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05:49:30 - 05/19/2024
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Airborne
Dodge Dakota
10/16/2001
00:49:56
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 Subject: Rear diff. question.
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Message:
O.k O.k, here I go asking the questions that I seem not to be able to find the answer to. As far as rear gear ratio's go, what is the difference? I know the basics about them, but for example, my Dak came with 31x10.50 15's and I just found out the rear gears are "3.55's", and I just upgraded my tires to 32x11.50 15's. I know the speedo is going to be off and all that, but the question is as far as the gearing goes, will the gears be somewhat compatiable to push the truck or will I be looking into getting a new rear end and all that jazz?
I know about the drive shaft spin in relation to the rear wheel spin, but I think I am too tired to try to figure it out tonight, so I hope when I go to bed, I will wake and all the little "Dakota elves" will enlighten me as to what I need to do, if anything.
Thanks in advance and hope some others get enlightened from these responses, also.
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TallQuad
Dodge Dakota
10/16/2001
02:38:46
|  RE: Rear diff. question.
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Message:
If I had a scanner I would post a chart up about gear ratios and what size tire will work best with what size gear. But for your purpose Airborne, you should be just fine with your current 3.55's. If you can imagine, I acutally ran 33's with a 3.07 rearend on my jeep for over a 2 years!! I don't encourage that, but I still had enough power. 4.10's or 4.56 would have been ideal.
As for the Dakota, I figured out that 3.92's with 33 inch tires are pretty close (ratio wise) as the stock tires with 3.55's. So 32's put you near the middle, which is fine with a V8. Even if you went with 33's it will still work (meaning it won't hurt anything). I have 3.92's, so what do the fellas with 3.55's say about it (w/32's or 33's)?
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albert
Dodge Dakota
10/16/2001
05:21:21
|  RE: Rear diff. question.
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Message:
This is the formula to figure out your new gear ratio.
old tire diameter/new tire diameter x original
ratio
This should come out to about 3.44, but you have to remember to actually measure the tires yourself because most of the time they aren't exactly 31" or 32". You shouldn't need to replace your gears unless you go to anything above a 33".
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Hawkeye
*GenIII*
10/16/2001
09:44:49
| RE: Rear diff. question.
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Message:
33's and 3.55's here. I have ran this combo on every truck I have had. I cant smoke the tires like I could with the stock ones but they still do ok. I have planned on going to 3.92 gears since I got the truck. Now that I have the 33's I will definitely go with them. Would go with 4.10's but the 3.90/92's are all that available for 2000 and up Daks right now. Only reason I am changing is to give me a little better towing as I did loose a little there. The 3.90's will put me back around where I was with the 32's and 3.55's, maybe a little better. Dont go by the charts that you see published as to the best gear and tire setup 100%, as they dont take into account the differences in tranny gears among brands. Two diff brand trucks may both have 3.55 gears and 32 inch tires but at 65mph in 4th gear on an automatic tranny, they may not be turning the same rpms if that 4th gear is diff between the 2. You have to go by what your truck has as far as the individual gears in the tranny, your ring and pinion, and tire size to get your final drive ration. Hope this hasnt completely confused you.
'00 QC 4x4
4.7 3.55 LSD
33x12.50 Pro Comp X-T's
http://johnammons.tripod.com/home.html
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