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ed
Dodge Dakota
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11/04/2003
12:45:29
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 Subject: 3.92 or 3.55
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which is the better setup overall
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JZ
Dodge Dakota
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11/04/2003
13:24:37
| RE: 3.92 or 3.55
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It depends what you want to do. 3.55s will give you a little better gas mileage, while 3.92s will give you a little better acceleration and towing power.
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gen1dak
Dodge Dakota
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11/04/2003
17:39:24
| RE: 3.92 or 3.55
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With the 3.92's, you wind up with a final drive ratio in the 2.70's. That's the same as thousands of Mopars, even a lot of old Chargers from the 60's when equipped with 318, 383 2v. Anyway, even with them, I found myself wishing the overdrive didn't kick in til I was goin' about 10 mph faster in moderately congested highway areas. With 3.55's, this would be even more annoying, and I'd be more likely to lock the OD out more often. Both have good/bad sides. At the same time, I found myself how it'd tun with 3.55's at 80+ cruising. See what I mean?
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Mark
*GenII*
11/04/2003
17:41:16
| RE: 3.92 or 3.55
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I swapped out my 3.50 for a 3.92 and it was nice. I have 28" tires. Speedo is a bit off. Helps me rack miles up faster though. haha
-Mark Hryckiewicz
1993 Sport RC SB 5.2L Auto
Mark.DodgeDakotas.com
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dakotadude
Dodge Dakota
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11/04/2003
19:21:13
| RE: 3.92 or 3.55
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Mark,
How much did the gear swap speed you up in the quarter mile?
Thanks
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Mark
*GenII*
11/04/2003
20:18:28
| RE: 3.92 or 3.55
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Dakota Dude, I have never been to the track. It feels faster off the bat though.
-Mark Hryckiewicz
1993 Sport RC SB 5.2L Auto
Mark.DodgeDakotas.com
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CrankYankers
Dodge Dakota
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11/04/2003
23:39:13
| RE: 3.92 or 3.55
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Mileage calculates from your MPH, not RPMs, so it will not affect it. 392s will very slightly lower mpg but not too badly. It's worth it if you're buying a new truck to get the 392s.
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Mark
*GenII*
11/05/2003
00:22:39
| RE: 3.92 or 3.55
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Crank Yankers... is on right now. Good show...
The newer dakotas don't have the speedometer problem that mine has. I have a 1993 model and the speedo is off.
-Mark Hryckiewicz
1993 Sport RC SB 5.2L Auto
Mark.DodgeDakotas.com
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Gen II Geoff
Dodge Dakota
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11/06/2003
02:37:02
| RE: 3.92 or 3.55
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I just put 3.90's in my 95 stock was 3.55:1. The speedo is way off. I put 225-70-15's on before and it read low. Now its pretty high.
I'm still trying to find the correct gear for my speed sensor. Seeing as how the speed sensor turns the speedometer the odometer will be off also.
The way I see it, its counteracting the 2 years I've had my taller tires on the truck.
However I need to get it corrected as I drive through lots of little hick towns on my way to school / work every day. The cops there don't like loud trucks flying through their streets.
I've only had my 3.90's on for a few hundred miles but there is quite a difference. I can walk away from a z28 up untill about 50 mph. that says a little something.
later Geoff
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Gen II Geoff
Dodge Dakota
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11/06/2003
02:40:40
| RE: 3.92 or 3.55
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I suppose I should mention that I swapped a mild 318 in place of my 239 v6 last year. With a krc 206 cam, ported intake manifold and tb. Open 14x2 air filter, MSD ignition and wires. electric cooling fans from a maxima, 180 t-stat autolite 3923's, and a mopar perf pcm. 46 RH trans. Borla muffler (dual exit) and a catco cat. stock paint job (- stripes) magnum v6 emblems still in tact along with factory wheels. Between the BFG Radial T/A's, 3.90:1 gears and a Lock-Rite locker it grabs pretty well :-)
later
Geoff
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gen1dak
Dodge Dakota
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11/06/2003
03:11:33
| RE: 3.92 or 3.55
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Nifty little product to get those speedometers back to normal:
http://www.abbott-tach.com/cablex.htm
Uses the electronic sensor to correct for the computer, and a cable-drive interface to correct cable-drive speedos.
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01Motorsport
Dodge Dakota
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11/06/2003
09:03:55
| RE: 3.92 or 3.55
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I had a '92 with 3:55 auto, now a '01 with 3:92 5-spd. There's about 200 rpm more on the highway, nothing major. The '92 weighed about 250 pounds less, but the efficiency of the 4.7 over the 5.2, and 5-spd over the auto, accounts for 17.5 overall mpg for the '92, and 19mpg overall for the '01. The city mileage with a 3:92 is terrific. It's a nearly perfect gear for a 4.7.
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Gen II Geoff
Dodge Dakota
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11/06/2003
11:54:50
| RE: 3.92 or 3.55
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thats a good idea, but I've got an electronic speed sensor so I've just gotta pull out the ole' TI calculator and see how fast I'm really going.
later
geoff
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Mark
Forum Moderator
11/06/2003
13:07:43
| RE: 3.92 or 3.55
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I just subtract five in the city streets and ten on the highway. It doesn't bother me too much. Eventually I'll get it fixed up. My little cable that shows the gear selector is also busted so its always indicating first gear. I guess I had the truck so long that I know it without need for instrumentation. hahah
-Mark Hryckiewicz
1993 Sport RC SB 5.2L Auto
Mark.DodgeDakotas.com
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Gen II Geoff
Dodge Dakota
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11/06/2003
17:42:13
| RE: 3.92 or 3.55
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I'm in the same ballpark mark. Everything mechanical runs well, but my gear indicator doesn't work, the dash rattles and the seat is burned.
Geoff
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MD
Dodge Dakota
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11/06/2003
19:37:37
| RE: 3.92 or 3.55
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Need more info - is it an auto or 5spd? Do you tow heavy loads (2500lbs +). 4.7?
If most of your driving is hwy and you don't tow, and max mileage is a consideration, 355's are OK - especially with the low 1st gear of the 5sd, if that's what you have.
However, with the auto trans, and if you drive in hilly to mountanous terain at all, or tow, 392's, or even 410's are the way to go.
If you have taller than stock tires, that must also be given consideration when asking about the "best" gear ratio.
I have the 4.7, auto and 410's. I pull a boat from Nevada to northern Idaho. I am not concerned that I probably lose a mile or so per gallon during normal driving - the 410's are the best gear for me, especially considering I am soon to install a slightly taller tire - thus making my effective ratio approx. 3.88.
Not such an easy question, is it?
MD
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