Best way to monitor clutch slip

[robz]

What pid would best monitor this?
I figure watching the rpm is one way.
Is there anything for input shaft speed?
Any suggestions to monitor this?
Thanks

[mistermike]

VSS and RPM should be at a fixed ratio in gear. If they drift apart, the clutch is slipping.

[robz]

VSS and RPM should be at a fixed ratio in gear. If they drift apart, the clutch is slipping.

anyone else?

[joecar]

Create a calc pid for this: Trans Input RPM = VSS * 336 * GR / TD

where:
VSS = vehicle speed [MPH]
TD = tire diameter [inches]
GR = overall gear ratio = trans ratio * axle ratio

T56 in 3rd gear (1.30), thru 3.46 axle at 70 MPH on 275/40R17 tires

TD = 2 * (275 * 0.40) / 25.4 + 17 = 25.66 inches

GR = 1.30 * 3.46 = 4.498

Trans Input Speed = 70 * 336 * 4.498 / 25.66 = 4123 RPM

Then in your log you can compare engine RPM to Trans Input RPM, or you can create a calc pid for RPM / Trans Input RPM.

This is what Mr.Mike is saying to do.

Cheers,
Joe

[robz]

Create a calc pid for this: Trans Input RPM = VSS * 336 * GR / TD

where:
VSS = vehicle speed [MPH]
TD = tire diameter [inches]
GR = overall gear ratio = trans ratio * axle ratio


Then in your log you can compare engine RPM to Trans Input RPM, or you can create a calc pid for RPM / Trans Input RPM.

This is what Mr.Mike is saying to do.

Cheers,
Joe

sent pm

[joecar]

Replace calc_pids.txt with the following [see attached file]

(be sure to first save your existing calc_pids.txt):

# ==============================================================================
# File details
# ------------
#
# This section defines various details about the file format.

*FILE

#Parameter  Value            Description
#---------- ---------------- ---------------------------------------------------
VERSION     7.1.1            File version
DECSEP      .                Decimal separator used in this file



# ==============================================================================
# Units
# -------------------
# See sae_generic.txt for more information on the *UNITS section

*UNITS

#Code     System     Abbr     Description
#-------- ---------- -------- -------------------------------------------------------------

None      None       ""       "No units"
inch      Imperial   "in"     "Inches"


# ==============================================================================
# Add slot definitions here
# --------------------------------
# See sae_generic.txt for more information on "SLOT" formats
#
#Units             Low          High      Fmt  Expression
#------------ ------------- ------------- ---- --------------------------------------------------------------

*CLC-00-080
inch               0.0          60.0      0.2  "26.2"

*CLC-00-090         
factor             0.0          10.0      0.2  "4.10"

*CLC-00-101        
rpm                  0          8000      0.0  "{SAE.VSS.mph} * 336 * {CALC.AXLE} * 2.66 / {CALC.TIRE}"

*CLC-00-102        
rpm                  0          8000      0.0  "{SAE.VSS.mph} * 336 * {CALC.AXLE} * 1.78 / {CALC.TIRE}"

*CLC-00-103        
rpm                  0          8000      0.0  "{SAE.VSS.mph} * 336 * {CALC.AXLE} * 1.30 / {CALC.TIRE}"

*CLC-00-104        
rpm                  0          8000      0.0  "{SAE.VSS.mph} * 336 * {CALC.AXLE} * 1.00 / {CALC.TIRE}"

*CLC-00-105        
rpm                  0          8000      0.0  "{SAE.VSS.mph} * 336 * {CALC.AXLE} * 0.74 / {CALC.TIRE}"

*CLC-00-106        
rpm                  0          8000      0.0  "{SAE.VSS.mph} * 336 * {CALC.AXLE} * 0.50 / {CALC.TIRE}"


# ==============================================================================
*PRN - Parameter Reference Numbers
# --------------------------------
# See sae_generic.txt for more information on the *PRN section
#
#Code                      PRN  SLOT         Units            System           Description
#------------------------- ---- ------------ ---------------- ---------------- ------------------------------------------

CALC.TIRE                  F080 CLC-00-080   inch             Testing          "Tire diameter"
CALC.AXLE                  F090 CLC-00-090   factor           Testing          "Axle Ratio"

CALC.TIS_1ST               F101 CLC-00-101   rpm              Testing          "Trans Input Speed 1st Gear"
CALC.TIS_2ND               F102 CLC-00-102   rpm              Testing          "Trans Input Speed 2nd Gear"
CALC.TIS_3RD               F103 CLC-00-103   rpm              Testing          "Trans Input Speed 3rd Gear"
CALC.TIS_4TH               F104 CLC-00-104   rpm              Testing          "Trans Input Speed 4th Gear"
CALC.TIS_5TH               F105 CLC-00-105   rpm              Testing          "Trans Input Speed 5th Gear"
CALC.TIS_6TH               F106 CLC-00-106   rpm              Testing          "Trans Input Speed 6th Gear"

Of course, if you have other calc pids in your existing calc_pids.txt, you need to copy the 3 sections above (colour coded) to your calc_pids.txt without disturbing your existing definitions.




Edit History:
0. initial post.
1. changed MPH to RPM.
2. changed SAE.VSS to SAE.VSS.mph.
3. changed gauge/chart high to 8000.

[joecar]

After copying the calc_pids.txt file do this:
- start the scantool,
- open your log file,
- goto the PIDs F8 tab,
- select the tire and axle calc pids shown in the attached pic,
- select whichever other TIS pids you want,
- press the replot button,
- on the dash tab, add the TIS pid(s) to your chart display
- press the replot button.

[Bruce Melton]

I guess you are referring to what I might call "runaway" which is slip after engagement? It seems this is how many LS clutches overheat and first fail > in third gear near max torque?

[Ninety8C5]

Create a calc pid for this: Trans Input RPM = VSS * 336 * GR / TD

where:
VSS = vehicle speed [MPH]
TD = tire diameter [inches]
GR = overall gear ratio = trans ratio * axle ratio


Then in your log you can compare engine RPM to Trans Input RPM, or you can create a calc pid for RPM / Trans Input RPM.

This is what Mr.Mike is saying to do.

Cheers,
Joe

If the PID is calculating Trans Input Speed, shouldn't the PID be RPM instead of MPH in the calc_pids file?

I think you need to add mph to {SAE.VSS.mph}. The numbers looked high without it.

[joecar]

If the PID is calculating Trans Input Speed, shouldn't the PID be RPM instead of MPH in the calc_pids file?

I think you need to add mph to {SAE.VSS.mph}. The numbers looked high without it.

Ah, yes RPM not MPH, slipping brain...