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Old 01-01-2021, 05:53 PM   #60 (permalink)
Master EcoModder
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OK I will now start shopping rear axles out your model van.

Chevy and Ford are running the same transmissions, 6L80 and 8L80s.

Doing some fast number crunching it seems what I dreamed of a decade and was impossible to get is not being made today.

By my numbers you got to be running a 2:00 something rear end gear. Most likely around a 2.73. Could be different depending on your tire sizes, I did my numbers for my 18s and correct tire sized for my 93...

Can you tell me your tire sizes?

Those gears I cannot get for my old 10 bolt rear end...

Now I can consider going with the 6L80 and a newer rear end as lower gears are again being made....

And yes those super low grannie gears are make it power off so well.

A .70 OD seems to tallest gear anyone has made, so nearly all OD transmissions could get the same MPG in top gear with the same rear axle.

What the have done is add MUCH lower low gears.. 1St is a 4.56 on the 8L80 and it is a 4.17 in the 6L80 only a 2.84 in the 4L60.

FYI the 6L80 has a slightly taller top gear, it is a 69.1 (Close to a .70) vs the 8L80's .65, so can possibility get a touch better MPG.


Last edited by racprops; 01-01-2021 at 07:01 PM.. Reason: Mistake
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