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1989-1993 Supercoupes with AOD: What rpm do you hit when in overdrive at 55mph?

4K views 24 replies 9 participants last post by  Grog6 
#1 ·
I'm curious to see what rpm is to compare with the 2.73 and 3.08
 
#3 ·
The biggest problem is that there's not enough torque to run 2.73s and the 1st gear in the AOD.

Well, there is, but you'll lose out on the first part of the 1/4 mile due to having to get up into the torque curve.

Why are you looking for longer legged gearing? *is curious*

RwP
 
#4 ·
I have 2.73s on my car and it really kills the acceleration. I'm thinking about going with the 3.27 to increase 0 to 60, but I also want the good mpg. Also, i dont have a super coupe, I have the 5.0. The reason I'm asking is because it's the "best" thing to compare it to ?
 
#5 ·
Actually, no, the SC isn't the "best" thing to compare it with; the best thing is a 5.0HO.

The 3.08 was the stock issue most years; and it does tolerable at best. A 2.73? I bet that car feels like a dead pig off the line.

I've got some 3.55s to go into Ruby as I redo her drivetrain; 3.73 is about as stiff as I'd go for a highway-also car, but YMMV natch.

RwP
 
#6 ·
I think this is a trick question because who would actually drive 55?

They put 2.73's in V8 T-Birds for years, pretty much all years in the 70's and 80's. In the 60's they used 2.75's with the 429's. Talk about a waste of big block power.

I am curious which year the OP has, and if he actually has 2.73's. If it's an 88 or older, definitely!

Al
 
#9 ·
This is incorrect -I have a 91 Cougar LS, 5.0HO, stock 2.73 rears switched to 3.73's about a 1 second improvement in 1/4 mile times, LOL. 5000RPM shift out of first was at 60 mph or so:grin2:
 
#13 ·
I'm about an hour away from the car unfortunately. I'll look at the tag when I get a chance. Was under 1400 rpm at 55, just over 1600 at 70. I worked at a Ford dealership during college when I did the gear swap. Discussing options with the Ford tech we decided to find a junkyard rear with the trac-lok to build while I was still driving the car with the 2.73 open diff. I've been mistaken before but don't think I am here....
 
#24 ·
A big FWIW

I recently switched to 3.73 from my stock 3.08 5.0 lx and mpg went from 24.5 mpg at 74 mph to maybe 21 or 22 (any long drive involves hills in my area). I don't do long trips with it since doing mods but it was a 21% gear reduction using my math:grin2: so a fuel economy reduction is expected/guaranteed when you are in high gear and past about 1500 rpm.

As far as 0-60mph went for me. I switched to 3.73's in part to improve the time since it had to shift to second before it would hit 60mph. I remember not being able to hit 60 mph in first without hitting the 5000 rpm red line and I won't try it now with 3.73's. My tach does have a 500 rpm echo or something that can't really be trusted at high or WOT. Nobody has offered to time me so 0-60 is still a mystery.
 
#25 ·
Put an acceleration app on your phone, and you can see the shifts.

Should be able to see the timing as well.
 
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