"Bump" when taking off

This may be a dumb question (no flaming, please). When I first take off from a start (only when first starting the vehicle), there is a mild "bump" that occurs. Mildly audible and tactile. Is that just the AWD working? Or is there something wrong?

Bump? Is it related to the first shift from a cold start? My '05 has a hard first shift (1st to 2nd gear) when the weather gets cold.

It's not a shift - it definitely happens when first taking off from a standstill. It feels like the locker locking/unlocking in my dad's 4x4. I back out of my garage, crank the wheels one way and begin to take off which is when i feel it.

maybe its becuase of your rear brake pads are sticking with the rotor (my assumption would be due to the ebrake). So once you move ur car, the rotor break contact with the pads and that might generate a noice?

Any more suggestions as to what the noise could be? I guess I just want to rule out if it's a problem that needs the dealer. Maybe I'll mention it at my next oil change?

Check the suspension, make sure that there aren't any ball joints gone bad or anything loose. Do it as soon as possible - it can be really bad if one wheel thinks it shall go on an excursion somewhere.

Sounds like binding on a brake rotor.

I back out of my garage, crank the wheels one way and begin to take off which is when i feel it.

So the suggestion is that the rotor isn't binding on backing out of the garage but is binding on first forward motion? HPH

Sounds like binding on a brake rotor.

 

+1

 

In my car that'll happen sometimes when it rains or is very cold. I can actually release the parking brake and rock the car back and forth with my body weight to loosen it up a bit. Ease out of the first park of the day and you should be fine.

I think in another thread somewhere the OP came to the conclusion that it was the ABS. He pulled the fuse and the noise went away. I get the same thing/sound in my car.

its the brake rotor

i have that on my 00 GT on both of the rear brakes

it sort of gets unstuck after being parked overnight with the handbrake on

When it gets really cold i just leave it in gear instead - fixes the problem

I think in another thread somewhere the OP came to the conclusion that it was the ABS. He pulled the fuse and the noise went away. I get the same thing/sound in my car.

 

This would be me.

 

http://legacygt.com/forums/showthread.php?t=98295

 

To the OP, does it happen every time you take off from a standstill? Or only in the morning, or only after the car has been sitting at least 30 min?

 

Say you back out of your driveway, then take off in 1st gear, it clunks. Repark it on your driveway, back out, then take off in 1st again, does it clunk again? If so, it's something different than the ABS self check. If it only does it once in the morning, and on occasion after the car has been sitting, that is the ABS check.

 

Pull your ABS fuse if in doubt.

It's not a shift - it definitely happens when first taking off from a standstill. It feels like the locker locking/unlocking in my dad's 4x4. I back out of my garage, crank the wheels one way and begin to take off which is when i feel it.

 

happend to me when I had my 08legacy n/a AT. After i backed up and pressed the gas going to go to work on the first 2-5mph, I hear *bog* sound from the back under the car. It is not that loud. kinda like a cellphone dropped on a carpeted floor 5 inches high. or something:spin:

My car was making a noise after starting the car, putting it in drive, and driving several feet forward. I had asked the dealer about this and the tech said that it wasn't normal, so he looked at the car and said that the U-joint was loose. Since you can't replace just the U-joint, he ordered and replaced the entire drive shaft, under warranty. Of course, the problem remained after the repair. I wasn't happy.

 

I posted something about this here a few months ago. Another poster said that it was the ABS/VDC doing a self-test. I told the same tech and he said that there was no way it could be that and said that I should bring the car back in because there might something wrong with the driveline. Of course, he never heard the sound, so it's hard to believe he could diagnose it. I never bothered to go back as it's a bit of a long drive to the dealer and I just had it in for service a few days before.

 

The next time I had my oil changed at the dealer, I had a different service advisor and I asked him about it and he said that it was most likely the ABS/VDC, and since it does it only once every time I start the car, it was normal. He did add that if for some reason it starts getting louder or happens more often, bring it in and they'd look at it.

 

While I can't confirm that this is really the cause of the sound, I don't think I'm too concerned with it. I guess I should get the manual out and see if it mentions anything about it.

This would be me.

 

http://legacygt.com/forums/showthread.php?t=98295

 

To the OP, does it happen every time you take off from a standstill? Or only in the morning, or only after the car has been sitting at least 30 min?

 

Say you back out of your driveway, then take off in 1st gear, it clunks. Repark it on your driveway, back out, then take off in 1st again, does it clunk again? If so, it's something different than the ABS self check. If it only does it once in the morning, and on occasion after the car has been sitting, that is the ABS check.

 

Pull your ABS fuse if in doubt.

 

I guess I haven't tested it that closely to see if it happens at extended parks, or with short rest periods. I know that it can happen without the parking brake being applied, as I don't use that when in the garage.

I guess I haven't tested it that closely to see if it happens at extended parks, or with short rest periods. I know that it can happen without the parking brake being applied, as I don't use that when in the garage.

 

It definitely is not the parking brake. At least in my case. It comes from the front right of the car, right about where the electronic brain and workings for the ABS unit are under the hood.

Bump? Is it related to the first shift from a cold start? My '05 has a hard first shift (1st to 2nd gear) when the weather gets cold.

+1

 

My '06 just started doing this and our weather is down in the 30s. I find if I back out of the garage and then go forward to the corner while the idle is still a bit high, I get this. If I let the car warm a bit so the idle has dropped, this doesn't clunk as much. I also put it in Sport mode and into 2 while pulling away and avoided the clunk entirely. I can coast down, we live on a hill.

 

We've had no moisture and I hardly ever use the ebrake, so I'm sure it's the driveline. Somehwere. I wouldn't worry unless it clunks hard and sounds bad. Growling or howling would be bad.

Okay - so the general consensus is not to worry about it. Thanks. When I go in for my 15K mile service, I'll mention it but it sounds like it may just be ABS stuff going on.

I get something similar sometimes... When i first move the car in the morning, if i release the clutch a bit abrubtly in 1st gear i can hear a kind of deep "bass" sounding thump as soon as the clutch pedal passes its "bite" point. Any ideas on what it might be guys? Thanks!