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      09-22-2008, 01:50 AM   #45
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I found this on the M5 Board back when I had one. Applies to SMG or M-DCT

"Without being on the accelerator the downshift throttle blip will assume you are still decelerating and rightly be short of the perfect rev match. It blips up enough to protect the transmission and clutch and to prevent an engine-load jolt, but not so much that it slows the engine load. When you do your final gear downshift in anticipation of entering and accelerating through/out of the corner, you should be giving some gas when braking and downshifting (heel-toe or left-right foot brake-gas). This signals the SMG to rev match higher and when it completes the shift, it will start loading the suspension through the turn-in for better balance and a smoother/faster braking/acceleration transition."
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      09-22-2008, 02:41 AM   #46
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i was right on the release of the pricing.................

http://www.m3post.com/forums/showthr...=106643&page=6

i am an executive recruiter in the auto industry so i speak with everyone.....
I would love nothing more than for you to be correct.

Maybe BMW will release some official news regarding the update soon.
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      09-22-2008, 07:06 AM   #47
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Quote:
Originally Posted by lvwirelessguy View Post
I found this on the M5 Board back when I had one. Applies to SMG or M-DCT

"Without being on the accelerator the downshift throttle blip will assume you are still decelerating and rightly be short of the perfect rev match. It blips up enough to protect the transmission and clutch and to prevent an engine-load jolt, but not so much that it slows the engine load. When you do your final gear downshift in anticipation of entering and accelerating through/out of the corner, you should be giving some gas when braking and downshifting (heel-toe or left-right foot brake-gas). This signals the SMG to rev match higher and when it completes the shift, it will start loading the suspension through the turn-in for better balance and a smoother/faster braking/acceleration transition."
Can somebody try this and report back? Is it really this simple?
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      09-22-2008, 11:24 AM   #48
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Quote:
Originally Posted by Radiation Joe View Post
Can somebody try this and report back? Is it really this simple?
I have tried this at Thunderhill - results were the same than without doing it - no downshift...I really believe this has to do with the ABS slightly kicking in and nothing with the throttle position. I actually approached turn 15 in 4th and was stuck in 4th and the car wouldn't even accept throttle input anymore...I had to shift to N and back in order to downshift and get on the throttle again.

The DCT downshift problem is a software related feature/fault and has nothing to do with you being off or on the throttle while downshifting. I wonder if there is really anybody out there that has driven their M-DCT car hard on the track that didn't experience this problem??? Sprited driving on the street doesn't count, as I don't think that anybody would be going 140MPH and brake down to 50MPH in the shortest distance possible...
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      09-22-2008, 12:38 PM   #49
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Quote:
Originally Posted by sfbimmer13 View Post
I have tried this at Thunderhill - results were the same than without doing it - no downshift...I really believe this has to do with the ABS slightly kicking in and nothing with the throttle position. I actually approached turn 15 in 4th and was stuck in 4th and the car wouldn't even accept throttle input anymore...I had to shift to N and back in order to downshift and get on the throttle again.

The DCT downshift problem is a software related feature/fault and has nothing to do with you being off or on the throttle while downshifting. I wonder if there is really anybody out there that has driven their M-DCT car hard on the track that didn't experience this problem??? Sprited driving on the street doesn't count, as I don't think that anybody would be going 140MPH and brake down to 50MPH in the shortest distance possible...
+1

There should be a "OFF" button for the DCT safety features, like for the DSC.
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      09-22-2008, 12:41 PM   #50
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Quote:
Originally Posted by swiss_cornholio View Post
+1

There should be a "OFF" button for the DCT safety features, like for the DSC.
that would work for me - in particular since the problem doesn't show up in daily driving...
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      09-22-2008, 01:01 PM   #51
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Downshift

Quote:
Originally Posted by sfbimmer13 View Post
I have tried this at Thunderhill - results were the same than without doing it - no downshift...I really believe this has to do with the ABS slightly kicking in and nothing with the throttle position. I actually approached turn 15 in 4th and was stuck in 4th and the car wouldn't even accept throttle input anymore...I had to shift to N and back in order to downshift and get on the throttle again.

The DCT downshift problem is a software related feature/fault and has nothing to do with you being off or on the throttle while downshifting. I wonder if there is really anybody out there that has driven their M-DCT car hard on the track that didn't experience this problem??? Sprited driving on the street doesn't count, as I don't think that anybody would be going 140MPH and brake down to 50MPH in the shortest distance possible...
Actually I demonstrated it to the service adviser during a couple of 80-20 mph stops on a deserted street. Scared the hell out to him and other cars when I did it on the freeway.

Last edited by MarksM; 09-22-2008 at 01:02 PM. Reason: sp
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      09-22-2008, 01:09 PM   #52
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Does this fault surface the very first time you downshift under very heavy braking or does it take a couple of laps before it happens. If the answer is a couple of laps or so then I am under the impression that it's an ABS issue, if not then I am stumpe.
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      09-22-2008, 01:16 PM   #53
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First lap of the second session after I am warmed up. Usually don't get too aggressive on the first session.
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      09-22-2008, 01:23 PM   #54
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Quote:
Originally Posted by Radiation Joe View Post
Can somebody try this and report back? Is it really this simple?
I can confirm that this is true for SMG II. It describes that system exactly. I am hoping this "feature" gets added back for DCT.
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      09-22-2008, 01:26 PM   #55
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First lap of the second session after I am warmed up. Usually don't get too aggressive on the first session.
first lap in the first session - consistently
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      09-22-2008, 02:30 PM   #56
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the back in the trunk of my M3...do you all notice there this HUGE silver box sort of like a hardrive.. I am guessing thats the main computer system that runs the car including ECU.. Am I right?

please correct me if I am wrong..
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      09-22-2008, 02:31 PM   #57
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For me it was usually second lap of each session. My first laps are always slightly slower as I let the tires and my brain come up to temp.

I'm not an engineer but I disagree that this is ABS related issue, because I'm not into the ABS when the downshift ignore occurs. The tranny has accelerometers build into it and my suspicion is that when the tranny senses a certain deceleration value it doesn't downshift in order to prevent the rear wheels from breaking loose due to the combination of wheel braking and engine braking overcoming the rear wheel traction. Not that was ever an issue with SMG, it seems as if the DCT engineers erred to much on the side of safety.

Quote:
Originally Posted by lvwirelessguy View Post
I found this on the M5 Board back when I had one. Applies to SMG or M-DCT

"Without being on the accelerator the downshift throttle blip will assume you are still decelerating and rightly be short of the perfect rev match. It blips up enough to protect the transmission and clutch and to prevent an engine-load jolt, but not so much that it slows the engine load. When you do your final gear downshift in anticipation of entering and accelerating through/out of the corner, you should be giving some gas when braking and downshifting (heel-toe or left-right foot brake-gas). This signals the SMG to rev match higher and when it completes the shift, it will start loading the suspension through the turn-in for better balance and a smoother/faster braking/acceleration transition."
I don't get it, please explain again why I need to give it gas while I'm threshold braking? What is wrong with the way DCT downshifts without help from the driver? Seems to work fine, as long as I'm not breaking the back end loose under braking by downshifting, I'm not sure it needs any assistance by the driver giving it some gas.
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      09-22-2008, 02:38 PM   #58
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Quote:
Originally Posted by Fkellym3 View Post
the back in the trunk of my M3...do you all notice there this HUGE silver box sort of like a hardrive.. I am guessing thats the main computer system that runs the car including ECU.. Am I right?

please correct me if I am wrong..
The silver box on the drivers side aft of the wheel well is the HD radio receiver in my car.

Are you planning to tie this into the DCT issue or is this a
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      09-22-2008, 02:53 PM   #59
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Originally Posted by skierman64 View Post
I'm not an engineer but I disagree that this is ABS related issue, because I'm not into the ABS when the downshift ignore occurs. The tranny has accelerometers build into it and my suspicion is that when the tranny senses a certain deceleration value it doesn't downshift in order to prevent the rear wheels from breaking loose due to the combination of wheel braking and engine braking overcoming the rear wheel traction. Not that was ever an issue with SMG, it seems as if the DCT engineers erred to much on the side of safety.
I wonder if its possible to disable ABS in the E9X M3? For the E46, I think that if you hold down the DSC button for a few seconds, it disables ABS in addition to disabling DSC. I doubt this procedure will work in an E9X, but I wonder if there is some other way to do it? This would be helpful in debunking the ABS theory. Just a thought.
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      09-22-2008, 02:55 PM   #60
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Depends on which box. There is an amp in the drivers side "wheel well" and the BMW Asssit module box is under the center trunk mat area.
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      09-22-2008, 02:59 PM   #61
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Quote:
Originally Posted by mkoesel View Post
I wonder if its possible to disable ABS in the E9X M3? For the E46, I think that if you hold down the DSC button for a few seconds, it disables ABS in addition to disabling DSC. I doubt this procedure will work in an E9X, but I wonder if there is some other way to do it? This would be helpful in debunking the ABS theory. Just a thought.
No way to disable that i have seen.

Pulling the ABS fuse/relay MAY work....it may also cause the car to freak out too. Who knows what it would do to the DCT...

Also, on my GT3, if you had a wheel "lifted" (going out of a step driveway at an angle), and tapped the brakes, it would cause an ABS fault and disable the system for you. There was no "shut off" for the ABS taht I was aware of, but this worked everytime. Maybe the M3 will also disable it if it senses a fault.

Just had a thought...............maybe unplug one of the ABS sensors (pick a wheel!). I am sure it will cause a fault. Being as it is in fault mode, it may deactivate the system entirely. Worth a shot, and it would be easy to do and reverse.
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      09-22-2008, 03:02 PM   #62
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Quote:
Originally Posted by skierman64 View Post
For me it was usually second lap of each session. My first laps are always slightly slower as I let the tires and my brain come up to temp.

I'm not an engineer but I disagree that this is ABS related issue, because I'm not into the ABS when the downshift ignore occurs. The tranny has accelerometers build into it and my suspicion is that when the tranny senses a certain deceleration value it doesn't downshift in order to prevent the rear wheels from breaking loose due to the combination of wheel braking and engine braking overcoming the rear wheel traction. Not that was ever an issue with SMG, it seems as if the DCT engineers erred to much on the side of safety.



I don't get it, please explain again why I need to give it gas while I'm threshold braking? What is wrong with the way DCT downshifts without help from the driver? Seems to work fine, as long as I'm not breaking the back end loose under braking by downshifting, I'm not sure it needs any assistance by the driver giving it some gas.

If you want a full rev-matched downshift you must give it gas while downshifting. If you just brake while downshifting it only blips enough to protect the transmission & clutch.

I know this well since my last 3 BMW's have been either SMG II, SMG III or M-DCT
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      09-22-2008, 03:11 PM   #63
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Quote:
Originally Posted by lvwirelessguy View Post
If you want a full rev-matched downshift you must give it gas while downshifting. If you just brake while downshifting it only blips enough to protect the transmission & clutch.

I know this well since my last 3 BMW's have been either SMG II, SMG III or M-DCT
Should have been at Pahrump on Sat or Sun to demo it for us.
Because nothing short of gentle braking worked.
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      09-22-2008, 03:14 PM   #64
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Originally Posted by GT3 Tim View Post
Depends on which box. There is an amp in the drivers side "wheel well" and the BMW Asssit module box is under the center trunk mat area.
that..under the center trunk mat area.....

what is that?
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      09-22-2008, 03:18 PM   #65
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Quote:
Originally Posted by lvwirelessguy View Post
If you want a full rev-matched downshift you must give it gas while downshifting. If you just brake while downshifting it only blips enough to protect the transmission & clutch.

I know this well since my last 3 BMW's have been either SMG II, SMG III or M-DCT
I don't agree with this assessment. I find that it rev matches perfectly without driver assistance. In fact even on the track at high rpm I found many times I had to look to see if it had downshifted or not (because of the downshift ignore issue) because it was so smooth I couldn't feel it in the seat of the pants under hard braking. I don't feel any downshift driveline jolt because the downshifts aren't perfectly matched. However, I do think the amount of downshift blip is dependent on which S setting you have selected.

I'm not discounting you have a lot of SMG/DCT experience, I just haven't felt what you're saying.
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      09-22-2008, 03:22 PM   #66
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Quote:
Originally Posted by lvwirelessguy View Post
If you want a full rev-matched downshift you must give it gas while downshifting. If you just brake while downshifting it only blips enough to protect the transmission & clutch.

I know this well since my last 3 BMW's have been either SMG II, SMG III or M-DCT
Should have been at Pahrump on Sat or Sun to demo it for us.
Because nothing short of gentle braking worked.
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