Warped rotors give this pony the shakes

Dear Car Talk:

My 2008 Mustang GT shakes at around 60-65 mph when braking. The Hurst 5-speed stick shakes as well. When this is happening, the steering wheel moves from side to side.

I've had the alignment checked and the tires balanced and rotated, and the brake wear looks even. Sometimes, when braking at slower speeds, the steering wheel will shake. Before taking the car to a shop, is there anything I can look for? – Peter

RAY: You can look for the average price of two front brake rotors for a 2008 Mustang GT, Peter. And make sure you have at least that much in your checking account.

This is a classic case of warped disc rotors. The disc rotor is a key part of the brake system. The rotor is attached to the wheel, and when you step on the brake, you squeeze that rotor from both sides with the brake pads. If the rotor is warped, every time that high spot comes around, it pushes back on the brake pads.

When the warp is mild, you can feel it as a pulsing of the brake pedal. When it’s more severe, it can make the steering wheel or even the whole car shake when you brake. And if it’s really severe, it’ll loosen up a filling or two.

Frankly, I’m kind of disappointed in your mechanic, Peter. This is something so obvious that even my late brother could’ve diagnosed it if we woke him up from his nap under one of the cars in the shop.

So, I’d ask some friends if they can recommend a mechanic they really like. Or go to www.mechanicsfiles.com and use your ZIP code to search for a highly recommended mechanic in your area. Explain that the steering wheel shakes when you brake from high speed. If he says right away “it’s probably disc rotors,” you’ve found your new mechanic, Peter.

Acadia’s shifter problem could be a serious safety hazard

Dear Car Talk:

I have a 2017 Acadia. When the car is shifted into park, the dashboard shows a warning that the car is not in park! It says I can’t turn off the car until the car is in park, even though it’s in park.

If I leave the car like that, all the electrical stuff stays on and my battery will die. To get the car to shut off, I have to move the shifter back and forth from drive to park a number of times, until the car finally registers that it’s in park. Once it took over 20 times of doing that to get the car to shut off. When this happens, the car is not in park and seems to be in gear or at least in neutral because it will roll.

I contacted GMC and they said they were aware of this problem as it is showing up on vehicles from 2016 through 2018. They say their technicians are still working on it. My local GMC dealer is going to try to research the problem as well. I understand there’s even a class-action suit against GMC for continuing to sell the Acadia with this known problem.

Bottom line: the car says it's in park, but the engine won't shut off. I am concerned that someday I will not be able to shut it off at all. Any ideas? – John

RAY: Yes, it's a bad shifter assembly, John. GMC has recently issued a Technical Service Bulletin for this problem. If you go back to your dealer, they should now know how to fix it. If you originally complained about the problem while your car was under warranty, GMC should fix it for free. If you're out of warranty, it'll probably cost you $250- $300.

But even if you have to pay for it out of pocket, you should get it fixed. The last thing you want is for the car to roll away with your mother-in-law strapped into the back seat. Well, I guess that depends on how you feel about your mother-in-law. And your Acadia.

If you do shell out your own money, definitely hang onto your receipt. Should GMC eventually be forced to issue a recall for this problem, they’ll have to reimburse you.

The key question is whether the car is able to roll away – as you say yours is. If that’s true, this is a serious safety issue, and GMC will be forced to recall the vehicles.

If you’re mistaken, and it’s “just” a problem where you can’t turn off the vehicle and your battery dies, that’ll frost your shorts, but it may not fall under the safety purview of the National Highway Traffic Safety Administration.

In either case, get it fixed right away. Then lodge a complaint with NHTSA (www.nhtsa.gov – “report a problem”). If your Acadia really can roll away when this problem occurs, be sure to tell NHTSA that. That’s crucial information. If NHTSA gets enough complaints, they can open an investigation, which is what can lead to a safety recall.

You can also check back at www.nhtsa.gov from time to time and search your car under “Recalls” to see if any action has been taken.

Once it’s fixed, remember to cancel your membership in the Battery of the Month Club, John.

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