Bang/Clunk/Kick - after giving gas from a rolling stop - Feels like just got hit!

[fmugur]

Originally Posted by tdog05

-- This occurs almost every time you roll to a stop and don't stop completely and give it gas to take off. (Sometimes very hard, sometimes very soft kick/clunk/slam) If you stop completely, this does not happen at all - anytime.

I do not have any lights on or errors - Just one occurrence of the Fail safe message and it went away with a restart.

If you read these forums, there are a lot of people who have resolved this issue without replacing the entire tranny or having it rebuilt.

Yup, that's the exact problem on my daughter's 4.4 and Doru seemed that he fixed his with an oil flash. It is a transmission problem but I don't know the technical explanation for it. It seems like there is a disconnect between the gears and wheels and when you press the gas makes the connection while the high torque is applied.
When I drive my daughter's car I adapted and if you press slowly on the gas you can feel when the coupling is done and then you can press hard on the gas... I know you want it fixed. I might do the oil flash in the spring too.

[tdog05]

Originally Posted by fmugur

Yup, that's the exact problem on my daughter's 4.4 and Doru seemed that he fixed his with an oil flash. It is a transmission problem but I don't know the technical explanation for it. It seems like there is a disconnect between the gears and wheels and when you press the gas makes the connection while the high torque is applied.
When I drive my daughter's car I adapted and if you press slowly on the gas you can feel when the coupling is done and then you can press hard on the gas... I know you want it fixed. I might do the oil flash in the spring too.

Yes, that is exactly what is happening.

You can feel it engage and then you can press the gas and then it doesn't happen if you time it right. Again, this doesn't happen from a full stop, but only from a rolling stop.

Thanks!

[fmugur]

Originally Posted by tdog05

-- Okay, so you are recommending a flush and filter replacement then. Est cost?

Check this site and email him if there is no price.
6 Speed oil change kit BMW

[fmugur]

Originally Posted by tdog05

Yes, that is exactly what is happening.

You can feel it engage and then you can press the gas and then it doesn't happen if you time it right. Again, this doesn't happen from a full stop, but only from a rolling stop.

Thanks!

Yup.

[tdog05]

Originally Posted by fmugur

Check this site and email him if there is no price.
6 Speed oil change kit BMW

Thank you!

[Quicksilver]

Mine has done the old bump thing for years. The reset procedure
has worked even though I've had to do it maybe once a year.
Reprogramming has also helped as well but nothing completely stopped it. Hope things work out for ya..

EDIT: The language assessment is correct.
If your offended by a post then just let it go.

Originally Posted by tdog05

What the hell is going on?

Or another way to describe it is that it feels like I just got rear ended by another car -- after giving it gas from a rolling stop or on an slight incline.

1. Try the reset procedure - (turn key to position 2, press accelerator & hold for 25 seconds, turn off car, restart). - Does this work?

[fmugur]

Originally Posted by Quicksilver

Mine has done the old bump thing for years. The reset procedure
has worked even though I've had to do it maybe once a year.
Reprogramming has also helped as well but nothing completely stopped it. Hope things work out for ya..

EDIT: The language assessment is correct.
If your offended by a post then just let it go.

The reset procedure is only good for this problem until the tranny module re-learns the shifting timing. The reprogramming wipes out all the recorded value and it's like a reset.
Once re-learnt then the problem is back. The tranny is readjusting these values anyway. That's the reason you have to keep doing it...

[garrett.fell]

I had the same issue with mine. Software update on the transmission control software solved the problem 90% plus for me. It's done it a few times but NOTHING like it was before. Probably 2+ years ago for me.


Sent from my iPhone using Tapatalk

[edogg]

Originally Posted by tdog05

-- Okay, so you are recommending a flush and filter replacement then. Est cost?

A transmission drain and refill will cost about $500-$700 at an indy shop (price quoted from 3 indy shops near me).

Fluid is about $100. If you replace the pan along with the filter, it's about $200 in parts. If you replace the filter alone, that's about $100 in parts. There's also a "mechatronic sealing sleeve" that might be worth replacing while you're in there. And then an hour or two in labor.

I went with the full pan replacement when I did mine - along with the mechatronic seal. Figured it was worth going all the way with it.

BTW, be careful with the term "flush" when it comes to BMW transmissions. You may have seen this in your internet searching already but it's worth mentioning.

Some say that flushing the tranny (i.e. pumping new fluid through the system to make sure all of the old fluid comes out) can dislodge gunk and cause problems.

And they say that a safer route is to just drain out what naturally comes out when you open up the drain holes. Then fill it back up. This doesn't force new fluid through the system and there's a lower risk of dislodging something that could gum up the works. And you wind up with some new fluid but not 100% new. And that's sufficient for healthy transmission operation.

The three indy shops I contacted recommended the "drain and fill" approach rather than "flush" approach. So that's what I went with.

[Riggodeaux]

I'm not clear from the OP's description of the problem whether this might be the rear suspension/bushing type 'thunk' or a tranny problem. As previously noted, this doesn't sound like the 'trifecta' warning lights indicative of the simple transfer case gear fix. Tdog, if your inspection isolates the problem to your auto tranny engagement, I suggest you visit a tranny specialist with BMW experience for a diagnosis before spending time/money on 'might be.' Where are you located [where is Parker?] If in SoCal, I vaguely recall there is a ZF certified vendor near San Diego? that does repairs and rebuilds ZF trannies. Id your locale and someone may have a suggestion for you.