Hi all:
I’m looking to DIY tackle some things that have been bothering me about my 8HP for many years and I’m hoping that there are some folks here with some experience who could offer some advice. This is a 2011 BMW 535i X-Drive with 8HP45Z in AWD configuration and around 143,000km / 88,000mi on the odo. I have DIYed a pan and fluid change a couple of years ago, the dealer may have at my request as well. I do everything by the book using ZF instructions and have access to ISTA+ to pull codes.
I am planning to do another pan change, and drain/fill with ZF LG8. I have 90%+ decided that I will be changing the solenoids. I’m wondering if there is anything else I should be looking at doing at the same time (e.g. any of the kits from Sonnax). I don’t want to do any unnecessary, risky work in the valve body that I do not need to do. However, at the same time I would like to fix my problems if I can. As an enthusiast, these are really detracting from my enjoyment of the car, even though lots of “appliance drivers” might not even notice the issues.
This will already be too long so I won’t post details here, but I’ve looked at some shift logic diagrams, and wondered if I should get any additional valvebody parts/kits for Clutch C or E (because C and E are involved in 1-2, 2-3 and 2-1 - all of which I have issues with, and C has high adaptation)
Some of the problems I’ve been having have been there since the car was in factory warranty and had <30,000km, but there were never any codes and I could never demonstrate problems serious enough to warrant any action while under factory or extended-factory warranty. Of course many problems chose not to show themselves when the dealer foreman was in the vehicle.
There has never been a single transmission code set that can be seen with ISTA. As long as I can remember clutch C has had a borderline high adaptation pressure >300mbar.
Today’s adaptations (I can provide more historical values if needed):
Description of my problems:
So:
Thanks!
I’m looking to DIY tackle some things that have been bothering me about my 8HP for many years and I’m hoping that there are some folks here with some experience who could offer some advice. This is a 2011 BMW 535i X-Drive with 8HP45Z in AWD configuration and around 143,000km / 88,000mi on the odo. I have DIYed a pan and fluid change a couple of years ago, the dealer may have at my request as well. I do everything by the book using ZF instructions and have access to ISTA+ to pull codes.
I am planning to do another pan change, and drain/fill with ZF LG8. I have 90%+ decided that I will be changing the solenoids. I’m wondering if there is anything else I should be looking at doing at the same time (e.g. any of the kits from Sonnax). I don’t want to do any unnecessary, risky work in the valve body that I do not need to do. However, at the same time I would like to fix my problems if I can. As an enthusiast, these are really detracting from my enjoyment of the car, even though lots of “appliance drivers” might not even notice the issues.
This will already be too long so I won’t post details here, but I’ve looked at some shift logic diagrams, and wondered if I should get any additional valvebody parts/kits for Clutch C or E (because C and E are involved in 1-2, 2-3 and 2-1 - all of which I have issues with, and C has high adaptation)
Some of the problems I’ve been having have been there since the car was in factory warranty and had <30,000km, but there were never any codes and I could never demonstrate problems serious enough to warrant any action while under factory or extended-factory warranty. Of course many problems chose not to show themselves when the dealer foreman was in the vehicle.
There has never been a single transmission code set that can be seen with ISTA. As long as I can remember clutch C has had a borderline high adaptation pressure >300mbar.
Today’s adaptations (I can provide more historical values if needed):
- Clutch A: -102 mbar 18ms
- Clutch B: -84 mbar 48ms
- Clutch C: 350 mbar 21ms
- Clutch D: 96 mbar 13ms
- Clutch E: 242 mbar 15ms
Description of my problems:
- One of the oldest problems - a noise during the 1-2 and sometimes 2-3 upshift. If it’s making the noise (never would with a dealer foreman in the car) it usually happens during light-medium acceleration (very light acceleration won’t do it, and driving more aggressively makes it go away too). The shifts feel slow when it’s happening. I would call it “extra protective” of the transmission - seems to be a lot of power cut and it takes a long time to do the shift. The noise is most audible with everything closed up and it sound like someone a few lanes over spinning their tires in the rain. The noise ramps up just before the shift itself starts and ramps down after it’s complete. I think the noise is from the transmission as it is synchronized with the shift, but that is unconfirmed with something like chassis ears.
- Also a very old problem: Lurch in take off from brief stops. I believe this is actually a VERY slow 2->1 downshift when stopping. This is worst in situations like neighbourhood 4 way stop intersections with no traffic, where I come to a stop and immediately proceed. At first the power seems to go nowhere, and then the car lurches forward and starts accelerating with no change in engine character when the lurch happens. Disabling neutral idle control seems to help a little with this, but it doesn’t fix it. I believe I'm taking off in 2, even though the dash shows 1 the shift hasn't completed. When I stop longer this doesn't happen. Even light acceleration demonstrates the issue.
- When neutral idle control is enabled, creeping forward feels pulsed and surge-y.
- When cold (e.g. below -8C or -10C) the 2-3 upshift (or was it 3-4) will hunt back and forth the first few times. This is a very new problem. In these temps I’m driving very gently when the vehicle isn’t warmed up and I’ve experienced this a couple of times. If it was the only thing, I'd chalk it up to being cold.
- The transmission is making some bad shift decisions of late, or failing to complete a shift when it calls for it, then the shift comes late with a jerk. Not all the time, but more than it should.
So:
- Is there support for changing solenoids as a solid idea?
- Anything else I should look at, or merely see what happens after solenoids and fluid?
- Any more info or clarification I can provide?
Thanks!