joints properly timed, e.g., joints at opposite ends of a shaft oriented properly with each other rotationally, although I would have expected this problem to have shown at speed much less than 70 mph.

Sorry about that. It was in the back end. It's not wheels or tires or drive shaft. absolutely nothing to do with
streeing or brakes. I also forgot to mention this was a
brand new car. Still under warranty. I think it had 300
miles on it. Maybe less.

The differential pinion shaft and the transmission output shaft are to far out of parallel? ie its a suspension problem?

Nope. But your on the right page. As i said before. It's in the back end and not the body or suspension. i'll give it away if i say any more. Actually probably not. no one
will guess this or have ever seen this or heard about it.
Well, you will when i tell you. I'll tell you this. It's not the crush washer.

HI Kalining

I have 2009 software for Ford, GM, Chrysler, and Honda. I have to buy a Techstream and a Consult III for Toyota and Nissan respectively. They will wait for a bit, that 12K expense combined isn't budget able at this time.

I have software for a 2010 MY. Even I had to laugh at that, why would they label a car a 2010 when it is going to come out in Jan 09??

BTW, the reason I am fully up to date is when people crash them, they aren't under warranty anymore.

Now back to the GN. The most important things to me are, why were so many parts replaced, and the problem not "diagnosed"? Typically its because things like vibration have never really been "teach-able". The guys are pretty much left to throw parts, or spend their time for free.

What I would not do is attempt to guess what this vibration was, mainly because I try and stress the importance of being able to analyze the car in front of you today. If I had a GN in the bay today with a vibration, the information gained by the one you had is actually of very little use. Now once the problem is narrowed down to say the differential assembly, since you said this was "not the crush washer" then we could allow for a little bit of input, but not until then.

Going back to the raw diagnostic steps, some of the things that can be done are measure the vibration frequency, and compare it to engine speed, transmission component speed, driveshaft speed, wheel and tire speed, or engine accessory speed. Every vibration that can be felt by the occupants will resonate with something that is moving and this information is necessary to assist in locating the problem. A drive shaft will produce a vibration somewhere from three to four times as fast as a tire/wheel assembly will at any given speed. You can actually temporarily add a weight to a wheel to give yourself a known vibration as a reference. You can do the same with the drive shaft with some hose clamps, lining the screws of the clamps up and intentionally alter the balance of the drive shaft for a reference to the vibration speed. Engine, engine accessory, and even internal transmission component vibrations will be engine speed/gear ratio dependent. Engine and engine accessory vibrations can be measured sitting in the stall. Transmission components will be gear dependent. The torque converter would go with the engine for diagnostic purposes. What people need to know is the experience of the technician driving the car can make testing of the majority of the components, and their exclusion from needing to do so unnecessary, because the learned seat of the pants feel will have the tech recognizing the major source of the problem in a road test of a few miles.

Now for entertainment purposes only. I'm going to guess what might have been wrong. The vibration was in the rear axle, but it was not a centripetal force vibration. It was a vibration caused by run-out. The run-out could have been a bent pinion gear, it could have been a warped differential case or ring gear. Both of these conditions would be detectable by measuring the pinion turning torque, which BTW this is the same measurement used by a technician to determine the pinion bearing pre-load as the crush washer is set. Warpage of the ring gear, or differential case or a bent pinion gear would cause the torque required to turn the pinion gear to have a measurable difference. If it's every turn of the pinion, then it's a bent pinion gear. If it takes three to four turns of the pinion to find the "tight spot", then it's a ring gear, differential case problem.

A technician wrestling with a vibration problem has to distinguish any centripetal vibration from one caused by run-out in a component as well as from something like tire stiffness variation. Otherwise, they get a lot of practice replacing good parts.

Well, John. Your on the page. It is in the rear axle
assembly but nothing is bent, binding or broken. Remember this car is brand new. As far as throwing parts at it G.M. is paying. We are told what to replace by their warranty reps. We don't care. We get payed. All replaced warranty parts are tested and if found good are put back in stock and sold to the employees. New code software, We have our own computers in our stalls connected directly to the factory. We can down load any updates and flash the e.c.m. or b.c.m from our own stalls. They have C.D. burners so sometime the updates get accidently copied and taken home. The copies are supposed to be used in our laptops for an on road drive and update. The laptops are connected directly to the e.c.m.'s for real time diagnostics. The new updates cost us nothing if we happen to be working at home. They are protected from the general public though, through propriatory software.

As I said, I have the same software any GM tech does. All of my updates are done through a live DSL connection with GM. The same goes for Chrysler, and Honda. Ford still gives me a DVD, as does Toyota. I don't flash Nissans as of yet.

So the warranty reps get to do the guessing, you just changed the parts they pointed at. That's part of why I quit being a dealer tech......

That is the best part John. We get payed for every screw up
they can't pin point. Job secuity. We don't care how long it takes. They eventually wash their hadns of it and we take over. We usually know what is wrong by now. We will
run straight time. Could be a few days before we decide it's fixed. It's all warranty. The customer doesn't pay. They usually get a loaner car. We can usually milk warranty
for thousands. I was a trimmer for years and as you know that is the hardest job to make money at. Myself and the other trimmer would average 10 - 12 hours in a 6 hour day.
We usually went home or hit the bar at noon or 2 P.M. Our day was over. Best job in the world.

Kalinin. Your dealer tech outline does not match my experience. As a flat rate tech, the labor dollars per flat rate hour was set so that we needed to turn 60 hours a week, in that forty hour window to earn a decent paycheck. Try and pay us straight time, and we were running at 2/3rds of a real wage.

As far as the manufacturer rep pointing at a part and saying replace it, I can recall that happening about four times in eight years. Warranty time hardly ever paid enough to do that simple R&R at that point, not even considering any time lost up to that moment trying to figure the car out. Back then they did not pay diagnostic time. I guess we were just supposed to always know what was wrong based on a reported symptom. Oh, wait. People still think it works that way.....

The thing is you have to know how to use a pencil. You
NEVER turn in a flat rate time for a job. You always clock over because you found something else wrong. There is not one tech in this shop that can't beat a flat rate time. He doesn't stay employed very long if he can't. Your nuts if you don't clock over on warranty on a related problem. EX. Replace tail light bulb pays point 2. That is 6 minuets. You have to go to the parts dept. and wait your turn for your bulb, return to your stall and replace the bulb. You just pissed away 1/2 hour and if your tower operator or time keeper doesn't like you he will clock you in only when the car jockey rings you your car. If your smart your tool box is full of bulbs and small parts and you NEVER EVER turn in a .2 untill you get your next car. By then your up to a .6 or .8 I can usually tell what is wrong with the car by reading the work order before i get the car in my stall then i go to the parts dept. and order my parts. I'm running time on the car already. My time keeper likes me. Those two guys are god. Do not make them mad. So do you want to know what was wrong with the buick ? It triggered an inspection everytime we serviced one of those cars.

Before you guys wind up at Ground Zero what the h*ll caused the vibration???????????????????????

mxyplx. What caused "this" vibration that kalinin is talking about, I have no ides. Without feeling it first hand I don't know how speed plays a role, and if the vibration can be altered or manipulated in some way that would make it clear what was happening.

Remember at this point I don't know if this is a centripetal vibration, or something else. I don't know if the vibration was only there under specific drive-line loads, or speeds.

FWIW, I have had vibrations in the rear axle assembly from;

1. Bent Pinion.
2. Differential case, and/or ring gear run-out.
3. Missing bolts from the ring gear/ differential case
4 Axle shaft flange run-out.
5. Differential pin fractured. (They were lucky it didn't simply lock up the rear axle)
6. Differential pin worn through differential case.
7. Incorrect side gear clearance.
8. Missing worn limited slip clutches.

There are more, but this is enough to demonstrate my perspective that it does not help to know of one vehicle's problem, and truly believe it will be a silver bullet to help me diagnose another. I have no expectation to see that something that I have listed here was the cause of the problem. However every one of these refer to a vehicle I diagnosed in the past, that had the reported symptom of a vibration, that came from the rear of the car, specifically the rear axle.

**Your nuts if you don't clock over on warranty on a related problem.**

There's a term for this. It's called fraud. BTW, warranty work is done under flat rate too, it's just lower than the other flat rate book which is padded a bit. You can punch the clock on the work order at anytime you want. If it's a 2/10's job it's a 2/10's job regardless.

I too was a GM dealership mechanic many moons ago. The district rep came by from time to time to audit the work orders and the parts replaced. After inspection, anything that looked usable was destroyed or the shop wouldn't be paid for it. Don't think he ever authorized 100% of the warranty work that was done. The shop always seemed to have to eat some of it.

I have seen a few times where there was a problem vehicle when the service writer picked a car off the lot to turn in warranty paper work to cover what would otherwise be unpaid warranty work done on a customer's vehicle. That's also fraud. It bothered me untill I saw how much they chopped off the reimbursement seemingly just for the hec of it.

Gary I share your sentiments here. When my natural talents combined with adequate training were not enough by by themselves to fix the problems the customers vehicles had, AND be reasonbly paid for doing so, it was clear there was something wrong with the system. I was the guy that got the cars when they came back because they didn't get fixed the first time, and management would say things like, "We need you to help us out with this one". Then when that problem was solved it was "We can't pay you for that one, so here is some gravy work to make up the time".

From my POV, I should have been paid for the nightmare(s), as well as I should have gotten to be paid for the easy stuff, that way I would have made a decent wage. Oh well, I can still show what it was like back then with these kinds of posts. Meanwhile the drive to succeed has put me where I am today. Which BTW is not in even in my own shop this morning, I'm doing training this week and I'm in south west NY state teaching other techs how to deal with the hybrid cars. Tomorrow it will be right back to the shop and to my own customers. But the best part of all is I have to deal with none of the games kalinin felt had to be played in order to earn a living. That crap has nothing to do with being a tech/mechanic. JHMO

It isn't fraud. I said " related problems ". Too bad you worked at some BAD dealers or shops, John. Every dealership i worked for has said at one time to me, Can you help us with this "? Actually, they said "we need you to fix this once and for all the other guy can't do it." I get payed, too bad you didn't. It's called a debit. The other tech that worked on it first looses his money and it is payed over to me. I make a very good wage. We also get bonuses. Anything over 8 hours a day we get fifty percent of the work order, parts and labour. No offence john but you don't know how the system works or you didn't like flat rate. Maybe flat rate doesn't like you ? By the way. You win the cigar. There were 3 bolts missing in a row from the crown gear. Not only that but there were no threads in the differential case to put the bolts in so they were left out. It took about 70 M.P.H. to cause a vibration. Yes there is an audit if the tech makes too much money too fast. We make sure that doesn't happen very often because they will lower the flat rate. My audits were all found to be legel and exceptable. Myself and 4 others are the highest payed techs in that part of the shop. Except for the body shop techs and painters. They even start out with a higher rate. When we have a good week
we average $1400.00 in 40 hours. SOMETIME. Don't get me wrong. The tech has to be good at what he does with almost
no come backs and has to make at least 80% of his stall or
he is gone. I've seen many techs not make 3 months.

**It isn't fraud. I said " related problems ".**

I think you're full of beans. Your definition of "related problems" = a bad diagnosis of the original problem...again and again and again.

Warranty work is not a money maker for anyone. My experience was the district rep checked all dealerships. Doesn't make sense not to. Otherwise the company would most likely be ripped off right and left. Hmmmmm, maybe that's why GM's going broke. Canadian dealership mechanics/service writers robbing them blind.

**"We can't pay you for that one, so here is some gravy work to make up the time".**

john g, that's the way service writers I had used square things up as well.

"that's the way service writers I had used square things up as well."

In their eyes......

You guys have no idea how our system works. I've read the posts. Your system sucks the big one. Our service writers have NOTHING to do with the dishing out of work. They are not allowed on the floor most of the time. All work is distributed by the tower operator. The service writer has no idea when the car is going on the floor or what tech gets it. They just write up the work orders. That is all they do. " Related warranty work ". So a U joint breaks under warranty or the clip lets go. The drive shaft whips smashing the yoke and punches up the floor boards. The U joint is replaced under warranty. The rest of the damage is not repaired ? I don't think so. That is called related damage. A tire blows under warranty and the steel belt rips off half the fender. The tire is replaced under warranty. What about the fender ? The "extras" all go under flat rate or straight time and we get payed. 90 percent of the time the insurance co. pays us. You guys have a really bad system down there. No wonder you can't make money. Our dealerships are privatly owned. Our labour rate is $119.95 per hour. We are booked solid every day. Actually we are behind by 2 days. I'm the newest tech they have. I've only been there 11 years. Some have been here 25 years. If they weren't making money do you think they would still be here ? There are 17 of us on the service floor and we all make a very good wage. I think there are 15 in the body shop. They make more than we do. We have been in business 37 years so i thing we might be doing something right. So tell me. A signal switch, or any electrical switch shorts and flashes the harness. Burns the under dash and or padding. So you are telling me you get payed warranty to replace the switch only ? What about the rest of the damage caused by the switch ?

Flat rate... The carrot or the stick... I know all to well how flat rate works, and how poor management gets to survive because the burden falls to the tech to make his/her living, which results in management profits reguardless of their help or hinderence to the business. If you are in a good shop, thats good for you. Your shop is the exception, not the rule.

We did not have a "tower", the service writers dispatched the work directly.

"So a U joint breaks under warranty or the clip lets go. The drive shaft whips smashing the yoke and punches up the floor boards. The U joint is replaced under warranty. The rest of the damage is not repaired ? "

The U-joint would get repaired. In fact the car would probably just get the driveshaft replaced, and maybe the yoke if it was necessary. That would probably pay ".5 or .6" total. The body damage would be off to the body shop, it also would be repaired "under warranty", by a body shop tech.

The tire example, would have tire tech doing the tire, a body shop tech fixing virtually everything else. As a line tech, I'd probably only see the car if there was a problem after that.

The electrical problem you quoted is an extreme. Normally any swtich fault does not damage any other components. If it did the repair would vary, but sounds like a body shop issue, not a line techs.

If I did have to repair a connector or pin, It was usually a nightmare back then. I would have scraps of wiring harnesses laying around and be expected to repair the connections by splicing in pieces. Management would "throw me some gravy work" to make up the time.

Labor rates here are about 1/2 of your $119/hr With two shops in the area under $50, and one still under $40.

The dealers within 5 miles of here are between $75 and $85.

** A tire blows under warranty and the steel belt rips off half the fender. The tire is replaced under warranty. What about the fender ? **

Actually, I believe the tire would be covered under the tire manufacturers warranty, not the manufacturer of the vehicle. Don't beleieve me, grab the warranty and/or owners manual out of any new vehicle on the lot. Post back where it says that GM warranty's Goodyear tires. The body damage in this example would come out of your insurance policy unless the tire manufacterer would spring for it which I doubt. I bet their warranty is phrased to limit their liablitly to damage to the tire. The damaged fender wouldn't have been the result of vehicle manufacterer defect.

Damage to wiring or loss of the vehicle from a fire due to a defective componant would certainly be covered under warranty. That would be a 'related problem'.

Unless refering to a crane or an airport, I have no idea what you mean by 'tower operator'. The service writers where I worked are the people who make contact with the costomer. They fill out the paperwork describing the complaint and verify if they can. That's an important job. They give estimates for costomer work, schedule the work, and assign it to a mechanic. From then on he's the go between between the mechanic and the costomer or manufacturer which ever the case may be. They were my boss. They interviewed and hired me. They in effect, ran the shop, not sit around on their thumbs somewhere out of sight.

In your original post, there were no other 'related problems'. There was one misdiagnosis after another. I don't even think the tire balacing would have been covered under vehicle or tire warranty anyway. Though I do remember us sending warranty cars out for tire balancing. I thought the shop/dealership just ate that expense for customer satisfaction's sake. What would have happened in the case you discribed, barring the use of creative paperwork, would have been after somewhere between the 1st and 3rd attempt to fix the original problem, the district rep wouldn't authorise any more payments. Their position would be that they already paid to correct this problem, and rightly so. He'd assume the tech doesn't know WTF he's doing. The only way they would have paid for all that as you said is if your service writer consulted the district rep and he directed the work of replacing the engine, trans, etc, before hand. If that were the case, I'd be surprised if he still has a job with GM today.

The example in your original post was why imo warranty flat rate is a rip off of the shop and mechanic. The manufacture's positon is something like since it's new and clean, everything comes apart easier. Though there may be some truth to that, it's still mostly BS. When a car that's 5 or 10 years old comes in with a problem, it's a pretty safe bet it's been working fine for some time. What you have to do then is figure out what's worn or broken. When something new comes in, something may not have ever been right in the first place like your missing bolts. For me it's harder to figure out what's wrong with something that never worked than something that used to and then quit. They seldom if ever paid extra diagnosis time on account of that.

Dealerships here are privately owed also. They are franchises which I'm sure is the same everywhere.

Gary. i agree but let me explain. " Tower operator - time
keeper " that is how our system works. They are two people that are on the second floor or mezzanine floor above the shop floor. They can see the entire shop from any direction. They know when a tech is finished a car or
wasting time. They and ONLY they dish out the work. They are god. Don't tick them off. They will starve you. As i said before our service writers have NOTHING to do with who gets what work and what car goes where. Our service writers are low man on the totem poll.Usually the lowest payed garbage job in the shop. They have NO POWER over the service tech or the shop floor. They know better not to even try. The ones that do are banned from the floor. Yes the tire warranty will pay for the tire and as i said the insurance co. pays for the car's damage. We fix it and get payed. In that Buick case the warranty rep said change the motor and trans. The rep TELLS the sevice manager what to do. He wanted the motor and trans changed so we did it.
We got payed. Again back to the service writer. If they ever try to diagnose a problem before a mechanic sees it
and they are wrong, they usually are, they get banned from the floor or fired. A service writer told me what was wrong with a car and did what he said. ( we hated this
brown noser ). It didn't work ( i knew what was wrong )
I left it his way. The customer picked up the car and found out it wasn't fixed. You should have seen the poor
writer trying to talk his way out of that one. He got fired. Couldn't happen to a nicer guy. If we have problems diagnosing a car we call the tower. Our time keeper will punch us over on straight time or shop time then back on flat rate when we have it figured out. As long as there is no abuse on this everyone is happy. The good techs are taken care of very nicely. We are happy. All our dealerships have towers. The new ones are on the main floor.

I only worked for two dealerships. Neither had a second floor. I don't even think I've been in a dealership that had a second floor. The service writers I had were not minimum wage idiots with pencils and a clip boards. They were well paid. Most had a back ground in mechanics. Having seen all the problems that come in, knowing what the resolution was, and reading all the TSB's, when they gave me a work order, especially for warranty work, and suggested I check for something in particular, I checked it. I think all the time keepers I had ever did was make sure everyone on commission got at least minimum wage for the hours worked. The service writer was the main guy in the shop.