Join the Car Talk Community!

Discussion Rules

Welcome to the Car Talk Community!

Want to ask a question or join the discussion? Great! Join now.

Sign In Register

vibration after breaking, but only in drive

Just got the transmission serviced, and a new cv, front driver's side axle. Right after the axle was put on (about 1 week after the transmission service) I noticed a strange vibration that started a second or so after breaking, but only after going a certain speed (at least 35). The vibration stopped when I took my foot off the break. The vibration got worse, and it seemed the car vibrated when it 55 mph, and my mechanic put in a different axle (a better fit, he said), and tuned up the car. The vibration when driving seemed to disappear (although I haven't gone on the highway yet), but the vibration after breaking now occurs right after breaking, in drive, but disappears when I put the car in neutral or park. Any ideas what could be causing the vibration? This is a 2003 Subaru Outback.

Comments

  • edited January 2011
    I've read that 3 times and still can't figure out what you're saying. The car vibrates when you put the brakes on? Or after you've come to a stop? Or you're driving along and use the brakes to slow down and while still moving the car vibrates when you release the brakes? What if you're going along, pop the car in neutral and then put on the brakes? Where do you feel the vibration? Brake pedal? Steering wheel? Seat? All over?

    You need to clarify what you mean.
  • edited January 2011
    Sorry- I am rather inexperienced at this. I checked the car out a bit today again- it seems to act differently each time I drive. When I apply the brakes, and come to a stop, after a second or so a vibration builds, seemingly coming from under me and sort of in the middle. I hear it more than feel it. The vibration continues when I release the brakes, but stops if I put the car in neutral or park, or if I accelerate. I do not feel the vibration if I apply the brakes and only slow down. I have not tried driving and popping the car into neutral and then applying the brakes because of the snow storm- didn't get to drive much today.
    Thanks for trying to understand. I hope this is clearer.
  • edited January 2011
    It sounds like you're describing an engine vibration which occurs at a dead stop only. This could be caused by a faulty mount (would be very rare for a Subaru) or an engine performance problem, possibly due to a problem with the Idle Air Valve allowing the engine idle to drop too low.

    Question. Does the tachometer needle remain constant or does it drop a little when this vibration occurs?
  • edited January 2011
    That clarifies perfectly well. It sounds like your car is just running a little rough. Do watch the tachometer - as it goes to vibrating its probably dropping some.

    Many times a car runs a little rough just because of simple maintenance items. So report back on the age/history of spark plugs & wires, fuel and air filters, and any other kinds of "tune-up" type work that has been done on the car. If, according to the owner's manual, any of that maintenance is not up to date the place to start is by making it so.

    Is your check engine light on?
  • edited January 2011
    Thanks. Actually, right after the vibration began, the mechanic put in a different cv axle and gave the car a tune up. This did not help much. He checked the engine mounts, and they are fine. I didn't notice and the mechanic didn't say if the tachometer light goes on when it vibrates. There is some question about the torque converter, now, and the transmission, since the vibration only occurs in drive gears, not in neutral or park. The vibration stops immediately when the car is put into neutral or park, and begins again back in drive gears (d, 1,2, 3, r) or when accelerating.
    Thanks- any suggestions on how to detect torque converter problems without taking out the transmission?
  • edited January 2011
    The vibration begins when I stop after applying the brakes (after driving a bit), and then the vibration stops only if I put it into neutral or park or begin accelerating again. The engine mounts have been checked, the car has been tuned up (right after the vibration began) and the cv axle was changed (again) to a better one. I haven't noticed and the mechanic has not said anything about the tachometer needle. I'll remember to look today when I take the car out.
    There has been mention of a faulty torque converter, but I understand there's no real way of checking this without taking out the transmission. Any ideas on this?
    Thanks!
  • edited January 2011
    Having it in in a gear (D, R or whatever) puts load on the engine. When you shift to N or P it takes that load off, so the engine doesn't have to do as much work. It just sounds like the engine isn't running quite right and it is showing that with a little bit of load on it.

    As for the tune-up - there really isn't any such thing anymore, so the phrase "tune-up" doesn't refer to anything specific. Take out your invoice and describe exactly what was done during this tune up.

    Someone should check your fuel pressure.

    As for the tachometer - you would be the one to look at it. At idle the typical car will run at something like 750-900 rpm. If I get OK4450's question right, he wants to know whether or not your idle is going below normal, and perhaps whether it is surging up and down a bit. So when you're sitting at idle in D with the car vibrating, what does the tach show? What happens when you put it in N? If it is surging up and down some then you probably have a vacuum leak.

    I am doubting the torque converter story.
  • edited January 2011
    I just went out to check, but don't have time right now to let the car warm up properly. The tachometer, when I am driving, is usually between 300 and 400, sometimes goes to 500- quite different from the 750-900...?? Right now, in idle, it didn't get up beyond 100, but stayed steady. I will check again later after it is on the road a while.
    The vibration seems to be getting louder, and happens now even when I am not driving much (just moved to a different parking spot).
    The tune up just included new plugs and plug wires. The transmission was serviced right before New Year's eve- I guess it was "flushed". It has been suggested that the transmission "service" could have kicked up something in the transmission.
    It has also been suggested that putting in a cv axle (the first one) that was 3/4 - 1 inch too long could have damaged something in the transmission. My mechanic says this could not have happened because the parts fit together well even though the axle was a bit long. He changed the axle to one that fit perfectly and the vibration is still there (louder than ever now- and it seems to be the whole front end that is vibrating).
    Thanks for all your suggestions. I hope it's not the torque!
This discussion has been closed.