Wheel slip or clutch slip?

[mj6234]

I know there are some issues with this log (low rail pressure, throttle closures, etc) but ignore for now please. I am without the Helix and trying to see the limit on stock HPFP after messing with the VCV tables. This is E40 on GC Lites in 3rd gear if anyone cares.

Oh @carabuser - you told me months ago I had a vacuum/boost leak or bad solenoids. And it was a vacuum leak - a bad o-ring on one of the DVs. It really did matter for spool and other tuning (which I am still learning at).

I am curious if the 'flat line' of RPM at 4350 RPM and 4900 RPM is clutch slippage (I have 6MT) or wheelspin. I think it would be wheelspin? The RPM seem to hold steady (or drop slightly) for some period of time. If it was clutch slippage, wouldnt I see the RPM shoot up? For reference I have a 550i clutch on SMFW. I realize that I will exceed the limits of it at some point, just trying to figure out if I have already.

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[RSL]

WOT rpm curve is also effectively an acceleration rate plot. It may be nothing more than unevenness in the road, which should be somewhat obvious in the driver's seat.

If it's consistently there logging in other locations, get rid of some torque and see if it goes away. Otherwise, you can try logging wheel speeds. If the drive tire(s) speed relatively follows any RPM jogs, it's either tire spin or the road.

 

[AzNdevil]

6mt? clutch is starting to slip...
hybrid twins + ethanol = twin plate clutch is pretty much a must
hybrid twins + pump = if you drive it hard enough you need a twin plate clutch as well

two easy ways to test this,
log in 4th start at 2k rpm
highway speeds (60ish mph) in 5th, floor it

 

[mj6234]

6mt? clutch is starting to slip...
hybrid twins + ethanol = twin plate clutch is pretty much a must
hybrid twins + pump = if you drive it hard enough you need a twin plate clutch as well

two easy ways to test this,
log in 4th start at 2k rpm
highway speeds (60ish mph) in 5th, floor it

This twin disc? Man, prices have come down on them. Spec stage3+ is $1K vs this is $1300?

BMW MS Organic Twin Disc Clutch Kit With Flywheel - DKM MS-006-075

BMW MS Organic Twin Disc Clutch Kit With Flywheel - DKM MS-006-075

www.fcpeuro.com

 

[AzNdevil]

This twin disc? Man, prices have come down on them. Spec stage3+ is $1K vs this is $1300?

BMW MS Organic Twin Disc Clutch Kit With Flywheel - DKM MS-006-075

BMW MS Organic Twin Disc Clutch Kit With Flywheel - DKM MS-006-075

www.fcpeuro.com

spec is garbage from my experience with them on e36 (super heavy clutch pedal that didnt grab all that well) and a honda fk8 (shit tolerances and main assembly/pressure plate, clutch wont disengage in high revs unless clutch pedal is held in for ~2 seconds)

i am currently using a xclutch twin plate ceramic unsprung so i cant comment on the dkm, ive seen people using them on facebook so i guess you might get a better response there...

 

[jzx_andy]

I've heard good things about the DKM but bear in mind it is an organic clutch and won't last long if you put a lot of heat through it with hard launches and track driving.

 

[iminhell1]

Pretty easy to explain what you're seeing once you look at Throttle Position ...

turn traction control off and retest.
If traction was off, it's a PID control issue. Too much overshoot, target and measured are too close and you're getting throttle closure. Fix the tune.

 

[SLOWESTN54]

X clutch is the way if you end up needing a new clutch

 

[carabuser]

Pretty easy to explain what you're seeing once you look at Throttle Position ...

turn traction control off and retest.
If traction was off, it's a PID control issue. Too much overshoot, target and measured are too close and you're getting throttle closure. Fix the tune.

Yes, looks like overboost and throttle closures. Target boost is 20.2 and you are at 22.8.

With the timing being static it's probably not TC, rather just wheel spin.