Question about Speedo calibration?
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From: Manassas VA
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St. Jude Donor '14
Question about Speedo calibration?
Hi,
Is there some way you can calibrate a corvette speedometer on your own for example with an Autotap or something?? I guess you would need to put the car on a machine to measure the actual speed then adjust it accordingly, and that would be rather difficult on your own.
Here is my second question. If I change the gears or the size of the tires would it effect what my speedometer reads??? I would think so... Correct or Not? Or does the car take the speed of the vehicle from someplace other then the wheels??
Thanks
Robert
Is there some way you can calibrate a corvette speedometer on your own for example with an Autotap or something?? I guess you would need to put the car on a machine to measure the actual speed then adjust it accordingly, and that would be rather difficult on your own.
Here is my second question. If I change the gears or the size of the tires would it effect what my speedometer reads??? I would think so... Correct or Not? Or does the car take the speed of the vehicle from someplace other then the wheels??
Thanks
Robert
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From: Murphy TX
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Re: Question about Speedo calibration? (Bluewasp)
You shouldn't need to "calibrate" your speedo. The PCM sees a signal (from the VSS) that (more or less) indicates the instantaneous angular velocity of the rear axle (independent of gear ratio.) The only configurable variable is tire height.
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From: Manassas VA
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St. Jude Donor '14
Re: Question about Speedo calibration? (ToplessTexan)
You shouldn't need to "calibrate" your speedo. The PCM sees a signal (from the VSS) that (more or less) indicates the instantaneous angular velocity of the rear axle (independent of gear ratio.) The only configurable variable is tire height.
[Modified by Bluewasp, 6:52 PM 1/28/2002]
[Modified by Bluewasp, 6:54 PM 1/28/2002]
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From: Murphy TX
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Re: Question about Speedo calibration? (Bluewasp)
What program/tool do you use to input the tire height??
You must edit values in the PCM so we're talking about Hypertech, Superchips, Powerloader, Fastchips, etc, and now thankfully LS1-Edit :)
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From: Murphy TX
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Re: Question about Speedo calibration? (Buckmaster)
My understanding of a gear change is that they are programmed so the speedo automatically adjusts, however if you have an A4 you will need your shift points adjusted by way of a PCM program. I believe there is actually a "plug in" type hook-up (for lack of a better term) to the diffs on the C5 :D
Someone correct me if I'm wrong :)
Someone correct me if I'm wrong :)
If you change tire height you need to fuss with programming. Shift points may or may not require reprogramming, depends on the application.
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Re: Question about Speedo calibration? (ToplessTexan)
There was an earlier post on this that was pretty good. It turns out that, as the VSS is on the ring gear carrier, changing gear ratios by changing the pinion gear tooth count (Such as changing from a 3.15 to a 3.42:1) doesn't affect the speedometer reading. Changing rear tire diameters will affect the speedometer, but you can correct that with a HPP III. :cheers:
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From: South Riding Virginia
Re: Question about Speedo calibration? (6Speeder)
:confused:
What is an HPP III? I did a search for it and came up empty. Is it an abbreviation?
Is it difficult to operate? For reasons I won't get into here right now , I want to know how difficult it would be to "DECALIBRATE" my speedo by about 6-7 MPH .
Thanks! :rolleyes:
What is an HPP III? I did a search for it and came up empty. Is it an abbreviation?
Is it difficult to operate? For reasons I won't get into here right now , I want to know how difficult it would be to "DECALIBRATE" my speedo by about 6-7 MPH .
Thanks! :rolleyes:
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From: Murphy TX
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Re: Question about Speedo calibration? (flip68)
Hypertech Power Programmer III
You can work it if you can push a button in response to a yes or no question. :) If you have an A4, bear in mind that if you change tire height you will also affect shift points.
[Modified by ToplessTexan, 10:45 AM 1/29/2002]
You can work it if you can push a button in response to a yes or no question. :) If you have an A4, bear in mind that if you change tire height you will also affect shift points.
[Modified by ToplessTexan, 10:45 AM 1/29/2002]
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Re: Question about Speedo calibration? (ToplessTexan)
changing gear ratios by changing the pinion gear tooth count ...(Such as changing from a 3.15 to a 3.42:1) doesn't affect the speedometer reading. Changing rear tire diameters will affect the speedometer, ...
ding... ding... ding
I think we have a winner! :)
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From: South Riding Virginia
Re: Question about Speedo calibration? (Mike Mercury)
Mike,
I think I understand from your post that changing tire sizes would accomplish what I want to do.
I would like to try and DECALIBRATE my speedo 7-8 MPH and maintain the original tires/rims that are on the car.
Any other suggestions?
I was wondering if products like the Hypertech Programmer III or Autotap
would allow me to do this via the OBDII port?
Any insight would be GREATLY appreciated.
Thanks,
Felipe
:confused:
I think I understand from your post that changing tire sizes would accomplish what I want to do.
I would like to try and DECALIBRATE my speedo 7-8 MPH and maintain the original tires/rims that are on the car.
Any other suggestions?
I was wondering if products like the Hypertech Programmer III or Autotap
would allow me to do this via the OBDII port?
Any insight would be GREATLY appreciated.
Thanks,
Felipe
:confused:
Safety Car
Joined: Aug 2000
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From: Murphy TX
Cruise-In II Veteran
Re: Question about Speedo calibration? (flip68)
I would like to try and DECALIBRATE my speedo 7-8 MPH and maintain the original tires/rims that are on the car.
Any other suggestions?
I was wondering if products like the Hypertech Programmer III or Autotap
would allow me to do this via the OBDII port?
Any insight would be GREATLY appreciated.
Thanks,
Felipe
:confused:
I was wondering if products like the Hypertech Programmer III or Autotap
would allow me to do this via the OBDII port?
Any insight would be GREATLY appreciated.
Thanks,
Felipe
:confused:
