View Full Version : Best way to monitor clutch slip
robz
January 7th, 2008, 06:33 AM
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
January 11th, 2008, 11:02 AM
VSS and RPM should be at a fixed ratio in gear. If they drift apart, the clutch is slipping.
robz
March 2nd, 2008, 05:22 AM
VSS and RPM should be at a fixed ratio in gear. If they drift apart, the clutch is slipping.
anyone else?
joecar
March 2nd, 2008, 11:22 AM
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
:beer:
robz
March 9th, 2008, 02:42 PM
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
:beer:
sent pm
joecar
March 10th, 2008, 03:03 AM
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.
:cheers:
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
March 10th, 2008, 03:20 AM
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
March 10th, 2008, 04:57 AM
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
March 10th, 2008, 06:15 AM
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
:beer:
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
March 10th, 2008, 06:51 AM
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... :cheers:
joecar
March 10th, 2008, 07:19 AM
Thanks for the feedback, I recorrected post#6.
robz
March 10th, 2008, 10:15 AM
Thanks you Joe!
and thanks for the MAF Bruce M.
mistermike
March 12th, 2008, 10:15 AM
This is what Mr.Mike is saying to do.
Cheers,
Joe
:beer:
But, said so much more eloquently by you.
Great job, joe.
joecar
March 12th, 2008, 10:30 AM
Thanks Mike... :cheers:
Powered by vBulletin® Version 4.2.5 Copyright © 2024 vBulletin Solutions Inc. All rights reserved.