Car vibrates constant and violently shakes when braking

There's no way to diagnose this without seeing the car, but I can provide some generalizations. It looks like this all started with a standard brake job last year, and that included new rotors. Had the vibration started at exactly that time, the elusive cause was likely to have been a chip of rust or other debris got caught between the new rotor and the hub it's mounted on. That would make the rotor and the wheel wobble. Most cars today come with cast aluminum wheels. Those corrode quickly and some of that can break off and get stuck against the rotor. The next time that wheel is removed, then reinstalled, that debris is again caught in between, but this time it only causes the wheel to wobble, not the rotor. The way to find this is with a dial indicator mounted solidly next to the wheel, then you spin that wheel by hand or by running the engine, in gear, on a hoist. Many inexperienced mechanics will remove the wheel and run it on a tire balancer. That will only show the "run out" if that debris is stuck to the wheel and if the same part of the wheel rests against the mounting flange on the balancer as it does on the car. Doing it this way will identify that debris maybe ten percent of the time. That's not the proper way to do it.

If this wobble started a few months after the brake job was done, that is also real common, with an easy solution. When we make parts out of cast iron, we set them aside for 90 days to "age" before they get their final machining. Most replacement rotors come from China. There's nothing wrong with their quality, but when they make parts out of cast iron they cast 'em, machine 'em, pack 'em, and ship 'em, then they age on your car. It's almost a certainty they're going to warp a little within three months. The standard repair is to return to the shop that did the brake job and allow them to take a light cut on the rotors to true them up. Most reputable shops do that at no additional charge. That warping rarely occurs a second time. The owners who have the most trouble and most frustration are those who don't understand this and demand new rotors under warranty. Those new rotors are going to do the same thing, so that isn't the proper solution.

I have to give one of the shops some slack when they found the bent wheels. A common joke when I'm helping my friend in his shop and we can't find a certain tool, is after he hollers that he found it over there, my reply is, "fine, but I'll keep looking over here". If a mechanic thinks he found the cause of a problem, what would your reaction be if he wanted to keep looking? Customers are already rightly concerned with cost, and so are we. When we inspect the steering and suspension systems, we check every part. At this time we do not stop with the first worn part we find, since they all have the same mileage and the same amount of wear. The difference is by the time you've had the car looked at multiple times, we know all of the common parts have been checked and / or replaced, so there's no need to waste time going over that again. You're upset that the mechanic stopped when he found the problem with the wheels. I'd be upset if he didn't stop at that point.

It also seems like you've gotten a lot of misinformation from multiple sources. Remember how too many cooks spoil the soup? In particular, what led you to the engine mounts? Vibrations and shaking have to be caused by something that's rotating. Worn or loose ball joints, tie rod ends, control arm bushings, and struts can allow excessive wheel movement out of alignment, but they don't cause vibrations. In this case the initial cause has to be related to wheels, tires, brake rotors, and to a lesser extent, CV joints. In some models, a broken engine mount that lets that end of the engine drop down can cause an inner CV joint to bind as it rotates. That isn't a vibration anyone can overlook. The symptoms can vary as to speed or turning when it occurs, or during braking or acceleration related to the normal rocking of the engine. In most cases owners have no idea an engine mount has collapsed until we find it and tell them, then we're often accused of trying to sell parts that aren't needed.

As a former suspension and alignment specialist, it wasn't uncommon to ask a car owner to go with me on the initial test-drive. Sometimes I was able to point out their concern was a normal condition, and often they were able to show me what I wouldn't have noticed on my own. That test-drive also gave me the opportunity to show them what kinds of things I looked for that provided the clues as to where to look for the causes of problems.

I'm nor sure what to make out of what you were told about rusty tie rod ends. I had a lot of customers at the dealership I worked at bring their cars in once a year for a maintenance alignment. To insure the threads for the tie rod ends were easy to loosen and adjust next year, I sprayed them with a special "Rust Penetrant", but then I found when they came back a year later, that stuff had opened up the threads so much that water had an easy time getting in. They were rusted so tight that I needed a torch to get them loose. After that I used a different type of grease and never had that problem again. GM has used an odd type of tie rod design that is so prone to water getting into the threads, coupled with them being in an extremely difficult place to get at them, that they were usually rusted too tight to adjust after just one Wisconsin winter. Your model uses the more common design found on almost all other brands, and there's nothing about getting rusty ones loosened up that every alignment specialist hasn't run into before. With your design, if they were too rusted to adjust, they would have had to cut the linkage apart, then replace both the inner and the outer tie rod ends. If they only replaced the outer one, they had to unscrew it from the inner tie rod end, so that means they overcame any rust issues.

I'm also questioning what you were told about the anti-sway bar links. That bar only reduces the body's tendency to lean to one side during high-speed cornering. Before the mid '70s, most cars didn't even have anti-sway bars. This is another case of where owners usually don't even notice when a link is broken. Sometimes the broken ends will knock against each other over bumps, and you'll hear that, and sometimes broken mounting hardware will jungle like a tambourine, but none of that will cause any type of vibration.

My suggestion is to start with a very clear description of the symptoms, and be sure to know at exactly what speeds or other conditions these symptoms occur, like you already described, then go on a test-drive with the person driving who is going to be working on it. Point out if they need to observe shaking in the steering wheel, brake pedal, seat, or any combination of those. Also try to identify anything you can do to cause the symptom to occur, or to stop it from occurring. Once you get the next diagnosis, if it's going to be expensive, come here first for our opinion a to why this could be right or can't be right, and I'll describe the planned repair for you. You might consider looking at these articles too to give you more ideas of things we look for:

https://www.2carpros.com/articles/steering-wheel-shakes-when-accelerating-or-braking

https://www.2carpros.com/articles/popping-noise

The people at the dealership where I was the suspension and alignment specialist knew after a few months to schedule more time for my jobs than what was listed in the "flat rate" guides. Those huge books spell out what every procedure for every car model and year should take, then modifies that according to optional accessories that can get in the way, and it reduces the total time when multiple related procedures are done at the same time. This way every shop provides a similar written estimate for the same work, and the only variable is their hourly labor rate. This applies to standard procedures like replacing a water pump or a tie rod end. In my case I was paid 1.3 hours to perform a four-wheel alignment, regardless if it took me one hour or three hours. They knew I averaged 1.7 hours because I was very picky and I took the time to get it right the first time. Unlike the mass merchandizer I had worked for previously, not one single person at the dealership ever yelled at me for working too slowly in over ten years. I had a reputation for having the fewest "comebacks" or customer complaints of almost anyone there. Flat rate also means customers do not pay any extra when jobs take longer. Barbers work on flat rate too. One price regardless of the size of the head or how much hair is removed.

The downside is I got paid for less than 40 hours per week, and if the customer was waiting for their car, they had to wait a little longer, but that was better than having to come back a second time. My main point of this story is the service writers who interacted with the car owners knew to schedule extra time for my jobs. That prevented the next customer from arriving on time but then having to wait up to a half hour before I even brought their car into the shop. That also reduced my stress when I ran into unexpected problems on older cars and the rusted bolts that won't come loose, or the bolts that break off because of that rust. This is also when you find parts that are needed that you couldn't anticipate from a normal inspection. Upper strut mounts are a perfect example. Unless they're really badly worn and allowing the top of the strut to wobble around, there's no way to know when one is deteriorated until after the struts have been removed, and that happens after they've been inspected, found to be leaking, an estimate was written, and the job was sold. Now I have to visit the parts department to get the prices for the additional parts, get the service writer's attention, tell him of the additional needed parts, (which I really want to avoid), then he has to reach the customer to get the approval for the additional cost. All of that can add another half hour to the job. Meanwhile, that car is tying up my hoist while my next appointment is sitting in the parking lot. There's a lot more variables involved in scheduling jobs. We have to balance reducing the number of hours a work station is empty with multiple jobs overlapping and potentially not getting done. Fortunately, we had a lot of regular customers who understood that and they would drop off vehicles and leave them overnight, and some of them were able to simply wait a few days until they got a call their car was done. My dealership owners also knew I often worked late, after everyone else had gone home, to finish a job or to get an early start on tomorrow morning's first job. Many times my service writer showed up at 6:00 a.M. And found the finished paperwork for my 8:00 a.M. Appointment already done. Sometimes I had to waste time polishing my tools, but often he had fill-in jobs for me if my next appointment wasn't already there and waiting.

All of this wondrous scheduling went out the window when it came to inspections. I've had two-year-old cars take hours to find the cause of a tiny, elusive squeak, and I've had 20-year-old cars that took a few minutes to identify the cause of a handling problem. There's no easy way to schedule these kinds of jobs, and I'm sure that has caused a lot of ulcers among the service writers. When an experienced mechanic becomes involved with a job that is taking longer than expected, some of his next jobs may get handed down to a less-experienced person. That doesn't mean you get a lower-quality job. It means that mechanic may not have already invested in some of the expensive specialty tools, or he won't have the previous experience to know exactly which tools to have at hand, or the time-saving shortcuts or procedures that might make the job go faster. There's a ripple effect too. His scheduled jobs have to put on hold or passed down to someone else. Same thing happens when a mechanic calls in sick or has to leave suddenly for an unexpected training opportunity.

I've also gotten in trouble the other way. At that mass merchandizer I worked for previously, we often teamed up with two people to a car, so that job got done faster. Every week someone was angry because "they knew we didn't do a proper job because it got done too quickly". That's another cause of undeserved bad reputation. Can't win if the mechanic takes too long due to trying to do a quality alignment, and can't win when a two-hour brake job takes only one hour.

All of this boils down to your car sitting in the parking lot. The person you talked with on the phone could have told you they didn't get to your car yet, or they could fib and say it's being looked at. The first response will make you angry. The second one will appease you. If you were that person, would you want to get an earful from the customer, or would you try to keep them happy? They may be doing everything they can think of to rearrange the schedule so they can get to your car, but that isn't anything you want to hear about.

I realize this isn't helping to solve the problem, but coming from the other side of the desk, I've learned why the plumber doesn't show up when you expect him to, why the carpenter has to increase the amount he quoted for a job, and why the guys at the salvage yard don't have the part removed from a donor car that I needed today. It doesn't change the times these things occur. It just makes it less frustrating.

Our industry also suffers from very poor communication skills. With three words, one mechanic can tell another mechanic about a car that would take 1000 words to explain to the car's owner and not be as effective. Accountants, bakers, retail store managers, and doctors all have their own language that only they understand. When a mechanic finds a "blown head gasket" on a car, that's all he has to say to another mechanic. We both know, the approximate repair time and cost involved, what parts will be needed, whether the services of a specialty shop will be involved, what may have caused the problem, and what extra steps we might want to do to prevent this from happening again. Now we have to explain that to the service writer who very likely never was a mechanic. Once we assume he understands what we found, he has to translate that into something he thinks you will understand. This is another source of his ulcers. Way too often what people hear is not what was said. A lot gets lost in translation. Most experienced service writers learn to give up and dumb-down their explanations in an attempt to get approval for the job so they can move on to their next project that is likely sitting in the waiting room. All of these steps lead to miscommunication, but that doesn't mean they're attempts to defraud. Doctors don't discuss ailments and cures with patients either the way they would with another doctor. The difference is doctors bury their mistakes, and we hold them in esteem, while mechanics all have bad reputations because of a few, and our mistakes keep coming back.

What I would like you to consider is trying to stick with one shop for this problem. Ideally that would include just one mechanic, but that isn't always possible, and sometimes two heads are better than one. Keeping those scheduling problems in mind, try to start off with a test-drive like I described previously where you can show him the symptoms and be sure he understands your concern. Of great importance is when you notice a new problem when you pick up the vehicle, return to that shop immediately, or call to tell them of the problem. This is what we call that "comeback" I eluded to a minute ago. All of us do make mistakes. I even made one back in 1969. We deserve the opportunity to make it right. If it was the mechanic's fault, reputable shops will not charge you for the repair, and a few really good ones, like the one I for, will offer something in return such as a free oil change or car wash. Sometimes we find that additional parts or services are needed, not the fault of the mechanic, but those have to be paid for. Legitimately the customer can be expected to pay for them, but often the shop owner will cover the labor cost or will reduce the charges to soften the blow to your wallet. It's the disreputable shops that will charge as much as possible the first time because they know you're not coming back a second time. In my extended city of about 100,000, we had the Chrysler, GMC, Ford, Cadillac, and an import dealer that have very good reputations. They all borrowed service manuals to each other and often repaired each other's trade-ins. There were two notable exceptions; the Chevy dealer and one independent repair shop. The independent has gone out-of-business due to lack of customers, and the Chevy dealer has a very poor reputation due to his business practices. The same is true now of the other dealerships he bought up.

Word-of-mouth advertising is a good way to pick a shop, then look for someone who will devote as much time as necessary to explain what they're going to do for you. Busy shops where you have to schedule an appointment are a good sign of happy, repeat customers.

Try as much as possible to not jump from shop to shop. At each one, they'll have to start the diagnosis all over, and they're likely to start with the common stuff that has already been done multiple times. It's more efficient and less costly when the mechanic already knows the car's history, and can continue on from there. Any mechanic new to your car is going to have a big disadvantage in all the variables that have been introduced. I mentioned warped recently-new brake rotors, chips of corrosion that can break off cast wheels, then cause them to wobble when they're reinstalled a different way. Some of these variables may have nothing to do with the current problem, but they're going to complicate the issue.

At this point I would not leave anyone with a blank check, so to speak, to repair the car. That will leave them open to trying the most likely solution, and if that doesn't pan out, moving on to the next-most likely solution, and so on until it's finally figured out. There will be an unexpected charge for each of those repair attempts. Instead, in most states you can request a written repair estimate before any work is done. That can make it hard on us too as we can't verify the problem is solved until we do the repairs. Once you agree to a repair attempt, ask what assurance they can give you that will be the end of the problem. When only services are involved, and no parts, as in tire balancing, it is not uncommon for there to be no charge for that service, even if it could have been justified. To the shop owner, you didn't get the outcome you expect to pay for, so they won't charge for that.

Keep in mind too that by now there could be multiple causes to one symptom. There's the original cause, and any others that were inadvertently caused by the repair attempts. This is where that flat rate manual is of no use. There's no way to standardize the time needed to solve this type of problem. If you're going to start over with a new shop, head to a tire and alignment specialty shop. The people there are experts at finding the causes of noises, vibrations, and handling problems, and they're really good at reading tire wear patterns and correcting those causes.