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Dakaty
Dodge Dakota
11/12/2001
11:41:18
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 Subject: Rear end ratio - 3.92 or 4.11?
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I have a 2001 QC with a 5.9L auto and 3.55 rear LSD. I have installed most all of the "bolt on" basic mods.
I want to change my differential gears out. I think I want to go with the 3.92s. However, several sources say I should go with the 4.11s to really notice a difference.
My truck runs pretty good for a heavy truck and it is a dailey driver. I do want to increase performance but am wondering the the 4.11s are greared to low. I'm also wondering about the decrease in MPG, although I didn't get the truck for its economy.
Can anyone help me with this decision?
Thanks
Bill
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ALEX
Dodge Dakota
11/12/2001
11:47:16
| RE: Rear end ratio - 3.92 or 4.11?
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Some racers have used 5.38's and higher. Go with those to REALLY notice a difference. Maybe just 4.56's. Go to ring-pinion.com for some actual help, as I am just spewing crap that will not help you. When Bob Chandler started Bigfoot, he used 10.26 gears..... you might try those. You should REALLY notice a much bigger difference than the 5.38's will give you.
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CW
GenIII
11/12/2001
14:12:36
|  RE: Rear end ratio - 3.92 or 4.11?
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I would think that 4.11 should work really well with a big truck like that.
2001 4.7 5sp RC 3.91 sport plus
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swingman
Dodge Dakota
11/12/2001
14:56:01
| RE: Rear end ratio - 3.92 or 4.11?
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4.11 should be fine. Bernd advised me that 3.92 is enough for my 3.9L QC, so I'm assuming 4.11 should be enough for you.
Hope that helps!
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Dave
Dodge Dakota
11/12/2001
16:21:22
| RE: Rear end ratio - 3.92 or 4.11?
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IMHO, a 4.11 is a pretty tall gear for a daily driver! I'm not sure, but the carrier size might not be able to take a 4.11,you also have to take into account the ABS gear-thing that's on the carrier, you might not even be able to find a 4.11 thats compatiable with the ABS ring.If I were me, I'd just stick with the 3.92.I bought one off ebay for $30 and I'm just waiting to save up a little cash for the install.Just my 5.2 cents worth!
Dave
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CW
GenIII
11/12/2001
19:04:45
| RE: Rear end ratio - 3.92 or 4.11?
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The ABS ring is on the carrier and swaping gears has no effect on it. You can get the 4.11 for the 9.25 and I think the 8.25 without worring about anything other than the swap it's self. When you factor in the O/D the drivabilty doesn't really go down hill but milage probably will.
2001 4.7 5sp RC 3.91 sport plus
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Horbedarn
*GenIII*
11/12/2001
22:12:49
| RE: Rear end ratio - 3.92 or 4.11?
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I was thinking about doing 4.11 on my truck too. I need something to get off the line better. The gas milage shouldn't change much or at all because you will have to give it less gas to get going and keep it going. Does anyone know if 4.11 will fit in the front axle on the 4x4? Has anyone done the gear change themselves? I don't really want to pay someone to do that becasue of the amount of labor they charge. What is the best place to buy the gears and then an install kit?
Thanks
2000, CC, SLT, 4x4, 4.7, 3.55, Auto
Borla Cat-Back, JBA Headers, 72mm TB, 4" Z-Tube, 3923's, 180 T-Stat, IAT Adjuster
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Dakaty
Dodge Dakota
11/13/2001
11:09:52
| RE: Rear end ratio - 3.92 or 4.11?
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I contacted "ring-pinion.com" (someone on this site recommended them).
I talked with Jim (1 800 292 1031 - XTN 5531)
He recommended the 4.11 gears for my 2WD. Total parts cost is $308 including the "installation kit".
He sounded fairly knowledgable.
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alex
Dodge Dakota
11/13/2001
11:16:44
| RE: Rear end ratio - 3.92 or 4.11?
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I was spewing crap earlier, now I'm not. Randy's Ring & Pinion is one of the best companies in the business. That's a great price (the 3.90 gear set from Mopar is listed @ $600 and they don't even have a 4.11 ratio). Be sure that you figure in the price of installation, because setting up the rear axle and gears is complicated stuff to be tackling in the garage at night. Personally, I'd have a shop do it.
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bernd
*GenIII*
11/13/2001
12:29:46
| RE: Rear end ratio - 3.92 or 4.11?
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3.90 is more than plenty for the daily driver (3.92:1 is the factory ratio on the R/T's as well).
You can run 4.10's (I do) but you'll be running about 200-300rpm's higher at the same speed as with the 3.90'1. I've already gone from 3.55 (factory) to 3.90 and then to 4.10's (current).
1997 Dodge Dakota SLT - V6
Supercharged/Intercooled @ 10# w/Nitrous
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Dakaty
Dodge Dakota
11/13/2001
15:58:16
| RE: Rear end ratio - 3.92 or 4.11?
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Bernd
Do you think the 3.90s (3.92s) are well suited for the heavier QC? I had another mechanic (also has a race car) tell me I should go with the 411s. He said the mileage decrease would not be that drastic, but the performance increase would.
It sounds like you weren't satisfied with the 3.90s.
Thanks for the input..
Bill
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Pyhton97
Dodge Dakota
11/13/2001
16:08:27
| RE: Rear end ratio - 3.92 or 4.11?
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Can someone explain the difference between gears and the affects from them.
Thanks
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bernd
*GenIII*
11/13/2001
16:41:14
| RE: Rear end ratio - 3.92 or 4.11?
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Bill, the 3.90's are more than adequate even for the QC. I only switched out to the 4.10's to get the effective ratio back to something more normal on the street. (This was when I was still running the 32" BFG's.)
With the 4.10's in the truck...and with 255/50-17's, i'm strongly leaning towards the 3.90's again.
1997 Dodge Dakota SLT - V6
Supercharged/Intercooled @ 10# w/Nitrous
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Horbedarn
*GenIII*
11/13/2001
21:13:41
| RE: Rear end ratio - 3.92 or 4.11?
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I have 31" tires so 4.11 would be the best probably. It depends on what tire size you have. The smaller the tire the less of a change in gear you would need to do.
2000, CC, SLT, 4x4, 4.7, 3.55, Auto
Borla Cat-Back, JBA Headers, 72mm TB, 4" Z-Tube
3923's, 180 T-Stat, IAT Adjuster
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Dakaty
Dodge Dakota
11/14/2001
10:11:24
| RE: Rear end ratio - 3.92 or 4.11?
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I'm concerned that there will not be a noticeable performance gain between the 355s and the 392s. It looks like I may have to spend close to $700. For that much money, I want to be sure to notice the difference.
I'm running the 16" upgraded Dodge wheels.
Thanks for all the info.
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bernd
*GenIII*
11/14/2001
13:26:15
| RE: Rear end ratio - 3.92 or 4.11?
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There is a noticeable difference between the 3.55 and 3.90 gear ratios.
Normally, $500 for Ring & Pinion and Labor is the average cost. This should also include a 12mo/12K mile warranty from the shop.
1997 Dodge Dakota SLT - V6
Supercharged/Intercooled @ 10# w/Nitrous
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Tom Rogers
Dodge Dakota
JOIN HERE
8/20/2002
13:44:55
| RE: Rear end ratio - 3.92 or 4.11?
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I have a 5.2 liter dodge 98 dakota. I have 275/75/17inch times on it. I have the performance chip/k and n ram air shaker hood installed. What rear gear could I change it to that would be best for this configuration and why? 4.56? Is there a web page dedicated to this type of stuff I could research?
Thanks much
Tom
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POWER HUNGRY
Dodge Dakota
JOIN HERE
8/20/2002
20:28:39
| RE: Rear end ratio - 3.92 or 4.11?
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Web sites that have formulas for gearing,tire size calculations,and rpm at 60 mph:
(www.reiderracing.com) in the tech section
(www.ring-pinion.com)
And my favorite is RAY HALL TURBOCHARGING AT(www.turbofast.com)They have calculators for finding:
a turbo charged engines horsepower
an engines compression ratio or combustion chamber's volume
an engines C.R. under boost
a suitable turbo for an engine
a suitable turbo based on turbo compressor maps
what et, mph, weight or hp for drag racing
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tim
Dodge Dakota
JOIN HERE
8/20/2002
21:52:53
| RE: Rear end ratio - 3.92 or 4.11?
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i ordered my 5.9qc with 3:92 gears and they are fine i dont think i would want any bigger my gas milage sucks bad enough and it is okay off the line
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Hersbird
Dodge Dakota
JOIN HERE
8/21/2002
21:29:55
| RE: Rear end ratio - 3.92 or 4.11?
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Keep in mind R/Ts have 28" tires and the 3.92's if you have 31" tall tires then someting like 4.30's would give the overall equivilant ratio as a stock R/T. Now the Durango R/T owners who go to 4.56 gears notice a huge improvement in acceleration and sometimes an increase in mileage. It helps mileage around town and in hills and mountains, and hurts on those long flat freeways. Lots of Dakota R/T owners have went with 4.56's and really liked them. I am considering 4.56s as one of my first mods, but I seldom spend much time on the highway. Just for a comparison to the muscle car days. If you have 4.56 gears and 28" tall tires on a R/T you will be turning the same RPM at highway speeds as a Cuda with 26 inch tall tires and a 2.90 rear gear because of it's shorter tires and no overdrive (actually it would be even less on the R/T when the converter locks up.) 4.56 seems insane for highway use but with the taller truck tires and overdrive it's really no big deal.
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cb
Dodge Dakota
JOIN HERE
8/21/2002
23:09:23
| RE: Rear end ratio - 3.92 or 4.11?
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I went for 3.55 to 4.10 on my 4.7 cc auto, and actually increased my mpg by about 1~2 around town and about the same on the highway. And that is with a very heavy foot; or is that thing on the floor an on/off switch?
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conig
Dodge Dakota
JOIN HERE
8/22/2002
11:16:34
| RE: Rear end ratio - 3.92 or 4.11?
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cb what size tires do you have?
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