Vibration on takeoff and slow auto transmission change

[Telpro]

I recently purchased a 2004 Outback H6 and noticed on acceleration that there is a slight vibration which feels like it could be the drive shaft out of balance. Any thoughts or similar experiences? Also the auot transmission changes up very slowly, sometimes, under acceleration. Again, any thoughts or experiences?

[cardoc]

Vibration could be due to anything engine, trans or drivetrain related. Could you be more specific in the vibration?

The transmissions on these cars with the Phase II 4EAT are programmed to shift soft. You may feel a shift when its cold, but otherwise, not really. If you are talking about a delayed engagement into the next gear, that would depend on where your foot is on the accelerator; light or pushing it. Again, more specifics would help.

The only possibility with the vibration and long shifts would be related is if the fluid level is low which reduces flow to the torque converter and clutches.
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[Telpro]

Hi Cardoc,
The vibration only occurs with initial accleleration (not foot to the floor) and feels like it's side to side vibration which is why I thought it may be drivetrain related.
The delayed engagement into the next gear (your on the money with that description) usually happens when I give it more than moderate acceleration (again not to the floor).
The car has been serviced regularly and there has been no mention of low fluid level.
Thanks.

[plain OM]

In addition. . . .

Sydney . . . Australia? If so, your 2004 H6 might have the 5-speed automatic transmission (5EAT).

If it is the 4-speed transmission, there should be an AWD (or FWD) socket in the engine area fuse box. (Note: This does not apply to the 5-speed automatic.) Normally there's no fuse there, but if one is inserted, the AWD transfer of power to the rear wheels is turned off. With the fuse in, the car is front wheel drive only, and there won't be any appreciable torque on the rear drive train. If with the fuse in the vibration stops, then the problem is in the drive train.

Are all four tires the same brand, model, size and tread wear? Differences in the tires can lead to vibration during acceleration.

[cardoc]

Originally Posted by Telpro

Hi Cardoc,
The vibration only occurs with initial accleleration (not foot to the floor) and feels like it's side to side vibration which is why I thought it may be drivetrain related.
The delayed engagement into the next gear (your on the money with that description) usually happens when I give it more than moderate acceleration (again not to the floor).
The car has been serviced regularly and there has been no mention of low fluid level.
Thanks.

Morning,

The vibration is still iffy. It could be loose suspension or steering components or it just needs an alignment. On initial torque application to the wheels, if there is a loose component or the alignment is out, the wheels will "fight" each other. In the same token, a loose wheel bearing could do the same.

Other possible would depend on your answers to these: Does your car have VDC? As PlainOM stated, is it 4 or 5 speed? I would assume a 4.

Is the delay in upshift or downshift?

Upshifts are soft and may feel delayed when it is actually the way the solenoids operate fluid flow. If its more like a pause between 2-3, it could be the third clutch slipping. Downshifts will have a delay from 4-3 and 4-2. The programming is designed to keep transmission shifts as smooth as possible. They didn't want you to feel it. And, since it is an adaptive TCM, you could be losing a clutch and won't know it til its too late because the TCM will up the pressures if it sees a small change in engagement. The AT Temp light will flash at you if it sees a ratio issue indicating a full slipping clutch.

Drive the car around for about 10 minutes and park on a level surface and check the fluid level with the engine running in park. When you pull the dipstick, take notice of the color of the fluid.

[Telpro]

I live in Sydney, Australia and my Outback is a 5 speed auto with sport shift and all tyres are the same. I've only noticed the delayed engagement into the next gear when upshifting.

[plain OM]

I'm not clear on what the shifting symptom is. Two possibilities I can think of:

• when accelerating moderately, the engine rpm and car speed reach higher levels before the tranny finally shifts, but the shift itself is relatively normal; or,

• when accelerating moderately, the shift isn't normal -- there seems to be a period of time when the transmission is between gears, in other words the shift process itself takes noticeably longer.

The first symptom, as cardoc referred to earlier, is normal -- shift points are delayed in proportion to the throttle position and the difference between engine and torque converter turbine rpm. So as the rate of acceleration increases, the point at which the transmission upshifts is later.

If it's the second, then cardoc's explanation of the shifting process applies. Nevertheless, shifts will tend to be more noticeable under higher acceleration conditions. Also, during the actual shifting process, the engine power is briefly cut back (by the electronic, drive-by-wire throttle control) to reduce torque in the drive train. This helps make the shift smoother but shouldn't be very noticeable. However it might be disconcerting to a driver not used to this approach.

In regard to the vibration, another possibility is a worn/loose/broken rear transmission mount. But follow cardoc's suggestions first and see if that reveals anything.

[Telpro]

Thanks guys for your feedback. I'll have to cut back on the lead foot and get used to the unique auto transmission on my Outback. As for the vibration, it's due for a service soon so I'll give the mechanics your ideas (a worn/loose/broken rear transmission mount, a loose component or the alignment is out or a loose wheel bearing) and see if they can find the problem. The car has done 135,000km so it's inevitable I guess that there is wear some where with the drivetrain.

[cardoc]

Let us know what, if anything is found.