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-   -   3.21s with 6-spd (http://www.wranglerforum.com/f202/3-21s-with-6-spd-96164.html)

razor2006 05-31-2011 08:10 PM

3.21s with 6-spd
 
I've been heavily contemplating buying a 2-door JK. I definitely want a manual. That being said, I live in south-western Pennsylvania. It's fairly hilly terrain here. I'm curious if I'd do better with the 3.21s or 3.73s. I was looking at getting just a basic Sport JK and probably running the stock 225/75R16s (maybe I'd run 235s but that'd probably be about it.)

I do a fair mix of highway and short runs. More short runs than highway, but I'd say its probably about 65/35. I'm wondering which gearing would give me the best gas mileage

I searched for 3.21 and ran through a couple of pages, but didn't have much luck finding an answer for my question. I did see this chart though: http://www.wranglerforum.com/attachm...5&d=1302645832

I don't really know the 3.8L so I'm not sure where the powerband runs and what the most efficient RPMs are. I have a 5.3L powered GM truck right now, and I do best right around 2000 RPMs with it at 70mph.

Then again this question might be completely null and void because by the time I have my truck paid off, and trade it in, I'll probably be getting a '12 with the Pentastar motor, but for the sake of curiosity, I figured I'd post this anyway.

ToddMc 05-31-2011 08:20 PM

all i can say is from my experiance i have mine with a 4 inch lift and 37s and I changed gears to 5:13s i love it it runs about 2800 doing 70 mph on highway but I did loose some mileage

rics1997 05-31-2011 08:34 PM

You may regret 3.21's in the future while you won't 3.73. You just don't get the mod fever until you own one and it is pretty cheap just to buy the take off's of stock 17's with 255/75/17. I said when I got mine that the 255's were big enough. Then when I got muds I thought well a little bigger want hurt with 285/70/17. Now after getting the off road bug 33's are next. You just don't know and having the 3.73 is insurance.

Get the 3.73 option even if you have to get the tow package to get it.

JIMBOX 05-31-2011 08:36 PM

:whistling:-

http://www.wranglerforum.com/f33/re-...ons-92903.html

:dance::rofl: JIMBO

razor2006 05-31-2011 09:10 PM

Quote:

Originally Posted by JIMBOX (Post 1272565)

I don't see how this pertains in any way to the question I asked (aside from the chart that I already referenced)...

Anyway, allow me to reiterate for JIMBOX, I don't *plan* on running anything larger than a ~29.5" (P225/75R16) or ~30" (P235/75R16) tire. I'm sick of paying $600+ for tires for my truck. When I had my XJ I paid $400 for P235/75R15s and I was happy. That being said, driving around a fairly hilly area, consisting of mostly 10-15 mile trips with some highway driving at times, 3.21s or 3.73s for the best MPG?

My truck has 3.73s in it now, so I was kind of leaning toward that for a JK, but they're two entirely different animals, hence my curiosity.


Note: *plan*s change, but I won't be doing any lifting or offroading with it until after it's paid off.

JIMBOX 05-31-2011 09:13 PM

:whistling: Please forgive me for giving you ANY INFO--


Quote:

Originally Posted by razor2006 (Post 1272643)
I don't see how this pertains in any way to the question I asked (aside from the chart that I already referenced)...

Anyway, allow me to reiterate for JIMBOX, I don't *plan* on running anything larger than a ~29.5" (P225/75R16) or ~30" (P235/75R16) tire. I'm sick of paying $600+ for tires for my truck. When I had my XJ I paid $400 for P235/75R15s and I was happy. That being said, driving around a fairly hilly area, consisting of mostly 10-15 mile trips with some highway driving at times, 3.21s or 3.73s for the best MPG?

My truck has 3.73s in it now, so I was kind of leaning toward that for a JK, but they're two entirely different animals, hence my curiosity.


Note: *plan*s change, but I won't be doing any lifting or offroading with it until after it's paid off.

You won't have to worry about any data ever--from me !!

:nonono::nonono: JIMBO

rics1997 05-31-2011 09:22 PM

I think one point of the thread posted was that by going to larger numbered gears the thread points out that most actually got better gas mileage and more power going to said gears then with the higher gears that came stock in a Jeep they had with the same size tires. The JK has a very steep HP curve. The lower the gears not only makes more hp at a certain speed it also doesn't seem to hurt gas mile in doing so. And for the most part seems to increase gas mileage at the optimal speeds of 45-60 mph. The above thread goes into that in detail.

razor2006 05-31-2011 09:41 PM

Gotcha. I wasn't trying to turn you away or make you angry JIMBO, I know you're a big contributor here because I've seen your extremely helpful input on many threads. I do appreciate your advice, I just didn't clearly see the correlation between my question and that thread.

I suppose all in all I was looking for more of a direct answer. Sorry for coming off as brash and ignorant. My apologies.

JIMBOX 05-31-2011 09:58 PM

:) Thanx for the comeback--everythings copasetic !!


Quote:

Originally Posted by razor2006 (Post 1272713)
Gotcha. I wasn't trying to turn you away or make you angry JIMBO, I know you're a big contributor here because I've seen your extremely helpful input on many threads. I do appreciate your advice, I just didn't clearly see the correlation between my question and that thread.

I suppose all in all I was looking for more of a direct answer. Sorry for coming off as brash and ignorant. My apologies.

I guess my main purpose for that thread, was to tell you that There is no way anyone can live with a set of 3.21 gears in a jeep-3.73s are on the bottom of the barrell-4.10s are a squeekby, untill you get to 4.88/5.13 and 5.38s the jeep doesn't "WAKE" up, especially if you have an auto and/or tow--

Just keep your eyes open-I don't know what the hell Chrysler was thinkin when they used 3.21, (CAFE) probably--

Good luck

:rofl: JIMBO

razor2006 05-31-2011 10:53 PM

10-4. 3.73s it is. When I eventually do lift and go with bigger tires (come on, let's get real, I say now I don't plan on going bigger than factory, we all know that's not going to stick hehe), I'll be regearing. But until then 3.73s will probably do the trick :)

I'm too cheap to buy a Rubi so 4.10s aren't an option. I'm going to try and get my JK for $20k (tax, title, transfer, out the door). Whether or not that happens, heh, I guess we'll find out.

I'm looking at getting a standard Sport with the Freedom Top, A/C, Sirius, 3.73s, and the Smokers Group, which according to the neat little Jeep Builder on the Jeep website they claim $24,750 MSRP. I'm assuming the actual cost at the dealership might be a bit lower. My truck's trade-in blue book is $5500 as it sits right now, so I'm hoping by next summer when it's paid off and I go to trade it in it will be worth enough to offset the cost and get me to $20,000.

I've never bought a NEW vehicle, so I might just be chasing a hope and a dream here, but hopefully not.

JIMBOX 05-31-2011 11:09 PM

:D Heh Heh, if you're getting a 2012, you're probably gonna be like an explorer--the first of the group-so


Quote:

Originally Posted by razor2006 (Post 1272891)
10-4. 3.73s it is. When I eventually do lift and go with bigger tires (come on, let's get real, I say now I don't plan on going bigger than factory, we all know that's not going to stick hehe), I'll be regearing. But until then 3.73s will probably do the trick :)

I'm too cheap to buy a Rubi so 4.10s aren't an option. I'm going to try and get my JK for $20k (tax, title, transfer, out the door). Whether or not that happens, heh, I guess we'll find out.

I'm looking at getting a standard Sport with the Freedom Top, A/C, Sirius, 3.73s, and the Smokers Group, which according to the neat little Jeep Builder on the Jeep website they claim $24,750 MSRP. I'm assuming the actual cost at the dealership might be a bit lower. My truck's trade-in blue book is $5500 as it sits right now, so I'm hoping by next summer when it's paid off and I go to trade it in it will be worth enough to offset the cost and get me to $20,000.

I've never bought a NEW vehicle, so I might just be chasing a hope and a dream here, but hopefully not.

You're liable to find new incentives/rebates/bonus's--who knows, but

GOOD LUCK--

Let us know what happens !!

:dance::rofl: JIMBO

SeaComms 06-01-2011 08:48 AM

Razor, the stock tyres are 31.5in / 32in (245/75 17's or 255/75 17's) not 29.5. If you go down in size to 29.5 then the 3.21 gears would be fine. However, not many 16in rims will fit over the new larger front discs, at least over the 13in front discs we get down here anyways.

With the stock 31.5's the 3.21 diff is too tall (1750 rpm at 100km/hr / 60mph) and I am annoyed I got stuck with them. If you hold off til the 2012 I have heard that Chrysler have learnt and will be fitting 3.73's as the tallest gears again in any variation.

EDIT: Just looked at the US Jeep site - you guys do still get the 225/75 16's.. apologies! They omitted that version down here and our stock Sport has the 17in alloys with the 245/75's. I think the 3.21 diffs would be fine on them, but I would still recommend the 3.73 anyways.


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