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Old 08-06-2012, 12:48 AM   #5
jjrichar
OEM ///Member
 
Join Date: Sep 2009
Location: Australia
Posts: 244
My Ride: 330 Ci convertible
Here's my take on your problem. In my opinion it could be a couple of things. If you haven't downloaded the valve body document I put on the original post then I would do that as I will reference some of the information in it now.

I was fortunate to talk to a few different blokes lately who work on these transmissions all the time. A couple of things came out of it. Rarely when a transmission is being rebuilt will they need to replace any of the springs,pistons, or the orifices in the valve body. The only thing that is included in the rebuild kit are the black plugs that are stuck upside down in the channel plate. Did you replace these? If everything else looked fine, then they would go back in the valve body without issue. They said that when analysing a transmission, they would look at where the problem is, then look at the components activating it.

The change from 2nd to 3rd involves activating the F clutch. This might tell you that there is a problem with this clutch activation. If you've cleaned out the valve body already and all is ok, it may be the solenoid valve. One of the blokes I talked to said that often you could test a solenoid for resistance, but this was not necessarily a good test of if it worked OK. It could be a bit sticky, or slow to activate. For the F clutch to activate, MV1 and EDS3 deactivate. If I thought this was a problem I would swap some of these over with others of the same type in the transmission and see if the problem changed. You may be able to find your problem in this way. If you removed the transmission from the car and dismantled it, having a look at the clutch pack will tell you if all is good or not. If it has a spotty appearance, then it is slipping and will eventually fail. Attached is a photo of my C clutch to show you what I mean. when I showed this to one of the transmission techs, he immediately gave me the "well you will have to find out why this clutch is failing".



Here's another probable cause, and from your description, this is my best guess. You're driving a VW, which has the same transmission as my wife's Audi Allroad with regard to the transmission. Something that happens with our Audi is that it has quite an abrupt lockup clutch activation. I've wanted to get inside the transmission at some time to find out why, but haven't had the chance. One difference between the Audi and BMW setups is how the torque converter lockup clutch is used. On our Audi, it activates when in 2nd gear. On the BMW it's in 3rd. I initially thought this was a problem with 2nd to 3rd, but when driving in manual mode, it was obvious is was happening when I was in 2nd and not changing gear. Pretty obvious from the RPM gauge it was the TC clutch. What to do about it? For us, multiple oil changes over the years has made it less obvious, and it certainly hasn't gotten any worse. If you wanted to fix it, the first thing I would do is change over the EDS4 (EDS4's sole job is the TC clutch) solenoid to another and see if this makes any difference. If not, it's probably a TC issue, and requires it to be rebuilt.

Hope this helps.
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