Speedometer question
Thread Starter
Pro
Joined: Apr 2016
Posts: 512
Likes: 62
Speedometer question
I recently scored a Dana 44 w/a 3.45 gear for my '96 that currently has a Dana 36. I'm not sure what gears are in the 36 but it isnt a 3.45. What do I need to do to make the speedometer read correctly when I put the Dana 44 in? The trans in it is a 700r4 (or is it a 4l60e?). Any help is appreciated.
Team Owner
Joined: Sep 2003
Posts: 25,373
Likes: 2,734
I recently scored a Dana 44 w/a 3.45 gear for my '96 that currently has a Dana 36. I'm not sure what gears are in the 36 but it isnt a 3.45. What do I need to do to make the speedometer read correctly when I put the Dana 44 in? The trans in it is a 700r4 (or is it a 4l60e?). Any help is appreciated.
Le Mans Master
Joined: Aug 2015
Posts: 6,090
Likes: 1,972
From: St. Charles MO
You can use a signal conditioner. The trans sensor is fed to the ECM, the ECM then sends speed info on the grn/wht wire to several devices including CCM (speedometer and odometer), radio, HVAC. Read the install instructions, particularly with regards to affecting TCC slip calculations. There may also be issues with TCS, ABS, and active suspension as well. I don't know. WVZR is probably correct that a reprogram within the ECM is the best way, but not many people have access to the equipment, or know people that can do it.
EDIT: If you intercept the raw signal right out of the transmission, condition it, then send it on to the ECM, all systems affected by speed will be "recalibrated". So the $85 conditioner will work. Check with DakotaDigital that the SGI-5E can indeed be used to condition the raw VSS signal, but I think it can.
EDIT: If you intercept the raw signal right out of the transmission, condition it, then send it on to the ECM, all systems affected by speed will be "recalibrated". So the $85 conditioner will work. Check with DakotaDigital that the SGI-5E can indeed be used to condition the raw VSS signal, but I think it can.
I agree it would be better to recondition the signal before the PCM than after it. The PCM does use the speed info for various things, but the area where the speed accuracy is most important probably is in the control of the torque converter lockup.
The best way is indeed to update the PCM calibrations (aka get it "tuned") to re-calibrate the speedo. The bad news in a 1996 model is that in order to do this you have to buy a $400 software suite called Jet DST. Once you have that, it's simple to change the speedo calibration. It's just not cheap software.
Team Owner
Joined: Sep 2003
Posts: 25,373
Likes: 2,734
I think it's important for the OP to research this 'locally' - There was/is a couple of locals here that do PCM - Tire RPM(Revolutions Per Mile/Axle ratio calibrations for $100 or close to that $$$. A DIY with a ERA/Conditioner I believe is much 'trial/error'and presents wiring and location of device issues. The DIY option is likely 'overkill' when only a Axle ratio/Tire RPM calibration is of interest.
*** If the OP mentioned his location I'd think there's good likelihood that someone either can or knows someone in the vicinity that could help.
*** If the OP mentioned his location I'd think there's good likelihood that someone either can or knows someone in the vicinity that could help.
Last edited by WVZR-1; Aug 30, 2018 at 10:45 AM.
Racer
Joined: Jul 2017
Posts: 422
Likes: 53
From: PA
I recently scored a Dana 44 w/a 3.45 gear for my '96 that currently has a Dana 36. I'm not sure what gears are in the 36 but it isnt a 3.45. What do I need to do to make the speedometer read correctly when I put the Dana 44 in? The trans in it is a 700r4 (or is it a 4l60e?). Any help is appreciated.
If you can find a used (and reset back to factory) hypertech tuner the custom tune function allows you to change rear gear ratios.
Pro
Joined: Mar 2000
Posts: 690
Likes: 7
From: Bradenton, FL
Cruise-In II Veteran
Adjusting it in your ECM would be the best bet. One more option exists if your handy with electronics. I built a calibrator for my '85 with an Arduino Nano - couldn't find a gear to match my ZF6 to the 3.73. Works well and only costs about $10 to make. A fair amount of work, though.
Le Mans Master
Joined: Aug 2015
Posts: 6,090
Likes: 1,972
From: St. Charles MO
I don't disagree with anything ihatebarkingdogs is saying, btw.
Safety Car
Joined: Apr 2003
Posts: 3,793
Likes: 9
From: VA
I recently scored a Dana 44 w/a 3.45 gear for my '96 that currently has a Dana 36. I'm not sure what gears are in the 36 but it isnt a 3.45. What do I need to do to make the speedometer read correctly when I put the Dana 44 in? The trans in it is a 700r4 (or is it a 4l60e?). Any help is appreciated.
$90 to change the gears and fans:
http://www.lt1pcmtuning.com/service/
Another well known tuner:
http://www.pcmforless.com/
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