|
|
SUPPORT ZPOST BY DOING YOUR TIRERACK SHOPPING FROM THIS BANNER, THANKS! |
Post Reply |
|
Thread Tools | Search this Thread |
09-12-2010, 07:56 AM | #1 |
Major
75
Rep 1,143
Posts |
"Rubber-banding" effect in 1st
I thought this was normal for these cars, or otherwise a result of occasionally sloppy driving, but a BMW CCA instructor commented on this yesterday when he drove my car at pre-tech so I thought I'd get some opinions.
Once engaged in 1st gear, does anyone else notice an occasional "rubber-banding" effect in the driveline as you depress the accelerator, where power delivery is uneven and it takes a second for the car to rev freely? I want to say it's mostly clutch-related, because it was much, much worse with the CDV, and virtually unnoticeable in the Z4 3.0si, which has a different clutch altogether. Since the CDV replacement and ~2500 miles of practice on the M, it doesn't happen with the same severity or frequency. It does not happen in any gear beyond first. It also doesn't happen if I launch more aggressively, which probably explains why it didn't seem to be as prevalent in the cars I test drove, because I was definitely a bit more spirited on those drives (without being abusive, of course). |
09-12-2010, 10:13 AM | #2 |
Bad Lieutenant
233
Rep 3,517
Posts |
The only time I've experienced this is on very cold mornings, say below 40F, and only lasts until I'm into 2nd and does not repeat.
__________________
02 E39M5 | TiAg/Schwartz | Tubi Rumore | Ultimate Ti Pedals | E60 SSK | Jim Blanton 3.45 40/100% | Coby Alcantara | StrongStrut STB
|
Appreciate
0
|
09-12-2010, 11:47 PM | #4 |
Long Live the 1911
46
Rep 643
Posts
Drives: Hooptie
Join Date: May 2007
Location: USA
|
Maybe symptomatic of drive-by-wire. I haven't noticed, but will start paying attention.
|
Appreciate
0
|
09-13-2010, 04:36 AM | #6 |
Colonel
479
Rep 2,782
Posts
Drives: ESS/G-Power Z4M, VF Z4, 996tt
Join Date: Sep 2009
Location: Los Angeles
|
I've had it happen occasionally on cold starts. It rarely occurs once the car has warmed up.
|
Appreciate
0
|
09-13-2010, 06:43 AM | #7 |
Lieutenant
31
Rep 503
Posts
Drives: Z4 M Coupe
Join Date: Jun 2009
Location: Paphos
|
I get it too. I just take it as a peculiarity of the adaptive drive by wire throttle pedal.. I do a lot of driving in stop-start traffic and i think that messes up the mapping making it lethargic and "soft". I've found that resetting the throttle mapping adaptation every now and then helps a lot.
__________________
|
Appreciate
0
|
09-13-2010, 11:43 AM | #9 |
Viper Driver
36
Rep 1,311
Posts |
i'm assuming a clogged air filter may cause the 'jerkiness' in engaging first gear? fwiw, i've checked my air filter and do still occassionally notice the rubberbanding gear engagement in first.
|
Appreciate
0
|
09-13-2010, 08:41 PM | #11 |
Major
75
Rep 1,143
Posts |
The paper intake air filter I believe. I checked mine a few weeks ago and it still looked pretty clean, although I was able to shake out a decent amount of dust. A new one is on the way, just in case.
Still, I don't think it's an engine or throttle-related issue. The rubber-banding effect is not unlike what happens when someone is trying to learn how to drive stick, but that's not really an issue in this case. My 3er is buttery smooth in any gear, and it has the same ZF unit as the M and 3.0si as far as I can tell. As mentioned, it doesn't really happen with a more aggressive launch at slightly higher (2000+) RPM, which leads me to think that it's something to do with the clutch, particularly when engaged at lower (normal?) engine speeds. |
Appreciate
0
|
09-13-2010, 11:33 PM | #12 |
///M-fanatic
193
Rep 3,885
Posts |
ohhh icic. I hadn't quite seen the correlation between air filter & car behavior until just now lol..
anyhow, yeah I'm pretty certain it's just the difference between the ECU's and throttle mapping. Hence why people have reported that after an ECU tuning/upgrade, the throttle and power delivery is a lot smoother throughout the rev band, regardless of what gear you're in. Probably even in Reverse jk haha |
Appreciate
0
|
09-13-2010, 11:43 PM | #13 |
Brigadier General
218
Rep 4,726
Posts |
Are you saying you floor the car and it doesn't seem to give you full acceleration for a second? That's not normal. S54 is a very responsive engine, it was built specifically NOT to act that way.
__________________
|
Appreciate
0
|
09-13-2010, 11:47 PM | #14 |
///M-fanatic
193
Rep 3,885
Posts |
No, I think he was just referring to cold start and/or partial throttle (barely applying gas) situations, where the car does the bucking bronco almost. Which, I'm convinced is just the stock ECU's throttle mapping + drive-by-wire at work
|
Appreciate
0
|
09-13-2010, 11:51 PM | #15 |
Brigadier General
218
Rep 4,726
Posts |
I would describe that as bucking then not rubber banding. And I don't think I've ever experienced that.
__________________
|
Appreciate
0
|
09-14-2010, 06:48 AM | #16 | |
Lieutenant General
2432
Rep 11,667
Posts |
Quote:
I have experienced it on occasion, usually in stop & go traffic & when I'm not really focused. IMO, it's operator induced. I find it's smoother (or I am) if I give the throttle a little blip before engaging the clutch.
__________________
'21 M2C Hockenheim Silver
'18 718 Cayman S Lava Orange (sold) '13 E92 M3 Santorini Blue (sold) '07 Z4 M Coupe Alpine White (sold) |
|
Appreciate
0
|
09-14-2010, 06:57 AM | #17 | |
Major
75
Rep 1,143
Posts |
Quote:
I don't doubt that some of it is the driver -- as I mentioned, I notice it happening less if I change my throttle input as well. The intent of my post was just to verify that this has been experienced by others, and that it's not just my car, and see if anyone might have some insight as to why it seems easier to induce this behavior in the M (e.g. if this is some characteristic of the flywheel in this car). |
|
Appreciate
0
|
09-14-2010, 07:14 AM | #18 |
Lieutenant General
2432
Rep 11,667
Posts |
IMO, I think it happens more just because you have more power & torque in the M.
When bucking starts it's self perpetuating because the lurching causes your foot pressure on the pedal to change.
__________________
'21 M2C Hockenheim Silver
'18 718 Cayman S Lava Orange (sold) '13 E92 M3 Santorini Blue (sold) '07 Z4 M Coupe Alpine White (sold) Last edited by inTgr8r; 09-14-2010 at 07:41 AM.. |
Appreciate
0
|
09-14-2010, 08:20 AM | #19 |
Lieutenant Colonel
94
Rep 1,546
Posts |
I'd noticed this a couple of times in the past couple of weeks. Figured it was just me doing somethign wrong. The self-perpetuating really sucks too...can't help but do it. I just push the clutch back in and start over. Glad to know it's not just me...lol
__________________
|
Appreciate
0
|
09-15-2010, 01:40 AM | #20 |
///M-fanatic
193
Rep 3,885
Posts |
|
Appreciate
0
|
09-15-2010, 09:20 AM | #21 |
Bad Lieutenant
233
Rep 3,517
Posts |
You are probably sitting too far from the pedals.
__________________
02 E39M5 | TiAg/Schwartz | Tubi Rumore | Ultimate Ti Pedals | E60 SSK | Jim Blanton 3.45 40/100% | Coby Alcantara | StrongStrut STB
|
Appreciate
0
|
09-15-2010, 09:30 AM | #22 |
Lieutenant General
2432
Rep 11,667
Posts |
I can see how that would make it easier to induce.
Not my situation though, I have lots of angle in my knees. With me it's just once in a blue moon when I'm off thinking of something else; e.g. if I get stuck in stop & go traffic.
__________________
'21 M2C Hockenheim Silver
'18 718 Cayman S Lava Orange (sold) '13 E92 M3 Santorini Blue (sold) '07 Z4 M Coupe Alpine White (sold) |
Appreciate
0
|
Post Reply |
Bookmarks |
|
|