Gear Ratio Chart for JL Wrangler?

TheDLG

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Do we have enough info to create gearing charts for at least the pentastar in the JL like they have for the JK?





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AZCrawl

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Do we have enough info to create gearing charts for at least the pentastar in the JL like they have for the JK?
Go here and plug in the JL numbers, it works.

http://www.grimmjeeper.com/gears.html

TRANSMISSION: 850RE AUTOMATIC, EIGHT-SPEED OVERDRIVE
  • Availability: Standard — 2.0-liter I-4; Optional — 3.6-liter V-6
  • Description: Adaptive electronic control or Electronic Range Select (ERS) driver-interactive manual control and electronically modulated torque converter clutch
  • Gear Ratios:
    • 1st - 4.71
    • 2nd - 3.13
    • 3rd - 2.10
    • 4th - 1.67
    • 5th - 1.28
    • 6th - 1.00
    • 7th - 0.84
    • 8th - 0.67
    • Reverse - 3.53
TRANSMISSION: D478 MANUAL, SIX-SPEED WITH OVERDRIVE
  • Availability: Standard — 3.6-liter V-6
  • Description: Synchronized in all forward gears and Reverse, multi-rail shift system with top-mounted shift lever
  • 50% shorter throws
  • Gear Ratios:
    • 1st - 5.13
    • 2nd - 2.63
    • 3rd - 1.53
    • 4th - 1.00
    • 5th - 0.81
    • 6th - 0.72
    • Reverse - 4.49
    • Final Drive ratio - 3.45 standard, 3.73 optional (4.10 Rubicon)
TRANSFER CASE: NV241 COMMAND-TRAC
  • Available: Standard on Sport and Sahara
  • Type: Part-time
  • Operating Modes: 2WD High; 4WD High; Neutral; 4WD Low
  • Low Range Ratio: 2.72:1
TRANSFER CASE: NV241OR ROCK-TRAC
  • Available: Standard on Rubicon
  • Type: Part-time
  • Operating Modes: 2WD High; 4WD High; Neutral; 4WD Low
  • Low Range Ratio: 4.0:1
TRANSFER CASE: MP3022 SELEC-TRAC
  • Available: Optional – Sahara
  • Type: Full-time
  • Operating Modes: 2WD High; 4WD High; Neutral; 4WD Low
  • Low Range Ratio: 2.72:1
AXLES
  • Front: Dana 30, Dana 44 on Rubicon models
    • Differential Type: Open (Dana 30) or Tru-Lok electronic locking (Dana 44)
    • Axle Ratios: 3.45, 3.73, 4.10
  • Rear: Dana 35, Dana 44 on Rubicon models
    • Differential Type: Open (Sport and Sahara) with available Trac-Lok anti-spin, Tru-Lok electronic locking (Rubicon)
    • Axle Ratios: 3.45, 3.73, 4.10
 

The Great Grape Ape

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Do we have enough info to create gearing charts for at least the pentastar in the JL like they have for the JK?
If you’re comparing the Gearing chart to something like this, it would be virtually the same as the engine is only ever so slightly tweaked in the low RPM not impacted, and the charts are calculated at 1:1 so 4th & 6th gear in the new manual & auto respecively versus 5th and 4th in the old MT/AT transmissions.
__________

F447B418-56DC-4D28-AE44-2B6F17FA960C.jpeg

____________

Remember that the 1st gear is improved on both new transmissions, so responsiveness and feel would be improved of the line and getting tires moving, but the system load at 1:1 @ speed (65 or 70 depending on which version) that the charts focus on wouldn’t really change, other than the stock 3.21 & 3.73 options have been replace with the single 3.45 axle, but comparing like for like ratios would be the same as would be the case for the 4.10

Doing a Manual calculation like AZ posted would be more representative of expectations for specific setups, and give you ideas of how it would act outside of cruising.
 

The Lone Jeeper

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Well, only 3.53 on reverse for the automatic transmission (compared to 4.49 for the manual transmission). Does anyone know if they made it on purpose? Or isn't that a flaw or something?

On my side, I have a JK (tire size 34) and I regeared last year (4.56). But I have no idea how to calculate the gear ratio on reverse now. There only thing I'm sure : it's powerful as hell when I'm pulling a buddy on reverse.
 

The Great Grape Ape

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Well, only 3.53 on reverse for the automatic transmission (compared to 4.49 for the manual transmission). Does anyone know if they made it on purpose? Or isn't that a flaw or something?
No flaw, just like 1st gear it’s simply an optional choice from the mfr. and the previous MT / AT NSG370 / NAG1 were similarly disproportionate @ 4.06 & 3.16 respectively. Definitely noticeable in the JK too.

Also, if you were going to pick which was numerically superior, I would say that you wouldn’t want the MT, simply because the MT driver usually would be more into total command of the situation, and thus less likely to be surprised by torquey jump into reverse, not that auto pilots can’t be equallly diligent.

Oddly enough the ZF manuals have different reverse ratios listed, and that 3.53 seems noticeably higher than the other options in their literature (3.30 for Gen1 , 3.456 for Gen2), however considering the lower ratio first gear @ 4.71 instead of Gen2’s typical 5.00 is also an oddity for a 2nd Gen ZF8 , so maybe that’s to be expected.
 

AZCrawl

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I’ve screwed up too many cars on Gran Turismo to even think about messing with gears in the real world. Sounds like you guys know your stuff but this thread is miles above my head!
Basically, with the new transmission, if you go up a tire size, you probably shouldn't need to re-gear, if you go up two sizes, jump 2 gear sizes. On a Rubicon, this means, going from 33's to 37's, you should go from 4.10's to 4.56's to maintain the same RPM band as stock.
 

Jeepsterfreak

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Go here and plug in the JL numbers, it works.

http://www.grimmjeeper.com/gears.html

TRANSMISSION: 850RE AUTOMATIC, EIGHT-SPEED OVERDRIVE
  • Availability: Standard — 2.0-liter I-4; Optional — 3.6-liter V-6
  • Description: Adaptive electronic control or Electronic Range Select (ERS) driver-interactive manual control and electronically modulated torque converter clutch
  • Gear Ratios:
    • 1st - 4.71
    • 2nd - 3.13
    • 3rd - 2.10
    • 4th - 1.67
    • 5th - 1.28
    • 6th - 1.00
    • 7th - 0.84
    • 8th - 0.67
    • Reverse - 3.53
TRANSMISSION: D478 MANUAL, SIX-SPEED WITH OVERDRIVE
  • Availability: Standard — 3.6-liter V-6
  • Description: Synchronized in all forward gears and Reverse, multi-rail shift system with top-mounted shift lever
  • 50% shorter throws
  • Gear Ratios:
    • 1st - 5.13
    • 2nd - 2.63
    • 3rd - 1.53
    • 4th - 1.00
    • 5th - 0.81
    • 6th - 0.72
    • Reverse - 4.49
    • Final Drive ratio - 3.45 standard, 3.73 optional (4.10 Rubicon)
TRANSFER CASE: NV241 COMMAND-TRAC
  • Available: Standard on Sport and Sahara
  • Type: Part-time
  • Operating Modes: 2WD High; 4WD High; Neutral; 4WD Low
  • Low Range Ratio: 2.72:1
TRANSFER CASE: NV241OR ROCK-TRAC
  • Available: Standard on Rubicon
  • Type: Part-time
  • Operating Modes: 2WD High; 4WD High; Neutral; 4WD Low
  • Low Range Ratio: 4.0:1
TRANSFER CASE: MP3022 SELEC-TRAC
  • Available: Optional – Sahara
  • Type: Full-time
  • Operating Modes: 2WD High; 4WD High; Neutral; 4WD Low
  • Low Range Ratio: 2.72:1
AXLES
  • Front: Dana 30, Dana 44 on Rubicon models
    • Differential Type: Open (Dana 30) or Tru-Lok electronic locking (Dana 44)
    • Axle Ratios: 3.45, 3.73, 4.10
  • Rear: Dana 35, Dana 44 on Rubicon models
    • Differential Type: Open (Sport and Sahara) with available Trac-Lok anti-spin, Tru-Lok electronic locking (Rubicon)
    • Axle Ratios: 3.45, 3.73, 4.10
Great info!

The 3.73 is no longer a factory option. Sport/Sahara get 3.45 and Rubi gets 4.10 for both 6MT/8AT.

Would the 3.45 be numerically equivalent to the JK 3.73 with the new JL 8AT since you have 5 gears before hitting 6th 1:1 ratio?
 
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AZCrawl

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Great info!

The 3.73 is no longer a factory option. Sport/Sahara get 3.45 and Rubi gets 4.10 for both 6MT/8AT.

Would the 3.45 be numerically equivalent to the JK 3.73 with the new JL 8AT since you have 5 gears before hitting 6th 1:1 ratio?
I don't know, you can plug in the numbers on the site and find out though.
 

That One Guy

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If you’re comparing the Gearing chart to something like this, it would be virtually the same as the engine is only ever so slightly tweaked in the low RPM not impacted, and the charts are calculated at 1:1 so 4th & 6th gear in the new manual & auto respecively versus 5th and 4th in the old MT/AT transmissions.
So this M/T is double overdrive, with 4th at 1:1 and 5th and 6th as overdrives. Same as my honda. Are you saying that the old 6 speed was not double overdrive? 5th was 1:1 in the mercedes unit? That would make this new transmission seem significantly taller geared than the outgoing one.
 

That One Guy

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If you’re comparing the Gearing chart to something like this, it would be virtually the same as the engine is only ever so slightly tweaked in the low RPM not impacted, and the charts are calculated at 1:1 so 4th & 6th gear in the new manual & auto respecively versus 5th and 4th in the old MT/AT transmissions.
So this M/T is double overdrive, with 4th at 1:1 and 5th and 6th as overdrives. Same as my honda. Are you saying that the old 6 speed was not double overdrive? 5th was 1:1 in the mercedes unit? That would make this new transmission seem significantly taller geared than the outgoing one.
 

The Great Grape Ape

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Would the 3.45 be numerically equivalent to the JK 3.73 with the new JL 8AT since you have 5 gears before hitting 6th 1:1 ratio?
First gear yes, others no, and the combination for overdrive favours the 8AT+3.45 by 15% over the 3.21 axles, and by 33% over the 3.73.

First gear MT improvement to JL would make the 3.45 axle similar to the final drive of an equivalent 3.92 axle (not an option, just a #) , for the 8AT the improvement would be equivalent to a 4.53 axle, so yes, both end up being superior to the 3.73 in first gear, however, that numerical advantage quickly decays as you pass through 2nd.
 

The Great Grape Ape

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So this M/T is double overdrive, with 4th at 1:1 and 5th and 6th as overdrives. Same as my honda. Are you saying that the old 6 speed was not double overdrive? 5th was 1:1 in the mercedes unit? That would make this new transmission seem significantly taller geared than the outgoing one.
Yes, the new MT and AT both have two OD gears, whereas in the JK the 6spd NSG370 MT was 1:1 in 5th, and the 5spd NAG1 AT was 1:1 in 4th, so just 1 OD each.

Technically it’s not ‘just’ taller overall, more importantly it’s a significantly wider spread, bother shorter 1st and taller top OD.

However the 8HP/AT has the same top OD ratio as the prior 545RFE AT transmission in pre-2011 export Wranglers, and nearly the same as the old N.Am. 42RLE 4-speed AT too.

Unfortunately we didn’t get the typical 2nd Gen ZF8 5.00-0.64 spread, but instead got 4.71-0.67.

Not sure if that was due to the power band of the turbo or not, but the Pentastar would seem to better fit the 5.0-0.64 at the converter.
 
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That One Guy

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Yes, the new MT and AT both have two OD gears, whereas in the JK the 6spd NSG370 MT was 1:1 in 5th, and the 5spd NAG1 AT was 1:1 in 4th, so just 1 OD each.
The gears felt tall even in the 4:10 axle ratio JLUR I test drove. With the 3:44ish ratios in the Sport, I might not be using 6th gear very much.
 

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