PingPong

Well I decided that my 4low.. wasnt low enough. Instead of just regearing which would hurt my on road performance, I decided to buy a DD Machine doubler. Bascially this set up takes a np231 and turns it into a range box.

here is a pic of the kit. he includes all the hardware plus a shaft to connect both the range box to the secondary box.



here you can see the "crawl" box along with the secondary box. Luckily I has a "spare" 231w/sye installed sitting in my garage.

Here I have the doubler plate mounted to the "crawl" box. You use the plate to mark the case where to cut. Then you weld an aluminum plate to the end.



Thats where I have to stop for the day. I have a buddy coming by with a disc brake d44 I am buying

I want to that XJFiles for selling me the new input I need so I can run this setup. My front box was a 21 spline box.. I need a 23 spline setup.

91familyxj

This might sound dumb but is it 2 t cases put together? Does it just make it a lower gear?

96_xj

the way it acts is that the first case acts like a normal transfer case, then the second"doubler case" acts as a reducer-it reduces the first transfer case an extra amount.

say you have it in 4lo so a 2.71 gear ratio then you engage the second case all of that power is sent thru the second 2.71 gear ratio, so you essentially have a 5.42 final transfercase ratio. And thats a low crawl! now couple that with a low 1st gear (3.71 in the AX-15 manual, or 4.01 in the NV3550 manual) and then combine that with the axle gears you get a crazy low ration where you can probably dont have to touch the throttle and it will climb over stuff at idle.


I am keeping posted on how this turns out =]


aso the tera-low 4:1 kit has many leaky issues and grinding ane all of the bad stuff from a weak case....

and a NVG241OR swap from the rubbies is about $2000 for the super stout factory 4:1. and requires a bit more work

PingPong

96xj is absolutely correct.

It gives you option on what to run. If you are mud running high gear in both cases, it gives you a 2 low if you desire, it gives you single low for just regular crawling... and double low when you need the ratio to maintain traction. Then there is the fact that you can do this w/o changing axle ratios and achieve a much superior crawl ratio just by putting 2 cases together and making some driveshafts.

My final crawl ratio wil be 98.5to 1. I have thought about going a step further and swap in a T18 which has a 6.82to1 first gear. which would be real stupid low ratio. That swap probrably wil never happen as I would need a special adapter.

PingPong

also the 4to1 kit cost over a grand.. and only have 2 spds.... where as by me doing it this way I have 3 spds plus 2 low possible. Just more options. If I ever find it needed that I need more gearing I can alwyas do a tera low kit.

COSXJFAN

What is this set up going to run you?? If you don't mind me asking...

PingPong

The kit was 525 to my door. To have shafts retubed wil be around 300 bucks. More then likely less.

91familyxj

Sound sweet. So you would still have to engage the sencond case? So you can just run around in Lets as 4low and when you want it lower just engage the second t case? I think IM getting it.

PingPong

1st case high gear rear case2 hi Normal
1st case lo gear rear case 2hi 2.72x trans ratio
1 case lo gear rear case 4 hi 2.72 x trans ratio
1 case lo gear rear case 4 lo 7.3948x trans ratio

It basicaly gives you 2 lo capability, as well as double lo capability. I hope that clears it up some

rivercrazy

I'm pretty sure you multiply the two ratios which would actually give you a low-low crawl ratio of 7.34!! Now THAT'S a low crawl!

PingPong

I wasnt sure if you added it.. or mutiplied it. Mutiplied it will give me a crawl ratio of 114. something. All the same it will be awesome. I think I might should upgrade to 35's... but my 33's work so well.

91familyxj

Thats freaken cool. Ill keep fallowing this to see how it all works out for you.

caged

cool, i just grabbed my d300 from my buddy last night.
i'm doing the same thing. wasn't sure if i was gonna do a box4rocks or mad rooster kit, but now i think i'm gonna go with duffy's set up also.

PingPong

Duffy is a good guy to deal with so far. He spent about 1 hr talking to me about the swap. Man is full of tech.

With the set up you are doing you wont need new Driveshafts if you already have a sye. He also makes some bling triple shifters, but they are pricey.

COSXJFAN

That's not horrible!!