2006 4.4 5th gear lurching

[Duc]

Hey everyone,

Under warranty the P.O. took it in for hard shifting about a month or so ago. BMW replaced the seals on the mechatronic unit (square one, and the one that notoriously leaks at the terminal), as well as the 4 little round ones and put all new fluids and filter in. The P.O. believed this fixed the issue (which it likely mostly did). Unfortunately the real issue was never identified by the P.O. or BMW and now the X5 is out of warranty.

Alright, so onto the issue.

1. Intermittent hard shifts from 1st to 2nd when cold. Seems like it holds the gear too long and then drops it hard into 2nd. If you let the tranny get up to temp for a few minutes in the morning this issue isn't present. But if you hop in and go, bang, hard shift. Rest of the shifts after that are buttery smooth, even the next 1-2 shift.

2. Now this is the one that really worries me. When in 5th gear the transmission feels like it's skipping or lurching. This is ONLY in 5th gear. RPM stays steady. It almost feels like the transmission is going to shift. I can get it to do it consistently if I stay in 5th in manual shift mode, or if the trans selects 5th while in regular D. This isn't present in any other gears. There is no other slipping in any other gears, everything else is buttery smooth.

Based on my research, I think both of these issues will be fixed with a rebuild of valve body using a zip kit and new ZF solenoids. But I would like to know for sure. I'm hoping an expert on here can tell me whether or not issue 2 is likely to be resolved by the valve body refresh, or if you think its an issue inside the transmission itself. I'm really hoping it's not a bad clutch pack.

Any insight would be greatly appreciated here!

[upallnight]

Originally Posted by Duc

Hey everyone, I just recently picked up my first X5. I just wanted to say that I've already solved a bunch of little issues and installed an OE AUX cable all thanks to this forum.

Well, about 30 minutes after driving away with the X5 after purchase I noticed a bit of a transmission issue while stuck in rush hour traffic that didn't rear it's ugly head while I was test driving it. As it was a private sale, I am now stuck with fixing it myself.

First a bit of back story. The car only has 149,000 KM on the clock. BMW warranty claims history shows that a new transmission was installed at 29,000km. So the tranny is a little younger than the rest of the car.

Under warranty the P.O. took it in for hard shifting about a month or so ago. BMW replaced the seals on the mechatronic unit (square one, and the one that notoriously leaks at the terminal), as well as the 4 little round ones and put all new fluids and filter in. The P.O. believed this fixed the issue (which it likely mostly did). Unfortunately the real issue was never identified by the P.O. or BMW and now the X5 is out of warranty.

Alright, so onto the issue.

1. Intermittent hard shifts from 1st to 2nd when cold. Seems like it holds the gear too long and then drops it hard into 2nd. If you let the tranny get up to temp for a few minutes in the morning this issue isn't present. But if you hop in and go, bang, hard shift. Rest of the shifts after that are buttery smooth, even the next 1-2 shift.

2. Now this is the one that really worries me. When in 5th gear the transmission feels like it's skipping or lurching. This is ONLY in 5th gear. RPM stays steady. It almost feels like the transmission is going to shift. I can get it to do it consistently if I stay in 5th in manual shift mode, or if the trans selects 5th while in regular D. This isn't present in any other gears. There is no other slipping in any other gears, everything else is buttery smooth.

Based on my research, I think both of these issues will be fixed with a rebuild of valve body using a zip kit and new ZF solenoids. But I would like to know for sure. I'm hoping an expert on here can tell me whether or not issue 2 is likely to be resolved by the valve body refresh, or if you think its an issue inside the transmission itself. I'm really hoping it's not a bad clutch pack.

Any insight would be greatly appreciated here!

Thanks everyone! Oh, and I've included a shot of the new X5 if anyone is curious. It's a sport package and I have the factory 19" wheels with it, these are just for winter.

Hopefully RPhil will chime in on this or go to youtube and check out Gary Ferraro's videos on the ZF5hp24 trans including his video on valve body rebuilding. If it was my X and I was going to pull the valve body out I will just ship it to Gary's shop and have him rebuild the valve body. Too many check balls and orifice tubes that can be installed incorrectly

[Duc]

Originally Posted by upallnight

Hopefully RPhil will chime in on this or go to youtube and check out Gary Ferraro's videos on the ZF5hp24 trans including his video on valve body rebuilding. If it was my X and I was going to pull the valve body out I will just ship it to Gary's shop and have him rebuild the valve body. Too many check balls and orifice tubes that can be installed incorrectly

I'm hoping RPhil sees this post as well. I have seen some amazing contributions by him in other threads.

I've watched all of Gary Ferraro's videos on the ZF6HP26, he has some great tear down and valve body rebuild videos.

I'm in Canada, so shipping the VB to his shop might not be worth it, I may be better off just buying a reman from a ZF distributor directly.

Although based on my reading and the countless videos on the subject I have watched I am confident in my ability to rebuild the valve body myself. I also work at a motorcycle dealership (BMW, Ducati, Triumph) and have many sources of information if I get stuck. I also have people I can trust that I can get to rebuild it for me.

[RRPhil]

Even after 15 years in production, mechanical hardware issues on the 6HP26 appear to be virtually non-existent. It’s a pretty bullet proof transmission, except of course for its Achilles heel - the EDS solenoids - and maybe also the rear stator bush which can wear in certain models (due to the material specified) and allow the E clutch to leak. A leaking E clutch would affect 4th, 5th & 6th gears so this doesn’t sound like your issue.

In 5th gear the B & E clutches are applied. The B clutch is also used in Reverse and 3rd gears and, as already mentioned, the E clutch is also used in 4th & 6th gears. As you don’t appear to be having any problems in any of these other gears it sounds unlikely to be a clutch issue?

The four clutch-activating EDS solenoids are all ‘turned off’ in 5th gear. As the EDS 2 (B clutch) & EDS 4 (E clutch) blue cap solenoids have a falling pressure characteristic with current, they apply full pressure under zero current to apply the two clutches.



I suppose that the torque converter lock-up clutch (driven by the EDS 6 solenoid) is another possibility but, again, why would this only affect 5th gear and not 6th, 4th, etc.?

So unfortunately I can’t think of an obvious reason for the issue that you have. It certainly isn’t a difficult job to strip and rebuild the Mechatronic unit (just remember to take ESD precautions to protect the electronics) so, for the sake of the cost of a Sonnax Zip Kit and a bonded separator plate (make sure that you get the correct one), I would encourage you to give this a try.





Phil

[Duc]

Originally Posted by RRPhil

Even after 15 years in production, mechanical hardware issues on the 6HP26 appear to be virtually non-existent. It’s a pretty bullet proof transmission, except of course for its Achilles heel - the EDS solenoids - and maybe also the rear stator bush which can wear in certain models (due to the material specified) and allow the E clutch to leak. A leaking E clutch would affect 4th, 5th & 6th gears so this doesn’t sound like your issue.

In 5th gear the B & E clutches are applied. The B clutch is also used in Reverse and 3rd gears and, as already mentioned, the E clutch is also used in 4th & 6th gears. As you don’t appear to be having any problems in any of these other gears it sounds unlikely to be a clutch issue?

The four clutch-activating EDS solenoids are all ‘turned off’ in 5th gear. As the EDS 2 (B clutch) & EDS 4 (E clutch) blue cap solenoids have a falling pressure characteristic with current, they apply full pressure under zero current to apply the two clutches.



I suppose that the torque converter lock-up clutch (driven by the EDS 6 solenoid) is another possibility but, again, why would this only affect 5th gear and not 6th, 4th, etc.?

So unfortunately I can’t think of an obvious reason for the issue that you have. It certainly isn’t a difficult job to strip and rebuild the Mechatronic unit (just remember to take ESD precautions to protect the electronics) so, for the sake of the cost of a Sonnax Zip Kit and a bonded separator plate (make sure that you get the correct one), I would encourage you to give this a try.





Phil

Phil, you are a god when it comes to these things. This information is fantastic. You certainly know your stuff. If you were local I would buy you a beer.

I think a mechatronic rebuild would be a good thing to do in my case, if anything it's great preventative maintenance.

[upallnight]

Originally Posted by Duc

Phil, you are a god when it comes to these things. This information is fantastic. You certainly know your stuff. If you were local I would buy you a beer.

I think a mechatronic rebuild would be a good thing to do in my case, if anything it's great preventative maintenance.

You can always send him some money to buy a beer through Paypal. I sent a tip to a Chap in the UK who helped me fix my plasma tv. He pointed out which capacitors I needed to change to get the TV running again. Save me a ton of money instead of taking it into the tv shop.

[RRPhil]

The bulletin boards and forums have been very good to me and have enabled me to convert a hobby into a small thriving business which brings in work just through reputation, without the need for any advertising. This is compensation enough .

Phil

P.S. I think that your E53 6HP26 may have the electronic park lock (?) in which case you have the ‘E’ version of the Mechatronic unit which is fitted with the additional two ‘on-off’ solenoids. My photos show the ‘M’ version which is fitted to the Range Rover where the park lock and manual valve are activated manually (via an old-fashioned cable from the shift lever). The Zip Kit is the same for both though.

[upallnight]

Originally Posted by RRPhil

The bulletin boards and forums have been very good to me and have enabled me to convert a hobby into a small thriving business which brings in work just through reputation, without the need for any advertising. This is compensation enough .

Phil

P.S. I think that your E53 6HP26 may have the electronic park lock (?) in which case you have the ‘E’ version of the Mechatronic unit which is fitted with the additional two ‘on-off’ solenoids. My photos show the ‘M’ version which is fitted to the Range Rover where the park lock and manual valve are activated manually (via an old-fashioned cable from the shift lever). The Zip Kit is the same for both though.

But with the convenience of the internet, a couple of quid for a beer is not going to hurt anyone. It's just the thought behind it and to show your appreciation for the help you received.

[upallnight]

Nice looking X5. RB would be so jealous of those running boards.



Found the twin to your X.

[kfdE53]

Hi Duc, if it makes you feel any better, my 2006 4.4 has been having the same issue for the past 15,000 miles. It now has 107K miles on it. I too was having a hard shift between 1st and 2nd. 30K miles ago, I had the tranny oil changed. Helped a little but not much. About 2 months ago I had a German car specialist simply reprogram the transmission computer (specifically the tranny). Problem solved. Shifts beautifully smooth now in low gears; however, 5th gear still doing the same lurching when cruising at highway speeds. Not sure if I should invest in a repair right now as it doesn't seem to have worsened over the last 15000 miles.