4.10 on automatic mustang 5.0 2012
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Joined: November 2, 2011
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Originally Posted by BlackMamba03
You'd have to get a tune. The tune would address all your shifts to go with the new gears. American Muscle has 4.10's in their Grabber Blue test car and they love it.
Mach 1 Member
Joined: March 20, 2011
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From: Bremen, Indiana
Too much gear for a street going car. First gear would be absolutely useless. There is such thing as too much gear and this would be it. Your talking over 20% more gear then stock. Thats a bunch. Unless your living life a 1/4 mile at a time I'd say 3.55's would be all you would ever need IMO.
Mach 1 Member
Joined: December 13, 2008
Posts: 844
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From: Midwest
This explaination is using antique reasoning from the old days. The towering intellects probably have a reason for going with a 4.10.
My understanding of the major issue with 4.10's is that the trans must shift into 5th gear before the end of the 1/4. Fifth gear is .87.
And if you get significant tire spin in 1st or 2nd, then the trans goes into limp mode.
On the street, a 4.10 gear with a 4.17 1st gear is useless. The potential for the tires breaking loose is too high and you are not in the power band very long.
To put it in Fox body terms, the 1st gear in the WC T-5 is 2.95. The rear gear needed to get the same multiplication factor found in a 6R80 (with a 4.17 1st gear and a 4.30 rear gear) is 5.79. Who needed to run a 5.79 then? Nobody.
Using my antique calcs from the old days the best gear for this setup is a 3.55 (actually a 3.68) to go through the traps at 7000 and a 27.25 inch tall tire and not shift into 5th.
FWIW, to go through the traps at 6k with a 1.14 4th gear, the rear gear is a 3.16.
Hmmm. If I get a 6r80, I'd experiment with tire height first.
My understanding of the major issue with 4.10's is that the trans must shift into 5th gear before the end of the 1/4. Fifth gear is .87.
And if you get significant tire spin in 1st or 2nd, then the trans goes into limp mode.
On the street, a 4.10 gear with a 4.17 1st gear is useless. The potential for the tires breaking loose is too high and you are not in the power band very long.
To put it in Fox body terms, the 1st gear in the WC T-5 is 2.95. The rear gear needed to get the same multiplication factor found in a 6R80 (with a 4.17 1st gear and a 4.30 rear gear) is 5.79. Who needed to run a 5.79 then? Nobody.
Using my antique calcs from the old days the best gear for this setup is a 3.55 (actually a 3.68) to go through the traps at 7000 and a 27.25 inch tall tire and not shift into 5th.
FWIW, to go through the traps at 6k with a 1.14 4th gear, the rear gear is a 3.16.
Hmmm. If I get a 6r80, I'd experiment with tire height first.
Last edited by 825LTRGT; Nov 16, 2011 at 09:28 AM. Reason: Noodled some more.
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