Rear end gears, gauges

[JeremyNH]

Doubt it's 4.56s. I haven't seen many (read NONE) with 4.56s. I know there out there, but just because it's a 4L80 don't mean crap. Prolly get 3.42s if wanted...

He says that he has a 4L60 with a new rear end and that he thought the rear end was 3.73 which would be stock for a 1/2 ton 4x4. If there is a wide discrepancy between actual and reported speed then obviously the ratio is wrong. If the differential is from a 3/4 ton with a 4L80e it would have a lower ratio than 3.73. It cannot be higher than 3.73 else what he has observed (fast acceleration, speed reads high) wouldn't be the case. Rather the opposite. Could be his pwm is set for a 3.42 and he has a 4.10. Same result - about 10mph difference at cruising speed and high rwt in low gears. The 4.56 has the same final drive ratio in a 4L80e as the 3.73 in a 4L60e for 1st and 2nd which is why they weren't uncommon. Maybe not in your experience but certainly not as an absolute. Differentials available were 3.42, 3.73, 4.10, and 4.56. Take your pick but it looks like he has about a 0.75 error and 3.42 to 3.73 doesn't explain that. PWM set for 3.42 with a 4.10 rear or pwm set for 3.73 with a 4.56. Given that he thought it to be a 3.73 I would suspect the latter.

 

[JWS6196]

https://harristuning.com/Tbi/vssb-drac-calibration/
This is what I had to do to get my speedo accurate.
however, since I have an ‘89 with a moonie cluster, mine were on the speedo circuit panel.

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[D-93-b]

Can someone please explain how to post videos? I think it would help a lot if I post videos of the gages. I’m awful at explaining things easier to show you


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[Erin]

Should just have to click upload a file then go to your phone’s photo library & select the video you want to upload.

 

[D-93-b]

Should just have to click upload a file then go to your phone’s photo library & select the video you want to upload.

When I go to my gallery there’s no videos,only pictures.
If I save the videos to my files and attempt that route all the videos in my files are grey. Like it shows them but you can’t select them. Can select photos or pdf though.


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