Transfer case re-gearing

cruiseroutfit

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I hope you guys are aware that both high range OD and UD gear sets are already available and have been.
There's no need for anybody to spend a minute/penny on R&D for a product that's already available from a very reputable manufacturer/vendor and that is Terrain Tamer.

Myself and another one of the resellers ( @NLXTACY aka Joey aka Witts' End )
who offer these parts along with the rest of the Terrain Tamer product line are on this thread.

;)
Long distance bump here but @moab cj5 tagged me in on this thread tonight. To be clear the new offering high-range UD we were discussing re R&D was a 20% consisting of a new Japan made input, idler shaft/gear & output combo, not the 10% input & output available from Seamaster and TT. Sadly things fell flat due to a variety of reasons and I've not looked into the project for coming up on a year.
 
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I'd love to hear more about the install and your before and after driving impressions.
Down hill control while wheeling is where I really like the low range gears. Slows the big pig down. Besides that its not that amazing. Slower equals more control, less blurring gas to jump over stuff....rather than crawl.
 

orangefj45

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IMG_3291.JPG
At this point we've sold & installed a number of these gear sets. We just shipped another set of OD gears out yesterday along with a low 3.1:1 gear set.
We currently have a few sets in stock; both UD & OD as well as the 3.1:1 low range sets. All the gears & shafts we sell & install are made by SeaMaster. Great quality components!!!!

Georg @ Valley Hybrids & Cruiser Brothers
 

cruiseroutfit

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Georg, I know you have stated that the over/underdrive gears for hi range do not affect the low range gearing, but I do not see how that is possible.

If I understand this case, in high range power flow is through the three gears at the back of the case. From the factory, the input and output gear have to be the same tooth count to achieve a 1:1 ratio. The idler gear may or may not be the same tooth count, but it doesn't effect the ratio either way.
You're spot on, with any change to the high-range ratio, you are proportionally changing the low range ratio as well.

Final T-Case Gearing Chart with different options, whipped this up quick so feel free to check my math.

Gear Chart pic.JPG
 
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cruiseroutfit

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We currently have a few sets in stock; both UD & OD as well as the 3.1:1 low range sets. All the gears & shafts we sell & install are made by SeaMaster. Great quality components!!!!

Georg @ Valley Hybrids & Cruiser Brothers
Georg, have you ever stocked the 36221-60121M?
 

orangefj45

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Georg, have you ever stocked the 36221-60121M?
We have not. Terrain Tamer lists the part and we are waiting to hear back about availability.
But we both know that the "M" gears, just like the UD & OD gears and other low production items can take a while to procure.

Have you seen one of these gears in person?

Georg @ Valley Hybrids & Cruiser Brothers
 

cruiseroutfit

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We have not. Terrain Tamer lists the part and we are waiting to hear back about availability.
But we both know that the "M" gears, just like the UD & OD gears and other low production items can take a while to procure.

Have you seen one of these gears in person?

Georg @ Valley Hybrids & Cruiser Brothers
I have not, it's odd as some application guides recommend it be used with the 60080/60100 H/L gears but others do not and they physically fit without. I've got one on order. I'm still a little foggy what it offers beyond the OE 36221-60121?
 

iptman

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You're spot on, with any change to the high-range ratio, you are proportionally changing the low range ratio as well.

Final T-Case Gearing Chart with different options, whipped this up quick so feel free to check my math.

View attachment 1613583
Nice! So with both the UD high and low range low gears installed you get 3.3:1 low range gearing.
 
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Nice! So with both the UD high and low range low gears installed you get 3.3:1 low range gearing.
Only in theory, because it will depend on the tire size you run. The greater the diameter, the lower the final gear ratio will be.
Don't get me wrong, it won't drop to really sucky levels.

You would only get that 3.3:1 ratio with 31" tires.
 

cruiseroutfit

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Only in theory, because it will depend on the tire size you run. The greater the diameter, the lower the final gear ratio will be.
Don't get me wrong, it won't drop to really sucky levels.

You would only get that 3.3:1 ratio with 31" tires.
Zero theory, every time your transmission output spins once, your t-case will spin 3.3 times, tires have zero impact there. Now that can be multiplied by transmission 1st gear & axle ratio for crawl ratio and compound with tire size for "realized crawl ratio"
 
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Zero theory, every time your transmission output spins once, your t-case will spin 3.3 times, tires have zero impact there. Now that can be multiplied by transmission 1st gear & axle ratio for crawl ratio and compound with tire size for "realized crawl ratio"
The only difference is that you don't drive on your transmission. You actually need tires. And the size of those tires will affect you ratio on the pavement.

All that math only applies to the OEM tire size.
What is the number one reason we all want to regear everything on our rigs after we get bigger size tires?
Everything falls out of spec with 33", 35", 37" etc.

If everything stays the same, then how come there will always be a difference between 33's and 37's?
Yes the drivetrain will remain constant in it's ratios, but the tire sizes will affect everything in all gears 1 through 4, high or low.

There is a good reason people have installed 4.88 and 5.29 gears once they got a bump in the tire size.


And yes, I can provide the math to support what I said, upon request.
 
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I think you misundestood Kurt's post you quoted. The ratio quoted is for transfercase output. Everyone knows tires factor into your driving experience, but the gear reduction is the gear reduction, regardless of tire size.
 
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I think you misundestood Kurt's post you quoted. The ratio quoted is for transfercase output. Everyone knows tires factor into your driving experience, but the gear reduction is the gear reduction, regardless of tire size.
Agreed. It stays constant.
But at the output shaft, not on the pavement where it counts.

Some people might think they would get a full 5.29 ratio, but in reality when coupled with >37" tires, that ratio will go down to a more OEM spec.

The low gear (higher numerically) compensates for the tire size increase, it does not add anything unless you run OEM size tires. Then you will really feel the new gearing.

In essence we try to keep the engine RPM in a certain range where the power/torque output is optimal for the condition we are in. That will be accomplished by regearing either the transmission (difficult to do), transfer case (easier) or axle gear (still easier).
 
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