The Official 3rd Gen Dual Case, Dual Locked Thread

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I've never thought about doing it this way. I've always planned to go with an Atlas II transfer case. Has anyone use an Atlas...or is this the preferred method?

Thank you
- Russel
 
Subscribe....

I've never thought about doing it this way. I've always planned to go with an Atlas II transfer case. Has anyone use an Atlas...or is this the preferred method?

Thank you
- Russel


I've got both....an Atlas II in my buggy and I've had dual Marlins in a 91 Hilux and now a 99 T4R. IMO, the Toyota cases are a better design in terms of packaging....though you can't argue they are as strong as the Atlas. I also have a 3 speed TWF Hero case for my next buggy....but I can't tell you anything about that as I haven't run it yet. If money's no object, get the Hero....but from most rigs, a dual Toyota case is fine.
 
what's a reasonable price for a complete transfer case for this? (semi-local guy has one)

I don't know about your area but here in Arizona I have seen them from $150 and up, I wouldn't pay more than $200 because you can get a brand new heavy duty box from Advanced Adapters for like $199. What is he asking? Remember, I would encourage you to put a set of bearings in the case since the old ones are probably 30 + years old and usually abused as in never having the oil changed etc, and since you have to buy a 23 spline gear in it you are really just paying for the case, and some bearing retainers, syncro hubs and shift forks. The syncro hubs will be the hardest to get.
here is the link for the Case from AA at Lowrange offroad:

http://www.lowrangeoffroad.com/toyo...ta-gear-drive-rf1a-transfer-case-51-5911.html

Shift forks
http://www.lowrangeoffroad.com/toyo...transfer-case/top-shift-conversion-kit-a.html
 
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Had some time yesterday so zapped off a few emails to try and locate a vendor willing to do a group buy on adapters and related parts.

More to come hopefully...
 
I'm still not clear about the 21/23 spline but and how it relates to the gearing..

If the 1st gen transfer case has 4.7:1 gears included, would they necessarily work with the 23 spline conversion?

It looked like at least on one of the gears was made into the shaft (from what I could see in the little internet photo)

Is this not the case?


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I'm still not clear about the 21/23 spline but and how it relates to the gearing..

If the 1st gen transfer case has 4.7:1 gears included, would they necessarily work with the 23 spline conversion?

It looked like at least on one of the gears was made into the shaft (from what I could see in the little internet photo)

Is this not the case?

So this is a good discussion that we haven't had here yet. The 21/23 spline issue really has nothing to do with gearing except as it has to do with input spline count. Originally Toyota only made 21 spline transfer case input shafts that are yes on the reduction gear. Then when Toyota released the 22ret (turbo) they increased the spline count and therefore shaft size to 23 to deal with the increased torque and power output. Our trucks with the 3.4L engines all have 23 spline transmission output shafts. There is a sleeve that goes between the transmission output shaft and the input shaft of the transfer case. So we have to change the gear set in the reduction box to go from 21 spline to 23 spline so they can work together. If you found a transfer case from a turbo truck or Runner then you wouldn't have to change the gear since it would already be 23 spine, but they are like hens teeth. So since we have to change the gear set to match the spline count it gives us the chance to change the gear ratio at the same time.

Clear as mud I know. LOL

[MENTION=28464]eimkeith[/MENTION] is the case you are looking at already have 4.7 gears in it? if so make sure you confirm that it has 23 spline, if it doesn't then I would pass as they most likely want to much for a case you will have to change the gear set in anyway. But if it is in good shape you could sell the gear set to a mini truck guy to recoup some of the cost.

BTW. For guys doing this with the 4cyl. I believe that you have a 21 spline transmission so that makes things a little less expensive in this process.
 
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So this is a good discussion that we haven't had here yet. The 21/23 spline issue really has nothing to do with gearing except as it has to do with input spline count. Originally Toyota only made 21 spline transfer case input shafts that are yes on the reduction gear. Then when Toyota released the 22ret (turbo) they increased the spline count and therefore shaft size to 23 to deal with the increased torque and power output. Our trucks with the 3.4L engines all have 23 spline transmission output shafts. There is a sleeve that goes between the transmission output shaft and the input shaft of the transfer case. So we have to change the gear set in the reduction box to go from 21 spline to 23 spline so they can work together. If you found a transfer case from a turbo truck or Runner then you wouldn't have to change the gear since it would already be 23 spine, but they are like hens teeth. So since we have to change the gear set to match the spline count it gives us the chance to change the gear ratio at the same time.

Clear as mud I know. LOL

[MENTION=28464]eimkeith[/MENTION] is the case you are looking at already have 4.7 gears in it? if so make sure you confirm that it has 23 spline, if it doesn't then I would pass as they most likely want to much for a case you will have to change the gear set in anyway. But if it is in good shape you could sell the gear set to a mini truck guy to recoup some of the cost.

BTW. For guys doing this with the 4cyl. I believe that you have a 21 spline transmission so that makes things a little less expensive in this process.

Due to this 21-23 spline issue, I've realized that it makes sense to just go ahead and do a 4.7 setup, but are you saying that doing so requires modification to the box to clear this different gear set?
 
[MENTION=28464]eimkeith[/MENTION] is the case you are looking at already have 4.7 gears in it? if so make sure you confirm that it has 23 spline, if it doesn't then I would pass as they most likely want to much for a case you will have to change the gear set in anyway. But if it is in good shape you could sell the gear set to a mini truck guy to recoup some of the cost.

It doesn't; it is a stock case that comes with this additional 4.7 gearset

So, I'm hearing that the gearset in question cannot be converted to 23 spline, correct? (judging by the photo, I'd've assumed that I could just buy the correct shaft from TG...)
 
Due to this 21-23 spline issue, I've realized that it makes sense to just go ahead and do a 4.7 setup, but are you saying that doing so requires modification to the box to clear this different gear set?


Yes some minor dremel work is required to fit the 4.7 gear set but nothing major. There is a cost savings if you stay with 2.3 and just change the input gear.

23spline 2.28 Input Gear - Trail Gear

about $375 savings over going with the 4.7 set. Also, there is an argument that the 4.7 is too low. I can honestly say I can not imagine a situation where I would need lower than my current double low.



It doesn't; it is a stock case that comes with this additional 4.7 gearset

So, I'm hearing that the gearset in question cannot be converted to 23 spline, correct? (judging by the photo, I'd've assumed that I could just buy the correct shaft from TG...)

Correct that Gear set won't work for you. If he will sell the case without the gearset for a good price then grab it Also make sure it is a top shift and not a forward shift case. A forward shift case will have shift forks sticking out of the front of the case Top shift will not.
 
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Correct that Gear set won't work for you. If he will sell the case without the gearset for a good price then grab it Also make sure it is a top shift and not a forward shift case. A forward shift case will have shift forks sticking out of the front of the case Top shift will not.

cool. moving forward on case only. thx.
 
Anyone have some pics of their dual in?need some crossmember idea! Lol thanks

I would look at the Trail Gear crossmember. Depending on how you value your time, it's totally worth the $300 to just be able to weld in and be done. I've got some diehard anti-TG friends that have bought it and been very happy.

what's a reasonable price for a complete transfer case for this? (semi-local guy has one)

I'd hit car-part.com and search for an 85 4Runner tcase. I picked mine up for $50 and all you really need is the shifter and case itself because a 4.7 gear set comes with new bearings and you ditch the 4x4 section.

Due to this 21-23 spline issue, I've realized that it makes sense to just go ahead and do a 4.7 setup, but are you saying that doing so requires modification to the box to clear this different gear set?

Super easy to clearance the reduction box with a 4.5" inch angle grinder.

So this is a good discussion that we haven't had here yet. The 21/23 spline issue really has nothing to do with gearing except as it has to do with input spline count. Originally Toyota only made 21 spline transfer case input shafts that are yes on the reduction gear. Then when Toyota released the 22ret (turbo) they increased the spline count and therefore shaft size to 23 to deal with the increased torque and power output. Our trucks with the 3.4L engines all have 23 spline transmission output shafts. There is a sleeve that goes between the transmission output shaft and the input shaft of the transfer case. So we have to change the gear set in the reduction box to go from 21 spline to 23 spline so they can work together. If you found a transfer case from a turbo truck or Runner then you wouldn't have to change the gear since it would already be 23 spine, but they are like hens teeth. So since we have to change the gear set to match the spline count it gives us the chance to change the gear ratio at the same time.

Clear as mud I know. LOL

[MENTION=28464]eimkeith[/MENTION] is the case you are looking at already have 4.7 gears in it? if so make sure you confirm that it has 23 spline, if it doesn't then I would pass as they most likely want to much for a case you will have to change the gear set in anyway. But if it is in good shape you could sell the gear set to a mini truck guy to recoup some of the cost.

BTW. For guys doing this with the 4cyl. I believe that you have a 21 spline transmission so that makes things a little less expensive in this process.

4 cylinder guys have a 26 spline tcase so it requires a different rear coupler from the v6 guys. Still a 23 spline input on the crawler from the transmission but you need a 26 spline output on the crawler to mate with the stock chain drive tcase.
 
4 cylinder guys have a 26 spline tcase so it requires a different rear coupler from the v6 guys. Still a 23 spline input on the crawler from the transmission but you need a 26 spline output on the crawler to mate with the stock chain drive tcase.

That is great info that wasn't here yet, who offers that rear coupler? Trail-Gear, Marlin, Inchworm? Do you have a build thread? I added you to the list :bounce:
 
That is great info that wasn't here yet, who offers that rear coupler? Trail-Gear, Marlin, Inchworm? Do you have a build thread? I added you to the list :bounce:

I'm lame and jumped ship to TW after I got my Tacoma but I'm putting together my build on here too.

I think any of the above offer the coupler. It's normally in stock less than the regular 23 spline input but it's out there. Found out the hard way that you can put the 23 spline side of the coupler onto the 26 spline output of the trans and break an ear off your trans when you try to pull the crawler on. :redface:

I wish I had made a crawler my first mod on the truck when I got it. On a stick truck, I would put a crawler ahead of a solid axle because it is that good. Auto you can get away with 2.56 for longer but the auto with 4.7/2.56 wheels amazing too.
 

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