AOD vs 9" with highway gears

THR1LL3R

THR1LL3R

Senior Member
So I got my F1 on the road the last month or so and Im not happy with it on how high it revs on the highway(3300rpm@65). Over the summer swapped in a 302/C4 out of a van into my truck and kept the Dana44 with the 3.92 gear and a 29" tall tire. Im on the fence about doing the AoD or the rear instead(faster/easier). The pros of the AOD is I can keep the gears and have the best of both worlds and the cons will be all the work to swap it out and I will still have the oddball rearend. The Pros of the 9" is how easy it would be to swap it in but the cons are,still wont be as efficient on the highway even with a highway gear, the low end off the line will suffer and Ill probably have a pretty penny in the rear end itself. I feel like the AOD will add value to the truck and will give the motor more life.I got a line on a 10,000 mile AOD for $200 andI found a F100 9" with destroyed gears for $100... What do you guys think would suit me best?
Dave
 
I'm running a Dana 60 with 3.73's - 29" tires, a 30% O/D automatic and turning 2200 RPM at 65 MPH. Its a fine line you're trying to walk between fuel economy and power and IMO an O/D or 5 speed trans gives you more latitude to do that. Relating to your F1 I owned an 86 Bronco with the 5.0L 302-4 speed auto O/D trans and 3.08 rear gears which at 65 MPH would tach between 1900-2000 RPM. At 65 MPH the best fuel economy I got was 18 MPG. Lower 3.55 gears were recommended for use in a towing application. Depending on the cam and fuel system on your 302 my guess is that even with an O/D trans the 3.92 gears are going to be too low to give you decent fuel economy at 65 MPH. You might get a better response to this question on the HAMB.
 
AOD would be my choice. It would give you the best good drivability in town and a decent hwy gear. With 0.70 OD, you would be right around 2050 rpm at 65 mph with a 29" tire.
 
Yeah I'm defiantly leaning that way... It's a lot of work but saving on fuel and the life of the motor I'd think would pay off
 
I have a 66 f-100, stock it had a 3 on the tree with 3:70s. First I put a 300 with a c4, and changed the rear to 3:00. Came across an AOD cheep, and put it in without changing the rear. Waaaay to high! Went back to the 3:70s and it worked good. In a truck I would go with an OD, if you tow or haul you might need the lower gear.
 
A 9" rear is very heavy and it's hard to handle in a light car, a friend of mine put an 8"
with 4.10 gears behind an AOD and this works great with a 276 flatty. Hy way miles is around 20 and the 4.1 makes a llittle street light drags very interesting
 
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