Reverse rotation transfer case - JeepForum.com

 
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post #1 of 3 Old 08-09-2009, 06:24 PM Thread Starter
kfson
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Reverse rotation transfer case

Anyone hear anything about this (flipped axle association)?

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post #2 of 3 Old 08-09-2009, 06:40 PM
5-90
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Quote:
Originally Posted by kfson View Post
Anyone hear anything about this (flipped axle association)?
"Reverse rotation," as it is generally used, is really bogon emissions.

It came from the "Reverse Spiral" gearsets, which means that the spiral cut that makes the R&P a hypoid gearset is reversed for the front axle. This has two advantages:
1) It allows for a high pinion (pinion axis above centreline of axle)
2) It allows the front end gears to be driven on the stronger "drive" side, vice the weaker "coast" side.

Whichever direction the spiral goes, the gearset has to turn in the same direction. Having a RS-cut gearset means the front axle is a high-pinion, while having a standard-cut gearset in the front axle means it's a low-pinion.

Conversely, a RS/HP gearset must be replaced with another RS/HP gearset, using a LP gearset is just plain "unpossible." The teeth will not mesh.

The direction of the spiral in the gearset does not matter a whit to the transfer case - as it's going to turn the front output shaft in the same direction either way. Period. It just has to, when you think about it (if you spin the front output shaft in the opposite direction, you won't get anywhere. The front and rear axles will work against each other.)

Similarly, you can not flip an axle housing over to make a rear housing a front axle, or vice versa. Oiling passages are cast into the axle housing - if you flip it over, it won't oil properly and you will wreck bearings in very short order (axle bearings are under incredible loads.)

The closest you can get to "reversing" a transfer case is using a "flip kit" to turn one over, and put the front output on the opposite side (common with the Dana 300, and possibly the Dana 20. Most newer cases have pump-circulated fluid, and won't tolerate being flipped.) This only works with a very limited number of transfer case models, and the kits are already well-developed for the market.

All clear? Or did I leave something out? I'd be happy to explain further, if it would help you.

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post #3 of 3 Old 08-11-2009, 08:41 AM Thread Starter
kfson
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Quote:
Originally Posted by 5-90 View Post
"Reverse rotation," as it is generally used, is really bogon emissions.

It came from the "Reverse Spiral" gearsets, which means that the spiral cut that makes the R&P a hypoid gearset is reversed for the front axle. This has two advantages:
1) It allows for a high pinion (pinion axis above centreline of axle)
2) It allows the front end gears to be driven on the stronger "drive" side, vice the weaker "coast" side.

Whichever direction the spiral goes, the gearset has to turn in the same direction. Having a RS-cut gearset means the front axle is a high-pinion, while having a standard-cut gearset in the front axle means it's a low-pinion.

Conversely, a RS/HP gearset must be replaced with another RS/HP gearset, using a LP gearset is just plain "unpossible." The teeth will not mesh.

The direction of the spiral in the gearset does not matter a whit to the transfer case - as it's going to turn the front output shaft in the same direction either way. Period. It just has to, when you think about it (if you spin the front output shaft in the opposite direction, you won't get anywhere. The front and rear axles will work against each other.)

Similarly, you can not flip an axle housing over to make a rear housing a front axle, or vice versa. Oiling passages are cast into the axle housing - if you flip it over, it won't oil properly and you will wreck bearings in very short order (axle bearings are under incredible loads.)

The closest you can get to "reversing" a transfer case is using a "flip kit" to turn one over, and put the front output on the opposite side (common with the Dana 300, and possibly the Dana 20. Most newer cases have pump-circulated fluid, and won't tolerate being flipped.) This only works with a very limited number of transfer case models, and the kits are already well-developed for the market.

All clear? Or did I leave something out? I'd be happy to explain further, if it would help you.
I learned that 35 years ago.

I was asking about a newly developed (ing) "reverse spiral" transfer case. Anyone?
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