The Official 3rd Gen Dual Case, Dual Locked Thread

[Jaysen4runner]

Any of you guys have pics of your auto duals case?from the bottom??my buddy install his to his Tacoma hang down pretty low!

 

[theesotericone]

Any of you guys have pics of your auto duals case?from the bottom??my buddy install his to his Tacoma hang down pretty low!

Mine sits level with the bottom of the rear crossmember. I had to space my Savage skids 1/4" to allow it not to touch them but that's it. How low is he sitting?

 

[owyheerat]

Ok dual case experts, I need some help. I am currently running an inchworm gear built dual case (that I purchased through lowrange offroad) and it is working fine. I need to drop my tranny (I have a manual) due to worn sychros, so while I have the tranny and t-cases removed, I'm considering changing the gears in the crawl box to 4.7 (currently 2.28). I've looked on Marlin Crawler and I'm not confident of what to purchase, or if this can even be accomplished?

Can someone please point me to the correct part? I want to use Marlin Crawler (if possible), because I have a gift card.

Thanks

Durwin

 

[ajordan1975]

Ok dual case experts, I need some help. I am currently running an inchworm gear built dual case (that I purchased through lowrange offroad) and it is working fine. I need to drop my tranny (I have a manual) due to worn sychros, so while I have the tranny and t-cases removed, I'm considering changing the gears in the crawl box to 4.7 (currently 2.28). I've looked on Marlin Crawler and I'm not confident of what to purchase, or if this can even be accomplished?

Can someone please point me to the correct part? I want to use Marlin Crawler (if possible), because I have a gift card.

Thanks

Durwin

As in spline count of 21 or 27?

 

[owyheerat]

As in spline count of 21 or 27?

Correct. Except I think it's either 21 or 23 spline?

I could be wrong.

 

[rkntoy]

Correct. Except I think it's either 21 or 23 spline?

I could be wrong.

Pretty sure you need the 23 spline for the reduction box - but Low Range should be able to tell you.

 

[owyheerat]

Pretty sure you need the 23 spline for the reduction box - but Low Range should be able to tell you.

Thanks rkntoy. I was hoping you would chime in, cause I knew you had 4.7 in your crawl box.

So I have the coupler to fit the 2 cases together and have been running it for 2 years. What I'm wondering if I can just replace the gears in the crawl box? And if so, is it adviced? Obviously you are doing it. Have you had any issues? I've heard or read that it can put extra stress (torque?) on the stock T-case.

Thanks

Durwin

 

[ajordan1975]

W/ most t-cases out of first gen runners/second gen pickups are 21 spline unless they were turbo. Turbo trucks and runners had the R151 and 23 spline count.

 

[owyheerat]

W/ most t-cases out of first gen runners/second gen pickups are 21 spline unless they were turbo. Turbo trucks and runners had the R151 and 23 spline count.

I'm getting more confused.

My current setup is an inchworm gear built (no longer in business i guess) crawl (or reduction) box with 2.28 gears and appropriate coupler in front of the stock chain drive t-case. Which I believe has 2.56 gears in it. I have been using this set-up for 2 years and it works fine, I just want lower gears now.

So, my question is: does Marlin Crawler make a 4.7 gear kit / set for the crawl box? If so, can someone provide a link to the exact part? Also is it advisable to do so? Or does it put too much stress on stock case?

I don't believe we can put 4.7 gears in the 3rd gen stock chain drive t-cases? But if I'm wrong, someone please educate me. I'm all for learning

Thanks

Durwin

 

[ajordan1975]

4.70:1 Competition Chromoly Gear Kit | Marlin Crawler, Inc.

You can put it in the front box, but it's not always advised by Marlin

Marlin has a forum on his website.
Id ask this question of Big Mike (Marlins son and I think current CEO of Marlin)
He'd be the one to give you the best advise.

Sorry for confusing the situation. :bowl:

 

[owyheerat]

OK, i had looked at that and the 4.7 xd gear set. Also, I did search their forum and did post a question on there. But haven't got a clear answer.

How do I contact Big Mike? Does he frequent the forum?

thanks for the help. and don't worry, it takes very little to confuse me

 

[theesotericone]

I'm getting more confused.

My current setup is an inchworm gear built (no longer in business i guess) crawl (or reduction) box with 2.28 gears and appropriate coupler in front of the stock chain drive t-case. Which I believe has 2.56 gears in it. I have been using this set-up for 2 years and it works fine, I just want lower gears now.

So, my question is: does Marlin Crawler make a 4.7 gear kit / set for the crawl box? If so, can someone provide a link to the exact part? Also is it advisable to do so? Or does it put too much stress on stock case?

I don't believe we can put 4.7 gears in the 3rd gen stock chain drive t-cases? But if I'm wrong, someone please educate me. I'm all for learning

Thanks

Durwin

Yes, you can run 4.7 in the crawlbox. You can read for days about the added stress to the output shaft but plenty of guys run this set-up and very few have ever had an issue running the 4.7's in the crawlbox.

That would give you 2.57 stock low, 4.7 crawlbox lo, and 12.07 lo/lo.

No you can not put 4.7 in our stock chain drive case. No one has ever produced them.

 

[owyheerat]

Yes, you can run 4.7 in the crawlbox. You can read for days about the added stress to the output shaft but plenty of guys run this set-up and very few have ever had an issue running the 4.7's in the crawlbox.

That would give you 2.57 stock low, 4.7 crawlbox lo, and 12.07 lo/lo.

No you can not put 4.7 in our stock chain drive case. No one has ever produced them.

Great. Thanks for clarifying.

 

[owyheerat]

Yes, you can run 4.7 in the crawlbox. You can read for days about the added stress to the output shaft but plenty of guys run this set-up and very few have ever had an issue running the 4.7's in the crawlbox.

That would give you 2.57 stock low, 4.7 crawlbox lo, and 12.07 lo/lo.

No you can not put 4.7 in our stock chain drive case. No one has ever produced them.

Also, can you confirm the spine count on the input and output shafts? Or direct me where to find that info? I searched and didn't come up with the answer.

Thanks

 

[rkntoy]

Like [MENTION=143526]theesotericone[/MENTION] said - there are quite a few that run the 4.7 gears in the reduction box. You do have to do some grinding to provide clearance for the bigger gear.

Yes - I am placing more stress on my stock t-case. Everyone I talked to at Marlin told me not to do it. My thought process was that the stock t-case was designed to handle the max torque from a stock 3.4 with a comfortable safety margin (220 ft lbs). When I have the reduction box engaged on my 2.7 equipped rig I am rarely over 1500 rpm - usually in the range of 750-1200 rpm. Hard to find great torque curves for low rpms on the 3rz but I estimate the most I would be at at 1500 rpm is around 120 ft lbs.

So Marlin says it is fine for a 2.28 reduction box in a 3.4. A 4.7 gearset would be an additional 106% load on the stock t-case. With my 2.7 at 1500 rpm I am applying 83.333333333333333% less stress on my stock t-case than a 3.4 at max torque. Doesn't totally cover the difference of 23% (adding a supercharger to a 3.4 results in a 34% increase in torque and you don't hear anyone saying you will grenade your stock t-case) but good enough for me. Also, when I looked at people that said they broke their stock cases they were a lot harder on their rigs than I am. If I have enough traction to snap something in my t-case something else should have gone first 90+% of the time (like cv axles). And [MENTION=143526]theesotericone[/MENTION] and [MENTION=118730]AssBurns[/MENTION] can vouch for how slow I wheel.

Input splines - totally depends on what Inchworm did with the coupler piece (circled in pic) that you attached to your tranny output to connect with the reduction box. Trail Gear and Marlin both have couplers that require a 23 spline input for the reduction box. Inchworm probably did the same thing - but it would suck to get a 23 spline and find out that you needed a 21. The Low Range guys should know this.

Sorry - that was kind of long...

 

[owyheerat]

Like [MENTION=143526]theesotericone[/MENTION] said - there are quite a few that run the 4.7 gears in the reduction box. You do have to do some grinding to provide clearance for the bigger gear.

Yes - I am placing more stress on my stock t-case. Everyone I talked to at Marlin told me not to do it. My thought process was that the stock t-case was designed to handle the max torque from a stock 3.4 with a comfortable safety margin (220 ft lbs). When I have the reduction box engaged on my 2.7 equipped rig I am rarely over 1500 rpm - usually in the range of 750-1200 rpm. Hard to find great torque curves for low rpms on the 3rz but I estimate the most I would be at at 1500 rpm is around 120 ft lbs.

So Marlin says it is fine for a 2.28 reduction box in a 3.4. A 4.7 gearset would be an additional 106% load on the stock t-case. With my 2.7 at 1500 rpm I am applying 83.333333333333333% less stress on my stock t-case than a 3.4 at max torque. Doesn't totally cover the difference of 23% (adding a supercharger to a 3.4 results in a 34% increase in torque and you don't hear anyone saying you will grenade your stock t-case) but good enough for me. Also, when I looked at people that said they broke their stock cases they were a lot harder on their rigs than I am. If I have enough traction to snap something in my t-case something else should have gone first 90+% of the time (like cv axles). And [MENTION=143526]theesotericone[/MENTION] and [MENTION=118730]AssBurns[/MENTION] can vouch for how slow I wheel.

Input splines - totally depends on what Inchworm did with the coupler piece (circled in pic) that you attached to your tranny output to connect with the reduction box. Trail Gear and Marlin both have couplers that require a 23 spline input for the reduction box. Inchworm probably did the same thing - but it would suck to get a 23 spline and find out that you needed a 21. The Low Range guys should know this.

Sorry - that was kind of long...

Thanks rkntoy. I understand (now) the extra stress it would place on the stock case, but like you I have the little 4cyl engine.

I have tried calling Marlin Crawler a couple times, and haven't been able to get thru yet.

Regarding the coupler, I'm not sure what lowrange did. I will call them and see what they know.

Thanks again. I really appreciate the help.

 

[rkntoy]

Thanks rkntoy. I understand (now) the extra stress it would place on the stock case, but like you I have the little 4cyl engine.

I have tried calling Marlin Crawler a couple times, and haven't been able to get thru yet.

Regarding the coupler, I'm not sure what lowrange did. I will call them and see what they know.

Thanks again. I really appreciate the help.

No prob. I wonder if all the Inchworm setups were the same? Marlin may not want to answer.

 

[owyheerat]

No prob. I wonder if all the Inchworm setups were the same? Marlin may not want to answer.

Well, I just got off the phone with Low Range, and they looked up my order, and said it was a 23 spline input coupler.

I also, got thru to Marlin Crawler (finally) and the saleperson I talked to said, their 4.7 xd or competition gear set will fit in my reduction box, with some minor clearancing. He did not state any concern in putting 4.7 gears in front of stock chain drive T-case given my application (under powered 4 cyl). He also, said that worse case scenario if I find out it is a 21 spline input shaft, that I can purchase a new 23 spline 4 cyl adapter plate (from Marlin) that would bolt up to my existing reduction box.

Thanks to you, [MENTION=12930]ajordan1975[/MENTION], and [MENTION=143526]theesotericone[/MENTION] for helping me get this figured out.

Now that I know what to purchase, I wish I could find a coupon code for Marlin. Does anyone know of one?

Thanks

Durwin

 

[owyheerat]

So a follow up question.

When I pull the crawl box to replace the gear set, would it be wise to open up the stock T-case and inspect it? Is there anything I should replace? I've had it open a couple of times when I was installing the crawl box, but I don't really know what to look for as far as worn or damaged parts unless something was in pieces or very obvious.

For example does the chain (in the T-case) ever need to be replaced?
Are there any seals that should be replaced?

I'm just thinking since I will have it out of the truck, now would be the time to take care of any PM that could be done on the stock T-case.

I appreciate any input.

Durwin

 

[rkntoy]

So a follow up question.

When I pull the crawl box to replace the gear set, would it be wise to open up the stock T-case and inspect it? Is there anything I should replace? I've had it open a couple of times when I was installing the crawl box, but I don't really know what to look for as far as worn or damaged parts unless something was in pieces or very obvious.

For example does the chain (in the T-case) ever need to be replaced?
Are there any seals that should be replaced?

I'm just thinking since I will have it out of the truck, now would be the time to take care of any PM that could be done on the stock T-case.

I appreciate any input.

Durwin

Personally, if it is not leaking or making weird noises I would not crack it open.