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Discussion Starter #1 (Edited)
So, yesterday the temps hit 90. Driving home from work, the SMG was the smoothest it's been in a long time. I can't remember when it was the last time it shifted this well. Which component of the SMG would be so greatly affected by ambient temps and would make such a difference in shifting smoothness?
 

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So, yesterday the temps hit 90. Driving home from work, the SMG was the smoothest it's been in a long time. I can't remember when it was the last time it shifted this well. Which component of the SMG would be so greatly affected by ambient temps and would make such a difference in shifting smoothness?

No one ever believes me when I say this.

I suspect it is the solenoid control valves, but can't really prove it. It could either be the resistance values of the windings or it may be the actual o-rings on the cartridge outer diameter.

I have found that if you perform the adaptations on the SMG while it is warm, it will shift better once it is warm. Most of the time, adaptations are performed on a cold transmission since it's sitting in the garage and probably just came off the lift or just drove in the bay.


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Discussion Starter #3
So, it means my car was adapted when warm I guess?

No one ever believes me when I say this.

I suspect it is the solenoid control valves, but can't really prove it. It could either be the resistance values of the windings or it may be the actual o-rings on the cartridge outer diameter.

I have found that if you perform the adaptations on the SMG while it is warm, it will shift better once it is warm. Most of the time, adaptations are performed on a cold transmission since it's sitting in the garage and probably just came off the lift or just drove in the bay.


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So when the ambient temps are high it shifts really nice. Maybe I should adapt it when it's cold as it is colder than this 9 out of 12 months.
 

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The M Master Tech at my local Indy told me that ///M deliberately designs drivetrain components with a lot of slop at ambient temperatures. He said the reason is because it's expected that the cars will be driven very hard and by giving a lot of slop at low temperatures the design allows the parts to swell (thermal expansion) during heavy to extreme operation.

Certainly not an official statement from BMW, but it makes a lot of sense in my opinion.
 
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