Shaking steering / sluggish shifting

[cKGunslinger]

Vehicle info
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2008 Mazda 3
2.0L - 4 cyl
50,000 miles
5-speed manual

Recent work:
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Brakes checked - pads OK (bled and lubed)
Transmission fluid flushed
Tires rotated and balanced
Oil changed
Air filter changed


Issues:
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1. At high speeds (50mph+), when I apply the brakes, my steering wheel often (not always) start to shake/shimmy as the car slows. That's why I had the tires rotated and balanced, then had the brakes checked. The pads all looked new and were wearing evenly. After all that, it still happens. Been doing it for the past few months, actually.


2. Shifting weird. The 5-speed manual has always been tight and clean. Lately (~2 months or so,) it is acting a bit sluggish. Imagine how it feels to shift from 1st gear into 3rd or 4th at low speeds. That's what it feels like between all the gears, at all speeds. I shift and instead of the usual power, I get this noticeable lull for a few moments, then the acceleration resumes as normal. When I had the oil changed a few weeks ago, I was talked into a transmission flush and thought it might help, but the behavior is the same.


I'm thinking I may need an alignment for the first issue, although the fact that my tires and brakes are wearing even, and I don't really have any pull to either side when driving makes me think this may not be the case.

For the second, I'm just not sure. Surely the clutch isn't going bad so soon - I'm a rather conservative driver and have been driving standards for 15+ years. I always assumes it loosens up a little over time, but it this just feels so sluggish, and came on rather quickly.


What should I have looked at?

 

[radioouman]

The first issue is that your brake rotors are warped.

The second... no idea.

 

[zerocool84]

Like radioouman said, first problem is brake rotors. Get them turned.

 

[cKGunslinger]

Like radioouman said, first problem is brake rotors. Get them turned.

Really? I took it to a brake-place, they unmounted everything and said it would be a waste of money to replace the pads or turn the rotors, as they were in "like-new" shape. They only charged me $20 for the disassemble and the bleed.

Hmm..

 

[stevty2889]

First issue definetly sounds like an alignment issue(I've got the same problem, my car also pulls to the right as well).

Second issue..don't know.

 

[amdhunter]

1st - I'd say rotors as well.

2nd - slipping clutch? Try doing a WOT run in 5th gear from 25MPH. If the revs start to race faster than the car accelerates, your clutch is on its way out. From what I heard, clutch failures do happen suddenly for the most part.

 

[Hyperlite]

First issue is almost definitely warped rotors as others have said. get them turned, or just get new ones. they're cheap.

second issue sounds like a fuel delivery or combustion issue. It would be easy to diagnose the clutch slipping, as someone said, do the revs race when you feel a loss of power, or do they just increase more slowly? I'm willing to bet you have fouled plug(s). Has a check engine light come one? You're experiencing a cylinder misfire.

 

[cKGunslinger]

First issue is almost definitely warped rotors as others have said. get them turned, or just get new ones. they're cheap.

second issue sounds like a fuel delivery or combustion issue. It would be easy to diagnose the clutch slipping, as someone said, do the revs race when you feel a loss of power, or do they just increase more slowly? I'm willing to bet you have fouled plug(s). Has a check engine light come one? You're experiencing a cylinder misfire.

No engine light, but changing the plugs is next on my list. Maybe tomorrow afternoon. Then maybe a fuel filter or pump? Hmm..

 

[thomsbrain]

First issue is warped rotors for sure. Do not go back to the place you took it. "Brake places" are ironically not good places to go for brakes, because they are one step up from Jiffy Lube in terms of the goons they hire. Take it to an independent mechanic shop that specializes in Mazdas (specializing in Japanese cars in general will do fine if there aren't any Mazda-specific shops). They will know more about your brakes than any "brake specialty" shop. Also, get new rotors rather than "turn" or "machine" them. Machined rotors just warp again even faster and new ones don't cost much more.

For the second issue... MAP sensor, maybe? I'd try an ECU reset for starters. Again, your Mazda specialist will be the place to take it in for this issue. They can diagnose it while they install your new rotors.

 

[cKGunslinger]

second issue sounds like a fuel delivery or combustion issue. It would be easy to diagnose the clutch slipping, as someone said, do the revs race when you feel a loss of power, or do they just increase more slowly? I'm willing to bet you have fouled plug(s). Has a check engine light come one? You're experiencing a cylinder misfire.

Good call. I changed the plugs earlier this week and the car drives much smoother, especially when idling along in 1st and 2nd. Haven't experienced any shifting issues since. $17 fix.

 

[Bad Dude]

The first one is almost certainly warp rotor either on one side or both. If your car is only at 50K miles, wonder if the warranty is still good. Did you recently slam on the brakes fast or while going downhill and slam the brakes? That could give you warp rotors.

The 2nd problem. First of all, does your car manufacture recommends flushing the transmission? With the car at 50000 miles, there's no reason to flush it. What I would have done is drain and fill, then do it again after driving for 2000 miles or your next oil change. Do it a third time and it's like a flush and it's really safe as well. I know Honda never recommend transmission flush. This can really mess up your transmission. If you drive normal, you can change fluid at 30k-40k miles. Unless there's a leak on the pan, I would do it myself a drain and fill, as no one takes better care of your car than you.
At 50k, is a good time switch over to synthetic and your car will last much longer. Since you can prolong oil change up to 6000 miles, make sure you use a good oil filter like Mobil 1. You don't have to use Mobil 1 synthetic.
Don't forget your brake fluid, bleed and change it at 30k-40k miles. Don't wait longer as master cynlinder failure can occur.
Your power steering fluid, no one ever mention this one and most mechanic don't even tell you about it. Do it at about 50K and keep the steering rack going as long as your transmission if not longer.
Rotate your tires every 2nd oil change or every oil change if you use synthetic oil.

Keep your car running healthy by spending a little now and a lot less down the line.

Your 2nd problem could be bad tank of gas or premature fuel filter issue. Never run on almost empty tank or having to go to the reserve. Bad dirty gas.
Pull the plugs and look to see if there's oil in there. Check the condition of the plugs. Unless you have been abusing your car, I don't expect to find anything out of the ordinary.

Good luck.