[starboard]

I kept getting an intermittent vibration that felt like going over rumble strips. If I shift to DS, it immediately goes away.

2011 328i E93 with 84,000 miles.

Likely just need a fluid change or something more serious?

[rjahl]

Originally Posted by starboard

I kept getting an intermittent vibration that felt like going over rumble strips. If I shift to DS, it immediately goes away.

2011 328i E93 with 84,000 miles.

Likely just need a fluid change or something more serious?

D and DS setting only change transmission shift logic. So, unless the transmission is shifting gears with the change? something else is changing.

On second thought,

Those modes do affect the toque converter lock up points. Are you seeing a change in RPMs when you change modes?

[nsjames]

Originally Posted by rjahl

Those modes do affect the toque converter lock up points. Are you seeing a change in RPMs when you change modes?

this is what I would suspect.

The TCC seems particularly sensitive to crap fluid as well. Whens the last time it was serviced?

Mine had the slight shudder sometimes when purchased@101k, a full service made it shift fine. Now at 143K miles. Almost time to service it again.

[starboard]

I don't notice an appreciable change in rpms when switching from D to
DS. It has never had a trans fluid change (84,000 mi) so that is what I hope will fix things.

[nsjames]

definitely do the service.
assuming gm trans, super cheap to do the filter and the pickup sleeve.

mine was noticeably better after just a fluid change.
especially when cold.

[rjahl]

Originally Posted by nsjames

definitely do the service.
assuming gm trans, super cheap to do the filter and the pickup sleeve.

mine was noticeably better after just a fluid change.
especially when cold.

Do the service.

The fluids are not good past 60,000 miles or so.



Most people don't understand how these torque converter clutch functions. They are not on-off devices. They have large operating bands where they are allowed to "slip" while either closing or opening. There are dozens of maps that control the TCC function, each mode has a set for each gear. Modes being D,DS, manual, winter, safety, warm up and such. These maps are based on throttle position and output shaft speeds.

An example, 6 gear in D, TCC lock up might start at 65 mph and gradually clamp full at 72 MPH. Opening would start at 70 and be fully released at 60. Some gears/ modes like D in first could have the TCC disabled completely. This is why you can never really feel the TCC lock up or release.

Also the TCC is usually released prior to each gear change and re-clamped after, if conditions permit.

It's the busiest clutch in the gearbox.

[starboard]

So trans shop can't get it to act up. They see the torque converter as a common problem with this model but don't want to proceed unless they are certain. Seems to only do this after warmed up. Full trans fluid change is almost $800 (not doing it myself), so I'd like to not do the fluid change and then need to replace converter.

Only rumbles in D and only during modest acceleration.

[nsjames]

which transmission do you have?

$800 is outright robbery for servicing the GM trans, and is only slightly less rapey for the ZF. Either DIY or find a new mechanic.

do the fluid, it's basic maintenance. ignoring the shudder will eventually lead to a full on converter failure, which may very well kill the trans with shit.

ignoring any issue with a transmission always ends up costing more money.