Real world survey 3:55 vs 3:73 - TCCoA Forums
 
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post #1 of 12 (permalink) Old 08-28-2009, 10:53 AM Thread Starter
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Real world survey 3:55 vs 3:73

While i'm gathering the last of my goodies for the winter project, i'm really undecided as to the rear gear ratio. I'd like to see some highway rpm numbers from the guys that have either 3:55's or 3:73's at 65mph. I do alot of highway driving to get to any big city and am curious about the difference in rpm of the two gear choices. TIA

95 Thunderbird LX 4.6
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post #2 of 12 (permalink) Old 08-28-2009, 11:49 AM
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approximately 2150RPM for 3.55's and 2250RPM for 3.73's.

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post #3 of 12 (permalink) Old 08-28-2009, 12:00 PM
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you want real world?

you won't be happy with either.

anything from your stock gear to 4.10's will not see a reduction in MPG....maybe 1 mpg.

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post #4 of 12 (permalink) Old 08-28-2009, 12:14 PM Thread Starter
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Not so much about the gas mileage, just curious about the rpm change from stock.

95 Thunderbird LX 4.6
K&N cold air intake. True 2 1/4" duals, Xenon GFX. 3:55 Trac loc. Beefier trans, 2800 stall convertor, MkV111 aluminum driveshaft.
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post #5 of 12 (permalink) Old 08-28-2009, 12:15 PM
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Quote:
Originally Posted by Buckcreekbilly View Post
Not so much about the gas mileage, just curious about the rpm change from stock.
gotcha....just at minimum, go with the 3.73's!

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post #6 of 12 (permalink) Old 08-28-2009, 12:16 PM
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I am also interested in this...

Also wanted to know if any computer tunes are needed for changing to either one of those? Are they a direct bolt-on? Like would I be able to buy them, get a trans-shop to put them in, and drive away?

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post #7 of 12 (permalink) Old 08-28-2009, 12:22 PM Thread Starter
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Far as i know, your stock computer will handle up to 2 gear changes higher, so 3:55's need no extra. If you go to 3:73's, then ya need it done in a custom tune.

95 Thunderbird LX 4.6
K&N cold air intake. True 2 1/4" duals, Xenon GFX. 3:55 Trac loc. Beefier trans, 2800 stall convertor, MkV111 aluminum driveshaft.
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post #8 of 12 (permalink) Old 08-28-2009, 12:35 PM
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You will govern out super early if you dont have a chip. I went from 3.08 to 3.55 and my governor started kicking in around 94, i think it was like 105 or so before...its been too long since I had a governor. I have 3.73 now and it wasnt much of a difference from the 3.55s. I am very seriously considering going 4.10 soon though, although I think i need a speedcal for that
-Rob

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post #9 of 12 (permalink) Old 08-28-2009, 12:36 PM
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Go with 4:10's at least.
Unless this your daily driver.
I still managed 14 mpg @ 60 mph with e85 with 4:10's.
On gas that would be17.5 mpg.

Last edited by r429460; 08-28-2009 at 12:41 PM.
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post #10 of 12 (permalink) Old 08-28-2009, 01:21 PM
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3.55s would be a waste, and 4.10s might be too much. I have the 3.73s in my lincoln, and I regularly cruise at 75-80mph, and the rpms are in the 2400-2500rpm range. I take my car on long drives too, down to VA and NC, and the rpms never bother me. On the highway, I still get 22mpg out of the lincoln, and that is with 3.73s, a cobra intake, no EGR, and a 5-speed swap. Also, on the highway the 3.73s actually make the car much more pleasant to drive because you no longer need to downshift to have enough power to pass someone. They are definitely the gear the car should have come with from the factory.

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post #11 of 12 (permalink) Old 08-28-2009, 01:28 PM Thread Starter
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Quote:
Originally Posted by MadMikeyL View Post
3.55s would be a waste, and 4.10s might be too much. I have the 3.73s in my lincoln, and I regularly cruise at 75-80mph, and the rpms are in the 2400-2500rpm range. I take my car on long drives too, down to VA and NC, and the rpms never bother me. On the highway, I still get 22mpg out of the lincoln, and that is with 3.73s, a cobra intake, no EGR, and a 5-speed swap. Also, on the highway the 3.73s actually make the car much more pleasant to drive because you no longer need to downshift to have enough power to pass someone. They are definitely the gear the car should have come with from the factory.
Kinda right along the lines i was thinkin, thanks for your input everyone. Looks like i'll go with my original thinkin and get some 3:73's.

95 Thunderbird LX 4.6
K&N cold air intake. True 2 1/4" duals, Xenon GFX. 3:55 Trac loc. Beefier trans, 2800 stall convertor, MkV111 aluminum driveshaft.
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post #12 of 12 (permalink) Old 08-28-2009, 02:43 PM
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3.55's suck, I can't wait to get rid of mine.

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