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4T65 Speed Calibration


Imp558

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I'm not sure what I'm doing wrong but this speedo will not read correctly no matter what I do!

I set the tire size (205/70/15), and the gear ratio (3.29:1) and the sprocket ratio (1.121) and my speedo is still off! The PCM Cal file is GTP, and the tranny plate crossed as a Riviera L67, but I tried every other optioned gear ratio for that tranny and tried the overall ratio (2.93:1) and my speedo is at best 4% fast! At worst I got 8% faster. Is there something else I should be changing since this tranny and PCM were from different cars in the constants or something?

 

http://www.gmtuners.com/transmission/1997_4T65-E.pdf

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According to google a riv has a 3.05 final ratio?

I'm not sure what I'm doing wrong but this speedo will not read correctly no matter what I do!

I set the tire size (205/70/15), and the gear ratio (3.29:1) and the sprocket ratio (1.121) and my speedo is still off! The PCM Cal file is GTP, and the tranny plate crossed as a Riviera L67, but I tried every other optioned gear ratio for that tranny and tried the overall ratio (2.93:1) and my speedo is at best 4% fast! At worst I got 8% faster. Is there something else I should be changing since this tranny and PCM were from different cars in the constants or something?

 

http://www.gmtuners.com/transmission/1997_4T65-E.pdf

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How do you know that your speedo is 4% or 8% fast? If you are comparing it to your HUD or the speed coming from your tuning program, I would say it is the cluster itself.

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How do you know that your speedo is 4% or 8% fast? If you are comparing it to your HUD or the speed coming from your tuning program, I would say it is the cluster itself.

GPS android app, Verified it against 2 other c.ars and its correct.

 

L67ss I've been referencing the PDF file posted The link above to. But I have a good supercharged Riviera calibration file And it has the same gear ratio as the PDF says.

 

I feel confident that its not a problem with misinformation. Tomorrow I'm going to check a few things against my original regal calibration file as far as speedometer scaling in the constants and maybe I'll find something there.

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Dont doubt ir, i dont trust google myself. I try to get pdfs for all my donors. Thats y i sed it witha ? Mark :)

GPS android app, Verified it against 2 other c.ars and its correct.

 

L67ss I've been referencing the PDF file posted The link above to. But I have a good supercharged Riviera calibration file And it has the same gear ratio as the PDF says.

 

I feel confident that its not a problem with misinformation. Tomorrow I'm going to check a few things against my original regal calibration file as far as speedometer scaling in the constants and maybe I'll find something there.

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what do you need exactly? Schematics or torque specs and stuff? alldatadiy.com is not expensive if you get coupon codes online and it'll give you everything on a specific car, better than Chiltons but not quite as good as a GM service manual. Light years beyond Haynes.

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