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Discussion Starter #1
I remember a thread that I read a while ago about someone on the board who could calibrate the speedometer from a GTV6, I couldn't find the thread, but was hoping to see if he could check one for me.

Also: Is there a difference in the speedometer from the later model cars which had the face plate that went up to 140 MPH?
 

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The Speedometer has no adjustment pot and the calibration is fixed. There is information in my Milano Speedometer thread which describes using a Dakota Digital box when early type speedometers are used with late GTV6 or Milano senders.
 

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Is it possible (or straightforward) to re-calibrate GTV-6 speedos that are 1985.5 and 1986?
The information that I provided in post #2 was incorrect. I have edited it. I confused the speedometer and tachometer. The tach has an adjustment pot. There is no adjustment pot in the speedometer.
 

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The information that I provided in post #2 was incorrect. I have edited it. I confused the speedometer and tachometer. The tach has an adjustment pot. There is no adjustment pot in the speedometer.
Thanks! I've got a funny issue in that my speedo is dead on accurate up to 50mph. After that, it runs approximately 10% slow. That is, when it reads 55, I'm really doing 60. When it reads 60, I'm really at about 65-66. When it reads 75 (which is not too often...), I'm really doing somewhere in the neighborhood of 82 or 83. I checked this with two different GPS units. And the reading on the tach in 5th gear corroborates this (e.g. about 2850 rpm in 5th should be 60 on 1985 cars, but reads 55).

The beguiling part is that under 50, it's just fine...
 

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My 83' gtv6 has a potentiometer adjustment for the speedo and I was able to calibrate it to the 60mph signal sent from the dakota digital gps box however, I'm not sure how accurate it is before or after that. I do know it's dead on at 60 and would guess that is as accurate as it ever was.
 

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Well I am looking to swap the stock speedometer for the one that goes up to 140 MPH, I can see a difference in the wiring but I am not sure if the sender is different? What is the wiring of these units and can I direct swap them?
Provided you haven't changed the transaxle sender, it should just plug and play.
 

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Discussion Starter #9 (Edited)
That's what I want to hear, I haven't done the rear end yet so its all original. figured I would take the unit apart and swap the milage indicator or just swap the face plate! I just can't understand why they used the top speed at 85?

Yes I grew up in the 70's / 80's so I am aware for government interference, but really, 85!
 

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I made the swap without problems (83') It was only when I put a later transaxle in (platinum) that I ended up with a gps sender. I highly recommend for no other reason than it is far more accurate than the stock speedo in any iteration.
 

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Are you able to safely monitor it when you are driving fast, and what about response time? My Garmin gives a speed readout but it lags the speedometer. No problem when you are cruising on the interstate but significant errors when you are accelerating and braking.
 

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Discussion Starter #13
I haven't tested it yet and that is the problem with using the portable navigation units. I will get a buddy of mine to pace me on the highway to give it a test at speeds. The response os the speedometer so far looks good and once I fix the needle I will be able to see what speed I am going better at a glance, well sort of,, you still have the issue with the steering wheel interference!
 

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Alfa Particle asked:

Are you able to safely monitor it when you are driving fast, and what about response time? My Garmin gives a speed readout but it lags the speedometer. No problem when you are cruising on the interstate but significant errors when you are accelerating and braking.

[/I have been very happy with the Speedometer app; I put my phone in the center section ahead of the hand brake handle, and occasionally glance down at it to check my rate of progress. It is invaluable in that I travel through some pretty controlled areas (radar cops on motorcycles), and I don't need a moving violation.

I have serious doubts that our 35 year old speedos will ever be accurate....COLOR]
 

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Hi guys, my 1984 GTV6 speedometer has IC burnt out and I was not able to see the model no for replacement. Anyone can tell me the info? Thanks
 
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