Why not larger than 3.06 for the low range?

[SaudiBronco]

When we look at the amazing crawl ratio of nearly 95:1 found on the Badlands (w/ manual), we understand that it mainly comes from the high ratio of its crawler gear (6.6) and the large axel ratio which is (4.7). However, the automatic transmission which doesn't have a crawler gear relies on its 1st gear that has ratio of (4.7). It produces a crawl ratio of 68:1 and that is less than what the Rubicon offers which is 77:1. The reason why the automatic Rubicon has higher crawl ratio is due to its larger low range ratio which is (4.0) compare to Bronco's (3.06). Below explains how the crawl ratios were calculated:

Bronco Badlands (Manual) = Crawler Gear (6.6) x Axel Ratio (4.7) x Low Range Ratio (3.06) = 95
Wrangler Rubicon (Manual)= First Gear (5.13) x Axel Ratio (4.1) x Low Range Ratio (4.0) = 84
Bronco Badlands (Auto) = First Gear (4.71) x Axel Ratio (4.7) x Low Range Ratio (3.06) = 68
Wrangler Rubicon (Auto) = First Gear (4.71) x Axel Ratio (4.1) x Low Range Ratio (4.0) = 77

I was wondering to know why Ford didn't use a larger ratio for the low range of the transfer case. That might not help much the manual transmission because it already has an amazing crawl ratio, but it would help the automatic Broncos. If a 4.0 ratio is used, the crawl ratio would be 88 instead of 68 which is higher than 77 of the Rubicon's!

Any thought?

Sponsored

 

[Stampede.Offroad]

I would have loved to see a super low gear in the auto that was only accessible by purposeful selection.

It is an unlikely development though, as I'm sure Ford would prefer to use the same part for multiple vehicles and just keep using what already exists. Not that a Ranger or F150 couldn't benefit from an auto option targeted at the off road or heavy load markets.

 

[irv0735]

While I understand your point, note that the 95 is not achieved with the Sasquatch package. The Manual transmission is not available with Sasquatch.

I believe the 95 is with Badlands+manual.

That said, a higher ratio for low could have helped, but I suspect they found it wasn't needed for the automatic variants and as you pointed out, achieved their goal with the crawl gear on manual.

 

[Gamecock]

When we look at the amazing crawl ratio of nearly 95:1 found on the Badlands (equipped with Sasquatch and manual), we understand that it mainly comes from the high ratio of its crawler gear (6.6) and the large axel ratio of Sasquatch which is (4.7). However, the automatic transmission which doesn't have a crawler gear relies on its 1st gear that has ratio of (4.7). It produces a crawl ratio of 68:1 and that is less than what the Rubicon offers which is 77:1. The reason why the automatic Rubicon has higher crawl ratio is due to its larger low range ratio which is (4.0) compare to Bronco's (3.06). Below explains how the crawl ratios were calculated:

Bronco w/ Sasquatch (Manual) = Crawler Gear (6.6) x Axel Ratio (4.7) x Low Range Ratio (3.06) = 95
Wrangler Rubicon (Manual) = First Gear (5.13) x Axel Ratio (4.1) x Low Range Ratio (4.0) = 84
Bronco w/ Sasquatch (Auto) = First Gear (4.71) x Axel Ratio (4.7) x Low Range Ratio (3.06) = 68
Wrangler Rubicon (Auto) = First Gear (4.71) x Axel Ratio (4.1) x Low Range Ratio (4.0) = 77

I was wondering to know why Ford didn't use a larger ratio for the low range of the transfer case. That might not help much the manual transmission because it already has an amazing crawl ratio, but it would help the automatic Broncos. If a 4.0 ratio is used, the crawl ratio would be 88 instead of 68 which is higher than 77 of the Rubicon's!

Any thought?

The automatic doesn't need that super low calculated crawl ratio...because the effective crawl ratio with the torque converter will be better than the manual. You don't want it much higher than where it is with an auto, and there is tons of reading out there that explains it in detail.

 

[SaudiBronco]

While I understand your point, note that the 95 is not achieved with the Sasquatch package. The Manual transmission is not available with Sasquatch.

I believe the 95 is with Badlands+manual.

That said, a higher ratio for low could have helped, but I suspect they found it wasn't needed for the automatic variants and as you pointed out, achieved their goal with the crawl gear on manual.

Thanks for the info. Post edited.

 

[Stampede.Offroad]

The automatic doesn't need that super low calculated crawl ratio...becasue the effective crawl ratio with the torque converter will be better than the manual. You don't want it much higher than where it is with an auto, and there is tons of reading out there that explains it in detail.

Yes, the torque converter can be a hidden multiplier for auto. Usually an estimated factor around 1.5 to 2 IIRC.

 

[MEMessina72]

I currently have a 2010 Jk Rubicon with 4 speed auto (2.84:1 first gear). With 4.10:1 RP, 4:1 transfer case, and 35" tires... my crawl ratio was 45:1. I just regeared to 4.88:1 RP and it's now 55:1.

I did Slick Rock and Rubicon with 45:1 and had no real issues.

The 10 speed auto and 4.7 with 35" is giving you a 67:1 crawl ratio.... that's good in my eyes.

 

[Snacktime]

It's called pushing through the brakes. Rather have a doubler than lower low range.

 

[Felix808]

Yes, the torque converter can be a hidden multiplier for auto. Usually an estimated factor around 1.5 to 2 IIRC.

Absolutely, crawl ratio is not as detrimental to an auto as it is a stick, but I noticed most autos spend far more time on the brakes than a low geared stick.

That 67 almost 68 :1 will be nice. I had a Tera 4:1 giving me 63:1 which worked great down low but I always was worried about the planetary gears letting loose like a few in our club, as it had a 3000 rpm limit & I only felt safe up to 3rd gear so I was always switching from low to high, so I swapped it with an Atlas 5:1 ending up with 80:1 w/ twin sticks.That was awesome. Never got stuck switching between low & hi ran all 5 gears with no rpm limit & no surging like you get with a chain transfer case & never had to touch the brake.

The 10 speed auto should give great results of not having to keep switching in & out of low range while still giving a good low range. Definitely worth the upgrade to the Advanced 4x4 with Automatic On Demand Engagement transfer case as well, otherwise you will only have 2.72's instead of the 3.06's

Sponsored