Has anyone else noticed that with their cars (particularly non-supercharged models with the ZF 5hp24?), accelerating immediately out of an aborted stop (ie a light turning green as you're about to come to a full stop) can cause a harsh shift?

I was on some dead service roads around a very underutilized shopping/industrial area in the southern bit of Gainesville, FL. Stop signs are used for traffic control. I semi-dutifully come to a near-complete stop, engine revs dip momentarily below 500 (a longstanding 'feature' of my baby), and I add some gas.

That was a mistake, as the shift was... very harsh. I replicated a milder version a few minutes later. This happened to me once before several months ago in Honolulu. I've learned to be careful when coming to a rolling stop and not immediately hit the gas as the car is downshifting. Today, my mind was very pro-occupied with the move to FL and various life tasks happening around it (like my LSAT next month).

I replaced the transmission 16 months (with fresh fluid, obviously) and 27,000 miles ago (yes, I drive a lot). The AT has 92,000 miles on it, overall.

Notes: Normally, shifts are totally imperceptible or close to it, including after these two (well, three if we count the HNL incident months ago) shifts. Transmission doesn't groan or hesitate when shifting between D, N, R, or P. During these harsh shifts, there weren't telltale signs of failure like the RPM needle "searching"/wandering or revving very high.

Edit: In my googling about, this isn't a particularly uncommon issue (rough shifts when accelerating out of an aborted stop).

 

The pressure spike resulting from accelerating before the transmission has completed the shift to first is probably the main cause of A drum failure. Replacing the main pressure valve with the ZF upgrade or the transgo part will help protect the transmission. Links below:

http://jagrepair.com/images/AutoRepa...%20ZF5HP24.pdf

ZF 5HP24 5HP24A TRANSMISSION PRESSURE REGULATOR VALVE KIT TRANSGO 5HP-24-PR FITS BMW A5S440Z JAGUAR AUDI ROVER - The American Powertrain Warehouse

 

It's typical that this is rearing its head at the worst possible time.

Point of order: if I recall correctly, when sport mode isn't engaged, I believe the transmission will generally only downshift to 2 when coming to a stop.

As soon as I settle in, I will look at ordering the updated parts. Hopefully, I will find a shop here in GNV willing to use my parts rather than hold my car hostage for a week while they futz around ordering them.

 

The 5HP24 shifts to first in both modes. The Mercedes transmission starts in second in N mode.