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      09-10-2008, 05:19 PM   #23
Dascamel
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Quote:
Originally Posted by BarryC View Post
One other question - have you tracked the car on street tires and experienced the same downshift problem? If the answer is yes and no downshift issue - then is the use of Rcompound tires enabling you to generate a more braking force and the transmission won't downshift because it "thinks" a spin could occur if a downshift is executed?

I'm probably off base here as I'm just throwing out ideas.

BC
Street tires, in an isolated area, tried hard braking from around 80-90 and taking a turn. It would not allow the shift until I was already turned and on the throttle. It really slows you down, need more power sooner. Wonder if a BMW tech will sit in the car and try that with him ...... Not an ABS issue wasn't even close, well within RPM range for the downshifts to occur.
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      09-10-2008, 05:40 PM   #24
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Hi Rupert,

As far as the DCT issue - did you try downshifting as you were taking your foot off the brake and going to throttle (more or less at turn in)? I'm assuming for the sake of smoothness that you don't jump off the brake and jump on the throttle and if so then I'd think there would be enough time to execute a downshift during this transition.

Additionally, I wonder if the lack of downshift during heavy braking is a designed in "safety" feature to keep from locking up the rear wheels and precipitating a spin... Granted it would be a remote possibility because of the ABS but we know how conservative BMW is. If this is true, then it should change gears once the brake pressure is relieved right?

This is all conjecture as I haven't tracked my car yet and I haven't been able to cause the car to not downshift on the street. Anyway - nice pics! Looks like you had a good time....

BC
I tried many different approaches and even when I relieved brake pressure it wouldn't downshift

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One other question - have you tracked the car on street tires and experienced the same downshift problem? If the answer is yes and no downshift issue - then is the use of Rcompound tires enabling you to generate a more braking force and the transmission won't downshift because it "thinks" a spin could occur if a downshift is executed?

I'm probably off base here as I'm just throwing out ideas.

BC
happened on street tires too...I really believe that this is not an intentional thing, but a bug in the software, since it won't even downshift once I am totally off the brake after turn in and than it suddenly shifts into 7th sometime

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Street tires, in an isolated area, tried hard braking from around 80-90 and taking a turn. It would not allow the shift until I was already turned and on the throttle. It really slows you down, need more power sooner. Wonder if a BMW tech will sit in the car and try that with him ...... Not an ABS issue wasn't even close, well within RPM range for the downshifts to occur.
agreed, similar experience here, one more thing, if it would be a liability thing it shouldn't allow the downshift when you are turned in, since this would be much more dangerous than braking and downshifting in a straight line :-)
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Last edited by sfbimmer13; 09-11-2008 at 08:06 AM.
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      09-10-2008, 09:05 PM   #25
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Rupert - got it! I can see how this would be frustrating....

Thanks!
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      09-11-2008, 02:34 AM   #26
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one more thing, if it would be a liability thing it shouldn't allow the downshift when you are turned it, since this would be much more dangerous than braking and downshifting in a straight line :-)
Very true - it really does sound like a software logic issue.
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      09-11-2008, 02:35 PM   #27
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I ran BFGoodrich gForce R1s 265/35/18 front and 285/30/18 back on TR Motorsports wheels - these tires are absolutely great and provide incredible amounts of grip. I monitored pressures carefully and ran between 43 and 47 PSI hot anything lower than that and the front tires would start to roll over the sidewalls
Wow that track day looked like it was a blast! Excellent job!

I have only heard good things about these tires on the track. What would you say about them performing at autocross (soloII). Did you have to wait a while before they heated up or did they grip right off the bat? Would these tires cold be significantly gripper than PS2's when cold?
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      09-11-2008, 03:49 PM   #28
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Wow that track day looked like it was a blast! Excellent job!

I have only heard good things about these tires on the track. What would you say about them performing at autocross (soloII). Did you have to wait a while before they heated up or did they grip right off the bat? Would these tires cold be significantly gripper than PS2's when cold?
they don't grip right off the bat, so I am not convinced that they would be any good at autocross - I also don't think that you will get the amount of heat into them that makes them sticky - they perform best after about 2 laps and get even better after that - the PS2's definitely provide better grip when cold
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      09-12-2008, 07:57 PM   #29
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Were you driving in S5? I am a novice driver, but noticed yesterday at a tracking event that in S5 I would intend to downshift from 4th to 3rd, but it would shift directly to 2nd. I finally switched to S3 and that problem didn't recur. I owned an e46 with SMG and the shifts were quicker in S5. With the DCT I really do not notice that they are quicker, just that you experience the surge. I'm not sure that the surge is helpful.
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      09-13-2008, 11:41 AM   #30
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Rupert
I just got back from Thunderhill & you are exactly right about the DCT not downshifting....when I started pushing the pace I had the same problem in S5...upshifts were always great...but it would NOT downshift when I wanted...so I was stuck in 4th when I wanted 3rd, etc.... One time it got really stupid and went into 6th??? Coming off turn 11 (slowest turn) at Thunderhill in 6th is not fun.....
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      09-13-2008, 12:28 PM   #31
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Quote:
Originally Posted by dawgdog View Post
Were you driving in S5? I am a novice driver, but noticed yesterday at a tracking event that in S5 I would intend to downshift from 4th to 3rd, but it would shift directly to 2nd. I finally switched to S3 and that problem didn't recur. I owned an e46 with SMG and the shifts were quicker in S5. With the DCT I really do not notice that they are quicker, just that you experience the surge. I'm not sure that the surge is helpful.
S5 and S6 I also tried S3 once, not on purpose though...forgot to push the M button.

Your experience seems odd and very different from other folks, including me

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Rupert
I just got back from Thunderhill & you are exactly right about the DCT not downshifting....when I started pushing the pace I had the same problem in S5...upshifts were always great...but it would NOT downshift when I wanted...so I was stuck in 4th when I wanted 3rd, etc.... One time it got really stupid and went into 6th??? Coming off turn 11 (slowest turn) at Thunderhill in 6th is not fun.....
Brian - I guess that sort of proves that the M-DCT has a problem and it is not just some rogue thing that effects only a few cars...guess the ones that say they don't have any problems with DCT just haven't pushed it hard enough.

I will be in Thunderhill next weekend and it doesn't look like the DCT SW update will be available by than...just checked with BMW yesterday....
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      09-13-2008, 04:42 PM   #32
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Rupert
When I was taking it easy on my 1st couple sessions it worked perfectly.....I would say anything over 80-85% pace messes it up...since I can't drive anywhere near 100% of the cars limits anyway

I noticed the shift problem the most under braking before 10-11-14 the most..... With your tires you probably will never go under 3rd..... Coming into 10 I was over 110mph but typically didn't brake that late there (I should, but kept thinking of a video where a miata hit the wall).....but I was hard on the brakes in 11 and trying to get 2nd which it wouldn't do most of the time, unless I slowed down too much but 2nd really was kinda useless there since the MDM would kick in big time in 2nd but not 3rd....under HARD braking for 14 (also from 120mph) I would want 3rd....but it would hold 4th instead.... so I would end up dropping to 3rd at close to the apex before 15.....

Hmm does PCA allow riders? I think they do....epsecially since I'm a PCA member too....I might have to come visit you next weekend!!
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      09-13-2008, 04:45 PM   #33
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Quote:
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Rupert
When I was taking it easy on my 1st couple sessions it worked perfectly.....I would say anything over 80-85% pace messes it up...since I can't drive anywhere near 100% of the cars limits anyway

I noticed the shift problem the most under braking before 10-11-14 the most..... With your tires you probably will never go under 3rd..... Coming into 10 I was over 110mph but typically didn't brake that late there (I should, but kept thinking of a video where a miata hit the wall).....but I was hard on the brakes in 11 and trying to get 2nd which it wouldn't do most of the time, unless I slowed down too much but 2nd really was kinda useless there since the MDM would kick in big time in 2nd but not 3rd....under HARD braking for 14 (also from 120mph) I would want 3rd....but it would hold 4th instead.... so I would end up dropping to 3rd at close to the apex before 15.....

Hmm does PCA allow riders? I think they do....epsecially since I'm a PCA member too....I might have to come visit you next weekend!!
Brian - PCA doesn't allow riders, if there are 2 people in the car one of them has to be an instructor...would be great if you would stop by though...
cheers Rupert
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      09-13-2008, 04:52 PM   #34
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Brian - PCA doesn't allow riders, if there are 2 people in the car one of them has to be an instructor...would be great if you would stop by though...
cheers Rupert
BUMMER......let me take a look at my schedule to see if I can sneak away....
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