Topic: How bad is a 4.7 crawlbox

[MidgetMike]

How do you convert a forward shift t-case to top shift i.e how far apart deos it need to come apart to do that, I have 4.7 in my case now and it's a forward shift and I am putting in another and want to know what I am in for I know it's worth it but I got to drive my truck as a dd so I need a time line help      

[cgbemis]

Here are the tear down instructions:


http://www.marlincrawler.com/docs/470install/470install_2.html.

Once you get it down to the reduction housing, just put your top shift rails in in place of the forward shift rails. Bolt a new shifter seat, gasket, and metal plate on to the top, and you should be done. Take your T-Case out the night before, and start early in the morning. You should have plenty of time.

[MidgetMike [OP]]

that sucks it's a load of work to convert I'll use the 4.7 case as the crawl box

[MidgetMike [OP]]

So can I leave my 4.7 case as a crawl box without 23 spline out, I  have Marlin gears from the American cutter back in 96 will they hold up, I just don't want to take 2 t-ases apart in one day and it looks like I have to take them bothall the way apart

[BigMike]

Hey-

To convert forward to top, you're gonna have to dig into 75% of the tcase.. and guess what? If you want to seperate the 4.70:1 gears from the rest of the tcase to use in a Crawl Box, you're gonna have to dig into 75% of the tcase.
Same amount of work.

And we do not recommend putting the 4.70s in the front case unless you use a 23-spline version of the dualcase adapter and run a 23-spline input gear in the 2nd case. If you go 4.70 in the front case and then 21-spline 2.28 in the 2nd case, then please drive the vehicle with care while in 1st gear Ultimate.

We've seen numerous 21-spline input failure, and actually when we first got the 4.70 gears back in '97, it was convinent to be able to sell complete Crawl Boxes with 4.70s already installed. Then you could just basically "bolt-in" an Ultimate setup.....and thats when we started busting up 21-spline inputs. The first 5 or whatever Ultimate Crawl Boxes we sold all came back and we had to eat it. I think we ended up building complete 4.70 transfercases and a complete 2.28 Crawl Box and assembling the two together and then returning it as a complete Dual Case Ultimate, not an Ultimate Crawl Box. We ended up wasting alot of time and money there, and hopefully you can avoid that too.

[FIREBALL]

Don't sweat it. Tearing down a t-case looks very intemidating at first, but if you are methodical and organized it really isn't that bad. Heck, even BigMike can do it, and he's a college kid.
Just follow the instructions, and be careful of the detent balls...don't loose them, or get them mixed up with the little allignment ball on the main shaft.

[MidgetMike [OP]]

Hey I'm a college kid  ha! I know but I have to take apart 2 t-cases and that sucks if that's the way it has to be, what if I use the MC-10 t-case adapter then will the 4.7 crawlbox be ok

g54 to 4.7 to MC-10 to chain driven t-case ?   

[cgbemis]

I wouldn't personally put a 4.7 gear set in the box in front of a chain driven T-Case. That sounds like your asking for trouble just cause you don't want to take apart a couple of T-Cases. It also won't be exceptionally cheaper considering the adapter is going to be $649 as apposed to the $329 for a dual case adapter. Do it right.

[MidgetMike [OP]]

I will have to get 3 t-cases and tear all three down completly then reassemble two and an adapter and then have an unassembled  t -case, or order a top shift conversion which makes the adapter $400 and still tear down 2 t-cases, I think that the extra $250 may offset the time and labor and if the chain driven will hold up then I will have on the fly 4x4 a 250 to 1 crawl ratio and slightly lower stock 4 low    that's why I'm asking questions though so I make the right decision