Topic: 21 to 23 spline dual transfer case

[jschroetter]

I have an 86 toyota rock crawler that came with a Marlin dual transfer case.

I totally grenaded the rear transfer case and went to swap in a new on this weekend.  As I purchased my truck with the dual case i am not 100% what it is all comprised of...

Anyway, I bought a new/used case.  The input shaft on this is 21 spline.  My Marlin box is 23.  Do I need to find a 23 spline replacement transfer case or??

Thank you for the help!

[Dingman.]

What gears are in your rear case that you blew up? And how bad is the damage?

If it is stock 2.28 spline gears, you can replace the input with a 23 spline 2.28 gear from a factory toyota turbo case, or buy a 23 spline input from marlin.

If you have 4.7 gears in the rear case and want to keep it that way, you need a new 23 spline 4.7 gearset, or at least the input.

If you are running stock gearing in both cases, your other option if you want to bolt that case up is to buy a 21 spline coupler for your dual case adapter.

I would highly recommend doing 23 spline if you can, and 4.7 gears in the rear case is awesome, and i would recommend that too over stock dual cases.

[jschroetter [OP]]

Awesome - thanks for the quick reply!

I did not pull the case apart but just looking through the shifter hole, you can see the gears are pretty chewed up.  The truck still moved but jumped like a rabbit.  Should have tore it down but I'm guessing it is a total loss in there. 

I will need to see if I can figure out what gearing is in there, I would guess they are 4.7 as is crawled quite slow in low/low.  I'm guessing i will need to buy a new complete 23 spline 4.7 gearset. 

Looking at the Marlin website, no gearsets appear to be available. what gives?

[Dingman.]

Awesome - thanks for the quick reply!

I did not pull the case apart but just looking through the shifter hole, you can see the gears are pretty chewed up.  The truck still moved but jumped like a rabbit.  Should have tore it down but I'm guessing it is a total loss in there. 

I will need to see if I can figure out what gearing is in there, I would guess they are 4.7 as is crawled quite slow in low/low.  I'm guessing i will need to buy a new complete 23 spline 4.7 gearset. 

Looking at the Marlin website, no gearsets appear to be available. what gives?

Try calling them to see if/when they are available.
Pop your tcase into low range if you still have it and count how many times you can spin the input gear in order to get one full rotation of the rear output shaft.

Or potentially easier.  If you had only the rear case in low range, did it feel twice as slow as just the crawl box in low range?

[jschroetter [OP]]

cool. 

i did the appropriate thing and called the prior owner.  Stock gears in the crawler box and reduction in the rear. 

I'm just going to buy an entire new case with reduced gears.  I fear i would mess up going the gear replacement route...

[Dingman.]

cool. 

i did the appropriate thing and called the prior owner.  Stock gears in the crawler box and reduction in the rear. 

I'm just going to buy an entire new case with reduced gears.  I fear i would mess up going the gear replacement route...

Nothing wrong with buying a brand new built case.

But...  if you are on the fence.

It is not horrible to install gears yourself, if you were able pull the case out yourself, you can follow directions and install 4.7 gears yourself if you choose to.  There are also plenty of good people here that could walk you through any issues you might run into.

Good luck!

[jschroetter [OP]]

I think I am going to take on the gear transfer on my own.  Wish me luck!

[Dingman.]

If you run into any snags, feel free to post up!  Dont foreget to put a snap ring on the 4.7 gears. You have to take them off of your 2.28 gears if i remember correctly, it has been many years since i have dealt with 4.7 installs, so maybe that is included now? 

[jschroetter [OP]]

I've got the 4.7 gears already installed so I am hoping it is like for like (Wrecked the case last year). 

last week Marlin had gears, this week they do not .

I will search around for a set...

[T-Revv]

Looking at the Marlin website, no gearsets appear to be available. what gives?

We were out and got an order in, and they sold out before they were even in.  We should get more in on the 15th of next month. 

I think I am going to take on the gear transfer on my own.  Wish me luck!

Zippo put a really good walk through on the forum for this endeavor, it is not a daunting as it seems.  Especially if you follow zippo's instructions.   There are also some instructions in the tech section of marlincrawler.com .