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metalman
07-24-2002, 08:58 PM
There are 4-5 guys on this board that know what I'm talking about & the rest of the people here have either experienced it or not.
I was one of the first guys on this board to have a 6 speed & modify it & then traded for the SMG which easily was the best thing I could have done for consistency on the street & track but this slip thing has really been annoying. I track my car more than just about anyone on this board including Steve Medina (no hard feelings steve & your more than welcome to come up to the motorsport ranch anytime you'd like) & feel I know the car inside & out but it gets frustrating trying to get to the bottom of a problem that other people feel is just normal. The car shifted perfect for the first 2-3000 miles on it & now that I have 9000+ it still slips.

95% of the time if you take the engine to redline in any gear & the lights on the tach start to move counterclockwise & you shift you get a hard aggressive shift but if you don't then you get the slip.

Again if anyone has this same problem or knows someone with it not on the board please get them to write to me directly by e-mail & I will start a list to get to the proper person whose name I won't mention but I do know well & we will get to the bottom of this.

Thanks.

falcon98
07-24-2002, 09:06 PM
Clutch plate may be getting contaminated with fluid. No problems with my TiS/IR 2002 with SMG @4,500 mi. Good Luck!<br>Falcon98

StoneWalk
07-24-2002, 11:06 PM
I know what you are talking about, and I get it once in a while. It is almost certainly an SMG logic issue - it's allowing more slip than should probably be used under certain conditions.

Usually it is associated with a fairly high S-mode, say S5 or S6, at least 3/4 throttle, and at least 5k revs - basically when you're running fairly hard and ask for a shift. Rather than the usual fast shift and grab, you get an extended rev-slide down to the new rpm. Slips the clutch for a good second or so instead of the usual tiny fraction of a second.

The good news is it doesn't much slow you down, but I agree that it would seem to be putting more wear than I'd like on the clutch. Thus I attempt to avoid the conditions that cause it. Seems more prone to happen at 75% throttle than 100%, and in certain rev ranges. I'm also looking into the "pull paddles" reset method. If it gets more common, I may try the disconnect-battery reset trick.

Since it only happens rarely, and it can be made to go away with certain reset tricks, my guess is that it's related to the adaptive SMG logic - it's getting into a spot where it's heuristics are telling it to apply not quite enough pressure on the clutch during some shifts, thus it gets slippage. One might assume that in the long run, BMW will improve the logic, maybe even with a patch for our SMG computers. Meanwhile, I think we have to just reset our adaptation logic once in a while to get it to quit doing it's slip thing (or maybe vary our driving styles if we figure out what provokes it - I have an idea that it's sudden changes in driving style which confuse the SMG, but don't have any supporting data yet. Give me time :)

ACS S3 Sport
07-25-2002, 04:23 AM
it is more obvious that after my exhaust... as soon as I depress the gas, the rev goes up, but it soon drops down for about 200 rpm, then starts to rise up again.... The rev drops down while I change in another gears too.. I guess this is a common problem in the SMG, don't think BMW can be able to fix that up... else they would have improved this kinda problem in your SMG2 already, right?

As what you said, the clutch doesn't slip only when you change HARD at the red line, same as my car...

Hope you can find the reason why it slips!!! hope to hear from you soon too!!!

Cheers,

Richard


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