Looking to change my rear gears

STROKETHISF350

STROKETHISF350

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Sep 1, 2012
Messages
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Hey everyone, I have been wanting to do a gear swap On the truck in my sig. I currently have 3.73 and at 70 mph I'm at about 2k rpms. With the allison my truck goes into 5th at 40 mph and never really feels like it's under any kind of load. I know a set of 3.55 would probly be the best choice but I was considering something even Taller. What do you guys think and what would be a good gear choice. I'm looking to improve fuel economy a little and make the truck where it's not screaming at 80 mph goin down the interstate. Also, I've heard the new fords Are running 3.31 gears. Does anyone know if this is true or not and how do they perform, thanks in advance
 
The 3.08 is out there, Yukon makes them. I don't think anyone here cares to share Any info on this subject unfortunately
 
I've got factory 3.73's in my truck and I'm perfectly happy with the mileage I get considering the truck weighs 8200lb with a full tank, 5er hitch, my fat ass, and everything else I carry in the truck. I can pull just under just 19 unloaded with the cruise running 72-75 with IDP's Extreme Street tune. I've been averaging 15 in mixed driving conditions and 12-13 towing.
 
the 3.31 ratio fits the dana 60 and 10.5. the 30,8 ration isn't available in the front ford dana 60 , so the highest ratio you can get is 3.31. I want to run those in my excursion with 12v and g56... my first gen runs 3.07's and a 5 spd

Thanks,
Deo
 
It has low end grunt but its real easy to bog the engine.. I found if I run 1200 rpm and lop around its too low rpm wise, and gets worse fuel mileage, and you can feel the driveline and trans load up... etc.. the Getrag doesn't like power applied at low rpms etc.. I tow in 4th direct and its nice, od is fast like triple digit fast if yoiu have the hp and th ebrakes to stop you, first gens like mine aren't to fun at 85-100...lol, the stock brakes are not good.
Thanks,
Deo
 
Im sorry ,.. BUT!!!! You lost me at Allison. Is this a real question??

Ok.. get a 3:50 ish gear. the 3:73 should work great but if you want more and spend tghe money a 3:50 ish should suit you well so long as you dont tow heavy loads.
 
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It was a serious question.. My allison goes into 5th at 40 mph and the converter locks at 50 or so. With the way the trans is geared the truck never even feels like it under a load so I think I would Benifit from a 3.55
 
Around 1700 rpms or so at 70 so when I wana go 80 the engine isn't screaming and doesn't kill my mileage
 
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