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Unread 07-23-2010, 01:15 PM   #16
Unlimited04
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Quote:
Originally Posted by TheBoogieman View Post
You like to give your opinion on big tires and gears when you've never seen anything above a 31.
and your Jeep has never seen anything but a paved road or driveway, yet you give your opinion on bumpstop length and whether a lift will fit certain tires, without ever checking clearances properly.

btw, these aren't 31s.

but I couldn't stand using 2nd and 3rd gear and 4000rpms trying to maintain speed above 45mph on country roads and Denver highways, not even venturing into the mountains - Story.

Quote:
Originally Posted by TheBoogieman View Post
I forgot you and your mom bought lemons and complain constantly instead of just dumping the LJ for an 02' auto TJ.It depends a lot on where you live.
I didn't have a choice in the matter...Jeep figured noone needed a NV3550 LJ in 2004 . I told my mom to buy a 6-speed...she wanted an auto...women.

Quote:
Originally Posted by TheBoogieman View Post
In Florida,3.07's and 35's might be fine.
I don't think 3.07s and 35s is acceptable anywhere.

Quote:
Originally Posted by TheBoogieman View Post
I never used OD with any vehicle I've ever had.
this aint the 1950s man, the gear is there for a reason. not using it is like wearing an eyepatch just to look cool, even tho you seen 20/20....then wonder why you trip over steps.

Quote:
Originally Posted by TheBoogieman View Post
My 03' could easily pull any hill here in va on the highway at 75mph(without OD).
you've just confirmed it, you're loosing an entire gear.

Quote:
Originally Posted by TheBoogieman View Post
Od was for flat trips to Richmond and 20 mpg.
try westbound I-80 in Nebraska, its REALLY flat. see if you can hold 80mph (the speed limit), in OD and get 20mpg in OD.

Quote:
Originally Posted by TheBoogieman View Post
My 5 speed 98' got 20 mpg and my bro's 05',6 speed on 35's gets 20 mpg highway.
again, completely different gearing. like I've said before 35s, 3.73s + NSG370 = 30s, 3.73s + 42RLE.

Quote:
Originally Posted by TheBoogieman View Post
Numbers don't lie.
You're absolutely right.

This is a stock 4.0L torque curve vs a stroker. Don't mind the stroker for this discussion, notice the 4.0L's torque curve is nice and flat between 2000-3000 rpms, with a gentle increase to its rated spec of 235 ft-lbs @ 4000rpms....after that it drops off. According to Jeep's literature, 85%+ of the torque is available off idle in that 2000-3000rpm range. when someone talks about being in the powerband - thats what they mean.


from: 2000 Jeep Wrangler Chart Photo 14
^^they're a little overzealous with the dyno correction numbers (shows 250 ft-lbs stock at 4k).

Now, as you said the numbers never lie.

Stock Ratios:
Sport-
42RLE, 3.73s, 30" tires = 2000 rpm @ 70mph.
NSG370, 3.73s, 30" tires = 2450 rpm @ 70mph.

Rubicon-
42RLE, 4.11s, 31" tires = 2150 rpm @ 70mph.
NSG370, 4.11s, 31" tires = 2600 rpm @ 70mph.

A difference of ~450 rpm's in each case with same size tires and axle ratio. Thats almost an entire gear.

33" Tires w/ Stock Overdrive Ratios @ 70mph:
Stock Sport Ratios-
42RLE, 3.73s = 1800 rpm
NSG370, 3.73s = 2200 rpm

Rubicon Ratios-
42RLE, 4.10s = 2000 rpm
NSG370, 4.10s = 2450 rpm

35" Tires w/ Stock Ratios @ 70mph:
Stock Sport Ratios-
42RLE, 3.73s = 1700 rpm
NSG370, 3.73s = 2100 rpm

Rubicon Ratios-
42RLE, 4.10s = 1900 rpm
NSG370, 4.10s = 2300 rpm

Ok, so now look and see which transmission is operating in the power band on the highway at 70mph. You can verify all those numbers from this gear ratio calculator.

Well obviously the 42RLE is pretty much out of the powerband all the time, even in stock configuration (hence the engine lugging complaints). So how can we fix that?

Well Boogie, we can do like you do and not use OD at all:
42RLE, 35s, 3.73s, 3rd gear = 2500 rpms.

But a Rubcion with the 6-speed turns 2300 rpm in 6th. So you've effectively just lost an entire gear. So what you say? Well you just lost that gear on the low end too, meaning now the Jeep can't go slow enough at idle when you want it to....whether that be low range or high range.

Or we can regear, and put the engine back in the powerband, and gain the OD back:

42RLE, 4.88s, 33s = 2250 rpm.
42RLE, 5.38, 35s = 2500 rpm.

Now remember above, how the stock 6-speed Rubicon turns 2600 rpm in OD 70mph? How do we get that in a stock 42RLE? You'd need 4.88s with those 31s.

So how do we get 2500-2600 rpm for turning 35s with both trannies?
42RLE = 5.38s gets you 2500 rpm.
NSG370 = 4.56 gets you 2600 rpm.

The point I'm making is the manual and auto are completely different beasts, and you need almost a full point deeper gear in the 03+ auto to get into the "powerband". As for my Jeep on 31s - I'm running at 2000rpms @ 70mph...lower than I'd like. With 33s, it was 1800 rpms...absolutely worthless. In 3rd with 33s, it was 2650 rpms...basically the same as the stock Rubicon 6-speed. I effectively lost an entire gear. Come follow me. You'll be begging for a regear for those 35s, or a set of 30s for those 3.73s.

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Unread 07-23-2010, 01:45 PM   #17
bowserw
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Thanks for all the info. After all of this I'm no longer leaning towards the 4.10s, now I'm completely on the fence... ugh, i need to mull things over.
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Unread 07-23-2010, 01:59 PM   #18
Rafikie
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Hey here is another thought...don't waste any money on that axle setup and call Currie instead
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Unread 07-24-2010, 12:33 AM   #19
-sean-
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Great post Mike. All fact.

I'll be plagiarizing that post when this same topic pops up again, that's at least once a week here on JF.
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Unread 07-24-2010, 03:43 PM   #20
AustinTexasXJ
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damn... now I need 4.56 or 4.88's..


stupid *** 3.07s
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Unread 07-24-2010, 05:54 PM   #21
jspb16
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i have 33s with 4.10 and my buddy has 35 with ruby stock gearing and he has destroyed his manual transmission for some reason...
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Unread 09-22-2011, 01:50 AM   #22
starfan_9
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Quote:
The point I'm making is the manual and auto are completely different beasts, and you need almost a full point deeper gear in the 03+ auto to get into the "powerband". As for my Jeep on 31s - I'm running at 2000rpms @ 70mph...lower than I'd like. With 33s, it was 1800 rpms...absolutely worthless. In 3rd with 33s, it was 2650 rpms...basically the same as the stock Rubicon 6-speed. I effectively lost an entire gear. Come follow me. You'll be begging for a regear for those 35s, or a set of 30s for those 3.73s.
Thanks for all this info, took me a while to find this thread
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Unread 09-22-2011, 04:41 AM   #23
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A better question is the d35 problem. You are already regearing, you might as well solve that issue at the same time.
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Unread 09-22-2011, 05:55 AM   #24
Rockram1
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try westbound I-80 in Nebraska, its REALLY flat. see if you can hold 80mph (the speed limit), in OD and get 20mpg in OD.

When did they raise the speed limit in Ne.to 80? I've been driving across Ne. for 20 years. In fact I'll be crosssing in the morning and I've never seen an 80 mph speed limit sign. I have however seen a few in Utah on I 15 and a few in west Texas. Since your touting facts you might want to get them right.
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